Objective—To determine arthroscopic findings in
lame horses with subtle radiographic lesions of the
medial femoral condyle.
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)
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)
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.
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.
Objective—To estimate prevalence of and identify
risk factors for fecal Salmonella shedding among hospitalized
horses with signs of gastrointestinal tract
Animals—465 hospitalized horses with gastrointestinal
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)