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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 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 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

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 identify foal-related risk factors associated with development of Rhodococcus equi pneumonia among foals on farms with endemic R equi infection.

Design—Prospective case-control study.

Animals—220 foals at 2 equine breeding farms in Texas during a 2-year period.

Procedure—Information collected for each dam included age, time housed on the farm prior to parturition, whether there were any peripartum illnesses, parity, and health of previous foals. Information collected for each foal included breed, sex, gestational age, month and year of birth, location of birth, type of flooring and bedding in stall, postpartum management and preventive health care, passive immunity status, supplementation of immunoglobulins, exposure to other farms or foals affected with R equi pneumonia, stall and pasture exposure, commingling with other mare-foal pairs, age at weaning, and whether the foal developed R equi pneumonia.

Results—32 of the 220 (15%) foals developed R equi pneumonia, of which 4 (13%) died. Foals at 1 of the 2 farms and foals born during the second year of the study were more likely to develop R equi pneumonia. Foal-related factors that were examined were not significantly associated with risk of R equi pneumonia in multivariate analyses.

Conclusions and Clinical Relevance—Results suggest that there are farm- and year-related effects on the risk that foals will develop R equi pneumonia. Other foal-related factors significantly associated with R equi pneumonia were not identified. (J Am Vet Med Assoc 2003;223:1791–1799)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether specific feeding practices were associated with development of colic in horses.

Design—Prospective matched case-control study.

Animals—364 horses examined by veterinarians in private practice in Texas because of colic (cases; n = 182) or any other reason (controls; 182).

Procedure—Participating veterinarians were sent forms at the beginning of the study to collect information on signalment, feeding management practices, farm management practices, and preventive medical treatments. Case and control horses were compared by use of conditional logistic regression to identify factors associated with colic.

Results—Risk factors for colic were a recent change in batch of hay, decreased exposure to pasture, a recent change in type of grain or concentrate fed, feeding > 2.7 kg (6 lb) of oats/d, feeding hay from round bales, and Thoroughbred breed. Recent anthelmintic administration decreased the risk of colic.

Conclusions and Clinical Relevance—Results suggest that certain changes in diet (eg, change in batch of hay, change in type of grain or concentrate, feeding hay from round bales) and management (eg, decreased availability of pasture) increase the risk of colic in horses. (J Am Vet Med Assoc 2001;219:1419–1425)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the association between high-speed exercise and risk of injury while racing among Thoroughbreds in Kentucky.

Design—Matched case-control study.

Animals—206 Thoroughbreds that sustained a musculoskeletal injury while racing and 412 Thoroughbreds that were not injured during the same races.

Procedure—Data regarding official timed workouts and races and the Beyer's numbers for the 3 races before the race during which injury occurred were extracted from past performance charts and compared between injured horses and control horses.

Results—For injured horses, cumulative distance of high-speed exercise during the 1- and 2-month periods prior to the race in which injury occurred was significantly less than that of control horses; for either period, a difference of 10 furlongs was associated with approximately 2-fold greater risk of injury. Beyer's numbers were significantly higher for injured horses than for control horses. These effects remained significant after adjusting for age and results of prerace physical inspection.

Conclusions and Clinical Relevance—In Kentucky, injured horses had significantly less cumulative highspeed exercise than did control horses during the 1- and 2-month periods prior to the race in which injury occurred. These results differ from those observed in California. The association of injury with cumulative high-speed exercise appears to vary among regions in the United States. (J Am Vet Med Assoc 2000; 216:1273–1278)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify types of musculoskeletal problems associated with lameness or poor performance in horses used for barrel racing.

Design—Retrospective case series.

Animals—118 horses.

Procedure—Medical records were reviewed for information on signalment, history, physical and lameness examination findings, diagnostic tests performed, diagnosis, and treatment.

Results—Most horses were examined because of lameness (n = 72 [61%]) rather than poor performance (46 [39%]), but owner complaint was not significantly associated with age or body weight of the horse. The most common performance change was refusal or failure to turn properly around the first barrel (19/46 [41%]). The right forelimb (n = 57 [48%]) was most commonly affected, followed by the left forelimb (51 [43%]), the left hind limb (31 [26%]), and the right hind limb (25 [21%]). In 31 horses (26%), both forelimbs were affected, and in 6 (5%), both hind limbs were affected. The most common musculoskeletal problems were forelimb foot pain only (n = 39 [33%]), osteoarthritis of the distal tarsal joints (17 [14%]), suspensory ligament desmitis (15 [13%]), forelimb foot pain with distal tarsal joint osteoarthritis (11 [9%]), and bruised feet (10 [8.5%]). In 81 (69%) horses, the affected joint was treated with intra-articular medications.

Conclusions and Clinical Relevance—Results suggest that in horses used for barrel racing that are examined because of lameness or poor performance, the forelimbs are more likely to be affected than the hind limbs, with forelimb foot pain and osteoarthritis of the distal tarsal joints being the most common underlying abnormalities. (J Am Vet Med Assoc 2005; 227:1646–1650)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the types of musculoskeletal problems that result in lameness or poor performance in horses used for team roping and determine whether these problems are different in horses used for heading versus heeling.

Design—Retrospective study.

Animals—118 horses.

Procedure—Medical records of team roping horses that were evaluated because of lameness or poor performance were reviewed to obtain information regarding signalment, primary use (ie, head horse or heel horse), history, results of physical and lameness examinations, diagnostic tests performed, final diagnosis, and treatment.

Results—Among horses evaluated by lameness clinicians, the proportion with lameness or poor performance was significantly greater in horses used for heading (74/118) and lower in horses used for heeling (44/118) than would be expected under the null hypothesis. Most horses examined for poor performance were lame. A significantly greater proportion of horses used for heading had right forelimb lameness (26/74 [35%]), compared with horses used for heeling (7/44 [16%]). Horses used for heading had more bilateral forelimb lameness (18/74 [24%]), compared with horses used for heeling (4/44 [9%]). Horses used for heeling had more bilateral hind limb lameness (3/44 [7%]), compared with horses used for heading (0%). The most common musculoskeletal problems in horses used for heading were signs of pain limited to the distal sesamoid (navicular) area, signs of pain in the navicular area plus osteoarthritis of the distal tarsal joints, and soft tissue injury in the forelimb proximal phalangeal (pastern) region. Heeling horses most commonly had signs of pain in the navicular area, osteoarthritis of the metatarsophalangeal joints, and osteoarthritis of the distal tarsal joints.

Conclusions and Clinical Relevance—Horses used for heading were most commonly affected by lameness in the right forelimb. Horses used for heeling had more bilateral hind limb lameness than horses used for heading. (J Am Vet Med Assoc 2005;226:1694–1699)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify farm characteristics and management practices associated with development of Rhodococcus equi pneumonia in foals.

Design—Prospective case-control study.

Animals—5,230 foals on 138 breeding farms with 9,136 horses.

Procedure—During 2003, participating veterinarians provided data from 1 or 2 farms with ≥ 1 foal with R equi pneumonia and unaffected farms. Data from affected and unaffected farms were compared by use of logistic regression analysis.

Results—A number of variables relating to farm size and desirable management practices were significantly associated with increased odds of farms being affected with R equi pneumonia. By use of multivariate logistic regression, affected farms were determined significantly more likely to have raised Thoroughbreds, housed ≥ 15 foals, used concrete floors in foaling stalls, and tested foals for passive transfer of immunity than unaffected farms. These results remained significant even after accounting for exposure of foals to other breeding farms during the first month of life.

Conclusions and Clinical Relevance—Breeding farms with large acreage and a large number of mares and foals have greater odds of being affected by R equi pneumonia. Clinical relevance of associations with Thoroughbred breed and concrete flooring in foaling stalls remains uncertain. Desirable management factors commonly used on farms were not effective for controlling or preventing development of R equi pneumonia. This finding indicates a need to focus on host factors that influence disease development. (J Am Vet Med Assoc 2005;226:404–413)

Full access
in Journal of the American Veterinary Medical Association