Low and very low birth weight in puppies: definitions, risk factors and survival in a large-scale population

Background

Neonatal mortality (over the first three weeks of life) is a major concern in canine breeding facilities as an economic and welfare issue. Since low birth weight (LBW) dramatically increases the risk of neonatal death, the risk factors of occurrence need to be identified together with the chances and determinants of survival of newborns at-risk.

Results

Data from 4971 puppies from 10 breeds were analysed. Two birth weight thresholds regarding the risk of neonatal mortality were identified by breed, using respectively Receiver Operating Characteristics and Classification and Regression Tree method. Puppies were qualified as LBW and very low birth weight (VLBW) when their birth weight value was respectively between the two thresholds and lower than the two thresholds. Mortality rates were 4.2, 8.8 and 55.3%, in the normal, LBW and VLBW groups, accounting for 48.7, 47.9 and 3.4% of the included puppies, respectively. A separate binary logistic regression approach allowed to identify breed, gender and litter size as determinants of LBW. The increase in litter size and being a female were associated with a higher risk for LBW. Survival for LBW puppies was reduced in litters with at least one stillborn, compared to litters with no stillborn, and was also reduced when the dam was more than 6 years old. Concerning VLBW puppies, occurrence and survival were influenced by litter size. Surprisingly, the decrease in litter size was a risk factor for VLBW and also reduced their survival. The results of this study suggest that VLBW and LBW puppies are two distinct populations. Moreover, it indicates that events and factors affecting intrauterine growth (leading to birth weight reduction) also affect their ability to adapt to extrauterine life.

Conclusion

These findings could help veterinarians and breeders to improve the management of their facility and more specifically of LBW puppies. Possible recommendations would be to only select for reproduction dams of optimal age and to pay particular attention to LBW puppies born in small litters. Further studies are required to understand the origin of LBW in dogs.

Birth weight as a risk factor for neonatal mortality: Breed-specific approach to identify at-risk puppies

In numerous species, low birth weight is a risk factor for neonatal mortality. In the canine species, definition of a low birth weight is complex due to the huge interbreed variability in size. To identify puppies at higher risk of neonatal death, data from 6,694 puppies were analysed. The data were collected from 75 French breeding kennels, examining 27 breeds and totaling 1,202 litters of puppies. Generalised linear mixed models allowed to identify birth weight, birth weight heterogeneity within the litter, and size of the breeding kennel as significant risk factors for neonatal mortality. Receiver Operating Characteristics (ROC) and classification and regression tree (CART) analyses were combined to define breed specific thresholds for birth weight allowing the identification of puppies at higher risk of neonatal mortality. Due to differences in birth weights between breeds, including when belonging to the same breed size, analyses were conducted at the breed level. First, ROC analysis thresholds were successfully established for 12 breeds (area under the ROC ≥ 0.70; sensitivity ≥ 75%; specificity: 45-68%) and they ranged from 162 g in the Maltese to 480 g in the Bernese Mountain dog. Secondly, CART analysis thresholds from 22 breeds ranged from 105 g in the Maltese and 436 g in the Boxer. Puppies were grouped into three categories according to birth weight: low, moderate and high risk of neonatal mortality (higher than the ROC threshold, between ROC and CART thresholds, and lower than the CART threshold respectively). In the current study, 44% of the puppies were classified as at moderate risk and 5.3% for a high risk of neonatal mortality. Thresholds defined by CART analysis (and not ROC analysis) were used to define low birth weight puppies and were sometimes quite different between breeds with similar birth weight distributions suggesting a variable relationship between birth weight reduction and neonatal death. These results allow the identification of puppies at an increased risk of neonatal death, thus requiring specific nursing to improve their chances of survival. With these high risk puppies identified, both animal welfare and kennel productivity is predicted to improve.

General and type 2 parvovirus-specific passive immune transfer in puppies - Evaluation by early growth

Failure of passive immune transfer put puppies at a higher risk of neonatal and weaning mortality due to low immune protection against infectious agents. The aim of this study was to investigate the evolution of the general via serum IgG concentration (IgG) and the specific via serum maternally derived canine parvovirus type 2-specific antibody titer (CPV2 MDA) passive immune transfer within the first 4 weeks of age. Furthermore, the relationship between general and specific immune transfer and the possibility of non-invasive evaluation was assessed. Puppies (169) were weighed systematically between birth and Day 28. IgG and CPV2 MDA were assayed in serum samples at 2 and at 28 days of age. At Day 2, there was a positive correlation between IgG and CPV2 MDA (ρ = 0.71; p < 0.001). At Day 2, 17.9% (27/151) of puppies presented a deficit of passive immune transfer according to IgG result (defined as IgG < 2.3 g/L) and 25.8% (39/151) of puppies were under the minimal protective CPV2 MDA titer (defined as <1:160). No correlation between IgG and CPV2 MDA was observed at Day 28 (ρ = 0.14; p = 0.11). Growth rate within the first 48 hours <-2.7% allowed to distinguish puppies at high risk of the general and specific passive immune failure (Youden's index = 0.79 and 0.75, respectively). The threshold value of early growth rate, although applicable only in puppies non-supplemented with milk replacer, allows identifying via non-invasive way individuals requiring a special care. Further investigation of the mechanism of passive immune transfer in dogs is necessary to understand the relationship between the general and specific immunoglobulin levels.

Effect of selected gastrointestinal parasites and viral agents on fecal S100A12 concentrations in puppies as a potential comparative model

BACKGROUND

Previous data suggest that fecal S100A12 has clinical utility as a biomarker of chronic gastrointestinal inflammation (idiopathic inflammatory bowel disease) in both people and dogs, but the effect of gastrointestinal pathogens on fecal S100A12 concentrations is largely unknown. The role of S100A12 in parasite and viral infections is also difficult to study in traditional animal models due to the lack of S100A12 expression in rodents. Thus, the aim of this study was to evaluate fecal S100A12 concentrations in a cohort of puppies with intestinal parasites (Cystoisospora spp., Toxocara canis, Giardia sp.) and viral agents that are frequently encountered and known to cause gastrointestinal signs in dogs (coronavirus, parvovirus) as a comparative model.

METHODS

Spot fecal samples were collected from 307 puppies [median age (range): 7 (4-13) weeks; 29 different breeds] in French breeding kennels, and fecal scores (semiquantitative system; scores 1-13) were assigned. Fecal samples were tested for Cystoisospora spp. (C. canis and C. ohioensis), Toxocara canis, Giardia sp., as well as canine coronavirus (CCV) and parvovirus (CPV). S100A12 concentrations were measured in all fecal samples using an in-house radioimmunoassay. Statistical analyses were performed using non-parametric 2-group or multiple-group comparisons, non-parametric correlation analysis, association testing between nominal variables, and construction of a multivariate mixed model.

RESULTS

Fecal S100A12 concentrations ranged from < 24-14,363 ng/g. Univariate analysis only showed increased fecal S100A12 concentrations in dogs shedding Cystoisospora spp. (P = 0.0384) and in dogs infected with parvovirus (P = 0.0277), whereas dogs infected with coronavirus had decreased fecal S100A12 concentrations (P = 0.0345). However, shedding of any single enteropathogen did not affect fecal S100A12 concentrations in multivariate analysis (all P > 0.05) in this study. Only fecal score and breed size had an effect on fecal S100A12 concentrations in multivariate analysis (P < 0.0001).

CONCLUSIONS

An infection with any single enteropathogen tested in this study is unlikely to alter fecal S100A12 concentrations, and these preliminary data are important for further studies evaluating fecal S100A12 concentrations in dogs or when using fecal S100A12 concentrations as a biomarker in patients with chronic idiopathic gastrointestinal inflammation.

Potential of connected devices to optimize cattle reproduction

Estrus and calving are two major events of reproduction that benefit from connected devices because of their crucial importance in herd economics and the amount of time required for their detection. The objectives of this review are to: 1) provide an update on performances reached by sensor systems to detect estrus and calving time; 2) discuss current economic issues related to connected devices for the management of cattle reproduction; 3) propose perspectives for these devices. The main physiological parameters monitored separately or in combination by connected devices are the cow activity, body temperature and rumination or eating behavior. The combination of several indicators in one sensor may maximize the performances of estrus and calving detection. An effort remains to be made for the prediction of calvings that will require human assistance (dystocia). The main reasons to invest in connected devices are to optimize herd reproductive performances and reduce labor on farm. The economic benefit was evaluated for estrus detection and depends on the initial herd performances, herd size, labor cost and price of the equipment. Major issues associated with the use of automated sensor systems are the weight of financial investment, the lack of economic analysis and limited skills of the users to manage associated technologies. In the near future, connected devices may allow a precise phenotyping of reproductive and health traits on animals and could help to improve animal welfare and public perception of animal production.

Characterization of the fecal microbiome during neonatal and early pediatric development in puppies

Limited information is available describing the development of the neonatal fecal microbiome in dogs. Feces from puppies were collected at 2, 21, 42, and 56 days after birth. Feces were also collected from the puppies’ mothers at a single time point within 24 hours after parturition. DNA was extracted from fecal samples and 454-pyrosequencing was used to profile 16S rRNA genes. Species richness continued to increase significantly from 2 days of age until 42 days of age in puppies. Furthermore, microbial communities clustered separately from each other at 2, 21, and 42 days of age. The microbial communities belonging to dams clustered separately from that of puppies at any given time point. Major phylogenetic changes were noted at all taxonomic levels with the most profound changes being a shift from primarily Firmicutes in puppies at 2 days of age to a co-dominance of Bacteroidetes, Fusobacteria, and Firmicutes by 21 days of age. Further studies are needed to elucidate the relationship between puppy microbiota development, physiological growth, neonatal survival, and morbidity.

Canine and feline colostrum

Puppy and kitten survival over the first weeks is particularly dependent on colostrum, a specific secretion of the mammary gland produced during the first 2 days post-partum. Colostrum is a source of nutrients and immunoglobulins. It also contributes to the digestive tract maturation. Colostrum differentiates from milk mainly based on its concentration in immunoglobulins G: 20-30 g/L in dog colostrum, 40-50 g/L in cats' vs <1 g/L in milk. IgG concentration rapidly drops after parturition (-50% in 24 hr). Immune quality of colostrum is highly variable between bitches, with no relationship with maternal blood IgG level, dam's age, breed size or litter size. In addition to systemic immune protection, colostrum also plays a major role for local digestive protection, due to IgA, lysozyme, lactoferrin, white blood cells and various cytokines. Energetic concentration of canine and feline colostrum is not superior to that of mature milk. It depends on colostrum fat concentration and is affected by breed size (higher in breeds <10 kg adult body weight). As puppies and kittens are almost agammaglobulinemic at birth, transfer of IgG from their digestive tract into their bloodstream is crucial for their survival, IgG absorption ending at 12-16 hr after birth. Energetic supply over the two first days of life, as evidenced by growth rate over the two first days of life, also affects risk of neonatal mortality. Early and sufficient suckling of colostrum is thus the very first care to be provided to newborns for their later health and survival.

Natural and artificial hyperimmune solutions: Impact on health in puppies

Colostrum and milk are complex mammary secretions providing the puppy with many nutritional and immunological factors, which play a crucial role for its correct development and survival. In the case of colostrum and/or milk intake deficiency, puppies are at increased risk of infectious diseases. This work reviews the various nutritional hyperimmune supplementations proposed to provide a passive immune protection and to positively impact puppies' health. Some strategies rely on canine immunoglobulins: canine colostrum banking and canine serum/plasma supplementation. Others involve heterologous sources of antibodies and other immune factors: bovine colostrum or hyperimmune egg powder. Among the different solutions evaluated from birth to weaning, canine plasma and hyperimmune egg powder showed promising beneficial effect on puppies' health. Canine plasma seems to positively impact not only growth (increased growth during the neonatal period), but also digestive health (higher species richness of intestinal microbiota) and the general health (tendency of lower morbidity). Puppies supplemented with hyperimmune egg powder presented increased neonatal growth and decreased risk of canine parvovirus infection. Nevertheless, natural canine maternal colostrum and milk ingestion remains the optimal guarantee for puppies' health and survival, as a source of immunity, energy and growth factors.

Reproductive performance and pre-weaning mortality: Preliminary analysis of 27,221 purebred female dogs and 204,537 puppies in France

The objective of this study was to describe efficiency of reproduction of purebred dogs in field breeding conditions, from mating to weaning in France. Data were collected between 2010 and 2014 in 5,667 French breeding kennels via a reproduction management software (Breeding Management System, Royal Canin, Aimargues, France). Effect of breed size (Mini: adult body weight <10 kg; Medium: 10-25 kg; Maxi: 25-40 kg; Giant: >40 kg), age of dam and male on pregnancy rate, abortion rate and litter size were evaluated by multivariable models. Data on 45,913 heats (all with mating), from 27,221 bitches from 248 breeds, were analysed. At mating, mean age (±SD) was 3.1 ± 1.8 years for bitches and 3.3 ± 2.0 for males. Males originated from the same kennel as the females in 88.5% of the matings. Based on breeder's evaluation of the pregnancy status, pregnancy rate (number of pregnant females based on breeders declaration/number of heats) was 87.8% and abortion rate was 6.8%. Finally, 81.9% of the mated females gave birth to a litter. On 37,946 litters (204,537 puppies), mean litter size was 5.4 ± 2.8 puppies (range 1-24), which was influenced by breed size and dam age (p < .0001). Stillbirth rate was 7.4% and puppy mortality rate (stillbirth + mortality until 2 months of age) was 13.4%. Prolificacy and puppy mortality rates were affected by breed size and within a breed size, by breed. Despite probable approximations (as data originate from breeders declaration), this large-scale analysis provides reference values on reproductive performance in dogs.

Influence of Breed Size, Age, Fecal Quality, and Enteropathogen Shedding on Fecal Calprotectin and Immunoglobulin A Concentrations in Puppies During the Weaning Period

Background

Fecal calprotectin and immunoglobulin A (IgA) are markers of intestinal inflammation and immunity in adult dogs.

Hypothesis

Fecal calprotectin and IgA concentrations in puppies are not influenced by fecal moisture in puppies but by enteropathogen shedding.

Animals

Three hundred and twenty‐four puppies.

Methods

Fecal consistency was assessed by gross examination. Fecal moisture was evaluated before and after lyophilization. Canine parvovirus and coronavirus were detected in feces by qPCR and qRT‐PCR respectively. Giardia intestinalis antigen was quantified by ELISA. The standard McMaster flotation technique was used to detect eggs and oocysts in feces. Fecal calprotectin and IgA concentrations were quantified by in‐house radioimmunoassays.

Results

For each marker (IgA and calprotectin), a strong positive correlation was observed between concentration in fresh feces and concentration in fecal dry matter. 75.6% of the puppies were found to be infected by at ≥1 of the enteropathogens evaluated. Fecal calprotectin concentration was significantly influenced by age (P = .001), with higher concentrations in younger puppies, but not by viral (P = .863) or parasitic infection (P = .791). Fecal IgA concentration was significantly influenced by enteropathogen shedding (P = .01), with a lower fecal IgA concentration in puppies shedding at ≥1 enteropathogen compared to puppies without any enteropathogen shedding, but not by age.

Conclusions

Fecal calprotectin and IgA are of no diagnostic value to detect presence of enteropathogens in clinically healthy puppies or puppies with abnormal feces, but could help to better understand the maturation of digestive tract.

Progesterone plays a critical role in canine oocyte maturation and fertilization

Canine oocyte maturation and fertilization take place within the oviducts under increasing plasma levels of progesterone (P4). In order to investigate the role of P4 in these processes, 51 beagle bitches were treated with the P4 receptor antagonist aglepristone at the end of proestrus and 32 females were kept untreated. Fifteen treated and 13 control bitches were inseminated at Days +1 and +2 after ovulation (Day 0). Stages of oocyte maturation and embryo development were determined after ovariectomy at different time points after ovulation. Aglepristone did not prevent ovulation but delayed the resumption of oocyte meiosis and inhibited its progression: first metaphase I (MI) stage was observed at 173 h postovulation and 39% of oocytes reached MII as late as 335 h postovulation in treated females whereas first MI occurred at 76 h and 100% of oocytes were in MII at 109 h postovulation in controls. Aglepristone extended the stay of morphologically normal oocytes within the oviducts: first signs of oocyte degeneration were observed at 335 h in treated versus 100- to 110-h postovulation in control bitches. In inseminated females, aglepristone prevented sperm progression toward the oviducts and fertilization, although motile spermatozoa were observed in the uterine tip flush and within the cranial uterine glands. A proteomic analysis of the tubal fluid from treated and control noninseminated bitches at Day +4 found evidence of 79 differential proteins potentially involved in the oocyte phenotype. In conclusion, P4 plays key roles in postovulatory canine oocyte maturation, aging, and in fertilization.

Methods and on-farm devices to predict calving time in cattle

In livestock farming, accurate prediction of calving time is a key factor for profitability and animal welfare. The most accurate and sensitive methods to date for prediction of calving within 24 h are the measurement of pelvic ligament relaxation and assays for circulating progesterone and oestradiol-17β. Conversely, the absence of calving within the next 12-24 h can be accurately predicted by the measurement of incremental daily decrease in vaginal temperature and by the combination of pelvic ligament relaxation and teat filling estimates. Continuous monitoring systems can detect behavioural changes occurring on the actual day of calving, some of them being accentuated in the last few hours before delivery; standing/lying transitions, tail raising, feeding time, and dry matter and water intakes differ between cows with dystocia and those with eutocia. Use of these behavioural changes has the potential to improve the management of calving. Currently, four types of devices for calving detection are on the market: inclinometers and accelerometers detecting tail raising and overactivity, abdominal belts monitoring uterine contractions, vaginal probes detecting a decrease in vaginal temperature and expulsion of the allantochorion, and devices placed in the vagina or on the vulvar lips that detect calf expulsion. The performance of these devices under field conditions and their capacity to predict dystocia require further investigation.

Lack of transplacental transmission of Bartonella bovis

Transplacental transmission of Bartonella spp. has been reported for rodents, but not for cats and has never been investigated in cattle. The objective of this study was to assess vertical transmission of Bartonella in cattle. Fifty-six cow-calf pairs were tested before (cows) and after (calves) caesarean section for Bartonella bacteremia and/or serology, and the cotyledons were checked for gross lesions and presence of the bacteria. None of the 29 (52%) bacteremic cows gave birth to bacteremic calves, and all calves were seronegative at birth. Neither placentitis nor vasculitis were observed in all collected cotyledons. Bartonella bovis was not detected in placental cotyledons. Therefore, transplacental transmission of B. bovis and multiplication of the bacteria in the placenta do not seem likely. The lack of transplacental transmission may be associated with the particular structure of the placenta in ruminants or to a poor affinity/agressiveness of B. bovis for this tissue.

The induction of a secondary corpus luteum on day 12 post-ovulation can delay the time of luteolysis in high-producing Holstein cows

Luteolysis before the time of maternal recognition of pregnancy is one cause of low fertility in high-producing dairy cows. The objective of this study was to assess whether induction of a secondary corpus luteum (CL) late in the luteal phase would delay the time of luteolysis. Twenty high-producing Holstein cows were synchronized to ovulation (Day 0) with the Ovsynch protocol and received hCG (1500 IU im) on Day 12. Corpora lutea formation (as evaluated by ultrasonography) and plasma P4 concentrations were monitored from Days 4 to 36. hCG treatment induced the formation of one secondary CL (CL2) in 11 of 20 cows (55%) from the dominant follicle (mean diameter: 14.2 ± 0.9 mm) of two-wave (3/11) and three-wave (8/11) cycles. The maximal diameter of the CL2 (23.3 ± 1.9 mm) was reached approximately 6 days after hCG treatment and was correlated with its structural lifespan (p < 0.01). Cows that formed a CL2 after hCG had higher mean plasma P4 concentrations on Day 14 (+4.5 ng/ml) and Day 18 (+3.0 ng/ml) compared with cows without CL2 (p < 0.05). The structural regression of CL2 begun approximately 8 days after that of the CL1, and the median time at which the first drop in circulating P4 levels occurred was later in cows that formed a CL2 than in those that did not (Day 26 vs Day 18; p < 0.01). Thus, the induction of a CL2 by hCG on Day 12 might reduce the risk of premature luteolysis in high-producing dairy cows after insemination.

Risk factors of weaning diarrhea in puppies housed in breeding kennels

Diarrhea represents one of the most frequent disorders in dogs. In puppies, degradation of feces quality is associated with a reduced daily weight gain and an increased risk of death. Prevention of diarrhea in puppies requires a global approach encompassing enteropathogens, environment and management practices especially when housed in groups. The purpose of this study was to determine prevalence of enteropathogens in puppies in breeding kennels and to identify risk factors of diarrhea. Two hundred and sixty six puppies (between 5 and 14 weeks of age) from 29 French breeding kennels were included. For each kennel, data about environment, management of the kennel and puppies’ characteristics (age, sex and breed) were collected. For each puppy, fecal consistency and fecal excretion of enteropathogens (viruses and parasites) was evaluated. At least one enteropathogen was identified in 77.1% of puppies and 24.8% of puppies presented abnormal feces. The main risk factor of weaning diarrhea was fecal excretion of canine parvovirus type 2 (odds ratio = 5; confidence interval 95%: 1.7–14.7). A targeted sanitary and medical prophylaxis against canine parvovirus type 2 should be implemented to decrease risk of weaning diarrhea.

Inadequate passive immune transfer in puppies: definition, risk factors and prevention in a large multi-breed kennel

The prevalence of neonatal mortality is high in the canine species and far from well-studied. In most domestic neonates, an appropriate colostrum intake is a key element of the control of neonatal mortality. The aim of this study was to evaluate the impact of passive immune transfer on puppy mortality, assessed through serum immunoglobulin G (IgG) concentration at 2 days of age. Factors impacting passive immune transfer and the value of an oral immunoglobulin supplementation to prevent it were also analyzed. A total of 149 puppies from 34 litters (12 breeds) within one breeding kennel were included. Blood samples were collected at 2 days of age and colostrum was collected from their dams 1 day after whelping to assay IgG concentration. Puppies were weighed at birth and at 2 days of age for calculation of growth rate. Mortality was recorded until 3 weeks of age. Seventy randomly assigned puppies were orally supplemented with hyper-immunized adult plasma twice within the first 8h of life. IgG concentration at 2 days of age was significantly correlated with weight gain during the first 2 days of life. The multivariable model with litter as a random effect demonstrated that neonatal mortality was not influenced by breed size, sex, supplementation, litter size, nor colostrum IgG concentration, but by puppy IgG concentration at 2 days of age. According to the ROC curve, the minimal IgG concentration at and below which puppies were at higher risk of death was determined at 230 mg/dl. Puppy IgG concentration was significantly associated with growth rate, but not with breed size, sex, supplementation, litter size or colostrum IgG concentration in a multivariable model with litter as a random effect. This study demonstrates that neonatal mortality in puppies is related to the quality of passive immune transfer. The oral supplementation with hyper-immunized canine plasma neither decreased risk of mortality, nor improved serum IgG concentration at 2 days of age in puppies. Attention must thus be paid to early colostrum intake to control the neonatal mortality in puppies.

Partial urorectal septum malformation sequence in a kitten with disorder of sexual development

A 2-month-old kitten exhibited simultaneously an imperforate anus, hypospadias, rectourethral fistula and genital dysgenesis (penis restricted to the glans, absence of prepuce and bifid scrotum). Surgical correction consisted of separation of the urinary and digestive tracts, perineal urethrostomy and connection of the rectum to the newly made anal opening. Pathological examination of the testes, conventionally removed at 9 months of age, showed no mature spermatozoa and underdevelopment of germ and Leydig cells. In humans, the absence of an anal opening in association with abnormal sexual development defines the urorectal septum malformation sequence. Here, we describe the first case of this syndrome in a kitten with a normal male karyotype (38,XY) and a normal coding sequence for the SRY gene. Both the rectourethral fistula and observed genital abnormalities might have been induced by a disturbance in the hedgehog signalling pathway. However, although four polymorphic sites were identified by DHH gene sequencing, none cosegregated with the malformation.

Expression of nuclear and membrane progesterone receptors in the canine oviduct during the periovulatory period

Important reproductive events take place in the canine oviduct in the presence of increasing concentrations of progesterone (P4). To investigate the potential effects of P4 on the canine oviduct, the expression of nuclear (PR) and membrane (PGRMC1 and 2, mPRα, β and γ) P4 receptors was studied by quantitative RT-PCR and immunohistochemistry. Oviducts were collected from Beagle bitches after the onset of pro-oestrus and before the LH peak (Pre-LH), after the LH peak and before ovulation (Pre-ov) and on Days 1, 4 and 7 post-ovulation (n=6 bitches/stage). PR mRNA concentrations decreased from Pre-LH to Day 7 in the ampulla and isthmus, whereas both PGRMC1 and 2 mRNA levels increased over the same period. The main change in mPR expression was an increase in mPRβ and γ mRNAs at Day 7 in the isthmus. Furthermore, PR proteins were expressed in the nuclei of luminal epithelial, stromal and muscular cells, whereas the expression of PGRMCs and mPRs was primarily cytoplasmic and localised in the luminal epithelium. The immunostaining for PR decreased at Day 4 in the stroma and muscle, whereas it remained strong in the epithelium from Pre-LH to Day 7. PGRMC1 staining was strong at Days 4 and 7 whereas PGRMC2 was highly expressed from Pre-ov to Day 7. The most intense immunostaining signals for all three mPRs were observed at Day 7. Our results strongly support the hypothesis that P4 is an important regulator of oviductal functions in the bitch through complementary classical and non-classical P4 pathways.

148 EXPRESSION OF OVIDUCT-SPECIFIC GLYCOPROTEIN IN THE CANINE OVIDUCT DURING THE PERIOVULATORY PERIOD

In the canine species, the oocyte is ovulated at the immature germinal vesicle (GV) stage and will reach metaphase II stage after 3 to 4 days spent in the oviduct. Fertilization and embryonic development to the blastocyst stage also take place in the oviduct. In a previous study (Tahir et al. 2012 Reprod. Domest. Anim. 47, 487), we reported the expression of oviductin (oviduct-specific glycoprotein) mRNA in the oviduct. The present study aimed to describe the oviductin protein expression (immunolocalization and Western blot quantification) and the effect of the oviducal region and the ovarian cycle. Beagle bitches were ovariectomized at 6 stages (6 bitches/stage): anestrus, after the onset of proestrus and before the LH peak (Pre-LH), after the LH peak and before ovulation (Pre-ov), 1 day (Day 1), 4 days (Day 4), and 7 days (Day 7) after ovulation. Three oviducal regions were collected [i.e. ampulla, isthmus, and ampulla-isthmus junction (AIJ)]. Ampulla and isthmus were fixed in paraformaldehyde, embedded in paraffin, and 7-μm sections were used for immuno-histochemistry using a goat polyclonal anti-human oviductin (N20; Santa Cruz Biotechnology, Santa Cruz, CA, USA) and the ImmPress kit (Vector Laboratories, Burlingame, CA, USA). Total protein from the AIJ was extracted and used for Western Blot using a mouse monoclonal anti-mouse antibody (H8; Santa Cruz Biotechnology). The expression of oviductin in AIJ was quantified in duplicate on blots using ImageJ software and normalized with actin levels. Relative amounts of oviductin were compared between stages by ANOVA followed by a Tukey test. Immuno-histochemistry revealed that oviductin was specifically expressed in the nonciliated cells of the oviducal epithelium from Pre-LH to Day 7, with a stronger staining in the isthmus than in the ampulla at all stages. Furthermore, the expression of oviduct-specific glycoprotein, detected by Western Blot, varied significantly with the stage (P < 0.0001). The oviductin protein expression was at its lowest level at anestrus, then increased significantly at Pre-LH and Pre-ov (35- and 41-fold higher levels than anestrus, respectively), reached a maximal level at Day 1 (66-fold higher than anestrus), then decreased at Days 4 and 7 (47- and 20-fold higher than anestrus, respectively). In conclusion, this is the first report of oviductin protein expression in the canine oviduct. The region-specific higher expression of oviductin at Day 1 post-ovulation suggests a potential role of this glycoprotein in gamete maturation and fertilization in the bitch.

121 EXPRESSION OF STEROID RECEPTORS IN THE CUMULUS - OOCYTE COMPLEX AROUND OVULATION IN THE BITCH

In the bitch, oocytes are ovulated at an immature stage (prophase I) and resume meiosis in the oviduct, 3 to 4 days after ovulation while they are still surrounded by 2 to 3 layers of cumulus cells. Canine cumulus-oocyte complexes (COC) are exposed to high and changing plasma concentrations of 17β-oestradiol (E2) and progesterone (P4) during the periovulatory period. In order to explore whether oocyte maturation may be regulated by steroids in this species, the expression of E2 (ERα, ERβ) and P4 (nuclear: PR; membrane: PGRMC1, PGRMC2, mPRα, mPRβ, mPRγ) receptors was studied in COC at precise times around ovulation. Ovaries were collected from Beagle bitches during anestrus (n = 4), after the beginning of proestrus, and before the LH peak (Pre-LH, n = 7), after the LH peak and before ovulation (Pre-ov, n = 8), and at Day 1 (n = 11) and Day 4 (n = 8) post-ovulation. Anoestrus COC were recovered from follicles smaller than 1 mm in diameter. The COC at the Pre-LH and Pre-ov stages were aspirated from preovulatory follicles (4.5–6 mm in diameter). Such follicular COC were partially denuded to leave the 2 to 3 innermost cumulus layers firmly attached to the zona pellucida. Post-ovulatory COC, naturally surrounded by 2 to 3 cumulus layers, were recovered by oviductal flushing. Total RNA was extracted from 3 batches of 10 COC per stage, then reverse transcribed. The expression of steroid receptors was assessed in duplicate by qPCR (LightCycler® 480, Roche Diagnostics) using the relative standard curve method and normalized by the geometric mean value of the two most stable reference genes (BGLR and RPS5; NormFinder software) chosen among four genes previously tested. Relative amounts of mRNA levels were compared between stages by ANOVA followed, when necessary, by a Tukey test. The ERα and ERβ expression did not vary significantly with the stage. In contrast, a significant variation between stages in nuclear and 4 membrane P4 receptor expression was observed (P < 0.0001 for PR; P < 0.001 for PGRMC1 and mPRβ; P < 0.05 for PGRMC2 and mPRγ). The PR mRNA levels were significantly higher at Pre-ov than at any other stage. PGRMC1 expression was significantly higher at Pre-ov and Day 4 compared with anestrus and Pre-LH, and was at an intermediate level at Day 1. The expression of PGRMC2, mPRβ, and mPRγ remained low from anestrus to Day 1 and increased significantly at Day 4. Lastly, mRNA levels of mPRα were below the detection limit at all stages. This is the first report of steroid receptor expression in canine COC at precise times around ovulation. The stage-specific variation in expression of nuclear and of several membrane P4 receptors around ovulation suggests a role for P4 in canine oocyte maturation. The exact localisation of these receptors in cumulus cells, oocytes, or both remains to be determined.

183 CANINE EMBRYOS OBTAINED BY INTRACYTOPLASMIC SPERM INJECTION

In vitro fertilization encounters 2 specific difficulties in the canine species, with no puppies born to date: low penetration rates (10–50%) and high polyspermia (around 50% of fertilized oocytes; Saint-Dizier et al. 2001 J. Reprod. Fert. Suppl. 57, 147–150). The objectives of the study were to test whether intracytoplasmic sperm injection (ICSI), which overcomes these 2 obstacles, could allow production of canine embryos, using in vivo- or in vitro-matured oocytes. The time of ovulation was determined on 8 Beagle bitches from our experimental kennel by blood progesterone assay and transabdominal ultrasound examination. After ovariohysterectomy 82 to 100 h after ovulation, 58 metaphase II (MII) oocytes were collected by tubal flushing. In parallel, 88 oocytes from 6 anoestrus bitches were matured in vitro (M199 + 20% fetal calf serum for 72 h in 5% CO2 at 38°C). Sperm was collected from 1 Beagle dog with excellent fertility record at natural mating. The sperm was diluted 1 : 100 in PBS/BSA without any selection process. Intracytoplasmic sperm injection was performed at 38°C in M199 HEPES + 20% BSA (4-μm injection pipette; 120-μm holding pipette). One motile spermatozoon of normal morphology was injected per oocyte. Injected oocytes were cultured in vitro for 48 h after injection (M199 + 20% fetal calf serum in 5% CO2 at 38°C) in 4-well open dishes. Oocytes were then fixed and DNA and tubulin were stained for observation by confocal microscopy (Chebrout et al. 2012 Microsc. Microanal. 18, 483–492). Among the 58 MII oocytes recovered in vivo, 7.4% lysed at injection and 20% degenerated during the 48 h after injection. Among the 40 injected oocytes still alive, 6 fragmented (15%) and 4 developed as embryos [10%; 2-pronuclei (n = 2), 2-cell and 6-cell). None of the other oocytes showed decondensed female chromatin. Among the 88 oocytes incubated for in vitro maturation, 13 (14.8%) reached MII. These were successfully injected; 48 h after injection, 3 were embryos at the 2-cell stage and 10 were at the MII stage with a condensed sperm head. Fifty-one non-mature oocytes were injected; 31 were at the germinal vesicle (GV) stage and the stage of others was not determined. Of the GV oocytes, 71% degenerated during culture after injection. The 9 surviving oocytes were still at the GV stage with condensed sperm head 48 h after injection. In conclusion, canine embryos can be obtained through ICSI. Nevertheless, this procedure induced low activation rates. Development at later stages, especially after transfer into a recipient female, is to be evaluated, in particular for in vitro-produced MII oocytes, of lower cytoplasmic competence (Viaris et al. 2008 Reprod. Fert. Dev. 20, 626–639).

176 IN VITRO MATURATION OF DOG OOCYTES IN CANINE FOLLICULAR FLUID

In the canine species, assisted reproductive technologies, especially in vitro maturation (IVM) and IVF, are still ineffective. The main limiting factor remains the immaturity of the oocytes collected from anestrus ovaries. The ability of an oocyte to reach the MII stage in vitro is linked to the diameter of its follicle and anestrus oocytes, collected from small (<1 mm) follicles, are profoundly immature (De Lesegno et al. 2008). The objective of this study was to improve cytoplasmic quality by mimicking in vivo conditions; that is, to test the effect of pure preovulatory follicular fluid (FF) on survival and IVM rates of anestrus dog oocytes, in order to improve the nuclear and cytoplasmic maturation of these immature oocytes. Follicular fluids samples were collected from 54 Beagle bitches at 2 stages: before the LH peak (n = 23 bitches) and after the LH peak (n = 31 bitches). Only follicular fluid samples from large (>4 mm) follicles were collected and pooled by stage. Control oocytes were matured in 20% FCS/M199 medium. Groups of 5 oocytes were in vitro matured in 30 μL of follicular fluid, in half-area 96-well plates (5% CO2, 38°C). After 72 h of IVM, oocytes were denuded, fixed, and stained for DNA and tubulin before observation by confocal microscopy, and nuclear stages were classified as GV-A to GV-E, MI, and MII (Reynaud et al. 2012). A total of 460 oocytes were collected from 13 anestrus bitches and allocated to either the control medium (n = 155), the Pre-LH FF (n = 145) or the Post-LH FF (n = 160) groups. After 72 h of IVM, the morphology of the cumulus–oocyte complexes (COC) in the post-LH group was different from that of the others: cumulus cells appeared more compact and darker. Analysis of the nuclear stages showed that the degeneration rate was significantly higher (P < 0.05) in the post-LH group (58.7%) than in the pre-LH (40.9%) or in the control group (34.4%). No significant differences (P > 0.05) were observed between the 3 groups in the rate of immature GVA-B oocytes (36.4, 28.5, and 25.3% in the control, Pre-LH, and Post-LH groups, respectively), in the rate of meiotic resumption (GV-C/D/E, MI, MII stages, 44.4, 51.9, and 38.7% in the control, Pre-LH, and Post-LH groups, respectively). Metaphase II rates were not significantly different (12.1, 8.6, and 4.8% in the control, Pre-LH, and Post-LH groups, respectively). In conclusion, canine COC may survive when exposed to IVM in pure follicular fluid, but the degeneration rate was higher in the post-LH group. The presence of follicular fluid did not inhibit meiosis resumption, but did not significantly improve IVM rates. To better mimic in vivo conditions, IVM in a sequence of media, such as IVM in follicular fluid followed by IVM in oviducal fluid remains to be tested.

Effect of blood handling conditions on progesterone assay results obtained by chemiluminescence in the bitch

Assay of blood progesterone (P4) is commonly practiced to determine the time of ovulation, diagnose luteal insufficiency, and predict time of parturition in bitches. Because of practical constraints, most blood samples cannot be assayed on site immediately after collection. The aim of this work was to evaluate the effects of various sampling and storage conditions on concentrations of P4 as determined by chemiluminescence immunoassay. The blood of 5 Beagle bitches was collected from the jugular vein to study the effect of the type of collection tube (silicone, lithium heparin, EDTA), the storage time of unseparated or separated plasma (2 h to 14 d), and the number of freeze-thaw cycles (1-10) on P4. The effect of each factor was tested within one assay session. None of the factors significantly affected P4. Thus, P4 appears to remain relatively stable in canine blood samples exposed to various processing and storage conditions.

Immunolocalization of progesterone receptors in the canine oviduct around ovulation

In the bitch, oocyte maturation, sperm storage, fertilization and early embryo development take place within the oviducts under high and increasing circulating progesterone concentrations. To investigate the potential effects of progesterone on the canine oviduct, nuclear progesterone receptors (PR) were localized. Oviducts were collected by ovariectomy from adult Beagle bitches during anestrus, after the onset of proestrus but prior to the Luteinizing Hormone (LH) peak (Pre-LH), after the LH peak but before ovulation (Pre-ov) and on Days 1, 4 and 7 after ovulation (n = 3 bitches per stage). The cellular distribution of PR was studied by immunohistochemistry (IHC) in the ampulla, isthmus and tubal part of the utero-tubal junction (UTJ). Plasma progesterone and 17β-oestradiol were assayed on the day of surgery. PR were specifically expressed in the nuclei of epithelial, stromal and muscular cells in the ampulla, isthmus and UTJ. The IHC scores did not vary from one oviductal region to another. However, the epithelium displayed higher scores than the stroma at anestrus, Pre-ov, Days 4 and 7, and also higher scores than muscle at Days 4 and 7 (p < 0.05). Immunohistochemistry scores in the stroma and muscle decreased at Days 4 and 7 compared with previous stages (p < 0.05). Furthermore, muscular IHC scores were positively correlated with circulating 17β-oestradiol concentrations and negatively correlated with circulating progesterone concentrations (p < 0.05). In conclusion, PR were identified in the canine oviduct, with differences in expression between tissues and times around ovulation, suggesting that progesterone may regulate tubal functions and reproductive events in this species.

Timing of the intestinal barrier closure in puppies

As puppies are born with very low immunoglobulin concentrations, they rely on passive immune transfer from ingested colostrum to acquire a protective immunity during the first few weeks of life. The purpose of this study was to describe the timing of gut closure in canine neonates. Twenty-two Beagle puppies received 3 ml of standardized canine colostrum at 0, 4, 8, 12, 16 or 24 h after birth using a feeding tube. Blood immunoglobulins G (IgG, M and A) were assayed 0, 4 and 48 h after colostrum ingestion. IgG absorption rate was significantly affected by the time of colostrum administration, and the IgG concentrations in puppies serum 48 h after administration were significantly higher when colostrum was ingested at 0-4 h of age than at 8-12 h or 16-24 h (1.68 ± 0.4, 0.79 ± 0.07 and 0.35 ± 0.08 g/l, respectively; p < 0.001). In the canine species, gut closure seems thus to begin as early as 4-8 h after birth and to be complete at 16-24 h. Consequently, this phenomenon appears to occur earlier in puppies than in most other species.

Impact of Bovine Herpesvirus 4 (BoHV-4) on Reproduction

Bovine herpesvirus 4 (BoHV-4) is increasingly considered as responsible for various reproductive troubles. This virus infects blood mononuclear cells and displays a specific tropism for vascular endothelia, mammary tissue, endometrium and foetal tissues. Viral multiplication can be reactivated by corticosteroids or stress, both factors present at calving. BoHV-4 has been isolated in a large variety of clinical cases, primarily metritis, vaginitis and mastitis, but also endometritis, abortion and orchitis. Its impact on reproductive performance has been suggested by several epidemiological studies: seroprevalence against BoHV-4 is higher in aborted females and in repeat breeders. Nevertheless, its intrinsic pathogenic power seems low, symptoms developing only when BoHV-4 cooperates with bacteria: within the uterus or mammary gland. BoHV-4 is rather currently considered as a cofactor for the development of an inflammatory reaction initiated by bacteria.

Chromatin patterns of immature canine oocytes after in vitro maturation

In canine species, in vitro maturation (IVM) rates of oocytes collected from anoestrous ovaries are low (<20%). Several IVM media have been tested without significant improvements. A critical step in the evaluation of culture conditions is the observation of the meiotic stage reached by the oocytes. The present study was designed to investigate the chromatin patterns of in vitro matured oocytes by visualizing Germinal Vesicle (GV) and Germinal Vesicle Breakdown (GVBD) structures at 72 h of IVM. Nuclear stages of 1678 oocytes were evaluated by confocal microscopy after IVM. 1204 oocytes were non-degenerated, and 94.4% were still immature and at GV stage. Five different patterns of chromatin configuration were observed. Higher percentages of oocytes with unmodified GV and with diffuse (58%; Type A) and filamentous chromatin (19%; Type B) were observed in comparison with those with modifications in the GV such as patched chromatin (12.5%; Type C), surrounded-nucleolus (3%; Type D) and in vivo type chromatin/fully grouped chromatin (2.5%; Type E). These results indicate that GVBD (absence of nucleolus, nucleus breakdown) is rarely observed in vitro. The percentage of type C-D-E GVs and MI (meiotic resumption) and of MII (completion of meiosis) can be used to evaluate meiotic resumption after IVM. Our results indicate that although a low number of in vitro matured oocytes exhibit the chromatin configurations observed in in vivo collected oocytes, chromatin changes in the GV can be induced during IVM.

Reliability of Hoechst 33342 staining under wide-field microscopy for evaluation of the nuclear status of living dog oocytes

Due to the marked cytoplasmic opacity of canine oocytes, the diagnosis of their nuclear status is difficult. The objective of the present study was to evaluate the accuracy of Hoechst staining observed under epifluorescence wide-field microscopy [living oocyte observation (LivOO)] by comparison to a reference technique [DNA staining with ethidium homodimer-2 under confocal microscopy; fixed oocyte observation (FixOO)]. Four Hoechst 33342 concentrations (200 ng, 500 ng, 1 μg, 2 μg/mL) were tested and 1 μg/mL was the lowest one with the lowest proportion of oocytes in which DNA was missed. At this concentration, LivOO procedure did not affect the degeneration rate. On 379 oocytes observed individually with the two techniques successively, diagnosis of meiosis resumption by LivOO was exact in 87.3% of the cases, but the meiosis resumption rate was underestimated (23.5% versus 34.3% with FixOO; p < 0.001). Diagnosis for metaphase II was exact in 80% of the cases, but LivOO detected only 72.7% of the metaphase II oocytes present. Metaphase rates did not differ between LivOO and FixOO. This study contributes to a better interpretation of in vitro maturation results. The developmental potential of metaphase II canine oocytes sorted after Hoechst staining is to be evaluated.

Validation of a fecal scoring scale in puppies during the weaning period

In puppies weaning is a high risk period. Fecal changes are frequent and can be signs of infection by digestive pathogens (bacteria, viruses, parasites) and indicators of nutritional and environmental stress. The aim of this study was to define a pathological fecal score for weaning puppies, and to study the impact on that score of two intestinal viruses (canine parvovirus type 2 and canine coronavirus). For this, the quality of stools was evaluated on 154 puppies between 4 and 8 weeks of age (100 from small breeds and 54 from large breeds). The scoring was performed immediately after a spontaneous defecation based on a 13-point scale (from 1; liquid to 13; dry and hard feces). Fecal samples were frozen for further viral analysis. Each puppy was weighed once a week during the study period. The fecal score regarded as pathological was the highest score associated with a significant reduction in average daily gain (ADG). Fecal samples were checked by semi-quantitative PCR or RT-PCR for canine parvovirus type 2 and canine coronavirus identification, respectively. The quality of feces was affected by both age and breed size. In small breeds, the ADG was significantly reduced under a fecal score of 6 and 7 for puppies at 4–5 and 6–8 weeks of age, respectively. In large breeds, the ADG was significantly reduced under a fecal score of 5 whatever the age of the puppy. Whereas a high viral load of canine parvovirus type 2 significantly impacted feces quality, no effect was recorded for canine coronavirus. This study provides an objective threshold for evaluation of fecal quality in weaning puppies. It also emphasizes the importance to be given to age and breed size in that evaluation.

69 DIFFERENTIAL AND QUANTITATIVE ANALYSIS OF DOG OVIDUCTAL FLUID

The major reproductive peculiarity of the bitch is that ovulation releases prophase I (germinal vesicle, GV, immature) oocytes. Resumption of meiotic maturation, as well as fertilisation and embryonic development to the morula stage occur in the oviduct. Because the dog is a biomedical model for human diseases and also a model for endangered canid species, the development of assisted reproduction techniques would be of great interest. To date, in vitro-produced canine embryos remain exceptional and no puppy has been born. The main limiting factors of in vitro embryo production are the low oocyte maturation rates, the poor oocyte quality and the high polyspermy. A better knowledge of the composition of oviductal fluid during the periovulatory period may help to mimic the in vivo conditions for in vitro oocyte culture and, thereafter, their fertilisation and embryonic development. The objective of this study was to analyse the oviductal fluid by a label-free quantitative proteomic workflow based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) protein separation, nano-scale liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) analysis and quantitative method using spectral counting. Ovarian cycles were followed by vaginal smears, ultrasonography and progesterone blood assays. Oviductal fluids were collected from 3 beagle bitches, after ovariectomies performed 3.5 days after ovulation. After dissection, the ampulla and isthmus were separated and flushed with 50 μL of PBS. Oviductal fluids were submitted to 1D SDS-PAGE and all bands were digested with trypsin. Peptide extracts were analysed on an Ettan multidimensional LC (MDLC) system coupled to a linear ion trap quadrupole (LTQ) mass spectrometer. After protein identification using Mascot server and with Swiss-Prot and National Center for Biotechnology Information (NCBI) databases, bioinformatic processing of data and statistic analysis (t-test with P < 0.05) were performed using the spectral counting quantitative module of the Scaffold software. Using this strategy, 427 proteins were qualitatively identified in canine oviductal fluid. Three proteins were specific of the ampulla, 10 specific of the isthmus and 414 were found in both oviductal parts. Among these common proteins, some were differentially expressed, from 1.25 to 9 times higher (HV303_Human, RLA2_Horse, SPRL1_Human, SODC_CANFA, PROF1_Human, ARF4_Bovin and TRXR1_Bovin). The gene ontology analysis displayed biological pathways specific to the biology of reproduction (6 proteins; RUVB1_Human, OVGP1_Pig, STAT3_Human, PLAK_Human, GPX3_Rat and DYL1_Human). These candidate proteins and especially oviduct-specific glycoprotein and glutathione peroxidase, will now be validated by immunodetection methods.

70 EXPRESSION OF NUCLEAR AND MEMBRANE PROGESTERONE RECEPTORS IN THE CANINE OVIDUCT DURING THE PERIOVULATORY PERIOD

In the bitch, the oviduct is the site of oocyte maturation (Day 1 to 3 after ovulation), sperm transport/capacitation, fertilization (Day 3 to 4) and embryo development to the morula/blastocyst stage (Day 4 to 8). Unlike other mammals, these events occur in the presence of high (>6 ng mL–1) and increasing plasma levels of progesterone (P4), but little is known about the regulation of oviductal functions by P4 in the bitch. The objective of this work was to study the mRNA expression of nuclear (PR) and membrane (PGRMC1, PGRMC2, mPRβ and mPRγ) P4 receptors in the canine oviduct during the periovulatory period. Thirty-six Beagle bitches were ovariectomized at 6 stages: anestrus, before the LH peak (pre-LH), after the LH peak (pre-ov) and after ovulation (Day 1, 4 and 7). Three oviductal regions were collected [i.e. ampulla, isthmus and utero-tubal junction (UTJ)]. Total RNA was extracted and then reverse transcribed. The expression of target genes was assessed in duplicate by quantitative PCR (LightCycler® 480; Roche Diagnostics, Meylan, France) using the relative standard curve method and normalized by the geometric mean of 2 reference genes (RPS19 and GAPDH). Relative amounts of mRNA were compared between groups by ANOVA followed, when necessary, by Duncan's test. The expression of nuclear and membrane P4 receptor mRNA varied according to the stage. Expression of PR mRNA was significantly higher at pre-LH, pre-ov and Day 1 stages [means of 1.8, 1.6 and 1.5 arbitrary units (AU), respectively] than at anoestrus, Day 4 and Day 7 (1, 0.4 and 0.5 AU, respectively) in the ampulla. Same patterns of expression were observed for PR in the isthmus and UTJ. Expression of PGRMC1 and PGRMC2 mRNA were at the lowest level during anoestrus (1 AU) and increased significantly from pre-LH to Day 7 in the ampulla (from 2.2 to 8.3 AU and from 1.3 to 5.4 AU for PGRMC1 and PGRMC2, respectively) and in the isthmus (from 0.4 to 2.6 AU and from 0.5 to 1.8 AU for PGRMC1 and PGRMC2, respectively). In the UTJ, mRNA levels for PGRMC1 and PGRMC2 were the highest at Day 4 (3.9 AU) and pre-LH (2.1 AU), respectively, compared to other stages. Expression of mPRβ mRNA did not vary according to the stage in the ampulla and the isthmus, whereas it was significantly lower at Days 4 and 7 (0.6–0.7 AU) compared to other stages (1–1.2 AU) in the UTJ. Expression of mPRγ was significantly higher at Day 7 (5.0 AU) compared to other stages (0.2–1 AU) in the ampulla and was significantly higher at both anoestrus (1 AU) and Day 7 (0.9 AU) compared to other stages (0.02–0.09 AU) in the isthmus, whereas it did not vary significantly in the UTJ. In conclusion, our data suggests that P4 may be an important regulating factor of oviductal functions and could mediate its actions through genomic as well as non-genomic pathways.

68 TRANSCRIPTIONAL GENOME ACTIVATION IN CANINE EMBRYOS COLLECTED IN VIVO

Early embryonic stages are supported by maternal transcripts from the oocyte cytoplasm. Progressive transcription of embryonic genome is a key step for further embryonic development, especially during in vitro culture. To date, in vitro culture from fertilization to the blastocyst stage is inefficient in the canine species. The objective of this work was to identify minor and major activation in in vivo-produced dog embryos. Ovariectomies were performed in 31 Beagle bitches from 102 to 266 h after ovulation (post-ov), precisely timed by transabdominal ultrasonography. Embryos were collected by tubal flushing with M199-Hepes and immediately transferred into transcription buffer. Transcriptional activity was evaluated through 5-bromouridine 5′-triphosphate (BrUTP) incorporation in nascent RNA, without microinjection (Aoki et al. 1997). Oocytes from anoestrus ovaries were used as positive controls. 5-Bromouridine 5′-triphosphate incorporation was revealed by immunocytochemistry (anti-bromodeoxyuridine primary antibody) and embryonic DNA was stained by ethidium homodimer-2. Staining was quantified under laser scanning confocal microscopy. Transcriptional activity was calculated as (mean nuclear intensity – cytoplasmic mean intensity) × nuclear area and expressed in arbitrary units (AU). It was compared to 1 (similar intensity in nucleus and cytoplasm; i.e. no transcriptional activity) by t-test; levels of transcriptional activity were compared between stages by variance analysis. Seventy embryos (from 7 to 21 per stage) from 31 bitches were analysed, from 2 pronuclei to morula stage. Between 28 and 125 nuclei were quantified per stage. At each stage, transcriptional activity was calculated per embryo and per nucleus. A significant transcriptional activity was detected as early as the 2 pronuclei stage (102–132 h post-ov; 1.15 ± 0.05 AU). Transcriptional activity per embryo significantly increased between the 2- and the 4-cell stage and between the 8-cell and the morula stage. In early 8-cell embryos, staining intensity of the various nuclei was markedly heterogeneous within the same embryo, all nuclei being intensively stained from the late 8-cell stage onwards. Transcriptional activity per nucleus increased also from the 2- to the 4-cell stage (respectively, 120–161 h post-ov, 1.15 ± 0.02 AU and 133–154 h post-ov, 1.35 ± 0.04 AU) until the 8-cell stage (153–225 h post-ov, 5.12 ± 0.55 AU). Transcriptional levels at these 3 stages differed significantly. It decreased between the 8-cell and the morula stage (230–266 h post-ov, 3.06 ± 0.13 AU), probably reflecting the acquisition of a selectivity in gene expression at major activation, as in other species; Nothias et al. 1995). Addition of the transcriptional inhibitor α-amanitin during BrUTP incubation decreased the transcriptional activity by 60% (P < 0.05). Embryonic gene expression (minor activation) thus begins in the canine embryo as early as the 2 pronuclei stage, with major activation taking place during the 8-cell stage.

130 EXPRESSION OF STEROIDOGENIC ENZYMES IN THE CAT OVARY DURING FOLLICULAR GROWTH

This study was designed to describe the expression of steroidogenic enzymes in the various compartments of the feline ovary, from primordial to preovulatory follicles: P450 side-chain cleavage (P450scc), 17α-hydroxylase (17α-OH), 3β-hydroxysteroid dehydrogenase (3β-HSD). Nine female cats were ovariectomized during behavioural oestrus. After validation of their specificity by Western blot on feline tissue, 3 polyclonal antibodies obtained in the rabbit were used for immunohistochemistry (anti-bovine P450scc; anti-pig 17α-OH; anti-human 3β-HSD). Three successive ovarian cryosections were incubated with antibodies and 2 sections were used as controls (purified immunoglobulin G from a nonimmunized rabbit). Immunostaining was revealed by streptavidin-biotin system (LSAB kit, DAKO S.A., Trappes, France), with aminoethylcarbazole as a chromogen. The staining was evaluated according to its localization, intensity (from 1 to 4) and number of cell layers stained. Histological examination after haematoxylin-eosin-safran staining allowed follicle diameter measurement and evaluation of the atresia. Analysis of variance was used to compare follicles from various size classes. A total of 343 follicles from 140 to 3250 μm in diameter were observed (i.e. all follicles present on the slides), of which 15.2% were atretic. The observations were similar for the 3 enzymes. From the preantral stage onward (diameter >140 μm), more than 85% of the healthy follicles had the theca interna positive for P450scc, 3β-HSD and 17α-OH (respectively, 87.3, 86.0 and 99.0%). Approximately 20 to 25% were also positive in the theca externa. Granulosa were stained in 9.5% (P450scc), 0.8% (3β-HSD) and 1.8% (17α-OH) of the healthy follicles, but always with a low intensity (<2). The follicular size did not affect the proportion of stained follicles, but the staining intensity decreased progressively until 1200 μm and increased thereafter. The number of positive layers decreased continuously until 1500 μm in diameter. Between 90 and 95% of the preovulatory follicles (>2000 μm) were positive in the theca interna; the signal was more intense and the number of stained layers was higher than in smaller follicles. The 3 enzymes were detected in all the atretic follicles, with a similar intensity as in healthy ones; they were also present in the interstitial tissue, but with a higher intensity. The staining pattern in the various ovarian compartments suggests that the major steroidogenic tissues in the cat ovary are the theca interna of healthy follicles and the interstitial tissue. The lack of expression of the 3 key enzymes in the granulosa cells, even in preovulatory follicles, strongly suggests that these cells, shaping the future corpus luteum, are probably unable to produce progesterone.

186 RELIABILITY OF HOECHST 33342 STAINING UNDER STANDARD EPIFLUORESCENCE MICROSCOPY FOR EVALUATION OF THE NUCLEAR STATUS OF LIVING DOG OOCYTES

Hoechst 33342 staining detected by standard epifluorescence microscopy (Epi) is widely used for nuclear stage determination of oocytes in numerous species. Because it maintains cell viability, observed oocytes can be further processed for assisted reproduction. This sorting would be of great interest in the canine, where oocytes resuming meiosis in vitro remain scarce. But because of the cytoplasmic opacity of the canine oocyte, the accuracy of this technique is questionable. The objective of this study was to evaluate the accuracy of Epi by comparison to a reference technique (confocal microscopy; Conf). Oocytes were obtained from anestrus ovaries of 46 pubertal bitches. In vitro maturation was conducted with 20 oocytes/well in 500 μL M199 with 20% fetal calf serum in a humidified atmosphere of 5% CO2 at 39°C for 72 h. After Hoechst 33342 staining (20 min at RT), oocytes were observed without fixation under Epi (IX70, Olympus, France) with the excitation beam attenuated by 150-fold and emission detected by a high sensitivity camera (CCD, Olympus). The mean time for capture was 300 ms. For Conf, oocytes were fixed, stained with Ethidium Homodimer-2 (2 μM for 20 min at RT) and examined with an Ion-Argon laser (LSM 310, Carl Zeiss, Germany). For each oocyte, the nuclear stage was successively determined by Epi and by Conf. The results of both observations were compared by chi-square analysis. The optimal concentration of Hoechst dye was first determined on 401 oocytes (200 ng, 500 ng, 1 μg, or 2 μg mL–1). The 1 μg mL–1 was the lowest concentration allowing the identification of the nuclear stage by Epi in the largest proportion of living oocytes seen with DNA by Conf. At this dye concentration, Epi did not significantly impact degeneration or meiosis resumption rates: 33.3 and 22.4%, respectively for 183 oocytes submitted to Epi before Conf, compared to 37.4 and 13.6% for 147 oocytes observed only under Conf. Finally, the concordance of the nuclear stage diagnosis was tested on 379 oocytes observed individually with Epi and Conf successively. On Epi, 149 oocytes were seen without DNA. Observed on Conf, 37.5% of these were also seen without DNA, 59.7% were in the germinal vesicle stage and 2% were in metaphase. On Epi, 89 oocytes were considered as having resumed meiosis. On Conf, meiosis resumption was confirmed for 88.7% of them, but Epi failed to detect 31.4% of the oocytes having resumed meiosis among the 379 cultured oocytes. Although 80% of the metaphase II oocytes identified by Epi were confirmed to have reached this stage, 23% of metaphase II oocytes present in the culture dishes were missed. In conclusion, probably because of the high density in lipids of the cytoplasm, Hoechst staining detected by Epi for canine oocytes sorting after in vitro maturation leads to erroneously discarding a high proportion of oocytes.

The canine oocyte: uncommon features of in vivo and in vitro maturation

The biology of the canine oocyte is unusual compared with that of other mammalian females. The present paper reviews both in vivo and in vitro specificities of canine oocytes. Final follicular growth in the bitch is characterised by an early appearance of LH binding sites in the granulosa, a high proportion of polyovular follicles and a preovulatory luteinisation, starting at the time of the LH surge. Through follicular fluid, preovulatory oocytes are thus exposed to high levels of progesterone, as high as 1000-fold plasma concentrations. The composition of the follicular fluid is affected by the size of the female. The more specific aspect of oocyte biology in the bitch is ovulation: oocytes are expelled immature, at the Prophase I stage. Ovulatory follicles are 6–8 mm in diameter, releasing oocytes from 110 µm, with dark cytoplasm. Resumption of meiosis occurs from 48 h postovulation, MII stages appearing 48–54 h after ovulation. The mechanisms controlling such a late meiotic resumption are still unknown. Granulosa cells seem to play a central role as in other mammalian species, but not with cAMP as the principal mediator. The importance of a transient reactivation of oocyte transcription a few hours before meiotic resumption is to be explored. These specific features may contribute to the low efficiency of IVM. Only 10–20% oocytes reach the metaphase stage and suffer from a poor cytoplasmic maturation. Moreover, in vitro culture of canine oocytes is associated with a high proportion of degeneration. To date, IVM of the oocytes is the main limiting factor for the development of assisted reproductive techniques in the canine. A better knowledge of the basic physiology of folliculogenesis and the molecular mechanisms controlling oocyte meiosis resumption in this species may allow us to overcome this obstacle.

Steroid hormones content and proteomic analysis of canine follicular fluid during the preovulatory period

BACKGROUND

Follicular fluid contains substances involved in follicle activity, cell differentiation and oocyte maturation. Studies of its components may contribute to better understanding of the mechanisms underlying follicular development and oocyte quality. The canine species is characterized by several ovarian activity features that are not extensively described such as preovulatory luteinization, oocyte ovulated at the GV stage (prophase 1) and poly-oocytic follicles. In this study, we examined the hypothesis that the preovulatory LH surge is associated with changes in steroid and protein content of canine follicular fluid prior to ovulation.

METHODS

Follicular fluid samples were collected from canine ovaries during the preovulatory phase, before (pre-LH; n = 16 bitches) and after (post-LH; n = 16) the LH surge. Blood was simultaneously collected. Steroids were assayed by radioimmunoassay and proteomic analyses were carried out by 2D-PAGE and mass spectrometry.

RESULTS

The concentrations of 17beta-estradiol and progesterone at the pre-LH stage were 737.2 +/- 43.5 ng/ml and 2630.1 +/- 287.2 ng/ml in follicular fluid vs. 53 +/- 4.1 pg/ml and 3.9 +/- 0.3 ng/ml in plasma, respectively. At that stage, significant positive correlations between follicular size and intra-follicular steroid concentrations were recorded. After the LH peak, the intrafollicular concentration of 17beta-estradiol decreased significantly (48.3 +/- 4.4 ng/ml; p < 0.001), whereas that of progesterone increased (11690.2 +/- 693.6 ng/ml; p < 0.001). Plasmatic concentration of 17beta-estradiol was not modified (49 +/- 9.6 pg/ml) after the LH peak, but that of progesterone significantly increased (9.8 +/- 0.63 ng/ml).Proteomic analysis of canine follicular fluid identified 38 protein spots, corresponding to 21 proteins, some of which are known to play roles in the ovarian physiology. The comparison of 2D-PAGE patterns of follicular fluids from the pre- and post-LH stages demonstrated 3 differentially stained single spot or groups of spots. One of them was identified as complement factor B. A comparison of follicular fluid and plasma protein patterns demonstrated a group of 4 spots that were more concentrated in plasma than in follicular fluid, and a single spot specific to follicular fluid. These proteins were identified as gelsolin and clusterin, respectively.

CONCLUSION

Our results provide the first demonstration of size-related changes in the steroid concentrations in canine follicular fluid associated with the LH surge. 2D protein mapping allowed identification of several proteins that may play a role in follicle physiology and ovarian activity at the preovulatory stage. This may help in the future to explain and to better understand the species specificities that are described in dogs.

IGF system and ovarian folliculogenesis in dog breeds of various sizes: is there a link?

The IGF system plays a crucial role in ovarian folliculogenesis, and changes in IGF-binding protein (IGFBP) levels modulate IGF bioavailability. Data from various mammalian models suggest a link between body size, IGF1 in serum and female reproduction parameters. Among the vertebrate species, the dog exhibits the widest span in body height. Height is known to be positively correlated with the concentration of serum IGF1. In this work, the ovarian physiology of 40 bitches exhibiting a wide span of height, and breed type was investigated. IGF1, IGF2, IGFBP3, estradiol (E(2)), and progesterone concentrations in plasma and preovulatory follicular fluid were quantified. A total of 455 follicles, 2-8 mm in diameter, were recovered at the preovulatory stage, measured, and punctured. Intrafollicular levels of IGF1 were positively correlated with plasma levels, and plasma IGF1 levels were positively correlated with both bitch height and weight. The concentrations were threefold higher in large dogs compared with small dogs. A positive correlation between intrafollicular and plasmatic IGFBP3 levels and a positive correlation between plasmatic IGFBP3 levels, and both height and weight of the bitches were observed. The number of preovulatory follicles and the diameter of the three largest follicles were positively correlated with bitch height. E(2) intrafollicular concentrations were higher in preovulatory follicles from small animals than in those from large animals. In conclusion, the strong variability in height between dogs appeared to be associated with dramatic differences in IGF1, and IGFBP3 levels, in both plasma and follicular fluid. These differences were associated with significant differences in some functional aspects of ovarian follicles.

Embryo biotechnology in the dog: a review

Canine embryos are a scarce biological material because of difficulties in collecting in vivo-produced embryos and the inability, to date, to produce canine embryos in vitro. The procedure for the transfer of in vivo-produced embryos has not been developed adequately, with only six attempts reported in the literature that have resulted in the birth of 45 puppies. In vitro, the fertilisation rate is particularly low (∼10%) and the incidence of polyspermy particularly high. So far, no puppy has been obtained from an in vitro-produced embryo. In contrast, cloning of somatic cells has been used successfully over the past 4 years, with the birth of 41 puppies reported in the literature, a yield that is comparable to that for other mammalian species. Over the same period, canine embryonic stem sells and transgenic cloned dogs have been obtained. Thus, the latest reproductive technologies are further advanced than in vitro embryo production. The lack of fundamental studies on the specific features of reproductive physiology and developmental biology in the canine is regrettable in view of the increasing role of dogs in our society and of the current demand for new biological models in biomedical technology.

Mitochondrial distribution patterns in canine oocytes as related to the reproductive cycle stage

This study investigates the mitochondrial (mt) distribution in canine ovarian oocytes examined at recovery time, as related to the reproductive cycle stage, and in oviductal oocytes. Ovarian Germinal Vesicle (GV) stage oocytes were recovered from bitches in anestrous (A, n=2), follicular phase (F, n=4), ovulation (O, n=2), early luteal (EL, n=7) and mid/late luteal phase (MLL, n=2). Oviductal GV, metaphase I (MI) or MII stage oocytes were recovered from six bitches between 56 and 110 h after ovulation. Mitochondria were revealed by using MitoTracker Orange CMTM Ros and confocal microscopy. In ovarian oocytes, three mt distribution patterns were found: (I) small aggregates diffused throughout the cytoplasm; (II) diffused tubular networks; (III) pericortical tubular networks. Significantly higher rates of oocytes showing heterogeneous mt patterns (II+III) were obtained from bitches in F (75%) and in O (96%) compared with bitches in A (31%; F vs. A: P<0.05; O vs. A: P<0.001), in EL (61%; O vs. EL: P<0.01), or in MLL (0%; F vs. MLL: P<0.05; O vs. MLL: P<0.001). Fluorescence intensity did not vary according to mt distribution pattern except that it was lower in oocytes recovered in EL phase and showing small mt aggregations (P<0.001). The majority of ovulated MII stage oocytes (79%) showed diffused tubular mt network. We conclude that mt distribution pattern of canine ovarian immature oocytes changes in relation to reproductive cycle stage and that patterns observed in oocytes recovered from bitches in periovulatory phases are heterogeneous and similar to those of in vivo matured oocytes.