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Abstract

Objective—To determine the prevalence of antimicrobial resistance to macrolide antimicrobials or rifampin in Rhodococcus equi isolates and to describe treatment outcome in foals infected with antimicrobial-resistant isolates of R equi.

Design—Cross-sectional study.

Sample Population—38 isolates classified as resistant to macrolide antimicrobials or rifampin received from 9 veterinary diagnostic laboratories between January 1997 and December 2008.

Procedures—For each isolate, the minimum inhibitory concentration of macrolide antimicrobials (ie, azithromycin, erythromycin, and clarithromycin) and rifampin was determined by use of a concentration-gradient test. Prevalence of R equi isolates from Florida and Texas resistant to macrolide antimicrobials or rifampin was determined. Outcome of antimicrobial treatment in foals infected with antimicrobial-resistant isolates of R equi was determined.

Results—Only 24 of 38 (63.2%) isolates were resistant to > 1 antimicrobial. Two isolates were resistant only to rifampin, whereas 22 isolates were resistant to azithromycin, erythromycin, clarithromycin, and rifampin. The overall prevalence of antimicrobial-resistant isolates in submissions received from Florida and Texas was 3.7% (12/328). The survival proportion of foals infected with resistant R equi isolates (2/8 [25.0%]) was significantly less, compared with the survival proportion in foals that received the same antimicrobial treatment from which antimicrobial-susceptible isolates were cultured (55/79 [69.6%]). Odds of nonsurvival for foals infected with resistant R equi isolates were 6.9 (95% confidence interval, 1.3 to 37) times the odds for foals infected with susceptible isolates.

Conclusions and Clinical Relevance—Interpretation of the results emphasized the importance of microbiological culture and antimicrobial susceptibility testing in foals with pneumonia caused by R equi.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare signalment of horses with cervical vertebral malformation-malarticulation (CVM) with that of control horses and to describe results of clinical examination, diagnostic imaging and necropsy findings, and reported outcome in horses with CVM.

Design—Retrospective case-control study.

Animals—270 horses with CVM and 608 control horses admitted to 6 veterinary hospitals from 1992 through 2007.

Procedures—Medical records of participating hospitals were reviewed to identify horses with CVM (ie, case horses) and contemporaneous control (non-CVM-affected) horses that were admitted for treatment. Signalment was compared between case horses and control horses. Results of clinical examination, laboratory and diagnostic imaging findings, necropsy results, and outcome were assessed for horses with CVM.

Results—Case horses were younger (median age, 2 years) than were control horses (median age, 7 years). Thoroughbreds, warmbloods, and Tennessee Walking Horses were overrepresented in the CVM group. Gait asymmetry and cervical hyperesthesia were frequently detected in horses with CVM. Vertebral canal stenosis and articular process osteophytosis were commonly observed at necropsy; agreement between the results of radiographic or myelographic analysis and detection of lesions at necropsy was 65% to 71% and 67% to 78%, respectively. Of 263 horses with CVM for which outcome was recorded, 1 died and 172 (65.4%) were euthanatized.

Conclusions and Clinical Relevance—Odds of a diagnosis of CVM were greater in young horses and horses of specific breeds. Detection of gait asymmetry and cervical hyperesthesia were frequently reported in association with CVM. Accurate diagnosis of lesions associated with CVM by use of radiography and myelography can be challenging. (J Am Vet Med Assoc 2010;237:812-822)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine risk factors for development of sequestra in cattle and identify factors associated with a successful outcome.

Design—Retrospective study.

Animals—110 cattle.

Procedure—Medical records of cattle treated at veterinary teaching hospitals in North America were reviewed. To determine risk factors for osseous sequestration, breed, age, and sex of cattle with osseous sequestration were compared with breed, age, and sex of all other cattle admitted during the study period.

Results—110 cattle were included in the study. Three had 2 sequestra; thus, 113 lesions were identified. Most sequestra were associated with the bones of the extremities, most commonly the third metacarpal or third metatarsal bone. Ninety-two animals were treated surgically (ie, sequestrectomy), 7 were treated medically, 3 were initially treated medically and were then treated surgically, and 8 were not treated. Follow-up information was available for 65 animals treated surgically and 6 animals treated medically. Fifty-one (78%) animals treated surgically and 5 animals treated medically had a successful outcome. Cattle that were 6 months to 2 years old had a significantly increased risk of developing a sequestrum, compared with cattle < 6 months old. Cattle in which sequestrectomy was performed with the aid of local anesthesia were significantly more likely to undergo 2 or more surgical procedures than were cattle in which sequestrectomy was performed with the aid of general anesthesia.

Conclusions and Clinical Relevance—Results suggest that sequestrectomy will result in a successful outcome for most cattle with osseous sequestration. (J Am Vet Med Assoc 2000;217:376–383)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify risk factors for equine protozoal myeloencephalitis (EPM) among horses examined at 11 equine referral hospitals.

Design—Case-control study.

Animals—183 horses with EPM, 297 horses with neurologic disease other than EPM (neurologic controls), and 168 horses with non-neurologic diseases (non-neurologic controls) examined at 11 equine referral hospitals in the United States.

Procedures—A study data form was completed for all horses. Data were compared between the case group and each of the control groups by means of bivariate and multivariate polytomous logistic regression.

Results—Relative to neurologic control horses, case horses were more likely to be ≥ 2 years old and to have a history of cats residing on the premises. Relative to non-neurologic control horses, case horses were more likely to be used for racing or Western performance.

Conclusions and Clinical Relevance—Results indicated that cats may play a role in the natural epidemiology of EPM, that the disease is less common among horses < 2 years of age relative to other neurologic diseases, and that horses used for particular types of competition may have an increased risk of developing EPM.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To investigate risk factors for the development of pasture- and endocrinopathy-associated laminitis (PEAL) in horses and ponies in North America.

DESIGN Case-control study.

ANIMALS 199 horses with incident cases of PEAL and 351 horses from 2 control populations (healthy horses [n = 198] and horses with lameness not caused by laminitis [153]) that were evaluated in North America between January 2012 and December 2015 by veterinarian members of the American Association of Equine Practitioners.

PROCEDURES North American members of the American Association of Equine Practitioners were contacted to participate in the study, and participating veterinarians provided historical data on incident cases of PEAL, each matched with a healthy control and a lameness control. Conditional logistic regression analysis was used to compare data on PEAL-affected horses with data on horses from each set of controls.

RESULTS Horses with an obese body condition (ie, body condition score ≥ 7), generalized or regional adiposity (alone or in combination), preexisting endocrinopathy, or recent (within 30 days) glucocorticoid administration had increased odds of developing PEAL, compared with horses that did not have these findings.

CONCLUSIONS AND CLINICAL RELEVANCE The present study identified several risk factors for PEAL that may assist not only in managing and preventing this form of laminitis, but also in guiding future research into its pathogenesis.

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in Journal of the American Veterinary Medical Association