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Abstract

Objective—To determine arthroscopic findings in lame horses with subtle radiographic lesions of the medial femoral condyle.

Design—Retrospective study.

Animals—15 horses examined because of lameness that had subtle radiographic evidence of osteochondral lesions involving the medial femoral condyle in at least 1 joint.

Procedure—Medical records were reviewed, and results of physical examination, radiography, and arthroscopy were recorded. Follow-up information was obtained through reexamination of the horses or telephone conversations with the referring veterinarians, owners, or trainers.

Results—Lameness severity ranged from grade 1 to 3 on a scale from 0 to 5. Radiography and arthroscopy were performed on 28 stifle joints. The 4 unaffected joints in 4 horses with unilateral hind limb lameness that underwent bilateral arthroscopy had no radiographic lesions, but 2 of the 4 had arthroscopic lesions. Of the remaining 24 joints, 20 had radiographic evidence of flattening of the apex of the medial femoral condyle and 4 had minimal subchondral lucency. Lesions were identified arthroscopically in 18 of the 20 joints with flattening of the condyle and in all 4 joints with subchondral lucency. Treatment consisted of abrasion arthroplasty or microfracture. Seven of the 9 horses with focal cartilage lesions and 2 of the 6 horses with generalized cartilage lesions were reportedly sound without any evidence of joint effusion at the time of final follow-up.

Conclusions and Clinical Relevance—Results suggest that horses with hind limb lameness and subtle radiographic lesions of the medial femoral condyle are likely to have arthroscopically apparent cartilage lesions and subchondral bone defects. (J Am Vet Med Assoc 2004;224:1821–1826)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate use of electroacupuncture for treatment of horses with signs of chronic thoracolumbar pain.

Design—Prospective study.

Animals—15 horses with signs of chronic thoracolumbar pain.

Procedure—Horses were randomly allocated to 1 of 3 treatment groups. Horses in group 1 received electroacupuncture stimulation (once every 3 days for 5 treatments), those in group 2 received phenylbutazone (2.2 mg/kg [1 mg/lb], PO, q 12 h, for 5 days), and those in group 3 received saline (0.9% NaCl) solution (20 mL, PO, q 12 h, for 5 days). Thoracolumbar pain scores (TPSs) were evaluated before (baseline) and after each treatment.

Results—Mean ± SE TPSs in horses receiving phenylbutazone or saline solution did not change significantly during the study. After the third treatment, mean ± SE TPS (2.1 ± 0.6) in horses receiving electroacupuncture stimulation was significantly lower than baseline (6.0 ± 0.6) TPS. Mean ± SE TPSs in horses receiving electroacupuncture stimulation were significantly lower than baseline TPSs and TPSs in horses receiving phenylbutazone or saline solution after the third treatment to 14 days after the last treatment.

Conclusions and Clinical Relevance—TPSs are useful for evaluating the efficacy of various analgesic methods used for treatment of thoracolumbar pain in horses. Electroacupuncture was effective for treatment of chronic thoracolumbar pain in horses. Results provided evidence that 3 sessions of electroacupuncture treatment can successfully alleviate signs of thoracolumbar pain in horses. The analgesic effect induced by electroacupuncture can last at least 2 weeks. Phenylbutazone administered PO did not effectively alleviate signs of thoracolumbar pain in horses in this study. (J Am Vet Med Assoc 2005;227:281–286)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of a dose of caffeine (2.5 mg/kg, IV) administered to physically fit Thoroughbreds during incremental exercise testing to fatigue on a treadmill.

Animals—10 conditioned Thoroughbreds.

Procedure—Horses were randomly assigned to receive caffeine or a control solution. Each horse received both treatments in a crossover design with a 3-week interval between treatments. Each horse was administered caffeine (2.5 mg/kg) or an equivalent amount of a control solution IV. One hour after injection, each horse performed an incremental exercise test to exhaustion. Hematologic values, heart rate, oxygen consumption, carbon dioxide production, plasma lactate concentration, urine and serum concentrations of caffeine and metabolites, and time until exhaustion were monitored. Statistical analysis was performed by use of a mixed-effects linear model.

Results—Significant differences in measured values when horses were treated with caffeine or the control solution were not detected.

Conclusions and Clinical Relevance—A dose of caffeine (2.5 mg/kg, IV) appears to have no effect on any performance variable of physically fit Thoroughbreds during incremental exercise testing to fatigue. (Am J Vet Res 2005;66:569–573)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the durations of the local anesthetic effect and plasma procaine concentrations associated with 5- and 10-mg doses of procaine hydrochloride (with or without 100 μg of epinephrine) administered SC over the lateral palmar digital nerves of horses.

Animals—6 healthy adult horses.

Procedures—The hoof withdrawal reflex latency (HWRL) period was determined by use of a focused heat lamp before and after administration of procaine with and without epinephrine. Blood samples were collected immediately before determination of each HWRL period to assess plasma concentrations of procaine via liquid chromatography–mass spectrometry–mass spectrometry (LC-MS-MS).

Results—10 but not 5 mg of procaine alone and 5 and 10 mg of procaine administered with epinephrine significantly prolonged the HWRL period (mean durations of effect, 5, 120 and 180 minutes, respectively), compared with baseline values. Plasma procaine concentrations did not correlate well with local anesthetic activity; for example, although the HWRL was prolonged to the maximum permitted duration of 20 seconds at 60 to 180 minutes following administration of the 5-mg dose of procaine with epinephrine in certain horses, plasma procaine concentrations were less than the limit of quantitation of the LC-MS-MS assay.

Conclusions and Clinical Relevance—Small doses of procaine coadministered with epinephrine provided long-lasting local analgesia and resulted in plasma procaine concentrations that were not always detectable via LC-MS-MS. On the basis of these results, the use of regulatory limits or thresholds for procaine concentration in equine plasma samples obtained after racing should be seriously reconsidered.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effects of a standardized exercise test to exhaustion in horses on leukocyte function ex vivo.

Animals—6 Thoroughbred geldings.

Procedures—Blood samples were obtained from each horse before exercise; at exhaustion (termed failure); and at 2, 6, 24, 48, and 72 hours after exercise to evaluate hematologic changes, rate of leukocyte apoptosis, and leukocyte production of reactive oxygen species (ROS) ex vivo. To assess leukocyte function, leukocyte ROS production in response to stimulation with lipopolysaccharide, peptidoglycan, zymosan, and phorbol myristate acetate was evaluated. Apoptosis was evaluated via assessment of caspase activity in leukocyte lysates.

Results—In response to lipopolysaccharide, production of ROS by leukocytes was significantly increased at 2 hours and remained increased (albeit not significantly) at 6 hours after exercise, compared with the preexercise value. In the absence of any stimulus, leukocyte ROS production was significantly increased at 6 and 24 hours after exercise. In contrast, ROS production in response to phorbol myristate acetate was significantly decreased at 6, 24, and 72 hours after exercise. Leukocyte ROS production induced by zymosan or peptidoglycan was not altered by exercise. Leukocytosis was evident for 24 hours after exercise, and neutrophilia was detected during the first 6 hours. A significant increase in the rate of leukocyte apoptosis was detected at failure and 72 hours after exercise.

Conclusions and Clinical Relevance—Results indicated that strenuous exercise undertaken by horses causes alterations in innate immune system functions, some of which persist for as long as 72 hours after exercise.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To estimate prevalence of and identify risk factors for fecal Salmonella shedding among hospitalized horses with signs of gastrointestinal tract disease.

Design—Cross-sectional study.

Animals—465 hospitalized horses with gastrointestinal tract disease.

Procedure—Horses were classified as positive or negative for fecal Salmonella shedding during hospitalization by means of standard aerobic bacteriologic methods. The relationship between investigated exposure factors and fecal Salmonella shedding was examined by means of logistic regression.

Results—The overall prevalence of fecal Salmonella shedding was 13%. Salmonella serotype Newport was the most commonly isolated serotype (12/60 [20%]), followed by Anatum (8/60 [13%]), Java (13%), and Saint-paul (13%). Foals with gastrointestinal tract disease were 3.27 times as likely to be shedding Salmonella organisms as were adult horses with gastrointestinal tract disease. Adult horses that had been treated with antimicrobial drugs prior to hospitalization were 3.09 times as likely to be shedding Salmonella organisms as were adult horses that had not been treated with antimicrobial drugs prior to hospitalization. Adult horses that underwent abdominal surgery were 2.09 times as likely to be shedding Salmonella organisms as were adult horses that did not undergo abdominal surgery.

Conclusions and Clinical Relevance—Results suggest that a history of exposure to antimicrobial drugs prior to hospitalization and abdominal surgery during hospitalization were associated with Salmonella shedding in adult horses with gastrointestinal tract disease. Foals with gastrointestinal tract disease were more likely to shed Salmonella organisms than were adult horses with gastrointestinal tract disease. (J Am Vet Med Assoc 2004;225:275–281)

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in Journal of the American Veterinary Medical Association