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Abstract

Objective—To determine the effects of treatment with platelet- and leukocyte-rich plasma (PRP) on future 2-, 3-, and 4-year-old racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated suspensory ligament branch (SLB) desmitis.

Design—Randomized clinical trial.

Animals—39 yearling Thoroughbreds.

Procedures—Yearling Thoroughbreds with radiographic evidence of performance-limiting proximal sesamoid bone inflammation and ultrasonographic evidence of associated SLB desmitis were identified and randomly assigned to undergo PRP (treatment group) or saline (0.9% NaCl) solution (control group) injection at the affected SLB-proximal sesamoid bone junction. Race records of horses for the 2-, 3-, and 4-year-old racing years were obtained. Data regarding amount of money earned and number of races started were used as outcome measures, and results for groups were compared.

Results—Horses treated with PRP were significantly more likely to start at least 1 race during the 2-year-old racing year than were horses treated with saline solution; no significant differences were detected between groups regarding that variable for the 3- and 4-year-old racing years. No significant differences between groups were detected regarding earnings for any racing year.

Conclusions and Clinical Relevance—Although PRP-treated horses were more likely to start a race during the 2-year-old racing year versus control group horses, results for horses in each group were not significantly different for the 3- and 4-year-old racing years. Therefore, the PRP treatment protocol evaluated in this study did not seem to improve future racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated SLB desmitis, compared with injection of saline solution.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To quantify the number of horses with Corynebacterium pseudotuberculosis infection identified in the United States from January 2003 through December 2012.

Design—Cross-sectional study.

Sample—State veterinary diagnostic laboratory records of 2,237 C pseudotuberculosis culture-positive samples from horses.

Procedures—44 state veterinary diagnostic laboratories throughout the United States were invited by mail to participate in the study. Data requested included the number of C pseudotuberculosis culture-positive samples from horses identified per year, geographic location from which the C pseudotuberculosis culture-positive sample was submitted, month and year of sample submission, breed and age of horses, and category of clinical manifestation (ie, internal infection, external infection, or ulcerative lymphangitis).

Results—Of the 44 invited laboratories, 15 agreed to participate and provided data on affected horses from 23 states. The proportion of C pseudotuberculosis culture-positive samples submitted during 2011 through 2012 (1,213/2,237 [54%]) was significantly greater than that for the period from 2003 through 2010 (1,024/2,237 [46%]). Corynebacterium pseudotuberculosis was recovered from horses in states where the disease has not been previously recognized as endemic. Affected horses were identified year-round. The greatest proportion of C pseudotuberculosis culture-positive samples was identified during November, December, and January (789/2,237 [35%]). No significant association between the clinical form of disease and age or breed of horse was observed.

Conclusions and Clinical Relevance—The occurrence of C pseudotuberculosis infection in horses increased during the 10-year period, and affected horses were identified throughout the United States. Further studies to determine changes in annual incidence and to identify potential changing climatic conditions or vector populations associated with disease transmission are warranted to help control the occurrence and spread of C pseudotuberculosis infection in horses.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare bony changes in the metacarpophalangeal joint (MCPJ) of racehorses with (cases) and without (controls) biaxial proximal sesamoid bone (PSB) fracture as determined by 2 grading scales applied to images of cadaveric forelimbs obtained by means of standing MRI (sMRI).

Design—Case-control study.

Sample—Forelimbs from 74 Thoroughbred racehorses (21 cases and 53 controls) that were euthanized at a Florida racetrack.

Procedures—Both forelimbs were harvested from cases and controls. Each forelimb underwent sMRI to obtain images of the MCPJ. Two grading scales were described and used for image evaluation; one assessed the density of the PSBs, and the other assessed the integrity of the subchondral bone (SCB) plate at the distopalmar aspect of the third metacarpal bone (MC3). Logistic regression was used to compare the grades between case and control limbs.

Results—Biaxial PSB fracture was associated with a total PSB grade (sum of lateral and medial PSB grades) ≥ 5 for the fractured limb, total MC3 SCB grade (sum of lateral and medial MC3 SCB grades) ≥ 5 for the contralateral limb, and the presence of orthopedic disease in the contralateral MC3.

Conclusions and Clinical Relevance—For cases with biaxial PSB fracture, the density of the PSBs in the affected limb was greater and the MC3 of the contralateral limb was more likely to have orthopedic disease, compared with those for controls. Further evaluation of sMRI as a screening tool for identification of racehorses at risk of biaxial PSB fracture is warranted. (J Am Vet Med Assoc 2015;246:661–673)

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To describe the chief complaints by owners and the types and prevalences of musculoskeletal problems associated with lameness or poor performance in cutting horses.

DESIGN Retrospective case series.

ANIMALS 200 client-owned cutting horses examined at the Texas A&M University Veterinary Medical Teaching Hospital between January 1, 2007, and December 31, 2015, because of lameness or poor performance.

PROCEDURES Medical records were reviewed, and data were collected regarding signalment, history, findings on physical and lameness examinations, results of diagnostic procedures performed, diagnosis, and treatment. Distribution of observed proportions of forelimb and hind limb involvement was compared with a hypothetical distribution of 50% by means of a χ2 test.

RESULTS More horses were examined because of a recent decrease in performance (116/200 [58%]) than for lameness (84 [42%]). All horses had at least 1 lame limb, with lameness affecting a total of 281 limbs. Of the 281 lame limbs, 189 (67%) were hind limbs and 92 (33%) were forelimbs. These proportions were substantially different from a hypothetical distribution of 50% hind limbs and 50% forelimbs. The most common performance change was that horses would not reverse direction to follow prespecified individual cattle, and the most common cause of lameness was pain localized to the stifle joint region (69 [35%]).

CONCLUSIONS AND CLINICAL RELEVANCE Cutting horses sustained more hind limb than forelimb musculoskeletal problems, and although these horses were more likely to be examined for decreased performance than lameness, veterinarians should be vigilant for problems affecting the stifle joint region.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether mares are a clinically important source of Rhodococcus equi for their foals.

Sample Population—171 mares and 171 foals from a farm in Kentucky (evaluated during 2004 and 2005).

Procedures—At 4 time points (2 before and 2 after parturition), the total concentration of R equi and concentration of virulent R equi were determined in fecal specimens from mares by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively. These concentrations for mares of foals that developed R equi–associated pneumonia and for mares with unaffected foals were compared. Data for each year were analyzed separately.

ResultsR equi–associated pneumonia developed in 53 of 171 (31%) foals. Fecal shedding of virulent R equi was detected in at least 1 time point for every mare; bacteriologic culture results were positive for 62 of 171 (36%) mares at all time points. However, compared with dams of unaffected foals, fecal concentrations of total or virulent R equi in dams of foals with R equi–associated pneumonia were not significantly different.

Conclusions and Clinical Relevance—Results indicate that dams of foals with R equi–associated pneumonia did not shed more R equi in feces than dams of unaffected foals; therefore, R equi infection in foals was not associated with comparatively greater fecal shedding by their dams. However, detection of virulent R equi in the feces of all mares during at least 1 time point suggests that mares can be an important source of R equi for the surrounding environment.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the pharmacokinetics of gallium maltolate (GaM) after intragastric administration in healthy foals.

Animals—6 healthy neonatal foals.

Procedures—Each foal received GaM (20 mg/kg) by intragastric administration. Blood samples were obtained before (time 0) and at 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36, and 48 hours after GaM administration for determination of serum gallium concentrations by use of inductively coupled plasma mass spectroscopy.

Results—Mean ± SD pharmacokinetic variables were as follows: peak serum gallium concentration, 1,079 ± 311 ng/mL; time to peak serum concentration, 4.3 ± 2.0 hours; area under the serum concentration versus time curve, 40,215 ± 8,420 ng/mL/h; mean residence time, 39.5 ± 17.2 hours; area under the moment curve, 1,636,554 ± 931,458 ng([h]2/mL); and terminal half-life, 26.6 ± 11.6 hours. The mean serum concentration of gallium at 12 hours was 756 ± 195 ng/mL.

Conclusions and Clinical Relevance—Gallium maltolate administered via nasogastric tube at a dose of 20 mg/kg to neonatal foals resulted in gallium serum concentrations considered sufficient to suppress growth or kill Rhodococcus equi in macrophages and other infected tissues.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the use of sucrose permeability testing to detect ulcers in the gastric squamous mucosa of horses.

Animals—13 adult horses ranging from 5 to 19 years of age.

Procedure—Following induction of gastric ulcers by intermittent feed deprivation, horses underwent sucrose permeability testing (administration of sucrose by nasogastric intubation followed by collection of urine at 2 and 4 hours after intubation) and gastric endoscopy. Squamous ulcers were assigned a severity score (range, 0 to 3) by use of an established scoring system. Horses were subsequently administered omeprazole for 21 days, and sucrose testing and endoscopy were repeated. Pair-wise comparisons of urine sucrose concentration were made between horses with induced ulcers before and after omeprazole treatment. Urine sucrose concentrations also were compared on the basis of ulcer severity score.

Results—Urine sucrose concentrations and ulcer severity scores were significantly higher in horses with induced ulcers before omeprazole treatment than after treatment. Urine sucrose concentrations were significantly higher for horses with ulcer severity scores > 1. Use of a cut-point value of 0.7 mg/mL revealed that the apparent sensitivity and specificity of sucrose permeability testing to detect ulcers with severity scores > 1 was 83% and 90%, respectively. Results were similar after adjusting sucrose concentrations for urine osmolality.

Conclusions and Clinical Relevance—Urine sucrose concentration appears to be a reliable but imperfect indicator of gastric squamous ulcers in horses. Sucrose permeability testing may provide a simple, noninvasive test to detect and monitor gastric ulcers in horses. ( Am J Vet Res 2004;65:31–39)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the importance of iron for in vitro growth of Rhodococcus equi, define potential iron sources in the environment and mechanisms by which R equi may obtain iron from the environment, and assess expression and immunogenicity of iron-regulated proteins.

Sample Population—10 virulent and 11 avirulent strains of R equi.

Procedure—In vitro growth rates and protein patterns of R equi propagated in media with normal, excess, or limited amounts of available iron were compared. Immunoblot analyses that used serum from foals naturally infected with R equi and monoclonal antibody against virulence-associated protein (Vap)A were conducted to determine immunogenicity and identity of expressed proteins.

Results—Excess iron did not alter growth of any R equi strains, whereas growth of all strains was significantly decreased in response to limited amounts of available iron. Virulent R equi were able to use iron from ferrated deferoxamine, bovine transferrin, and bovine lactoferrin. Only virulent R equi expressed an iron-regulated, immunogenic, surface-associated protein identified as VapA.

Conclusions and Clinical Relevance—Iron is required for the growth and survival of R equi. Sources of iron for R equi, and mechanisms by which R equi acquire iron in vivo, may represent important virulence factors and novel targets for the development of therapeutic and immunoprophylactic strategies to control R equi infection in foals. Expression of VapA is substantially upregulated when there is a limited amount of available iron. (Am J Vet Res 2003;64:1337–1346)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine factors associated with development of postoperative ileus (POI) in horses undergoing surgery for colic.

Design—Prospective case-control study.

Animals—251 horses undergoing colic surgery, of which 47 developed POI.

Procedure—Signalment, history, clinicopathologic data, pre- and postoperative treatments, lesions, complications, costs, and outcome were recorded for all horses during hospitalization.

Results—Variables associated with increased odds of POI included small intestinal lesion, high PCV, and increased duration of anesthesia. There was modest evidence that pelvic flexure enterotomy and intraoperative administration of lidocaine may have reduced the odds of developing POI.

Conclusions and Clinical Relevance—Findings during the preoperative and intraoperative periods can be used to identify horses at increased risk of POI. Reducing surgical and anesthetic duration should decrease the incidence of POI. ( J Am Vet Med Assoc 2004;225: 1070–1078)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether administration of killed West Nile virus vaccine was associated with pregnancy loss among broodmares.

Design—Retrospective cohort study.

Animals—595 mares.

Procedure—Records of pregnant mares with known vaccination history from 4 farms were reviewed. Information obtained from 595 mares included mare's identification; farm; age; breed; reproductive status; last breeding date; date last known pregnant; vaccination date; age of conceptus at vaccination; vaccination during the early embryonic, early fetal, and late fetal periods; and whether an early embryonic death (EED), early fetal loss (EFL), or late fetal loss (LFL) occurred. The relationships between the dichotomous outcomes of loss (eg, EED, EFL, LFL) and independent categoric variables (eg, vaccination during the early embryonic, early fetal, or late fetal periods) were examined.

Results—Vaccination of pregnant mares during any period of gestation was not associated with increased incidence of pregnancy loss.

Conclusions and Clinical Relevance—Many mares are already pregnant at the onset of mosquito season, when mares are more likely to be vaccinated than at other times. Our findings provide evidence that vaccine administration will not compromise pregnancy in horses. (J Am Vet Med Assoc 2004;225:1894–1897)

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in Journal of the American Veterinary Medical Association