Comparison of fertility, regular returns-to-estrus, and calving interval between Ovsynch and CO-synch + CIDR protocols in dairy cows

The main aims of the present study were to compare the pregnancy rate (PR), regular returns-to-estrus, and calving interval of a CO-Synch + controlled internal drug release (CIDR) device, commonly used to synchronize ovulations in beef cows, with the classical Ovsynch protocol in high-producing dairy cows. Holstein-Friesian cows (n = 128) from six commercial dairy herds, ≥40 days postpartum and not previously inseminated, were randomly assigned to one of two treatments. Cows submitted to Ovsynch protocol (group OS as control group; n = 66) received 10 μg of a GnRH analogue 7 days before and 48 hours after 25 mg PGF2α, followed by artificial insemination (AI) 16 hours after the second GnRH administration. Cows submitted to CO-Synch + CIDR (1.38 g of progesterone) inserted for 7 days beginning at the first GnRH administration (group CoS + CD; n = 62) had the second administration of GnRH concurrent with AI, 64 hours after CIDR removal/PGF2α administration. Nonpregnant cows with return-to-estrus between 18 and 24 days after first AI were reinseminated (second AI). Logistic regressions were used to analyze PR and returns-to-estrus. No effect of group or herd was observed in PR at first timed AI. However, the sum of cows pregnant at first AI and nonpregnant cows with regular returns-to-estrus and the total PR (first + second AI) were influenced by group treatment. Overall, cows of group CoS + CD (total PR = 56.5%) were 2.1 times more likely to became pregnant after AI and until first regular returns-to-estrus than cows of group OS. The calving interval was lower in group CoS + CD (425.9 ± 78.8 days; ±SD) than in group OS (475.3 ± 83.7 days). The CO-Synch + CIDR protocol was reliable to use in dairy herds and provided reproductive advantages when compared with Ovsynch protocol.

O protocolo hormonal ovsynch e suas modificações em vacas leiteiras de alta produção: uma revisão

A eficiência reprodutiva em vacas leiteiras de alta produção representa atualmente um dos maiores desafios para a viabilidade das explorações. O presente trabalho teve como objetivo reportar as modificações dos protocolos de indução ovulatória baseados na administração programada de prostaglandina F2α (PGF 2α) entre duas aplicações de hormona libertadora de gonadotrofina (GnRH ), seguida da inseminação artificial em tempo fixo (IATF ). Tendo por base o protocolo hormonal Ovsynch, novos protocolos foram desenvolvidos tentando aumentar a sua eficiência reprodutiva, seguindo diferentes estratégias: (1) manipulação dos padrões de desenvolvimento folicular antes da GnRH -1, (2) otimização do ambiente hormonal peri-ovulatório, (3) otimização do intervalo de tempo entre a PGF 2α e a GnRH -2 e o momento da IA após a GnRH -2, (4) suplementação com progesterona antes da IATF , (5) redução do período de dominância folicular e aumento do proestro, e (6) controlo do crescimento folicular após a IATF . As modificações do protocolo Ovsynch permitiram a manutenção da taxa fertilidade à 1ª inseminação, até aproximadamente 40 %, quando comparada com inseminações realizadas após deteção do cio natural, com a consequente melhoria da gestão reprodutiva das manadas. As pesquisas futuras deste tipo de protocolos de indução ovulatória deverão dar enfase a aspetos nutricionais e de produção leiteira das vacas assim como ao stresse térmico em países de zonas mediterrânicas, subtropicais e tropicais.

Dilated cardiomyopathy and sinoatrial dysfunction in an Estrela mountain dog

A 1 yr old male Estrela mountain dog was evaluated as a part of a screening program for dilated cardiomyopathy. The dog came from a family with a history of dilated cardiomyopathy but was asymptomatic. Occult dilated cardiomyopathy and sino-atrial dysfunction were diagnosed based on echocardiography and electrocardiography. These two disorders may be associated given that related dogs have been diagnosed with the same disorders. The dog has remained asymptomatic for 4 years following initial evaluation.

Histologic characterization of dilated cardiomyopathy in Estrela mountain dogs

Dilated cardiomyopathy (DCM) is the second-most-important acquired cardiovascular disease in dogs (excluding heartworm disease in some geographic regions) and a major cause of morbidity and mortality in Estrela Mountain Dogs. The objective of this study is to describe the histologic features of DCM in Estrela Mountain Dogs, with special attention to the localization and quantification of attenuated wavy fibers (AWFs), fibrosis, and fatty infiltration. Myocardial samples from 10 areas were collected from the hearts of 10 dogs with DCM and 7 dogs without signs of cardiac disease-namely, the basal, middle, and apical portions of the free wall of both cardiac ventricles and the interventricular septum, as well as the left ventricular papillary muscle. In each sample, the presence or absence of AWFs was noted, and fatty infiltration and fibrosis were quantified. Fatty infiltration, fibrosis, and AWFs were observed in the myocardium of all dogs with DCM, in contrast to what has been described in other breeds. The left ventricular myocardium was the best tissue for diagnosis of DCM, based on these histologic features. The authors concluded that quantification of fibrosis and observation of AWFs in the left ventricular myocardium are useful in the histologic diagnosis of DCM in Estrela Mountain dogs.

Serotyping of naturally Toxoplasma gondii infected meat-producing animals

Serotyping was previously described as a promising method for typing strains of Toxoplasma gondii. The majority of precedent studies utilized serum samples collected from human patients with different T. gondii-associated pathologies. The aim of this work was to study the applicability of the same procedure for serotyping naturally infected meat-producing animals. An ELISA test based on GRA6 and GRA7 C-terminal polymorphic peptides was used. Peptide GRA6II has polymorphisms specific for the archetypal strains type II, GRA6I/III for strains type I and III, GRA7I for strains type I and GRA7III for strains type III. As reference material, and to validate this approach, serum samples from eleven free-range chickens and fifteen pigs used for Toxoplasma genotypes isolation were selected. These strains integrate the Biological Resource Centre (BRC) ToxoBS Bank. Three serum samples from chickens and two from pigs had serotyping results in agreement with genotyping. Thirty-five serum samples from chickens, twenty-nine from pigs and fifty from sheep, seropositive for T. gondii, from which no isolate was obtained, were also serotyped. Serotype III appeared significantly more frequent among sheep. Our results show that serotyping still need refinement, but may become a valuable tool for typing Toxoplasma strains from animal origin.

Transthoracic echocardiography in Estrela Mountain dogs: reference values for the breed

Of 100 Estrela Mountain dogs, 74 were examined to obtain echocardiographic reference values for the breed. The influence of bodyweight, age and sex on different echocardiographic parameters was studied using either analysis of variance or regression analysis. Statistically significant differences were found between sex and heart rate as well as interventricular septal thickness at end-systole and left ventricular internal dimension at end-diastole. A statistically significant linear correlation was also found between several parameters and (1) age (mean arterial pressure, left ventricular internal dimension at end-systole, fractional shortening, circularity index in systole, aortic valve velocity time integral, pulmonic valve velocity time integral and mitral valve E wave peak velocity), (2) weight (left ventricular posterior wall thickness at end-diastole and end-systole, end-diastolic volume index, left atrium diameter, aortic valve peak velocity and mitral valve E wave deceleration time), (3) sex and age (left ventricle end-diastolic volume), and (4) sex and weight (aortic root diameter and pulmonic valve peak velocity). Reference values for the breed are presented, as well as dispersion graphics for selected parameters, based on a regression equation.

Molecular characterization of Cryptosporidium and Giardia isolates from cattle from Portugal

Fecal samples from 291 calves and 176 adult cattle in Northern Portugal were screened for Cryptosporidium and Giardia using a formalin-ethyl acetate concentration method. Acid-fast staining techniques for Cryptosporidium oocyst identification and direct microscopic observation of fecal smears for Giardia cyst identification were performed so as immunofluorescence microscopy examination. Polymerase chain reaction methods were employed to determine the genotype of each isolate. Molecular characterization was performed using amplification and sequencing of the hsp70 and 18SrRNA genes of Cryptosporidium and beta-giardin gene and glutamate dehydrogenase for assemblage determination of Giardia duodenalis. Seventy-four out of 291 calves (25.4%) and 8 out of 176 adult bovines (4.5%) were positive for Cryptosporidium. Forty-one out of 291 calf samples (14.1%) and 1 out of 176 adults samples (0.57%) were positive for Giardia. From the Cryptosporidium positive samples we obtained 63 isolates from calves samples and 7 isolates from adult samples. Additionally, Giardia was isolated in 13 out of 41 positive samples from calves and it was also possible to isolate Giardia from the positive adult sample. Molecular characterization of the Cryptosporidium and Giardia isolates showed us that C. parvum and G. duodenalis assemblage E were the prevalent species. C. parvum may infect humans, representing a potential public health risk. On the other hand, the assemblages B and A2 of Giardia, previously described in humans, were here identified in cattle. Further studies will be needed for determine the importance of cattle as carrier of zoonotic assemblages of G. duodenalis.

Artificial insemination of cows with semen in vitro contaminated with Neospora caninum tachyzoites failed to induce neosporosis

Neosporosis is a major cause of abortion in cattle all over the world. Congenital transmission as well as horizontal transmission by ingestion of oocysts has been described. The detection of Neospora caninum DNA in bull semen warrants the investigation of possible transmission through the use of contaminated semen. In this experiment four cows were artificially inseminated with frozen-thawed semen contaminated in vitro with viable N. caninum tachyzoites (group A) and four control cows were inseminated with tachyzoites-free frozen-thawed semen, from the same bull (group B). Serum samples were collected 15 days before the artificial insemination (AI) and at days 10, 14, 21, 28, 45, 60 and 75 post-insemination. All sera samples were tested for neosporosis by direct agglutination test (DAT). Three of the cows from group A had negative DAT titers (< or =1:20) in all of the samples, while the fourth cow from this group had a low titer of antibodies (1:80) at day 10, and became negative at day 45, suggesting a stimulation of the immune system by the tachyzoites placed in uterus, rather than the induction of an infection. All of the cows from group B had negative DAT titers (< or =1:20) in all of the samples. These results suggest that transmission of neosporosis by artificial insemination with frozen-thawed semen is an unlikely event.

Characterization of Toxoplasma gondii Isolates in Free-Range Chickens From Portugal

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 225 free-range chickens (Gallus domesticus) from Portugal was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 61 chickens with titers of 1:5 in 8, 1:10 in 6, 1:20 in 3, 1:40 in 23, 1:80 in 5, 1:160 in 4, 1:320 in 8, and 1:640 or higher in 4. Hearts, leg muscles, and brains of 15 seropositive (MAT 1:10 or higher) chickens were bioassayed individually in mice. Tissue from 38 chickens with titers of 1:5 or less were pooled and fed to a T. gondii-free cat. Feces of the cat were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 16 of 19 chickens with MAT titers of 1:10 or higher. Genotyping of 12 of these 16 isolates with polymorphisms at the SAG2 locus indicated that 4 were type III, and 8 were type II. None of the isolates was lethal for mice. Phenotypically, T. gondii isolates from chickens from Portugal were different from those of T. gondii isolates from chickens from Brazil.

Characterization of the B-cell immune response elicited in BALB/c mice challenged with Neospora caninum tachyzoites

Activation of B cells occurring in hosts infected with protozoan parasites has been implicated either in protective or parasite-evasion immune-mediated mechanisms. Intraperitoneal inoculation of Neospora caninum tachyzoites into BALB/c mice induces an acute response characterized by a rapid increase in the numbers of CD69-expressing peritoneal and splenic B cells. This early B-cell stimulatory effect preceded an increase in the numbers of total and immunoglobulin-secreting splenic B cells and a rise in serum levels of N. caninum-specific immunoglobulins, predominantly of the immunoglobulin G2a (IgG2a) and IgM isotypes. Increased numbers of B cells expressing the costimulatory molecules CD80 and CD86 were also observed in the N. caninum-infected mice. The B-cell stimulatory effect observed in mice challenged with N. caninum tachyzoites was reduced in mice challenged with gamma-irradiated parasites. Contrasting with the peripheral B-cell expansion, a depletion of B-lineage cells was observed in the bone-marrow of the N. caninum-infected mice. Intradermal immunization of BALB/c mice with diverse N. caninum antigenic preparations although inducing the production of parasite-specific antibodies nevertheless impaired interferon-gamma (IFN-gamma) mRNA expression and caused lethal susceptibility to infection in mice inoculated with a non-lethal parasitic inoculum. This increased susceptibility to N. caninum was not observed in naïve mice passively transferred with anti-N. caninum antibodies. Taken together, these results show that N. caninum induces in BALB/c mice a parasite-specific, non-polyclonal, B-cell response, reinforce previous observations made by others showing that immunization with N. caninum whole structural antigens increases susceptibility to murine neosporosis and further stress the role of IFN-gamma in the host protective immune mechanisms against this parasite.

Biologic and molecular characterization of Toxoplasma gondii isolates from pigs from Portugal

Little is known of Toxoplasma gondii infections in animals in Portugal. In the present paper, we report the first isolation of viable T. gondii from pigs in Portugal. Antibodies to T. gondii were found in 52 (15.6%) of 333 pigs prior to slaughter using the modified agglutination test (MAT) at a serum dilution of 1:20. Attempts were made to isolate T. gondii from 37 seropositive pigs. Samples of brain and/or heart from each pig were digested in acid pepsin, and bioassayed into mice. Viable T. gondii was isolated from 15 pigs. Restriction fragment length polymorphism on products of SAG2 locus amplified by PCR and microsatellite analysis revealed that 11 isolates were Type II and four were Type III. The results indicate that phenotypically and genetically T. gondii are similar to isolates from pigs from the U.S.

Prevalence of Neospora caninum infection in dairy cows and its consequences for reproductive management

This study was carried out to determine the prevalence of neosporosis in an area of intensive dairy production, in Portugal. Sera samples were obtained in a random basis from 114 cows in 49 herds (group A), and from 1237 cows in 36 herds with a history of abortion outbreaks (group B). All sera samples were tested for neosporosis by direct agglutination test (DAT). Additionally, attempts to isolate Neospora caninum in 42 aborted bovine fetuses from 38 dairy herds (group C) were carried out, utilizing a bioassay with immuno-depressed Swiss Webster mice. Parasitological confirmation was done by indirect fluorescent antibody test (IFAT). The prevalence of neosporosis in the group A was 28%. Group B had a significantly (P < 0.001) higher prevalence (46%) and Neospora caninum was isolated in 36% of the aborted fetuses (group C). These results indicate that neosporosis, a disease only recently (2001) diagnosed in Portugal, has a high prevalence in the country, particularly in populations with a story of abortion. Thus, neosporosis should systematically be considered in the differential diagnosis of abortion. In the context of embryo transfers, the importance of selecting Neospora-free embryo recipients is discussed, as well as the pertinence of assessing the Neospora status of traded and imported cattle.

First isolation of Neospora caninum from an aborted bovine fetus in Spain

Neospora caninum was isolated from the brain of a 6-mo-old aborted bovine fetus from Galicia, Spain. The fetal brain homogenate was inoculated intraperitoneally into cortisonized mice. The peritoneal exudate from the infected mice, along with mouse sarcoma cells (Tg180), was inoculated into a second group of mice, and parasites were harvested from the peritoneal exudate. The parasites were adapted to in vitro growth in Vero monolayers. The tachyzoites from the peritoneal exudate reacted positively with anti-N. caninum antibodies and not with anti-Toxoplasma gondii antibodies on indirect fluorescent antibody test. The tachyzoites were lethal to interferon gamma gene knock out (KO) mice and could be identified immunohistochemically in the tissues. The identity of the parasite was also confirmed by polymerase chain reaction amplification of N. caninum-specific fragments. The sequences of the amplified gene 5 fragments (GenBank AY494944) were found to be identical to that of an Austrian isolate of N. caninum but not to that of NC-1. This is the first isolation of viable N. caninum from Spain.

Determination of an optimized cut-off value for the Neospora agglutination test for serodiagnosis in cattle

A definitive diagnosis of neosporosis in cattle implies the examination of the aborted fetus. However, in many instances fetal material is not available. Therefore, most diagnosis are based on serological tests. At the moment, there are no consensuses about the cut-off for serodiagnosis of neosporosis in cattle, for any test. The objective of the present study was to estimate the best cut-off for the Neospora agglutination test (NAT) for serodiagnosis in cattle. For that purpose, 246 serum samples from 4 groups of dairy cows (aborted Neospora positive; not aborted healthy; aborted other diseases and herds endemic neosporosis) were collected and antibodies anti-N. caninum were determined by NAT. Additionally, immunoblot (IB) was performed with sera from all cows of the endemic neosporosis group and the patterns of seroreactivity were contrasted with the NAT titers for this group of cows. Evaluation of the optimized sensitivity and specificity was calculated using Youden's J-statistics. The best Youden's J-statistic was obtained at 1:40 titer, presenting 100% of sensitivity and 90.4% of specificity with negative and positive predictive values of 100 and 75.0%, respectively. The comparison between NAT titers and the IB banding pattern support the results of the statistical analysis, i.e. titers of 1:40 and higher showed a complex pattern of bands, while titers lower than 1:40 did not precipitate any bands. These results indicate that 1:40 was an optimized NAT cut-off for serodiagnosis in cattle.

First Portuguese isolate of Neospora caninum from an aborted fetus from a dairy herd with endemic neosporosis

Neospora caninum was isolated from the brain of an aborted 4-month-old fetus from a dairy cow herd with endemic neosporosis in Porto, Portugal. The fetal brain homogenate was inoculated interperitoneally first into outbred Swiss Webster mice given dexamethasone and then the peritoneal exudates from these mice was co-inoculated with mouse sarcoma cells in the peritoneal cavity of mice given dexamethasone. N. caninum tachyzoites were seen in peritoneal exudate of the second passage. Tachyzoites from the peritoneal exudate reacted positively with anti-N. caninum antibodies and not with anti-Toxoplasma gondii antibodies and contained N. caninum specific DNA. This Portuguese isolate of N. caninum has been successfully maintained in cell culture. The dam of the aborted fetus had an antibody titer of 1:10240 in the Neospora agglutination test (NAT). Antibodies to N. caninum were found in 76 of 106 cows from this herd in titers of 1:40 in 31, 1:80 in 22, > or =1:160 or more in 23 in the Neospora agglutination test. This is the first isolation of a viable N. caninum-like parasite from any host in Portugal.

Isolation of viable Toxoplasma gondii from naturally infected aborted bovine fetuses

Neospora caninum and Toxoplasma gondii are related parasites. The former is a common cause of abortion in dairy cattle. The latter has not been conclusively demonstrated in bovine fetuses. During the course of attempts to isolate N. caninum from aborted fetuses, T. gondii was isolated from 2 aborted fetuses, 1 from Portugal and 1 from the United States. Both isolates were made by bioassay of fetal brains in mice. The fetus from Portugal was about 5 mo in gestational age, and the fetus from the United States was a full-term stillborn.

First confirmed case of Neospora caninum-associated abortion outbreak in Portugal

In a dairy herd experiencing an abortion outbreak, 49% of the 119 cows were positive for Neospora caninum antibodies and the remaining 51% were seronegative. Using immunohistochemical analysis of foetal brain tissue, Neospora cysts and bradyzoite clusters were identified in two of the 15 aborted foetuses submitted for testing. Other agents that commonly cause abortions were not found. These results, coupled with neurological clinical symptoms in new-born calves, implicated N. caninum as the major cause of abortions in this dairy herd. This is the first report that associates N. caninum infection with bovine abortions in Portugal.