Factors affecting the reproductive performance of bitches: A prospective cohort study involving 1203 inseminations with fresh and frozen semen

Evidence-based practice in canine artificial insemination

A number of methods are currently used to predict the optimal date of insemination of the breeding bitch, particularly with the use of frozen-thawed canine semen which has a far shorter lifespan than fresh semen. Aside from confirming cytological oestrus, vaginal cytology is of no assistance in predicting the most fertile day(s) in a bitch; however, a neglected avenue of research suggests that vaginal cytology may be of great importance in confirming the days of optimal fertility retrospectively. Similarly, vaginoscopy provides clues as to the stage of a bitch's cycle but is inadequate as a sole determinant of her most fertile days. Nevertheless, vaginoscopy is useful to identify very late oestrus and the onset of dioestrus, as well as Stage I of labour (cervical dilatation). Due to variations in the rate at which circulating progesterone concentrations rise in individual bitches, the reliability of circulating progesterone concentrations for determining the optimal day(s) of insemination with frozen-thawed semen decreases as values rise. Moreover, progesterone assay results can vary widely due to extrinsic factors such as the time of blood sampling, sample storage conditions and the assay employed. Finally, this review investigates evidence surrounding various insemination routes and suggests that well-performed vaginal insemination, even with frozen-thawed semen, may be an acceptable approach for cases where transcervical insemination is impractical.

Comparing different sperm concentrations for optimizing cooled semen use in the dog

The use of shipping canine semen for artificial insemination has bloomed over the last 20 years. This allows for the spread of genetic material while overcoming geographical or time-related challenges. The optimal sperm concentration for cooled semen transport in the dog is unknown. Often canine semen is extended 1:3-5 vol:vol without standardized sperm concentrations for cooled shipment. We compared different sperm concentrations for cooled storage and hypothesized that lower concentrations would result in better semen quality. Semen was collected from healthy client-owned dogs (n = 8). Individual ejaculates were divided into a control aliquot (CON) extended 1:3 vol:vol with a commercial extender. The remaining sample was centrifuged and extended to 200 ×106 sperm/ml (C200), then serially diluted to 100, 50, and 25 ×106 sperm/ml concentrations (C100-C25). Aliquots were cooled for 24 h and then centrifuged and re-extended. Sperm concentration, plasma membrane integrity (PMI, %), motility (subjective total, STM; computer-assisted sperm analysis (CASA) total and progressive, TM, PM; %), and normal morphology (NM, %) were assessed in raw semen (T0), post-extension (T1), after 24 h of cooling (T2), and after processing at 24 h (T3). Cooling resulted in significant declines in STM and NM for all groups and in decreased PMI for CON and C25-50. After cooling (at T2), PMI was significantly lower for C25 compared with all the groups and higher for CON compared with C25-100 (p ≤ 0.038). Processing and re-extension after cooling further decreased the spermiogram parameters. At T3, PMI for CON was similar to C200 but significantly higher than C25-100, while C25 had the lowest PMI. For motility parameters and NM, C25 performed worse than all or most of the other groups. Comparing CON at T3 with C25-200 at T2, PMI, STM, and NM for CON were significantly lower than C25-200, C200, and C100-200, respectively. In conclusion, our results show that cooling canine semen for 24 h at 200 ×106 sperm/ml final concentration after processing or extending 1:3 vol:vol without centrifugation is preferred based on the highest PMI. If volume restrictions apply, processing raw semen and extending to the desired volume with higher sperm concentrations at the collection facility is superior to centrifugation and volume adjustment after 24 h of cooled storage.

A questionnaire-based investigation of the swimming puppy syndrome: 115 dogs

Swimming Puppy Syndrome (SPS) is a benign reversible condition of unknown etiology in multiple dog breeds. Affected dogs show laterally abducted limbs and are unable to stand and walk on their own. The current knowledge of this condition derives from few case reports or small case series. Therefore, the aim of this study was to collect data on the clinical course from a large cohort of dogs with SPS with an online questionnaire supported by video footage. Potential risk factors were compared between 110 litters with SPS and 103 unaffected litters. SPS was reported in 115 dogs from 48 different breeds comprising a wide range of small, middle, and large breeds. Litters with SPS were significantly smaller than unaffected litters. Cesarean sections were reported more frequently in affected litters, but the overall rate of reported birth complications did not differ significantly from unaffected litters. Most puppies were able to stand and walk at a median age of 4.5 weeks (up to 12 weeks) and clinical signs resolved at a median age of six weeks (up to 12 weeks). Puppies from large breeds showed faster recovery than puppies from medium and small breeds. Occasionally, residual deficits were reported and only three dogs failed to recover. A clustering of SPS occurred in closely related litters in four kennels of four different dog breeds (Greater Swiss Mountain Dog, Golden Retriever, Miniature Bull Terrier, Norwich Terrier). The study shows the benign clinical course of SPS in a large cohort of puppies from multiple dog breeds. Potential risk factors including reports on birth complications, size and muscle mass compared to littermates and diet of the dam during pregnany were evaluated and no influence on the occurrence of SPS was identified.

Factors Affecting Pregnancy Success in the Bitch Following Transcervical Insemination

Endoscopic-assisted transcervical inseminations (TCIs) have become increasingly popular. The aim of this retrospective clinical study was to evaluate data from the TCIs performed at our facility. We evaluated data from January 2018 through December 2021. This included 137 cases with fresh, 67 cases chilled, and 63 cases using frozen-thawed semen. All bitches underwent breeding management to determine the ideal breeding period. All semen samples were evaluated for total number of sperm, total motility, and progressive motility. Pregnancy was determined by B-mode ultrasonography about 4 weeks after the breeding. Litter size was determined by radiographs performed around the last week of gestation. The pregnancy rate was 83.21% for fresh, 67.16% for chilled, and 66.67% for frozen-thawed semen. There was a significant difference in litter size between fresh semen (6.82 puppies per litter) and both chilled (5.21 puppies per litter) and frozen-thawed (4.59 puppies per litter) semen (P < .05). There was no significant difference in litter size between chilled and frozen-thawed semen. There was no difference in pregnancy rates between clinicians performing the inseminations. Pregnancy rate was not different when sedation was used for the insemination (66.67%) compared to when sedation was not used (74.84%; P > .05). Performing 2 TCIs during the fertile period, regardless of the semen type, resulted in an increase of 6.6% in pregnancy rate (P > .05) and an increase of 0.7 puppies per litter, on average (P > .05). These results can be used to help guide recommendations for breeding clients on the best options to increase both pregnancy rate and litter size for their breeding.

Progesterone Analysis in Canine Breeding Management

Progesterone is a worthwhile addition to the clinical assessment of cycle stage for breeding, elective cesarian delivery, and reproductive management in the bitch if reliably measured. Clinical decisions based on systemic progesterone concentrations also require the rapid return of results. Most commercially accessible analyses capable of returning results within a day still rely primarily on immunoassays of one kind or another. Point-of-care instruments utilizing similar technology have been developed more recently to enable results to be generated in-house. Repeated monitoring of progesterone on whatever platform can be useful if consistent collection and analysis protocols ensure acceptable precision, accuracy, and repeatability.

Canine Cesarean Section: Emergency and Elective

Canine Cesarean Section (CS) is primarily performed to increase survival of newborns and less commonly to save the life or reproductive future of the dam. Conducting proper ovulation timing to accurately predict the due date will allow a planned, elective CS as an excellent alternative to a high-risk natural whelping, and possible dystocia, for certain breeds and situations. Techniques for ovulation timing, anesthesia, and surgery tips are provided.

Does Better Post-Thaw Motility of Dog Sperm Frozen with CLC Mean Better Zona Pellucida Binding Ability?

Even though the search for methods improving cryopreservation of canine spermatozoa led to an improvement of post-thaw quality, fertilizing results after insemination with frozen-thawed semen are still not satisfying. In this study, we focused on modification of spermatozoa membrane fluidity and investigated whether kinematic parameters as assessed by computer-assisted semen analyzer (CASA) can be improved. The primary aim of our study was to investigate whether the use of cholesterol-loaded cyclodextrins (CLC; 0.5 mg, 1 mg, 2 mg) and 2-Hydroxypropyl-ß-cyclodextrin (HBCD; 1 mg) positively influence capacitation status as examined by tyrosinphosphorylation, cholesterol efflux and zona binding assay (ZBA) of spermatozoa. The use of 0.5 mg of CLC increased the percentage of motile, progressive and rapid spermatozoa compared to the control. Addition of HBCD decreased motility and progressive motility of spermatozoa and the population with rapid movement in comparison to the control. The percentage of live spermatozoa without efflux of cholesterol compared to the control was increased when extender with 0.5 mg of CLC was used. There was no change in capacitation status. The zona binding ability of spermatozoa was significantly lower in the group with 0.5 mg of CLC than in the control. In conclusion, these results suggest that improvement of kinematic parameters does not necessarily coincide with better zona pellucida binding ability of spermatozoa.

Defining an Optimal Range of Centrifugation Parameters for Canine Semen Processing

Our objective was to determine a clinically relevant range of centrifugation parameters for processing canine semen. We hypothesized that higher gravitational (g) force and longer time of centrifugation would result in improved spermatozoa recovery rate (RR) but poorer semen quality. Cooled storage under standard shipping conditions was used as a stressor to evaluate long-term treatment effects. Individual ejaculates collected from 14 healthy dogs were split into six treatment groups (400 g, 720 g, and 900 g for 5 or 10 min). Sperm RR (%) was calculated post-centrifugation, and plasma membrane integrity (%, Nucleocounter^® SP-100™), total and progressive motility (%, subjective and computer-assisted sperm analysis), and morphology (%, eosin-nigrosin staining) were assessed on initial raw semen (T0), post-centrifugation (T1), and 24 h (T2) and 48 h (T3) after cooling. Sperm losses were minimal, and RRs were similar across treatment groups (median >98%, p ≥ 0.062). Spermatozoa membrane integrity was not different between centrifugation groups at any time point (p ≥ 0.38) but declined significantly during cooling (T1 vs. T2/T3, p ≤ 0.001). Similarly, total and progressive motility did not differ across treatments but declined in all groups from T1 to T3 (p ≤ 0.02). In conclusion, our study showed that centrifugation within a range of 400 g-900 g for 5-10 min is appropriate for processing canine semen.

Prevalence of cesarean sections in swiss Bernese Mountain Dogs (2001-2020) and identification of risk factors

BACKGROUND

Dystocia is an important limiting factor in animal breeding due to its cost, stress for the mother and risk of death for the neonates. Assessment of incidence and characteristics of dystocia and the inherent risk of Cesarean section are of major importance. The aim of the present study was to evaluate the reproductive performance of Bernese Mountain Dogs in Switzerland, with a particular focus on the prevalence of Cesarean sections due to dystocia, and identification of possible risk factors.

RESULTS

The investigated population included 401 bitches, 207 sires, and 1127 litters. Litter size was significantly influenced by age and parity of the dam. Incidence of Cesarean section was 30.4%, with 2.0% of procedures being elective. History of previous Cesarean section, age of the dam, and a small litter size significantly influenced the risk for Cesarean section. The stillbirth rate was 12.0%, and the number of stillborn pups was significantly higher for litters delivered by Cesarean sections after birth of the first pup. The inbreeding coefficient had a low to non-significant impact on all reproductive parameters (e.g., litter size, number of stillborn pups).

CONCLUSION

The sample of Bernese Mountain Dogs of our study had an increased prevalence of Cesarean sections compared to the literature, and advanced age of the dam, litter size and prior Cesarean sections in the dam's reproductive history was identified as significantly influencing factors. In order to improve pups' survival rate, elective Cesarean section may be indicated in bitches that have had a previous Cesarean-section/s, are of advanced age, and/or have a small litter.

Repeated pregnancy in a bitch, with a diagnosis of extensive cystic endometrial hyperplasia, after the exact determination of the optimal time for breeding

A 6-year-old bitch was presented to the clinical examination with the aim of determining the optimal time for intrauterine insemination by frozen-thawed semen. The bitch had already had two litters in the past. Extensive cystic endometrial hyperplasia was diagnosed by an ultrasound examination in the bitch. The timing of the endoscopic transcervical insemination by a combination of ultrasonographic examination of the ovaries and determining the progesterone concentrations contributed to the successful conception in the bitch. The ultrasonographic examination of the ovaries represents a non-invasive method which allowed us to view the changes on the ovaries in real time and, thus, is a very suitable method for the specification of the ovulation time in bitches. Cystic endometrial hyperplasia is considered to be a possible cause of infertility. Nevertheless, the bitch repeatedly conceived and had larger litter sizes. Moreover, a considerable reduction in the number of endometrial cysts was observed after the third pregnancy of the bitch. In the described clinical case, the influence of the cystic endometrial hyperplasia on the conception was not demonstrated.

Analytical and clinical performance of a fluorescence enzyme immunoassay for progesterone and determination of ovulation day in bitches

We evaluated the performance of a third-generation fluorescence enzyme immunoassay kit (FEIA; Tosoh Bioscience) for progesterone (P4) measurement in canine serum to identify the day of luteinizing hormone (LH) peak and ovulation in bitches. We conducted P4 assays on 54 serum samples using a FEIA and a chemiluminescence immunoassay (CLIA; Siemens). For the FEIA kit, the linearity test, recovery test, inter- and intra-assay CVs, and total error observed (TEo) were calculated. Serum samples from 28 bitches were used to evaluate the association of P4 concentration with the day of LH peak and the day of ovulation based on P4 thresholds (P4 ≥ 2 ng/mL, and doubling at 4-8 ng/mL in the following 48 h), and with pregnancy length. Linearity was 75-97% and 86-94% for high (37.0 ng/mL) and medium (3.8 ng/mL) pool serum samples, respectively. Recovery was 86.4-119%. Intra-assay CVs were 2.6%, 3.3%, and 5.2% for low (0.23 ng/mL), medium (6.24 ng/mL), and high (38.3 ng/mL) pool concentrations. Inter-assay CVs were 2.22% and 2.53% for P4 concentrations of 2.70 ng/mL and 8.2 ng/mL, respectively. TEo was 8.72% and 22.7% for P4 concentrations of 2 and 8 ng/mL, respectively. The mean pregnancy length from the day of LH peak and ovulation were 64.6 ± 1.7 and 63.3 ± 1.1 d, respectively. The third-generation FEIA kit that we tested was highly reliable.

Parameters in Canines After Cesarean Sections

This study evaluated fertility in canines after cesarean section and compared it with natural parturition. Parameters, such as the time of the next heat after the first parturition or cesarean section, the heat which was used for another breeding attempt, whether it was successful, the number of puppies that were born, and the necessity of another cesarean section were examined. The study relied on questioning patient owners at a University clinic. A Google online form was also used. Information for 261 dogs from different breed groups was included, of which 119 bitches were in the cesarean section group, and 142 were in the natural parturition group. In total, 93 ± 2.7% [LSMeans ± standard error (SE)] and 91.12 ± 3% (LSMeans ± SE) of the bitches became pregnant after cesarean section and natural parturition at the first breeding attempt. There was no significant effect on the breed group or whether the bitch had undergone a cesarean section before (p = 0.8 and p = 0.63). Bitches, which underwent a cesarean section, were more likely to have further cesarean sections performed (p < 0.001). However, neither the breed groups (p = 0.17), whether the bitch had undergone a cesarean section (p = 0.59), nor the number of previous parities had any effect on the number of puppies born (p = 0.95). The breed group bulldogs had a high proportion of cesarean sections. Only 42.11% of the bulldogs had a natural parturition as the first included parturition and only 31% gave birth naturally thereafter.

Dead or Alive? A Review of Perinatal Factors That Determine Canine Neonatal Viability

Simple Summary

The article summarizes the current knowledge on factors related to pregnancy, parturition, and newborns that affect the health status of a puppy and determine its chances for survival and development. The detailed information is provided in terms of breed predispositions, objectives of pregnancy monitoring, potential sources of complications, and veterinary advances in care and treatment of perinatal conditions. Successful pregnancy outcomes still pose challenges in veterinary neonatology; thus, publications presenting the current state of knowledge in this field are in demand.

Abstract

The perinatal period has a critical impact on viability of the newborns. The variety of factors that can potentially affect the health of a litter during pregnancy, birth, and the first weeks of life requires proper attention from both the breeder and the veterinarian. The health status of puppies can be influenced by various maternal factors, including breed characteristics, anatomy, quality of nutrition, delivery assistance, neonatal care, and environmental or infectious agents encountered during pregnancy. Regular examinations and pregnancy monitoring are key tools for early detection of signals that can indicate disorders even before clinical signs occur. Early detection significantly increases the chances of puppies’ survival and proper development. The purpose of the review was to summarize and discuss the complex interactions between all elements that, throughout pregnancy and the first days of life, have a tangible impact on the subsequent fate of the offspring. Many of these components continue to pose challenges in veterinary neonatology; thus, publications presenting the current state of knowledge in this field are in demand.

Factors influencing ease of whelping and its relationship with maternal behaviour and puppy perinatal mortality in commercially bred dogs

For dog breeders, parturition is a critical stage in the reproductive cycle of the dam. Evidence in other mammals suggests that a difficult labour can influence maternal behaviour and offspring viability during the first hours postpartum. However, the effect of whelping difficulty on the onset of maternal behaviour has not yet been investigated in domestic dogs. Here we developed an ease of whelping (EoW) index in dams maintained within a Commercial dog Breeding Establishment (CBE) environment and investigated the relationship between intrinsic and extrinsic factors (breed group according to size/weight, litter size, parity, whelping season and origin of the dam), EoW, early maternal behaviour and puppy perinatal mortality. The behaviour of 30 dams was observed throughout the whelping process, starting 24 h before delivery of the first puppy until birth of the last puppy. Parturition duration, birth interval, and behaviours indicative of distress, restlessness, and general activity were scored and included in a Principal Component Analysis to construct the EoW index. Subsequently, mother-pup interactions and puppy perinatal mortality were recorded during the first 24 and 72 h postpartum respectively. Results showed that EoW was significantly affected by whelping season, litter size and origin of the dam (whether she was born and raised within the CBE or brought in). Furthermore, mothers that experienced more difficult parturitions (higher EoW score) spent more time lying in contact with their puppies during the first 24 h postpartum. Time in contact with puppies was also significantly affected by breed group. Nursing duration was significantly affected by breed group and origin of the dam. Additionally, medium-size breed (10-20 kg) puppies were significantly less likely to experience perinatal mortality than large breeds (> 20 kg). These findings are particularly relevant for the welfare of breeding dams maintained in large-scale CBEs where the staff-to-dog ratio might be insufficient to adequately manage multiple simultaneous parturitions.

Ovarian hyperstimulation syndrome in a bitch caused by recombinant human chorionic gonadotropin treatment of suspected luteal insufficiency – a case report

Two bitches with a history of hypoluteoidism were treated by recombinant human chorionic gonadotropin (r-hCG) in repeated doses during early dioestrus. The level of progesterone increased, but the therapy led to hyperstimulation of the ovaries which resulted in ovarian hyperstimulation syndrome (OHSS), with subsequent development of oestrogen toxicity. This is the first case documenting OHSS in a canine after administration of r-hCG. Although manifested during dioestrus in our case report, the occurrence of OHSS is associated with similar administration of r-hCG to women. The described use of r-hCG is not appropriate for luteal insufficiency treatment, but seems to have a place in assisted reproduction technology because of its surprising effects. Further research of luteotrophic factors in bitches is warranted because of these unpredictable results. Lower doses and frequency of administration need to be considered for a better outcome.

Assisted reproductive techniques for canines: preservation of genetic material in domestic dogs

Assisted reproductive techniques (ARTs), such as artificial insemination, in vitro fertilization, and cryopreservation of gametes/zygotes, have been developed to improve breeding and reproduction of livestock and for the treatment of human infertility. Their widespread use has contributed to improvements in human health and welfare. However, in dogs, only artificial insemination using frozen semen is readily available as an ART to improve breeding and control genetic diversity. A recent priority in sperm cryopreservation is the development of alternatives to egg yolk, which is widely used as a component of the sperm extender. Egg yolk can vary in composition among batches and is prone to contamination by animal pathogens. The latter can be a problem for international exchange of cryopreserved semen. Low-density lipoprotein and skim milk are promising candidates for use as extenders, to ensure fertility after artificial insemination. Although not tested for its effects on fertility following artificial insemination, polyvinyl alcohol may also be a useful alternative to egg yolk as an extender. The development of cryopreservation techniques for canine embryos lags behind that for other mammals, including humans. However, given the success of non-surgical embryo transfer in 2011, studies have sought to refine this approach for practical use. Research on sperm cryopreservation has yielded satisfactory results. However, investigation of other approaches, such as cryopreservation of oocytes and gonadal tissues, remains insufficient. Techniques for the efficient induction of estrus may aid in the development of successful canine ARTs.

Sperm Global DNA Methylation (SGDM) in Semen of Healthy Dogs

Male infertility is an emerging problem in both humans and animals, and the knowledge of its causes is the first step to identifying new diagnostic and therapeutic strategies. In humans, alteration of sperm DNA methylation have been related to poor quality semen, impaired seminal parameters, azoospermia and reduced fertility. Although semen analysis is routinely used to evaluate the male reproductive potential in the canine species, no authors have attempted to relate semen characteristics to the sperm global DNA methylation (SGDM). The aim of this study was to evaluate the SGDM level in healthy dogs and to correlate it with semen parameters that are currently used in dog semen analyses. Conventional and unconventional (sperm DNA fragmentation and SGDM) seminal parameters of thirty dogs from different breeds were evaluated. A positive correlation was found between SGDM and sperm concentration (r = 0.41; p < 0.05), and total sperm count (r = 0.61; p < 0.001); SGDM was significantly lower in oligozoospermic vs non-oligozoospermic dogs (4.3% vs. 8.7%; p < 0.005). Our findings suggest that SGDM levels are related to conventional seminal parameters, and could be used as a marker of testis function and spermatogenesis in dogs.

Dystocia after Unwanted Mating as One of the Risk Factors in Non-Spayed Bitches-A Retrospective Study

Simple Summary

This is an article presenting the clinical data on the incidence of difficult labour in dogs being mated without owners’ intentions (accidental mating, unplanned breeding). Despite the widespread availability of spaying and its safety, unplanned and unwanted pregnancies in dogs are still a frequent concern. Unfortunately, in 8.3% (76/914) of cases, they result in difficult labour and deadly complications for the dam and her litter. Better owners’ education about the importance of neutering their pets and understanding of the benefits of early spaying by animal shelter managements and by breeders selling pets might improve the situation in the future. On the other hand, in such cases, it seems to be justified to advise the termination of pregnancy through spaying or the use of abortifacient drugs, despite the ethical concerns, because waiting for natural delivery could cause unnecessary suffering both to the bitch and her unborn puppies.

Abstract

This article presents a retrospective study on dystocia cases in bitches that were unintentionally mated and carried an unwanted pregnancy in the last 39 years. The evaluated medical records include 76 cases of difficult labour, which is 8.3% of 914 dystocia cases recorded during the period. Of these bitches, 38.2% (29/76) were 8 years, and 18.4% (14/76) were younger than 12 months. In 67/76 cases (88.2%), conservative (pharmacological and manual) obstetrical assistance proved to be unsuccessful, and caesarian section (CS) had to be performed, in contrast to the remaining recorded cases of dystocia (in which the pregnancy was intended and expected) when CS was performed significantly less often, in 71.5% (599/838) of cases. In unplanned pregnancies, 46.6% (110/236) of delivered pups were dead compared to only 26.4% (864/3273) dead pups in planned pregnancies. p value < 0.05 was considered significant. Despite the widespread availability of the spaying procedure nowadays and its safety, unplanned and unwanted pregnancies in dogs are still a concern in clinical practice. However, throughout the years investigated here, we observed an apparent decrease in the occurrence of dystocia after unintended mating, with much less recorded cases from year 2004 (71 vs. 5). Most probably, this is due to the increasing popularity of surgical castration in both females and males, and rising societal awareness of its importance, giving hope that some improvement in the welfare of dogs has already been achieved.

Factors influencing parentage ratio in canine dual-sired litters

Breeding a bitch with two different sires during a single estrous cycle has the potential to facilitate rapid genetic gain and improve reproductive performance within a canine breeding colony. There is limited data regarding the factors that contribute to the success of dual-sired litters in domestic dogs, and only anecdotal evidence suggesting that these litters rarely produce offspring from more than one sire. The objective of this prospective clinical study was to investigate multiple factors that likely affect the success of dual-sired litters on whelping rate, litter size and parentage ratio. These factors include: timing of artificial insemination (AI), order of sires, number of AI's per cycle, semen type, sperm quality and age of sire and bitch. Data collected over a 10 year period from twenty-nine estrous cycles (28 individual bitches of 10 different breeds) were evaluated after an initial AI with frozen semen from the 'genetically desired' sire and followed up with a second AI with either fresh (n = 9) or frozen (n = 16) semen or natural mating (n = 4) from a different, 'back up', sire. DNA parentage of each pup born was determined by using a primary panel of 288 SNPs. The whelping rate and litter size from previous single sire inseminations per estrous cycle, in the same bitches, (n = 16) over 25 estrous cycles using either fresh (n = 4) or frozen-thawed (n = 21) semen, were analyzed as controls. Of the 29 dual-sired breedings, 26 bitches whelped (89.7%), and 8 litters (30.8%) were of mixed parentage. In the litters of mixed parentage after a dual-sired breeding, a greater proportion of the offspring were from the second sire than the first sire (73.0% and 27.0% respectively; P < 0.05). Interestingly, in litters where all pups were of single sire parentage after a dual-sired breeding, 50.0% of the offspring were by the first sire and 50.0% were by the second sire. For litters of mixed or single paternity produced by dual-sired breeding there was no difference in average litter size. However, on a per estrous cycle basis for each bitch the whelping rate (89.7% v. 76.0%.) and litter size (5.5 ± 2.5 v. 4.0 ± 2.78) of all dual-sired breedings were greater (P < 0.05) compared to previous single-sired breedings (controls) respectively. This study demonstrates that offspring of mixed parentage derived from dual-sired breedings may be achieved. Furthermore, insemination with semen from two different sires may increase the whelping rate and litter size, which is an important consideration when using genetically valuable, or older individuals with potentially reduced fertility.

An exploratory analysis of demography and movement patterns of dogs: New insights in the ecology of endemic Rocky Mountain-Spotted Fever in Mexicali, Mexico

An outbreak of Rocky Mountain spotted fever (RMSF) transmitted by the brown dog tick (Rhipicephalus sanguineus sensu lato) has emerged as a major human and animal health concern in Mexicali, Mexico. Due to high rates of brown dog tick infestation, susceptibility, and association with humans, dogs serve as sentinels and have a key role in the ecology of RMSF. A cross-sectional household questionnaire study was conducted in six rural and urban locations to characterize dog ecology and demography in RMSF high-and low-risk areas of Mexicali. In addition, we tracked movement patterns of 16 dogs using a GPS data logger. Of 253 households, 73% owned dogs, and dog ownership tended to be higher in high-risk areas, with a mean dog:human ratio of 0.43, compared with 0.3 in low-risk areas. Dogs in high-risk areas had higher fecundity and roamed more, but the dog density and numbers of free-roaming dogs were comparable. There was a higher proportion of younger dogs and lower proportion of older dogs in high-risk areas. The high proportion of immunologically naïve puppies in high risk areas could result in a lack of herd immunity leading to a more vulnerable dog and human population. The marked increase of space use of free-roaming dogs in high-risk areas suggests that unrestrained dogs could play an important role in spreading ticks and pathogens. As means to limit RMSF risk, practical changes could include increased efforts for spay-neuter and policies encouraging dog restraint to limit canine roaming and spread of ticks across communities; due to dog density is less impactful such policies may be more useful than restrictions on the number of owned dogs.

Cold case: Small animal gametes cryobanking

Germplasm preservation of animals, whether they are valuable domestic breeds or rare species, is the main goal of gamete cryobanking. Dogs and cats act as models for this purpose thanks to the wide availability of biological material which can be employed to experiment protocols that can then be applied to wild animals. This review is focused on spermatozoa, oocytes and gonadal tissues cryobanking in small domestic animals, which is still an unsolved case. Like in a courtroom, evidences of cryoinjuries affecting cellular structures will be presented, penalties as loss of functionality due to cellular alterations will be described, and appeal as strategies to protect gametes from damages or rescue their functionality will be discussed. Differences and similarities between single cell or tissue cryopreservation will be highlighted, together with the rationale for the choice of one type of preservation or another and the fundamental principles which they are based on. The deep analysis of different aspects that still hamper the success of cryopreservation in small animals can help clarify where research is most needed. Therefore, as in a cold case, investigation should remain open in order to hopefully find the solution and make these procedures more and more efficient in the future.

Metformin Improves Quality of Post-Thaw Canine Semen

Simple Summary

Cryopreservation of semen is getting easier, however, fertilizing results after insemination with frozen-thawed semen is still not constant in canine species depending on the breed and could be still improved. In this study, we decided to modulate the mitochondrial activity through the addition of metformin in semen extender to increase germ cells’ quality. Metformin presented the absence of toxicity and an improvement in sperm motility after thawing, as well as an increase in the expression of several molecular markers associated with quality. In addition, the oxidative stress and DNA damage were reduced in semen frozen in the presence of metformin. Overall, these data suggest that metformin added in canine semen extender has beneficial effects on canine semen quality and could be associated with different components such as vitamins, to enhance the antioxidants status.

Abstract

Sperm cryopreservation is an assisted reproductive technique routinely used in canine species for genetic conservation. However, during cryopreservation, the DNA damages are still elevated, limiting the fertilization rate. The present study was conducted to evaluate whether supplementation of canine semen extender with a molecule limiting the metabolic activities can improve the quality of frozen-thawed canine spermatozoa. We used metformin, known to limit the mitochondrial respiratory and limit the oxidative stress. Before and during the freezing procedure, metformin (50 µM and 500 µM) has been added to the extender. After thawing, sperm exposed to metformin conserved the same viability without alteration in the membrane integrity or acrosome reaction. Interestingly, 50 µM metformin improved the sperm motility in comparison to the control, subsequently increasing mitochondrial activity and NAD⁺ content. In addition, the oxidative stress level was reduced in sperm treated with metformin improving the sperm quality as measured by a different molecular marker. In conclusion, we have shown that metformin is able to improve the quality of frozen-thawed dog semen when it is used during the cryopreservative procedure.

Canine fertility: The consequences of selection for special traits

Pedigree dogs and cats are bred aiming to conform breed standards with very poor consideration for breeding stock fertility. At the same time, the genetic asset underlining reproductive traits could be effectively analysed like in other species under selection. The definition of selection targets is very important in breeding protocols determination. The aim of the present work is to present an overview of the different correlations between reproduction and genetics, starting from selection procedure and inbreeding coefficient moving to genomic and the application of SNPs and GWAS on population study and identification of genes involved in phenotypical variation of reproductive traits in dogs. Particular relevance has been given to the concept of inbreeding which effects on canine reproduction have been presented. The use of genomic information in inbreeding coefficient calculation can be considered an improved effective procedure in the evaluation of the genetic variability loss in canine population and its negative effects on reproductive traits.

Uterine and umbilical resistance index and fetal heart rate in pregnant bitches of different body weight

The aim of this study was to compare uterine and umbilical artery blood flow and fetal heart rate (FHR) in small, medium and large body weight (BW) dogs during the second half of pregnancy. Purebred pregnant bitches were assigned to one of the following groups according to their BW: small (S; ≤10 kg), medium (M; 11-25 kg) and large (L; >25-45 kg). Uterine and umbilical Doppler and M-mode ultrasonography was conducted every 10 days from Day 30-60 (Day 0 = first day of gestation). From Day 40, uterine and umbilical artery resistance index (RI) progressively and differentially decreased in the three groups (P < 0.01) being less in L than S bitches (P < 0.01). Litter size but not maternal BW (P > 0.1) affected uterine RI on Days 40 (r = 0.39; P < 0.01) and 50 (r = 0.41; P < 0.01). Conversely, on Day 60, maternal BW (r = 0.61; P < 0.01) had an effect on uterine RI while litter size did not (P > 0.1). Fetal heart rate increased from Day 30-50 and decreased to the time of parturition (P < 0.01) without differences among groups at any time point (P > 0.1). Uterine and umbilical blood flow differentially increased throughout mid- and late-pregnancy in breeds with large and small BW. These differences were affected by litter size on Days 40 and 50, and by maternal BW on Day 60. Conversely, during this same period, FHR did not vary among BW groups. Physiological variations should be considered when gestational ultrasonic examination is interpreted in different BW bitches.

The Effect of N-N-Dimethylformamide on the Membrane Characteristics of Canine Spermatozoa After Cryopreservation, and its Relationship With Post-Thaw Motility

Some studies have demonstrated that glycerol is superior to amides in preserving sperm motion characteristics of canine sperm; however, little is known about the effect of these cryoprotectants on the membrane characteristics of canine spermatozoa after freezing/thawing. In this study, the effects of using either N-N-dimethylformamide (DMF) or glycerol (GLY) on the integrity and function of the canine sperm, after cryopreservation were determined. We hypothesized that the use of a multiparametric approach for assessing the effect of DMF on the membranes of canine sperm would explain the lower values reported for post-thaw motility. Ejaculates from 12 dogs were collected, split into 2 groups, and frozen using a tris-fructose-citrate-egg yolk-based extender containing either 7% (v/v) GLY or 7% (v/v) DMF. Frozen straws (n = 120) were thawed and analyzed for subjectively-assessed sperm progressive motility, normal morphology, plasma membrane integrity, plasma membrane function (HOST+), acrosome membrane integrity, high mitochondrial membrane potential, and simultaneous assessment of sperm membrane integrity and function by a triple-staining fluorescent procedure. Overall, sperm motility and membrane intactness/function were higher when GLY was used as a cryoprotectant, as compared to DMF (P < .05). A model to explain the variation in progressive motility using the values obtained from the sperm integrity and function parameters was designed. The percent HOST+ sperm and high mitochondrial membrane potential sperm were mostly associated with the changes observed in the progressive motility (r² = 0.84; P = .043) when either GLY or DMF were used as cryoprotectants. These results may explain the overall reduced sperm quality observed after cryopreservation, as a reflection of sublethal damage sustained by the sperm membranes.

A retrospective study of reproductive disorders in female dogs from the city of Uberlândia, Minas Gerais, Brazil

Diseases of the reproductive system are common in both sexes in the most varied of species. In female dog, these diseases produce different degrees of morbidity and mortality and are influenced by environmental conditions, reproductive history, and previous drug treatments. Reproductive disease may have different consequences, ranging from the absence of clinical signs to the impairment of fertility. The objective of this study was to determine the causes of reproductive diseases in female dogs admitted to the Veterinary Hospital, Federal University of Uberlândia, during a six-year period (2012-2017) and to identify the most frequently occurring diseases. Information relative to the species, age, breed, and sex of 32,944 were obtained for animals. Of these, 16,480 were female dogs and 1,185 were diagnosed with alterations to the reproductive system. The animals were divided into four groups according to age (puppies, young adults, adults, and old) and disease of the reproductive system (Group 1 - vaginal and vulvar alterations; Group 2 - alterations to the estrous cycle, ovary, and uterus; Group 3 - alterations to the gestational period and parturition). The highest occurrence of diagnoses (47%) was recorded in young adult female dogs (1 to 5 years old). The most frequent alterations in female dogs were pyometra (48.8%), dystocia (13.6%), and transmissible venereal tumor (TVT) (12.6%). Crossbred dogs were the most affected with alterations to the reproductive system, representing 60% of all the female dogs diagnosed with any pathologic alteration. In conclusion, a 7.2% occurrence of reproductive disorders shows the relevance of these diseases in small animals and suggests that new methods are needed for the prevention, early diagnosis, and treatment of these disorders.

Semen parameters and testicular dimensions in small breed dogs below ten-kilogram bodyweight

Because of few available data on semen parameters in small breed dogs, the study aimed to analyse semen and measure testes of dogs ≤10.0 kg bodyweight. Semen was collected from 41 fertile stud dogs, which were divided based on bodyweight: group 1 ≤ 5.0 kg and group 2 between 5.1 and 10.0 kg. Median values for ejaculate volume (group 1: x ~ 1.2 ml; group 2: x ~ 2.2 ml), total sperm output (group 1: x ~ 110.7 × 10⁶ ; group 2: x ~ 215.1 × 10⁶ ) and testicular volume (group 1: left testicle x ~ 2.8 ml, right testicle x ~ 2.7 ml; group 2: left testicle x ~ 5.5 ml, right testicle x ~ 5.0 ml) were lower in group 1 compared to dogs of group 2 (p = .001; p = .001; both testes: p < .001). There was no difference in sperm concentration (p = .985). Based on these results, introduction of an additional weight group to the commonly used reference values is recommended, since values for ejaculate volume, total sperm output and testicular dimensions for dogs ≤5.0 kg bodyweight differed significantly from values of dogs with a bodyweight from 5.1 to 10.0 kg.

A Solution for the Shortage of Detection Dogs: A Detector Dog Center of Excellence and a Cooperative Breeding Program

Currently, demand for US-bred and born detector dogs exceeds available supply, while reliance on foreign-bred sources introduces many unnecessary and unwanted risks. With proper management of a domestic supply line, U.S. breeders can improve both health and behavior by applying scientific principles to breeding and raising of detector dogs. A cooperative national detector dog breeding and development program will mitigate the current shortage of domestic-bred dogs that meet the health and behavior standards required by government, military, and law enforcement agencies. To coordinate such a cooperative, we propose a Detector Dog Center of Excellence (DDCoE) led by representatives of academic canine science programs guided by an advisory board of stakeholders. As a non-governmental organization, the DDCoE will oversee selective breeding of dogs owned by breeders, purchase the resulting puppies, and its members will supervise puppy raising until dogs are of a suitable age to be purchased by government agencies or other working dog organizations. The DDCoE will serve as an approved vendor to facilitate the procurement process. Breeding decisions will be based on proven quantitative genetic methods implemented by a specialized database. A national working dog semen bank will ensure conservation of diverse genetic material and enhance selection response by providing numerous potential sires. As a data collection and genetic evaluation center, the DDCoE will lead research to define quantitative traits involved in odor detection, to understand how these traits develop, and methods to optimize training of dogs endowed with enhanced odor detection ability.

Normal progesterone profiles during estrus in the bitch: A prospective analysis of 1420 estrous cycles

Appropriate timing of insemination in the bitch, through monitoring of serial serum progesterone concentrations, has historically been based on the detection of important physiological reproductive events which include the LH surge and ovulation 2-3 days later. Previous hormone profile studies during the estrus period in the bitch, in which determination of these physiological reproductive events has been defined, have been based on low numbers of bitches of similar breeds and body weights. Therefore, the aim of this large-scale prospective study was to define the normal serum progesterone profile during the estrus period in a large number of bitches of various breeds and body weights. In addition, we investigated if the rate of change in progesterone concentrations during the fertile period affected the reproductive performance of bitches after insemination with either fresh or frozen-thawed semen. A total of 1300 individual bitches, representing 84 different breeds, contributed 1420 estrous cycles and 4213 serum progesterone values over the 11-year (2007-2017) study period. The mean (±SD) progesterone concentration at estimated LH0 was 2.7 ± 0.6 ng/ml and at the time of estimated ovulation it was 4.8 ± 0.9 ng/ml and 7.2 ± 1.3 ng/ml (LH+2 and LH+3 respectively). There was no difference in the shape of progesterone profiles for bitches of different body weights. Furthermore, mean progesterone concentrations on each day between LH-6 and LH+7 were not different amongst bitches of different breeds and body weights and there was no effect of mean progesterone concentrations on any day on whelping rate or litter size. However, there was a significant effect of the rate of change in progesterone concentrations on litter size when frozen semen was used. The litter sizes of bitches inseminated with frozen semen with slow progesterone curves were significantly smaller compared to bitches with fast progesterone curves (3.9 ± 1.8 vs 5.6 ± 3.1 pups per litter respectively; P < 0.001). There was no effect of bitch age on the normal progesterone curve, or its rate of change. This is the first report of the normal progesterone profile during estrus in the bitch derived from a large number of serial progesterone measurements obtained from bitches of various breeds and body weights. Importantly, the predictability and reliability of this progesterone profile regardless of breed or body weight gives clinicians the confidence to accurately determine the optimal time for insemination, which is critical to reproductive success, especially when frozen semen is used.

Whelping and Dystocia: Maximizing Success of Medical Management

Dystocia can be defined broadly as "difficult birth" or more specifically as difficulty in the bitch expelling the pups through the cervix, vagina, and vestibule. It is a fairly common emergency presented to the small animal practitioner with an incidence rate of approximately 5%. The incidence of dystocia is highest in toy and brachycephalic breeds, and occurs frequently in small litters (<3 pups) due to fetal oversize and delayed onset of labor. As duration of labor progresses, the mortality of the pups and even the bitch increases, with the highest number of stillborn pups occurring after 6 hours from the time of active parturition. Practitioners should understand the mechanism of normal parturition so that abnormalities can be readily identified and medical or surgical intervention performed in a safe and timely manner.