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Abstract

Objective—To compare financial returns between pinhooked yearling horses (ie, bought and trained for approximately 5 months with the goal of selling the horse at "2-year-olds in training" sales) that had mild or severe training failure and horses that had planned versus nonplanned training failure.

Animals—40 Thoroughbred pinhooked yearling horses.

Procedure—During the period from September 1998 through and April 1999, 20 horses had mild training failure (1 to 11 days lost), and 20 horses had severe training failure (13 to 108 days lost). Horses were assigned to these 2 groups on the basis of frequency distribution (median) of days lost during training. Horses were also categorized on the basis of type of training failure (planned vs nonplanned training failure). The outcome of primary interest was financial return. Median financial returns were compared among groups by use of the Mann-Whitney U test.

Results—Median financial returns for horses that had severe training failure ($1,000) were significantly different, compared with horses that had mild training failure ($24,000). Analysis of results also indicated that median returns were significantly different among horses that had planned training failure (−$2,000; eg, horses with radiographic abnormalities detected during routine prepurchase examinations that required surgical treatment, resulting in days lost during training), compared with horses that did not ($10,000).

Conclusions and Clinical Relevance—Training failure has an economic impact on revenues in pinhooked yearling horses. Lameness, planned training failure, respiratory disease, and ringworm were common and important causes of training failure. (Am J Vet Res 2001;62:1418–1422)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To investigate the effect of late gestation, age, and parity on material properties of third metacarpal (MCIII) cortical bone in mares.

Animals

8 healthy mares (treatment group) that died or were euthanatized within 24 hours after parturition because of foaling complications and 6 age-matched, healthy, nonpregnant mares (control group).

Procedures

After random assignment for mechanical testing and microradiography, the dorsal half of transverse mid-diaphyseal sections of each MCIII bone was divided into lateral, dorsal, and medial regions. Cylinders of bone from each of the 3 regions were tested in compression in a single cycle to failure. Contact microradiographic views were taken of 100-µm-thick sections prepared from methylmethacrylate-embedded transverse dorsal region specimens, which were further divided into periosteal, intracortical, and endosteal regions for assessment of bone mineral density and porosity.

Results

Postpartum mares had lower yield strain in the dorsal and medial regions and failure strain in the medial region. Increasing parity was associated with decreasing elastic modulus in the dorsal region and yield stress and failure stress in the lateral region. Age and parity were positively correlated (r = 0.865; P = 0.0001), but significant correlations were not found between treatment group and age or between treatment group and parity. Increasing age and parity were associated with increasing porosity in the periosteal region.

Conclusions and Clinical Relevance

On the basis of the material properties evaluated for MCIII cortical bone in late pregnancy, any increased risk for fractures in mares in late gestation may be related to parity or age or both, and less likely to pregnancy per se. (Am J Vet Res 1997;58:182–187)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To identify race-start characteristics associated with catastrophic musculoskeletal (MS) injury in Thoroughbred racehorses at 2 racetracks in Florida during 1995 through 1998.

Design—Matched case-control study.

Animals—97 Thoroughbreds (case horses) that incurred a catastrophic MS injury during racing and 388 Thoroughbreds (control horses) randomly selected from noninjured participants and matched on the basis of racetrack and year.

Procedure—Incidence of MS injury was calculated for all race meets at 2 racetracks in Florida from 1995 through 1998. Race-start characteristics were compared among case and control horses, using conditional logistic regression.

Results—Overall incidence of MS injury was 1.2/1,000 race starts (97/79,416 starts). Incidence of injury was significantly higher for turf races (2.3/1,000 starts) than for dirt races (0.9/1,000 starts). Sex, number of days since last race, and racing surface were associated with risk of injury; geldings, ≥ 33 days since the last race, and turf racing surface were associated with a higher risk of injury.

Conclusions and Clinical Relevance—Incidence of injury among Thoroughbreds in Florida was associated with sex, number of days since last race, and racing surface. Days since last race may have been an indicator of previous health and lameness problems. Racing surface may have been a risk factor for MS injury because turf races tended to be more competitive than dirt races. Horses running in turf races were more likely to participate in races with a large field, handicap races, long races, and races with high purses. (J Am Vet Med Assoc 2001;218:83–86)

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

Six horses received intra-articular injections of a mixture of 1 μg of endotoxin/5 mg of equine tumor necrosis factor (eqTNF) monoclonal antibody in 1 antebrachiocarpal joint and an equal volume (2 ml) of 1 μg of endotoxin/5 mg of control antibody in the opposite joint. Synovial fluid sample collection (1 ml) was accomplished by use of an indwelling, intra-articular catheter at postinjection hours (pih) 0, 1, 1.5, 2, 5, and 8, and by arthrocentesis at pih 24. Joint fluid samples were analyzed for nucleated cell count, protein concentration, and tnf, interleukin 6 (il-6), il-1, and il-1-inhibitory activities. To monitor local inflammation, each carpus was graded semiquantitatively for swelling prior to each sample collection.

Tumor necrosis factor, il-1, or il-1-inhibitory activity was not detected in any synovial fluid sample collected before endotoxin/antibody was administered. However, low il-6 activity (< 100 U/ml) was found in 2 of 12 preinjection samples. In joints injected with endotoxin/control antibody mixture, maximal mean ± sem activities for tnf (1,019 ± 310 U/ml), il-1 (173 ± 102 U/ml), and il-6 (10.8 ± 3.1 × 104 U/ml) were observed at pih 2, 5, and 8, respectively. Tumor necrosis factor and il-1 activities returned to baseline values by pih 8 and 24, respectively; however, il-6 activity remained high. Interleukin 1-inhibitory activity (27.4 ± 2.25 IU/ml) was detected in all pih-24 samples from control joints, but was not detected at any other time in control joints (limit of detection, 20 IU/ml).

Tumor necrosis factor activity was not detected in any synovial fluid sample from joints treated with endotoxin/eqTNF antibody. In contrast, endotoxin-induced mean synovial il-1 and il-6 activities were not reduced significantly by eqTNF antibody. Mean il-1-inhibitory activity (pih 24) was higher in eqTNF antibody-treated joints (41.0 ± 7.7 IU/ml) than in control joints, but the difference was not significant. Mean wbc count and protein concentration in control and treated joints were maximal at pih 8. The curves for mean values of wbc count and total protein concentration were not significantly different in treated versus control joints. Swelling in each treated joint was either less than or the same as that in the opposite control joint at every time in the initial 8 pih. There was significant (P = 0.043) difference between treated and control joints at pih 5 and 8. These results describe a profile of synovial fluid tnf, il-1, il-6 bioactivities, and il-1-inhibitory activity during the initial 24 hours of synovitis induced by intra-articular administration of endotoxin in horses. Our eqTNF monoclonal antibody was effective in neutralizing tnf activity in synovial fluid when administered intra-articularly with endotoxin in horses. The induction of il-1, il-1-inhibitory activity, il-6, wbc, and total protein concentration responses are largely independent of tnf activity in synovial fluid of horses receiving endotoxin intra-articularly.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate horseshoe characteristics and high-speed exercise history as risk factors for catastrophic musculoskeletal injury in Thoroughbred racehorses.

Animals—377 horses (37,529 race starts).

Procedure—Shoe characteristics included material, toe grab height, heel traction device, pads, and rim shoes. Racing variables were obtained from a computerized database. Forty-three horses that had a musculoskeletal injury and then failed to race or train for 6 months (cases) and 334 noninjured horses from the same race in which a horse was injured (controls) were compared regarding risk factors.

Results—Overall, 98% of race starts were associated with aluminum shoes, 85% with toe grabs, 32% with pads, and 12% with rims on forelimb horseshoes. Among 43 horses with musculoskeletal injury, sex (geldings), an extended interval since last race, and reduced exercise during the 30 or 60 days preceding injury were risk factors for catastrophic injury. Odds of injury in racehorses with toe grabs on front shoes were 1.5 times the odds of injury in horses without toe grabs, but this association was not significant (95% confidence interval, 0.5 to 4.1).

Conclusions and Clinical Relevance—Results suggest that horses that return to racing after an extended period of reduced exercise are at high risk of catastrophic musculoskeletal injury. Results regarding the use of toe grabs as a possible risk factor for catastrophic injury were inconclusive because the probability of declaring (in error) that use of toe grabs was associated with an increased risk of musculoskeletal injury (eg, odds ratio > 1.0) was 38%. (Am J Vet Res 2005;66:1314–1320)

Full access
in American Journal of Veterinary Research

SUMMARY

In each of 4 horses, sterile synovitis was induced by intra-articular injection of 3 μg of Escherichia coli endotoxin (lipopolysaccharide, LPS) into one antebrachiocarpal joint; an equal volume (2 ml) of phosphate-buffered saline solution (PBSS) was injected into the opposite, control carpus. Blood and 1.5 ml of synovial fluid were obtained at postinjection hours (pih) 0, 2, 4, 8, 12, 18, 42, 66, and 144. Synovial fluid sample collection was accomplished by use of an indwelling, intra-articular catheter through pih 12, and by arthrocentesis subsequently. Joint fluid samples were analyzed for cell counts, protein concentration, cytologic variables, and tumor necrosis factor (tnf), interleukin 6 (IL-6), and prostaglandin E2 (PGE2) values. Tumor necrosis factor and 1L-6 activities and WBC count were also measured in blood. To monitor local inflammation, skin temperature of each carpus was imaged, using a thermographic scanner prior to each sample collection time.

Horses had minimal systemic effects. Mean (± SEM) rectal temperature increased significantly to 39 02 ± 0.15 C only at pih 18 after intra-articular injection of LPS. One horse had signs of mild depression from pih 7 to 18, but its vital signs did not change appreciably. Each horse had mild signs of discomfort in the LPS-injected limb from pih 1 to 3 until pih 8 to 10. Mean peak surface temperature of the LPS-injected carpi was significantly higher than that of control carpi from pih 8 to 144 (P < 0.05).

Mean synovial fluid WBC count in the LPS-injected and control carpi increased after injection and peaked by pih 8 (193,125 ± 8,528 cells/μl, LPS-treated; 16,425 ± 8,336 cells/μl, controls). Mean values for LPS-treated (principal) joints were significantly greater than values for control joints from pih 2 until after pih 66 (P < 0.05). Mean synovial fluid protein concentration increased in the principal and control joints, with values for the principal joints remaining significantly greater than values for control joints from pih 4 to 144 (P < 0.05). Mean TNF activity in synovial fluid was maximal at pih 2 (10,573 ± 5,924 U/ml). Interleukin-6 activity increased more gradually and peaked at pih 8 (1.78 ± 0.71 × 106 U/ml). Tumor necrosis factor activity did not increase above the minimal detectable value of 6 U/ml in the control joints. Mean PGE2 concentration in the principal joints peaked by pih 2 (3.6 ± 0.37 ng/ml) and remained significantly (P < 0.05) greater than the value for control joints from pih 2 through 66. These results indicate that a humane model of synovitis was created by intra-articular injection of LPS and can be used to establish the basic responses of synovial TNF, IL-6, and PGE2 in horses with early inflammatory joint disease.

Free access
in American Journal of Veterinary Research