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Abstract

Objective—To determine risk factors for Clostridium piliforme infection in neonatal foals on a Thoroughbred breeding farm in California.

Design—Case-control and retrospective cohort studies.

Animals—322 neonatal Thoroughbred foals either born on the study farm or born elsewhere but traveled to the farm with their dam during the 1998, 1999, and 2000 breeding seasons.

Procedure—Mare and foal records from 1998, 1999, and 2000 were examined, using case-control design methods to determine variables associated with increased risk of C piliforme infection in foals. Important risk factors identified in the case-control study were then reevaluated by use of a retrospective cohort design, using data from all neonatal foals present on the farm during the 3-year study period.

Results—Foals born between March 13 and April 13 were 7.2 times as likely to develop C piliforme infection as were those born at any other time of the foaling season. Foals of nonresident (visiting) mares were 3.4 times as likely to develop disease as were foals born to mares that were permanent residents of the study farm. Foals of mares < 6 years of age were 2.9 times as likely to develop disease as were foals born to older mares.

Conclusions and Clinical Relevance—Results of this research can be used to better understand the epidemiologic factors of C piliforme infection in horses. High-risk foals can be closely monitored to aid in early diagnosis and treatment, resulting in the best possible clinical outcome for affected individuals. (J Am Vet Med Assoc 2002;220:785–790)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the effectiveness of lincomycin and oxytetracycline for treatment of digital dermatitis (DD) in dairy cows through gross visual examination, histologic evaluation, and bacteriologic evaluation.

Design—Randomized controlled clinical trial.

Animals—25 cows with DD lesions from a commercial Holstein dairy herd.

Procedures—Cows with DD lesions were randomly assigned to 1 of 3 groups: topical treatment with 10 g of lincomycin hydrochloride (n = 11), topical treatment with 10 g of oxytetracycline hydrochloride (11), and no treatment (3) on days 1 and 2 (d1). Biopsy specimens were obtained for histologic examination from DD lesions prior to treatment and 28 or 31 days (d30) after treatment for histologic examination. Cows were clinically examined on d1, days 12 or 14 (d14), and d30.

Results—No difference was evident in clinical responses to lincomycin and oxytetracycline, so data were pooled; at d30, 8 of 11 of lincomycin-treated lesions and 7 of 11 oxytetracycline-treated lesions appeared visually healed, respectively. Gross visual examination suggested 73% (16/22) of treated cows were healed at d14 and 68% (15/22) of treated cows were healed on d30. Of the 15 lesions that appeared healed on d30, 7 of 15 were classified histologically as active (ulceration and bacterial invasion; 2/15) or incipient (5/15).

Conclusions and Clinical Relevance—Clinical responses to lincomycin and oxytetracycline did not differ. Agreement was good between gross visual and histologic assessments of DD lesions before treatment; agreement 1 month after treatment was variable. Histologic evaluation could not distinguish incomplete healing from lesion recurrence.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine whether a humoral response against spirochetes isolated from papillomatous digital dermatitis (PDD) lesions is elicited in dairy cattle affected with PDD.

Sample Population

41 cattle with PDD from 8 dairies (study population) and 30 cattle from 2 dairies free of PDD (control population). Additionally evaluated were 32 cattle from a dairy with a past history of PDD but no current disease, and 52 cattle from a dairy with high prevalence of PDD, 25 with and 27 without detectable lesions.

Procedure

ELISA were used to evaluate the humoral response of all cattle to representative isolates from 2 groups of spirochetes of unknown species isolated from PDD lesions. Specificity of the response was evaluated, using immune sera prepared against each of the spirochetes, and by adsorption studies of immune and field sera. The potential for confounding by an antibody response to other spirochetes associated with diseases of cattle was assessed.

Results

The antibody response (specific) to both PDD spirochete groups of cows with PDD was significantly increased, compared with that of cows from PDD-free dairies. There was no association between antibody response to PDD-associated spirochetes and antibody response to other spirochetal diseases of cattle. None of the cattle from the dairy with previous history of PDD but without current disease were classified as test positive by either PDD ELISA. There was a significant (P < 0.01) difference in classification results for both PDD ELISA for cattle with PDD from the dairy with a high herd prevalence of PDD, compared with cattle without detectable disease from the same dairy.

Conclusions and Clinical Relevance

The humoral response in cattle with PDD lesions was significantly different from that in cattle without detectable lesions, thus providing additional information regarding the potential role of spirochetes isolated from PDD lesions in the etiopathogenesis of PDD. (Am J Vet Res 1997;58:744–748)

Free access
in American Journal of Veterinary Research

Objective

To estimate prevalence of papillomatous digital dermatitis (PDD) in California dairies during 1993, to describe temporal and spatial patterns of PDD and response of cows to treatment, and to evaluate herd-related risk factors for PDD.

Design

Epidemiologic survey.

Sample Population

All southern California dairies and a 50% random sample of the rest of California dairies.

Procedure

A questionnaire was mailed to managers of 1,429 selected dairies.

Results

Prevalence of PDD during 1993 was significantly higher for dairies in the south (75.3%) and central (68.8%) regions, compared with north coast (33.3%) and north (23.1%) regions of the state. Herd mean and median proportions of affected cows in PDD-affected herds were 11.6 (SEM = 0.9) and 5%, respectively. Most (74%) dairy managers surveyed observed PDD for the first time during 1992 or 1993. Highest PDD activity was reported as taking place in summer in the south and in fall and winter in the north coast and north regions; an obvious pattern was not determined for the central region.

Clinical Implications

PDD was widespread in California dairies during 1993 and affected a high proportion of cows, especially in the south and central regions of the state. (J Am Vet Med Assoc 1996;209:1464–1467)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine sensitivity and specificity of western blot testing (WBT) of CSF and serum for diagnosis of equine protozoal myeloencephalitis (EPM) in horses with and without neurologic abnormalities.

Design—Prospective investigation.

Animals—65 horses with and 169 horses without neurologic abnormalities.

Procedure—CSF and serum from horses submitted for necropsy were tested for Sarcocystis neuronaspecific antibody with a WBT. Results of postmortem examination were used as the gold standard against which results of the WBT were compared.

Results—Sensitivity of WBT of CSF was 87% for horses with and 88% for horses without neurologic abnormalities. Specificity of WBT of CSF was 44% for horses with and 60% for horses without neurologic abnormalities. Regardless of whether horses did or did not have neurologic abnormalities, sensitivity and specificity of WBT of serum were not significantly different from values for WBT of CSF. Ninety-four horses without EPM had histologic evidence of slight CNS inflammation.

Conclusions and Clinical Relevance—The low specificity of WBT of CSF indicated that it is inappropriate to diagnose EPM on the basis of a positive test result alone because of the possibility of false-positive test results. The high sensitivity, however, means that a negative result is useful in ruling out EPM. There was no advantage in testing CSF versus serum in horses without neurologic abnormalities. Slight CNS inflammation was common in horses with and without S neurona-specific antibodies in the CSF and should not be considered an indication of CNS infection with S neurona. (J Am Vet Med Assoc 2002;221:1007–1013)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine major causes of death and the anatomic location of musculoskeletal injuries in Quarter Horse racehorses in California.

Design—Retrospective case series.

Animals—314 Quarter Horse racehorses with musculoskeletal injuries that were necropsied through the California Horse Racing Board Postmortem Program from 1990 to 2007.

Procedures—Postmortem pathology reports were retrospectively reviewed. Musculoskeletal injuries were categorized by anatomic region and described. The number of Quarter Horse starts and starters for the same period of time were obtained from a commercial database for determination of fatal injury incidence.

Results—Musculoskeletal injuries accounted for 314 of the 443 (71 %) Quarter Horse racehorses that died during the 18-year study period. Fatal musculoskeletal injuries occurred at a rate of 2.0 deaths/1,000 race starts and 18.6 deaths/1,000 horses that started a race. Musculoskeletal injuries occurred predominantly during racing (84%) and in the forelimbs (81%). The most common fatal musculoskeletal injuries were metacarpophalangeal and metatarsophalangeal joint (fetlock) support injuries (40%) and carpal (24%), vertebral (10%), and scapular (8%) fractures. Proximal interphalangeal (pastern) joint luxations resulted in death of 3% of horses. Fracture configurations of some bones were consistent with those of Thoroughbred racehorses. Evidence of preexisting stress remodeling of bone was reported for some fractures.

Conclusions and Clinical Relevance—Knowledge of common locations and types of fatal musculoskeletal injuries in racing Quarter Horses may enhance practitioners' ability to detect mild injuries early, rest horses, and help prevent catastrophic injuries.

Full access
in Journal of the American Veterinary Medical Association

Objective

To determine whether a two-month or longer period without official high-speed workouts (lay-up) is associated with humeral or pelvic fracture in Thoroughbred racehorses.

Design

Retrospective study.

Animals

Thoroughbred racehorses in California that were euthanatized because of a complete humeral or pelvic fracture.

Procedure

Age, sex, activity, number of lay-ups, number of days from a race or official timed workout to fracture, number of days from end of last lay-up to fracture, mean duration of lay-ups, and total number of days in race training were compared between horses with humeral fractures and horses with pelvic fractures. A case-crossover study was used to estimate relative risk for fracture of the humerus or pelvis occurring within hazard periods of 10 and 21 days following lay-up, compared with periods following more regular participation in official racing or timed workout events.

Results

Horses with pelvic fractures were more often female, older, and had 0 or ≥ 2 lay-ups. Horses with humeral fractures were typically 3-year-old males that had 1 lay-up. Horses with pelvic fractures had more total days in race training, fewer days from last exercise event to fracture, and a greater number of days from end of last lay-up to fracture than horses with humeral fractures. Return from lay-up was strongly associated with risk for humeral fracture during hazard periods of 10 and 21 days (relative risk = 71 and 45, respectively).

Clinical Implications

Risk of humeral fracture may be reduced if horses are cautiously reintroduced into race training after lay-up. (J Am Vet Med Assoc 1998;212: 1582–1587)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate selected shoe characteristics as risk factors for fatal musculoskeletal injury (FMI) and specifically for suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) of Thoroughbred racehorses in California.

Design

Case-control study.

Animals

Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994.

Procedure

Shoe characteristics were compared between case horses affected by FMI (155), SAF (79), and CDY (41) and control horses that died for reasons unrelated to the appendicular musculoskeletal system (non-FMI; 46). Multivariable logistic regression was used to estimate odds ratios for FMI, SAF, and CDY.

Results

Toe grabs were identified as possible risk factors for FMI, SAF, and CDY. The odds of FMI, SAF, and CDY were 1.8, 6.5, and 7.0, respectively, times greater for horses shod with low toe grabs than for horses shod without toe grabs on front shoes. Horses shod with regular toe grabs on front shoes had odds 3.5, 15.6, and 17.1 times greater (P < 0.05) for FMI, SAF, and CDY, respectively, compared with horses shod without toe grabs. The odds of horses shod with rim shoes were a third (P < 0.05) of those shod without rim shoes for either FMI or SAF. The apparent association between toe grab type and CDY may, in part, be attributable to concurrent SAF and CDY injuries in many horses.

Clinical Relevance

Avoiding the use of toe grabs should decrease the incidence of FMI, especially SAF, in Thoroughbred racehorses. The use of rim shoes that are more consistent with natural hoof shape may decrease injury risk. (Am J Vet Res 1996;57:1147-1152)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To develop a standard technique for evaluation of racehorse shoes, to assess homotypic variation (interlimb variation) in shoe characteristics, and to determine whether shoe characteristics varied with age and sex.

Design

Cross-sectional study.

Animals

Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994.

Procedure

Shoe characteristics were measured on horses examined after death. Percentage of agreement was used to compare shoe characteristics between limbs (homotypic variation). Using χ2analysis, shoe characteristics were compared between horses grouped by age and sex.

Results

Toe grabs were present on 90.5% of horses, and rim shoes were present on 15.9% of horses. Heel traction devices were less frequent on front (2.5%) than rear (6%) hooves. Pads were present on 24.9% of horses, with bonded rim pads most common. Special types of shoes were present on 5% of horses. Percentage of agreement between left and right front hooves and between left and right rear hooves was high (20/25 variables; % agreement ≥ 99). In contrast, percentage of agreement between left front and left rear hooves and between right front and right rear hooves was low (2/25 variables; % agreement ≥ 99). Presence of a pad was significantly (P < 0.05) associated with age, and several shoe variables (size, presence of a special shoe, overall wear matched) were significantly (P < 0.05) associated with sex.

Clinical Relevance

Except for variables related to special shoes, wear, and weight, 1 shoe for the respective fore- or hind limbs could be used as an indicator for the contralateral shoe worn by Thoroughbred racehorses without substantial loss of information. However, 1 shoe could not be used as an indicator for shoe characteristics of all 4 limbs. Some shoe characteristics are associated with age and sex, and these variables should be considered possible confounders in studies of shoe characteristics. (Am J Vet Res 1996;57:1141-1146)

Free access
in American Journal of Veterinary Research

Objective—

To estimate the minimum rate of abortion attributable to infection with Neospora sp in selected California dairy herds.

Design—

Prospective study.

Animals—

Twenty-six dairy herds containing 19,708 cows were studied. Fourteen herds had a history of abortions attributable to neosporosis, and 12 were herds in which neosporosis had not been identified as a cause of abortions.

Procedure—

During a 1-year period, all available aborted fetuses were submitted to veterinary diagnostic laboratories to determine the cause of abortion. Reproductive records of cows that aborted were reviewed.

Results—

Neospora sp infection was the major cause of abortion identified (113/266 abortions, 42.5%). The majority (232/266, 87.2%) of the aborted fetuses were submitted from herds with a history of abortions attributable to neosporosis, and Neospora sp infection was identified as the causative agent in 101 of 232 (43.5%) of the abortions from these herds. Fewer aborted fetuses were submitted from the 12 herds that did not have a history of abortion attributable to Neospora sp; however, neosporosis was confirmed as a cause of abortion in 6 of these 12 herds and was identified as the causative agent in 12 of 34 (35.3%) abortions from these herds. The disease was widespread throughout the state (19/26 herds in our study). Available reproductive histories of cows that had abortions attributed to neosporosis were evaluated, and 4 cows were identified that twice aborted Neospora-in-fected fetuses.

Free access
in Journal of the American Veterinary Medical Association