Use of a Bayesian risk-mapping technique to estimate spatial risks for mare reproductive loss syndrome in Kentucky.

OBJECTIVE: To estimate spatial risks associated with mare reproductive loss syndrome (MRLS) during 2001 among horses in a specific study population and partition the herd effects into those attributable to herd location and those that were spatially random and likely attributable to herd management. Animals-Pregnant broodmares from 62 farms in 7 counties in central Kentucky. PROCEDURE: Veterinarians provided the 2001 abortion incidence proportions for each farm included in the study. Farms were georeferenced and data were analyzed by use of a fully Bayesian risk-mapping technique. RESULTS: Large farm-to-farm variation in MRLS incidence proportions was identified. The farm-to-farm variation was largely attributed to spatial location rather than to spatially random herd effects. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that there are considerable data to support an ecologic cause and potential ecologic risk factors for MRLS. Veterinary practitioners with more detailed knowledge of the ecology in the 7 counties in Kentucky that were investigated may provide additional data that would assist in the deduction of the causal factor of MRLS via informal geographic information systems analyses and suggest factors for inclusion in further investigations.

Population-based study of fecal shedding of Clostridium perfringens in broodmares and foals.

OBJECTIVE: To determine the percentage of broodmares and foals that shed Clostridium perfringens in their feces and classify the genotypes of those isolates. DESIGN: Prospective cross-sectional study. ANIMALS: 128 broodmares and their foals on 6 equine premises. PROCEDURES: Anaerobic and aerobic bacteriologic cultures were performed on feces collected 3 times from broodmares and foals. All isolates of C. perfringens were genotyped. RESULTS: Clostridium perfringens was isolated from the feces of 90% of 3-day-old foals and 64% of foals at 8 to 12 hours of age. A lower percentage of broodmares and 1- to 2-month-old foals shed C. perfringens in their feces, compared with neonatal foals. Among samples with positive results, C. perfringens type A was the most common genotype identified (85%); C. perfringens type A with the beta2 toxin gene was identified in 12% of samples, C. perfringens type A with the enterotoxin gene was identified in 2.1% of samples, and C. perfringens type C was identified in < 1% of samples. CONCLUSIONS AND CLINICAL RELEVANCE: Clostridium perfringens was identified from the feces of all but 6 foals by 3 days of age and is likely part of the normal microflora of neonatal foals. Most isolates from broodmares and foals are C. perfringens type A; thus, the clinical relevance of culture results alone is questionable. Clostridium perfringens type C, which has been associated with neonatal enterocolitis, is rarely found in the feces of horses.

Serum thyroxine concentrations and pregnancy rates 15 to 16 days after ovulation in broodmares.

OBJECTIVE: To determine whether serum thyroxine (T4) concentration was associated with pregnancy rates 15 to 16 days after ovulation in mares and to determine whether thyroid hormone supplementation would enhance fertility in mares. DESIGN: Cohort study. ANIMALS: 329 clinically normal broodmares. PROCEDURE: Mares were examined 15 to 16 days after ovulation to determine whether they were pregnant; blood samples for determination of serum T4 concentration were collected at the same time. Sixty mares were receiving thyroid hormone supplementation prior to the study because of low serum T4 concentration (< 16 microg/dl) prior to breeding. RESULTS: Serum T4 concentration ranged from 4.5 to 53.9 mg/dl. Forty (12%) mares had low (< 16 microg/dl) concentrations, 283 (86%) had normal concentrations, and 6 (2%) had high (> 45 microg/dl) concentrations. Two hundred thirty-one mares were pregnant 15 to 16 days after ovulation. A significant association between serum T4 concentration (low, normal, or high) and pregnancy (yes or no) was not detected, and logistic regression analysis indicated that serum T4 concentration was not significantly related to pregnancy. Of the 269 mares not receiving thyroid hormone supplementation, 187 were pregnant, and of the 60 mares receiving thyroid supplementation, 44 were pregnant. There was no significant relationship between thyroid hormone supplementation and pregnancy status. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that serum T4 concentration in mares is not significantly associated with pregnancy 15 to 16 days after ovulation. Results also suggest that supplementation of mares that only have low T4 concentrations is not indicated or likely to be beneficial.