A Non-Reciprocal Autosomal Translocation 64,XX, t(4;10)(q21;p15) in an Arabian Mare with Repeated Early Embryonic Loss.

Balanced autosomal translocations are a known cause for repeated early embryonic loss (REEL) in horses. In most cases, carriers of such translocations are phenotypically normal, but the chromosomal aberration negatively affects gametogenesis giving rise to both genetically balanced and unbalanced gametes. The latter, if involved in fertilization, result in REEL, whereas gametes with the balanced form of translocation will pass the defect into next generation. Therefore, in order to reduce the incidence of REEL, identification of translocation carriers is critical. Here, we report about a phenotypically normal 3-year-old Arabian mare that had repeated resorption of conceptuses prior to day 45 of gestation and was diagnosed with REEL. Conventional and molecular cytogenetic analyses revealed that the mare had normal chromosome number 64,XX but carried a non-mosaic and non-reciprocal autosomal translocation t(4;10)(q21;p15). This is a novel translocation described in horses with REEL and the first such report in Arabians. Previous cases of REEL due to autosomal translocations have exclusively involved Thoroughbreds. The findings underscore the importance of routine cytogenetic screening of breeding animals.

Three autosomal chromosome translocations associated with repeated early embryonic loss (REEL) in the domestic horse (Equus caballus).

Repeated early embryonic loss (REEL) represents a considerable economic loss to the horse industry. Mares that experience REEL may be overlooked as potential carriers of a chromosome abnormality. Here we report three different autosomal translocations in Thoroughbred mares presented for chromosome analysis because of REEL. The karyotypes were 64,XX,t(1;21), 64,XX,t(16;22), and 64,XX,t(4;13), respectively. In order to confirm the chromosomes involved in the translocations, to map the breakpoints, and to determine if the translocations were reciprocal, genes surrounding the breakpoints were identified using existing maps and from the newly assembled horse genome sequence. Bacterial artificial chromosomes containing the genes of interest were identified and mapped to the translocation chromosomes by fluorescence in situ hybridization (FISH). FISH confirmed that the t(16;22) and t(4;13) translocations were reciprocal, while the t(1;21) was not. The breakpoints on horse chromosomes 1 and 16 appear to be the same or near breakpoints previously identified in translocations. These breakpoints are at the fusion boundary of human chromosomes 10 and 15 on horse chromosome 1 and at human chromosome 3p and 3q on horse chromosome 16. These sites may represent ancient breakpoints reused during equid evolution. Overall, chromosome abnormalities may have a greater influence on mare fertility than previously known. Thus, it is important to karyotype subfertile mares exhibiting REEL.

Chronic Neospora caninum infection and repeat abortion in dairy cows: a 3-year study.

The serological status of Neospora was monitored in animals older than 6 months in a dairy herd with a 3-year history of prevalent N. caninum and N. caninum-associated abortions. The numbers of animals in the herd tested each year of the study period were 259, 222 and 231, respectively. A separate analysis was performed on the 122 animals persisting in the herd for the 3 years. The overall seroprevalence of N. caninum in the herd decreased from 31.7% in the first year to 24.8% in the second year and to 19.9% in the third year of the study, while the overall abortion rate decreased from 20.6% in the first year to 5.5% in the second year, and 9.9% in the third. These decreases occurred in response to control measures adopted from the second year onwards, such as culling Neospora-seropositive aborted animals and inseminating Neospora-seropositive dams with beef bull semen. Of the total number of abortions recorded in seropositive animals, 51% were repeat abortions that occurred in 36.8% of the animals with a previous history of abortion. The initial seroprevalence of Neospora in the 122 animals followed for the 3 years was 18%, increasing to 21.3% in the second and third years. Seroconversion only occurred in four animals during the second and third years of the study and abortion occurred only in seropositive individuals. Of the total number of abortions recorded in the 122 animals, 61.5% were repeat abortions that occurred in 26.7% of the animals with a previous history of abortion. These results indicate that Neospora seropositivity can be very stable through time and N. caninum infected cows can show a high rate of repeat abortions. The present data reinforce the idea that annual serological screening for Neospora can be an effective and rapid method of detecting N. caninum infection, such that control measures can be established at the farm level.

Dendritic cells therapy confers a protective microenvironment in murine pregnancy.

The fetal-placental unit is a semi-allograft and immunological recognition of pregnancy, together with the subsequent response of the maternal immune system, is necessary for a successful pregnancy. Dendritic cells (DC) show a biological plasticity that confers them special characteristics regulating both immunity and tolerance. Therapy employing DC proved to diminish the abortion in the DBA/2J-mated CBA/J females; however, the underlying mechanisms remain unknown. Here, we evaluated whether DC therapy influences the presence of immunoregulatory populations of cells at the fetal-maternal interface. To address this hypothesis, we analysed the pregnancy-protective CD8, gammadelta cell populations as well as transforming growth factor (TGF)-beta1 and progesterone-induced blocking factor (PIBF) expression at the fetal-maternal interface from abortion-prone female mice that had previously received adoptive transfer of syngeneic DC. Syngeneic DC therapy induced an increase in the number of CD8 and gammadelta cells. Additionally, an upregulation of TGF-beta1 and PIBF expression could be detected after DC transfer. We suggest that DC therapy differentially upregulates a regulatory/protective population of cells at the fetal-maternal interface. It is reasonable to assure that this mechanism would be responsible for the lower abortion rate.

Influence of leptospirosis on reproductive performance of sows in Brazil.

The purpose of this study was to investigate the association between seropositivity for the most frequent Leptospira serovars and reproductive losses in sows in Brazil. Serum samples from 351 sows from 18 herds (in the state of Rio de Janeiro, Brazil) with low reproductive efficiency were tested (microscopic agglutination) for antibodies against serovars of Leptospira. Antibodies were detected in serum samples of 66.1% of all sows, most frequently serovar icterohaemorrhagiae (43.1%), followed by pomona (18.1%) and tarassovi (9.9%). Seroreactivity to icterohaemorrhagiae and pomona were associated (P<0.05) with impaired reproductive performance (and substantial economic loss). Seroreactivity for pomona was associated (P<0.05) with stillborn piglets and mummified fetuses, whereas seroreactivity to icterohaemorrhagiae was associated (P<0.05) with the number of piglets born dead.

Repetitive abortion in Neospora-infected ewes.

Pregnant ewes inoculated with cultured Neospora caninum tachyzoites in 1995, 1996, or 1995 and 1996 aborted or delivered weak or clinically normal lambs in 1996. Nine of 11 ewes in the study had previously produced infected lambs or fetuses after being experimentally infected in 1995. Fetuses and lambs produced in 1996 showed histologic lesions and zoites indicative of Neospora. Serologic responses and production of infected fetuses/lambs indicated systemic neosporosis in the ewes during gestation, although tachyzoites could not be cultured from maternal tissues. The repetitive infection of fetuses, and resulting clinical and histopathologic findings in the present study are similar to those reported in naturally infected cattle, adding to the already established similarities of neosporosis between sheep and cattle.

Early foetal death in the mare. Histological, bacteriological and cytological findings in the endometrium.

Fifteen mares which had each lost their pregnancies 2 to 8 times during the preceding 6 years were used in a study comprising 1 or 2 breeding seasons for each mare. During the research period all 15 mares conceived and 10 of the mares had normal pregnancies in the 1st experimental year. Five mares resorbed/aborted once or twice during the 1st year. This was followed by a pregnancy that terminated in a live foal. Histopathological examinations of uterine biopsies showed a wide range of histopathological conditions, from absence of changes excessive for the mare's age and parity to the most severe changes of the endometrium. Most likely, endometritis, acute as well as chronic degenerative endometritis, is the most common cause of early foetal death in the mare. Good breeding management is essential and was often enough to make the mares produce a foal. Additional treatment was needed in some of the mares and was based on the course of the conceptus loss and the condition of the endometrium, as determined by clinical, histological, bacteriological and cytological examinations.

Abortion of a mummified fetus associated with short uterine body in a mare.

A mummified fetus was aborted at 284 days of gestation from a Quarter Horse mare with a history of consecutive abortions. The abortion occurred 12 days after administration of supplemental progestogen had been discontinued. Results of a breeding soundness evaluation revealed that this mare had a short uterine body. Other abnormalities were not discovered. This condition may have been responsible for repeated abortions in this mare, and may represent a cause of fetal mummification other than twin pregnancy in mares.

Considerations for use of descriptive epidemiology to investigate fetal loss in dairy cows.

Various descriptive approaches were taken in a prospective investigation to characterize fetal loss in cows on a California dairy. The methods and observations were offered for consideration by practitioners engaged in dairy herd health medicine. For 4,732 pregnancies followed from 2,163 cows in a 6.5 year period, the respective proportions (percentage) of cows aborting (1--cumulative proportion not aborting by 260 days) and abortion densities (abortions per 10,000 cow-days-at-risk) were 10.63 and 6.29 for all fetal deaths, 9.36 and 5.49 for deaths resulting in fetal expulsion, and 1.39 and 0.80 for deaths resulting in mummification. The greatest risk of fetal death (119 deaths/10,000 fetuses/d) was observed between 98 and 105 days of gestation, and median age at fetal death ranged from 99.0 to 105.5 days. Abortion density for fetal deaths resulting in mummification for cows conceiving during September (1.61/10,000 fetuses/d) and October (1.63/10,000 fetuses/d) was tenfold greater than that for cows conceiving in February (0.16/10,000 fetuses/d) and was twice that of the overall rate (0.84/10,000 fetuses/d). For cohorts of nonculled cows, abortion rate increased after 5 years of age, after 5 pregnancies, or after 4 calvings. For cows with at least one previous abortion, the proportion aborting (14.50%) was higher than that for cows without a previous abortion (12.14%). For a given gravidity, abortion rate was higher among cows that had experienced a previous abortion, compared with those that had not. These methods and observations may help provide a logical foundation on which to base clinical hypotheses regarding causes of abortion, and they may offer insight into pitfalls of bias and confounding to be anticipated.

Toxoplasmosis and other causes of abortions in sheep from north central United States.

Between 1983 and 1989, we examined 1,201 aborted fetuses and dead lambs from the north central United States. Toxoplasmosis was diagnosed in 17.5%, campylobacteriosis in 9.9%, chlamydiosis in 4.7%, and miscellaneous infections in 15.1%. Inflammatory lesions suggestive of infectious causes were seen in 13%. Noninfectious causes were identified in 6.1%, and a diagnosis was not reached in 33.3%. An agglutination test was used to detect Toxoplasma gondii-specific antibodies in ovine fluids. Toxoplasma gondii antibodies were detected in 223 of 1,064 (20.9%) fluids from fetuses and dead lambs. Of 201 seropostive (greater than or equal to 16) fetuses and lambs, T gondii antibody titers (reciprocal) were 16 (21 fetuses and lambs), 32 (10 fetuses and lambs), 64 (2 fetuses and lambs), 128 (7 fetuses and lambs), 256 (9 fetuses and lambs), 512 (5 fetuses and lambs), 1,024 (15 fetuses and lambs), 2,048 (13 fetuses and lambs), 4,096 (13 fetuses and lambs), 8,196 (13 fetuses and lambs), 16,392 (19 fetuses and lambs), and greater than or equal to 32,784 (74 fetuses and lambs).

Local active suppression and successful vaccination against spontaneous abortion in CBA/J mice.

We report here that vaccination of CBA/J female mice with DBA/2 X BALB/c recombinant line that decreases the spontaneous abortion rate increases local active decidua-associated suppressor cell activity. In contrast, vaccination with a recombinant line that increases the abortion rate decreases suppressor cell activity. No correlation was seen between the effect on the abortion rate and the ability of cells from the fetoplacental unit to inhibit cytolysis by NK cells. Successful vaccination against spontaneous abortion may act primarily by augmenting suppressor cell activity in the decidua at the implantation site.

Placental lesions in habitually aborting cats.

An ovariohysterectomy was done on five female cats with a history of habitual abortion in the 3rd to 4th week of pregnancy and the foetuses and placentas examined. Histologic and electron microscopic examination showed multifocal placental necrosis which was deduced to begin in the syncytial trophoblastic cells and to extend to all the cells of the labyrinth. This lesion was followed by foetal autolysis. No bacterial, viral or mycoplasmal agents could be incriminated in the disease.