Computed tomographic (CT) arthrogram contributes to the diagnosis of an osteochondroma of the distal calcaneus in a horse

Osteochondromas in the horse are most commonly found as a solitary lesion affecting the distal radial metaphysis. In this location, diagnosis is reliant on radiographic and ultrasonographic examination and confirmed with post-operative histopathology. This case report describes the additional benefit of performing a CT arthrogram to aid the diagnosis of an osteochondroma in an atypical location.     

Gonadotropin-releasing hormone improves reproductive performance of dairy cows with slow involution of the reproductive tract

Eighty multiparous Holstein cows were assigned randomly at calving to receive either 100 microg of GnRH or saline 13 or 14 d postpartum (PP). From 4 to 28 d PP the cows' reproductive organs were palpated weekly per rectum, and cows were subclassified within each group as undergoing slow (delayed) cervical and uterine involution (abnormal) or as normal cows. Last milk obtained after removing the milking machine was assayed for progesterone 3 times a week for 120 d PP. Fourteen of the 80 cows were removed from the experiment because of culling or various veterinary treatments of pathologic conditions that could confound analysis of the GnRH treatment effects. As expected, the treatment of normal cows with GnRH had no significant effects on the first estrus or the first estrous cycle PP, on services per conception, days open, or any other reproductive trait measured. However, in the abnormal group of cows receiving saline, first rebreeding after calving was delayed (81 vs. 67 d), fewer were pregnant by 105 d PP (23 vs. 64%), and number of days open was greater (121 vs. 87 d) compared with those receiving GnRH; all were significant (P<.05). Treated abnormal cows were equivalent to the control normal cows. Thus, GnRH given 13 to 14 d PP to cows characterized as undergoing slow involution of the reproductive system, but with no other clinical problems, seems to assist in promoting rapid normal reproductive function. Subsequent losses due to culling were greatly reduced.     

Mercury vapor concentrations inside buildings

The concentrations of elemental gaseous mercury in several homes, offices, and laboratories in the Dallas area have been measured. The values are substantially higher than the ambient natural background concentration, about 3 nanograms of mercury per cubic meter of air in San Francisco, Dallas, and Washington, D.C.     

Seroprevalence of equine herpesvirus 1 in mares and foals on a large Hunter Valley stud farm in years pre- and postvaccination

OBJECTIVE: To examine the prevalence of equine herpesvirus 1 antibody in mares and foals on a large Hunter Valley Thoroughbred stud farm in New South Wales before and after the introduction of an inactivated whole virus vaccine. DESIGN: Cross-sectional serological surveys performed in February 1995 and 2000 to determine the prevalence of EHV-1 antibody-positive mares and foals. A further cross-sectional survey was carried out in 2001 to complement the 2000 data. STUDY POPULATION: Two hundred and twenty-nine mares and their foals were sampled in 1995 and 236 mares and their foals were sampled in 2000. The study population comprised all of the mares with foals at foot on this property at each sample period. Fifty mares were sampled in both studies. A further 264 mares and their foals were sampled in 2001. PROCEDURE: A blood sample was collected from each mare and foal at the beginning of February 1995, 2000 and 2001. Each sample was tested in triplicate using an antibody-detection ELISA that is type-specific for EHV-1 and EHV-4 antibodies. RESULTS: The prevalence of EHV-1 antibody-positive mares was not statistically different in 2000 compared to 1995. However, the prevalence of antibody-positive foals was significantly lower in 2000 than in 1995. In 2001, the prevalence of antibody-positive mares was higher than in 2000, but not different from that in 1995. The prevalence of antibody-positive foals in 2001 was not significantly different from the prevalence observed in 1995 or that observed in 2000. However, when the three studies were compared there was a significant variation in the prevalence of EHV-1 positive foals due to the variation between the 1995 and the 2000 data. CONCLUSIONS: Mares are the source of virus from which foals are infected early in life and following analysis of the 2001 data, the difference in the prevalence of EHV-1 antibody-positive foals between 1995 and 2000 was likely to be a reflection of seasonal, nutritional and management factors, rather than the result of vaccination.     

Serological responses of mares and weanlings following vaccination with an inactivated whole virus equine herpesvirus 1 and equine herpesvirus 4 vaccine

Equine herpesvirus 1 (EHV-1) is a major cause of respiratory disease and abortion in horses worldwide. Although some vaccines have been shown experimentally to reduce disease, there are few reports of the responses to vaccination in the field. This study measured antibody responses to vaccination of 159 mares (aged 4-17 years) and 101 foals (aged 3-6 months) on a large stud farm with a killed whole virus EHV-1/4 vaccine used as per the manufacturer's recommendations. Using an EHV glycoprotein D (gD)-specific ELISA and a type-specific glycoprotein G (gG) ELISA, respectively 13.8 and 28.9% of mares, and 42.6 and 46.6% of foals were classed as responding to vaccination. Additionally, 16.4 and 17.6% of mares were classified as persistently seropositive mares. Using both assays, responder mares and foals had lower week 0 mean ELISA absorbances than non-responder mares and foals. Responder mares were ten times more likely to have responder foals, and non-responder mares were six times more likely to have non-responder foals than other mares using the gG ELISA. Mares aged 7 years or less and foals aged 4 months or more were more likely to respond to vaccination than animals in other age groups. There was no association between response of mares and the number of previous vaccinations received and persistently seropositive mares did not respond to vaccination. This study documents the responses of mares and foals to vaccination in a large scale commercial environment in 2000, and suggests that knowledge of antibody status may allow a more selective vaccination strategy, representing considerable savings to industry.