Xenogenous fertilization of equine oocytes following recovery from slaughterhouse ovaries and in vitro maturation.

The in vitro production (IVP) of equine embryos using currently available protocols has met limited success; therefore investigations into alternative approaches to IVP are justified. The objective of this study was to evaluate the feasibility of xenogenous fertilization and early embryo development of in vitro matured (IVM) equine oocytes. Follicular aspirations followed by slicing of ovarian tissue were performed on 202 equine ovaries obtained from an abattoir. A total of 667 oocytes (3.3 per ovary) were recovered from 1023 follicles (recovery rate, 65%). Oocytes underwent IVM for 41 +/- 2 h (mean +/- S.D.), before being subjected to xenogenous gamete intrafallopian transfer (XGIFT). An average of 13 +/- 0.8 oocytes and 40x10(3) spermatozoa per oocyte were transferred into 20 oviducts of ewes. Fourteen percent of transferred oocytes (36/259) were recovered between 2 and 7 days post-XGIFT and 36% of those recovered displayed embryonic development ranging from the 2-cell to the blastocyst stage. Fertilization following XGIFT was also demonstrated by the detection of zinc finger protein Y (ZFY) loci. Ligation of the uterotubal junction (UTJ), ovarian structures, or the duration of oviductal incubation did not significantly affect the frequency of embryonic development or recovery of oocytes/embryos after XGIFT. In conclusion, equine embryos can be produced in a smaller non-equine species that is easier for handling.

Interpretation of the detection of Sarcocystis neurona antibodies in the serum of young horses.

Horses that are exposed to Sarcocystis neurona, a causative agent of equine protozoal myeloencephalitis, produce antibodies that are detectable in serum by western blot (WB). A positive test is indicative of exposure to the organism. Positive tests in young horses can be complicated by the presence of maternal antibodies. Passive transfer of maternal antibodies to S. neurona from seropositive mares to their foals was evaluated. Foals were sampled at birth (presuckle), at 24h of age (postsuckle), and at monthly intervals. All foals sampled before suckling were seronegative. Thirty-three foals from 33 seropositive mares became seropositive with colostrum ingestion at 24h of age, confirming that passive transfer of S. neurona maternal antibodies occurs. Thirty-one of the 33 foals became seronegative by 9 months of age, with a mean seronegative conversion time of 4.2 months. These results indicate that evaluation of exposure to S. neurona by WB analysis of serum may be misleading in young horses.

In vitro and xenogenous capacitation-like changes of fresh, cooled, and cryopreserved stallion sperm as assessed by a chlortetracycline stain.

Like the human female, the mare experiences reproductive tract pathology that may sometimes be circumvented by the use of assisted reproductive technologies (ARTs). One such technology, gamete intrafallopian transfer (GIFT), may be used in mares that exhibit ovulatory, oviductal, or uterine abnormalities that limit the use of common ARTs, such as embryo transfer. Homologous GIFT has been successfully performed in the horse; however, the logistics, costs, and associated risks of surgically transferring gametes to the oviducts of a recipient mare are considerably high. Use of a less costly species in a heterologous or xenogenous procedure would therefore be beneficial. This study represents the preliminary investigation into the use of sheep as recipients for xenogenous GIFT procedures using equine gametes. We investigated the capacitation response of fresh, cooled, or frozen stallion sperm after 1) in vivo incubation in the reproductive tract of estrous and anestrous ewes as well as 2) in vitro incubation in a modified Krebs/ Ringer extender at 37 degreesC with and without the addition of heparin at 10 IU/mL for up to 8 hours. A chlortetracycline (CTC) fluorescent stain was used to assess the capacitation response of sperm. Findings indicated that oviductal fluid samples recovered from estrous ewes had significantly higher numbers of sperm exhibiting capacitation-like staining patterns when compared to samples recovered from anestrous ewes (P < .05). Fresh semen yielded higher capacitation-like staining patterns after in vivo incubation than did frozen-thawed or cooled samples. A transition from majority CTC unreacted sperm to majority CTC non-acrosome intact sperm was demonstrated for both in vivo and in vitro studies. In vitro incubation of stallion sperm with heparin did not result in an increased capacitation-like staining response over time when compared with nonheparinized samples. Results from this study suggest that xenogenous capacitation of stallion sperm may occur in the estrous ewe.

Effects of season and diet on tensile strength and mineral content of the equine hoof wall.

Studies evaluating nutritional and seasonal influences on hoof strength and composition in horses, as well as the scientific justification for feeding supplements to improve hoof quality, are lacking. The horseman and veterinarian need controlled studies in this area to make informed decisions. This project quantified, in 2 trials, relative elasticity, tensile strength, % moisture, and mineral composition of hooves of 48 mature Thoroughbred mares maintained on different nutritional/management regimens, sampled quarterly over 12 month periods. Tensile strength was positively associated with sulphur content. Per cent moisture was not significantly associated with tensile strength, relative elasticity, or mineral content measures. Results indicated that both seasonal trends and nutritional regimes greatly affected hoof wall strength and mineral composition.

Intra-articular anesthesia of the distal interphalangeal joint alleviates lameness associated with the navicular bursa in horses.

OBJECTIVE: To determine if intra-articular anesthesia of the distal interphalangeal joint could alleviate lameness associated with the navicular bursa in horses. STUDY DESIGN: Experimental investigation. ANIMALS: Six clinically normal horses. METHODS: Lameness was induced in each horse by injecting either the left or right front navicular bursa with 5 mg of amphotericin-B. Forty-eight hours later each horse was videotaped walking and trotting before, and 5, 30, and 60 minutes after injecting the distal interphalangeal joint of the treated limb with 5 mL of 2% mepivacaine hydrochloride. All video recordings were then rerecorded onto master tapes in a random sequence. Four clinicians, unaware of the animal identity related to observation time or limb treated, independently viewed these tapes and graded the lamenesses. RESULTS: There was a significant reduction in lameness 5 and 30 minutes after anesthetic was injected into the distal interphalangeal joint. Lameness scores 60 minutes after anesthetic administration were not significantly different than baseline values. Gross pathological examination confirmed marked inflammation of the treated navicular bursae and normal appearance of the distal interphalangeal joints. CONCLUSIONS: Intra-articular anesthesia of the distal interphalangeal joint can alleviate lameness associated with the navicular bursa. CLINICAL RELEVANCE: Intra-articular anesthesia of the distal interphalangeal joint is not specific only for lameness originating in the distal interphalangeal joint.

Equine herpesvirus type 2: prevalence and seroepidemiology in foals.

Whole blood and serum were collected from foals to determine the prevalence of Equine herpesvirus type 2 (EHV 2) infection in foals, age at which infection can first be identified and serological responses to infection. Equine herpesvirus type 2 was isolated from peripheral blood mononuclear cells (PBMC) from 68 of 69 foals, 1-8-months-old, sampled once. Virus isolation was performed twice at intervals of 2-7 months on PBMCs from 33 foals and EHV2 was isolated on both occasions in all but one foal (negative, then positive). Regression analysis of log2-transformed reciprocal serum EHV2 virus neutralising (VN) titres revealed that in foals age 1-7 months, EHV2 VN antibody titre was positively correlated with age (r = 0.94). Paired serum samples were obtained from 58 foals, with the first samples collected age 1-6 months and the second samples collected 2-4 months later. There were significant (P < 0.05) increases in mean VN titres to EHV2 in foals sampled initially at age 1-4. Eight foals had blood sampled prior to sucking and at age 7, 20, 30 and 45 days. Each foal was negative for EHV2 in PBMC and each foal had a negative serum EHV2 VN titre immediately after birth. Each foal was positive for EHV2 in PBMC by age 45 days, with the earliest isolation at 25 days. Tracheal aspirate fluid and peripheral blood were collected from 20 foals without clinical signs of respiratory disease and from 30 foals with clinical signs of lower respiratory disease. In 20 foals without clinical signs of respiratory disease, EHV2 was isolated from tracheal aspirates (1/20 foals) and PBMC (20/20 foals) and in 30 foals with such clinical signs, from trachea aspirates (20/30 foals: P < 0.01) and from PBMC (30/30 foals). In one 6-month-old foal, EHV1, but not EHV2, was isolated from the tracheal aspirate, 3 months after EHV2 had been isolated from a tracheal aspirate. These results demonstrate a greater prevalence of EHV2 in lower respiratory secretions in foals with clinically apparent lower respiratory disease, but a cause and effect relationship between the virus and lower respiratory disease remains to be elucidated. It is noteworthy, however, that of virus isolations performed on 50 tracheal aspirates, a virus (EHV1) other than EHV2 was isolated only once.

Calcium decreases and parathyroid hormone increases in serum of periparturient mares.

Changes in serum concentrations of Ca and parathyroid hormone (PTH) may develop in periparturient mares, may be influenced by dietary Ca, and may be associated with changes in Ca concentration of mammary secretion. Milk and blood samples were taken from eight mares on Farm A and eight on Farm B for 10 d before parturition and from four mares on each farm for 5 d postpartum. Milk Ca was measured by two commercial tests. Serum samples were analyzed for PTH and total Ca in 16 mares and for ionized Ca in six (Farm A). Parturition was induced in eight mares on Farm A and four on Farm B; no significant difference in serum Ca or PTH was found between mares with induced and spontaneous foaling. Mean serum total Ca decreased from 12.5 mg/dL to a nadir of 11 mg/dL on d 2 postpartum, and mean PTH increased from 46 pg/mL to a peak of 186 pg/mL on d 2 postpartum. Serum total Ca concentrations were lower and serum PTH concentrations were higher in Farm A mares than in Farm B mares, probably reflecting dietary Ca (.35% of DM on Farm A and .55% on Farm B). The serum PTH peak and Ca nadir occurred on d 2 postpartum, 1 d later than reported previously in dairy cows. Milk Ca concentration increased progressively from 7 d before parturition; this increase preceded, so was not dependent on, prepartal changes in serum Ca and PTH.

The sensitivity, specificity and predictive value of measuring calcium carbonate in mares' prepartum mammary secretions.

A colorimetric test kit marketed for water quality analysis was used to measure calcium carbonate changes in diluted prefoaling mammary secretions. Daily samples (1 to 3 ml/day) were obtained from 59 Thoroughbred and Warmblood mares starting 14 days prior to foaling to the day of parturition. The sensitivity, specificity, and positive and negative predictive values of the test were calculated on the data collected from 56 mares and 377 prefoaling mammary secretion samples. The results indicate that this test is both sensitive and specific. The predictive value of a positive test (PVPT; positive test defined as the first occurrence that prefoaling mammary secretion calcium carbonate >/= 200 ppm) indicated that 51.4% of late term pregnant mares would foal within the ensuing 24-hour period, 84.1% within 48 hours and 97.2% within 72 hours. The predictive value of a negative test (PVNT; negative test defined as prefoaling mammary secretion calcium carbonate < 200 ppm) indicated that 99.6% of late term pregnant mares would not be expected to foal within the ensuing 24 hour period, % within 48 hours and 81.8% within 72 hours. This test is helpful as a prognostic tool in indicating the mare's approaching readiness for birth. It is also an accurate prognostic tool to predict that the mare is not likely to foal within 24h when calcium carbonate < 200 ppm in the diluted prefoaling mammary secretion.

Scrotal circumference measurements in purebred Dorset, Hampshire and Suffolk lamb and yearling rams.

Purebred Suffolk, Hampshire and Dorset lamb and yearling rams (n=753), underwent performance testing from 1986 to 1989. Scrotal circumference, birth date and entry weight were recorded for each ram entering the test station. Mean age in days at entry, weight (lbs), and scrotal circumference (SC; cm) were greatest for the Hampshire rams. For all rams combined (Dorset, Hampshire and Suffolk), the mean SC by month of age revealed rapid growth from 2 to 6 mo, with a 3- to 6-mo mean SC significantly (P0.05) for mean SC measurement and a less rapid increase in SC diameter. Between 12 and 13 mo a significant increase (P

Use of the point-score system for breeding soundness examination in yearling Dorset, Hampshire and Suffolk rams.

Performance tests were conducted on 583 purebred Dorset, Hampshire and Suffolk yearling rams at the Virginia Ram Test Station from 1986 to 1989. Birth dates at entry and weights (lbs) at entry and end-of-test were recorded for each ram. Entry and exit scrotal circumference (SC; cm) data were recorded for each year of the study. Breeding soundness examination (BSE) data at entry were obtained for only the last two years (1988-1989). The BSE followed the basic format recommended by the Society for Theriogenology. The number of seminal white blood cells per (100x) microscope field (WBC/LPF) were also recorded for each ram's ejaculate. Classification of rams into breeding groups (satisfactory, questionable and unsatisfactory) were made using a point-scale system based upon values obtained from SC, sperm motility and morphology assessments. Between-breed differences were noted for age at entry to the test station, weight per day of age, final weight at the end of the test period and average daily gain. Suffolk rams were younger in age (P0.05). Overall the percentage of rams classified as unsatisfactory, questionable and satisfactory was 11.8, 16.5 and 71.7, respectively. Rams with more than 10 WBC/LPF had significantly smaller SC at entry (P<0.01) than rams with less than 10 WBC/LPF. Most of the differences (75%) in BSE scores in this study were contributed by differences in semen quality (spermatozoal motility and morphology) not by differences in SC.

A survey of whole blood selenium concentrations of horses in Maryland.

We surveyed the whole blood selenium status of a randomly sampled population of horses from 4 contiguous counties in northern Maryland. Two hundred and two horses from 74 farms were sampled. Whole blood selenium levels greater than or equal to 0.100 parts per million (ppm) were considered adequate; blood levels less than 0.100 ppm were considered marginal or deficient. The average blood selenium concentration of the horses sampled was 0.137 ppm, with a standard deviation of 0.041 ppm. Blood selenium concentrations ranged from 0.050-0.266 ppm. Thirty-eight of 202 horses (18.8%) had a selenium level less than or equal to 0.099 ppm. Twenty-one of 74 farms (28.4%) had at least 1 horse with a selenium level less than or equal to 0.099 ppm. Animal husbandry practices had a significant influence on selenium status. Horses were more prone to having an abnormal selenium status if they were either maintained on pasture or used infrequently, or if their diet did not include mineral and vitamin supplements.

Dimethyl sulfoxide intrauterine therapy in the mare: effects upon endometrial histological features and biopsy classification.

The effects upon equine endometrial histological features produced by 10 to 30% concentrations of dimethyl sulfoxide (DMSO) in sterile saline were compared with the effects of sterile saline (0.9% NaCl) alone as an intrauterine infusion therapy in 16 barren mares. No harmful histological changes were noted (P>0.05) as a result of the therapy. Thirty percent intrauterine DMSO therapy produced a significant (P<0.01) improvement (i.e., reduction of chronic inflammatory cell infiltrates and reduction of periglandular fibrosis) in endometrial biopsy classification in 18 of the 27 barren mares evaluated; whereas only 2 of 18 barren mares improved following intrauterine saline treatment in the control group. In subsequent breeding trials, the pregnancy rates following intrauterine therapy were no different between DMSO-treated mares and saline-treated control mares (P>0.05); however, there was a trend toward a higher pregnancy rate following DMSO therapy. The inability to control for sire variability in the breeding trials may have contributed toward the result that no significant difference could be demonstrated in the pregnancy rates between treated and control mares.

Use of the partial farm budget technique to predict the economic impact of the flock management decision to use B-mode ultrasonographic pregnancy diagnosis.

A computer spreadsheet was developed to predict the economic impact of a management decision to use B-mode ultrasonographic ovine pregnancy diagnosis. The spreadsheet design and spreadsheet cell formulas are provided. The program used the partial farm budget technique to calculate net return (NR) or cash flow changes that resulted from the decision to use ultrasonography. Using the program, either simple pregnancy diagnosis or pregnancy diagnosis with the ability to determine singleton or multiple pregnancies may be compared with no flock ultrasonographic pregnancy diagnosis. A wide range of user-selected regional variables are used to calculate the cash flow changes associated with the ultrasonography decisions. A variable may be altered through a range of values to conduct a sensitivity analysis of predicted NR. Example sensitivity analyses are included for flock conception rate, veterinary ultrasound fee, and the price of corn. Variables that influence the number of cull animals and the cost of ultrasonography have the greatest impact on predicted NR. Because the determination of singleton or multiple pregnancies is more time consuming, its economic practicality in comparison with simple pregnancy diagnosis is questionable. The value of feed saved by identifying and separately feeding ewes with singleton pregnancies is not offset by the increased ultrasonography cost.

Disease outbreak investigation. Three case studies.

Three case studies of the investigation of outbreaks of disease or deviations from target performance are presented. The first is a study of a mastitis problem in a dairy herd, made evident by increased somatic cell counts. The pattern of the production problem is carefully analyzed and conclusions are reached that indicate an infection with environmental contaminant organisms, thus permitting control measures to be introduced. The second case study is an investigation of an outbreak of neonatal mortality in sheep. Analysis suggests a multiple etiology, with infection by border disease virus predominating. The third case study describes the investigation of foothill abortion in a beef herd in California and demonstrates the use of epidemiologic techniques to try to identify the source of infection in a subgroup of the study population, thus allowing specific control measures to be introduced.

The effects of prostalene and alfaprostol as uterine myotonics, and the effect on postpartum pregnancy rate in the mare following daily treatment with prostalene.

The effects of oxytocin and two prostaglandin (PG) F(2)alpha analogues, prostalene and alfaprostol, on uterine pressure in the mare were measured using balloon-tipped catheters connected to pressure transducers. The PGF(2)alpha analogues caused increased uterine pressure beginning 7 to 15 min postinjection and persisting for the duration of each 60 min recording session. Forty postpartum mares of light-horse breed were used to evaluate the effects of prostalene on postpartum pregnancy rate. Eighteen mares were injected by aseptic technique subcutaneously with 1 mg prostalene twice daily, beginning on the day of foaling (Day 0) and continuing for 10 consecutive days (Day 10) or until the mare was first bred at foal heat. Twenty-two postpartum mares were injected with 1.0 ml sterile saline by the same technique as the controls. Of treated mares, 76.9% were diagnosed pregnant after breeding versus 44.4% of the control mares (P = 0.07). Of treated mares, 66.7% bred at their second postpartum estrus became pregnant versus 28.6% of control mares (P = 0.03). Prostalene, given at 1 mg twice daily for 10 d postpartum, produced an increased pregnancy rate after both foal heat and second postpartum estrus breedings in the mare.

Early pregnancy loss in brood mares.

During 1985, linear-array ultrasonography was used to study early pregnancy loss in commercial brood mares: 600/1115 (54%) of the cycles resulted in detected pregnancy at Week 2 after ovulation and 80 (13%) of these pregnancies resulted in early pregnancy loss. The pregnancy loss rate was significantly higher (P less than 0.05) for twin pregnancies (10/41) than for singleton pregnancies (70/559). The pregnancy loss rate was significantly higher (P less than 0.05) at 2-4 weeks (29/60) than at 6-8 weeks (12/60). The pregnancy rate was significantly less (P less than 0.05) for post-partum mares inseminated at the foal heat (157/302) than for those inseminated at a subsequent oestrus (203/334). Mares with a history of endometritis had a significantly higher (P less than 0.05) per cycle pregnancy loss rate (7/26) than did mares with a history of not having endometritis (64/498). When mares that had lost pregnancies were re-mated, 37/75 (49%) detectable pregnancies resulted and 7 (19%) of these pregnancies were again lost. The per cycle pregnancy rate was 56% (153/273), 55% (177/319), 60% (130/216), 51% (72/142), 45% (34/76) and 33% (12/36) for mares aged 2-5, 6-9, 10-13, 14-17, 18-21 and greater than 21 years, respectively. The corresponding per cycle pregnancy loss rates were 12%, 14%, 9%, 14%, 24% and 33%.

Efficacy of ivermectin in controlling Strongyloides westeri infections in foals.

Twenty-eight foals whose dams were treated IM with ivermectin (200 micrograms/kg of body weight) on the day of parturition were compared with 35 foals whose dams were administered only the vehicle. The effect of ivermectin on the vertical transmission of Strongyloides westeri and foal heat diarrhea was determined by a comparison of results obtained in the 2 groups. Foals from treated mares had significantly fewer S westeri eggs per gram of feces from 17 to 28 days postpartum. There were no differences observed in the frequencies of severity of foal heat diarrhea between the treated and control groups. In another experiment, using the same foals, 32 foals were treated IM with ivermectin (200 micrograms/kg) at 21 days of age and were compared with 31 foals administered only the vehicle. Significantly fewer S westeri eggs were recovered from the ivermectin-treated foals on day 26 to day 32, the completion day of the trial.

Effects of washing on the bacterial flora of the stallion's penis.

Six stallions were subjected to extensive cleansing of the penis and prepuce with water, Ivory Soap and water, or Betadine surgical scrub and water. The stallions were all washed for 14 days, and then allowed 14 days respite. This pattern of washing and resting was repeated consecutively. Swabs were taken from all 7 stallions twice weekly and semen was collected once a week for bacteriological examination. All forms of cleansing altered the bacterial flora of the stallion's penis; the Ivory Soap tended to encourage the replacement of the normal flora with coliform organisms, while Betadine favoured the growth of Pseudomonas aeruginosa and Klebsiella spp. This experiment showed that the systematic washing of a stallion's penis will cause the normal flora to be replaced with pathogens and potential pathogens.