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- Author or Editor: Stephen M. Reed x
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Objective—To determine neurologic indications associated with abnormal results for computed tomography (CT) imaging of the head of horses affected by neurologic disorders.
Design—Retrospective case series.
Procedures—Signalment, history, clinical abnormalities, and clinicopathologic findings were obtained from medical records of horses examined because of neurologic disorders, and precontrast and postcontrast CT images of the head were reviewed. Data were analyzed by use of univariate and multivariate logistic regression.
Results—For a horse with abnormal mentation, odds of having abnormal results for CT imaging of the head was 30 times (95% confidence interval [CI], 2.36 to 374.63) the odds for a similar horse without abnormal mentation. For a horse with cranial nerve deficits, odds of having abnormal results for CT imaging of the head was 11 times (95% CI, 1.00 to 127.96) the odds for a similar horse without cranial nerve deficits. For a horse with seizure-like activity, odds of having abnormal results for CT imaging of the head was 0.05 times (95% CI, 0 to 0.90) the odds for a similar horse without seizures.
Conclusions and Clinical Relevance—These results suggested that alterations in consciousness and cranial nerve deficits were strong predictors of abnormal CT findings for the head of affected horses. Thus, CT can be a useful complementary diagnostic test in horses with these neurologic deficits. In contrast, alternative diagnostic tests (eg, electroencephalography and magnetic resonance imaging) should be considered in horses with seizure-like activity that do not have head trauma or cranial nerve deficits.
Objective—To determine the pharmacokinetics of voriconazole following IV and PO administration and assess the distribution of voriconazole into body fluids following repeated PO administration in horses.
Animals—6 clinically normal adult horses.
Procedures—All horses received voriconazole (10 mg/kg) IV and PO (2-week interval between treatments). Plasma voriconazole concentrations were determined prior to and at intervals following administration. Subsequently, voriconazole was administered PO (3 mg/kg) twice daily for 10 days to all horses; plasma, synovial fluid, CSF, urine, and preocular tear film concentrations of voriconazole were then assessed.
Results—Mean ± SD volume of distribution at steady state was 1,604.9 ± 406.4 mL/kg. Systemic bioavailability of voriconazole following PO administration was 95 ± 19%; the highest plasma concentration of 6.1 ± 1.4 μg/mL was attained at 0.6 to 2.3 hours. Mean peak plasma concentration was 2.57 μg/mL, and mean trough plasma concentration was 1.32 μg/mL. Mean plasma, CSF, synovial fluid, urine, and preocular tear film concentrations of voriconazole after long-term PO administration were 5.163 ± 1.594 μg/mL, 2.508 ± 1.616 μg/mL, 3.073 ± 2.093 μg/mL, 4.422 ± 0.8095 μg/mL, and 3.376 ± 1.297 μg/mL, respectively.
Conclusions and Clinical Relevance—Results indicated that voriconazole distributed quickly and widely in the body; following a single IV dose, initial plasma concentrations were high with a steady and early decrease in plasma concentration. Absorption of voriconazole after PO administration was excellent, compared with absorption after IV administration. Voriconazole appears to be another option for the treatment of fungal infections in horses.
Objective—To evaluate use of kinetic gait analysis for detection, quantification, and differentiation of hind limb lameness and spinal ataxia in horses.
Design—Prospective clinical study.
Procedures—Kinetic gait analysis with a force plate was performed for 12 clinically normal horses, 12 horses with hind limb lameness, and 12 horses with spinal ataxia. Kinetic variables were compared among groups, correlated to subjective grading, and used to build predictive models to assess the accuracy of discrimination.
Results—Subsets of kinetic variables were characteristically altered in ataxic and lame gaits. Ataxic horses had significantly increased lateral force peak and variation in vertical force peaks in both hind limbs. Lame horses had significantly decreased vertical force peak and increased variation in vertical force peaks only in the lame hind limb. These variables were used to differentiate between spinal ataxia and hind limb lameness with excellent accuracy. There were significant correlations between a subset of kinetic variables and subjective lameness and neurologic grades.
Conclusions and Clinical Relevance—Kinetic gait variables, specifically lateral force peak and the variation in vertical force, can be used to support the differential diagnosis between spinal ataxia and hind limb lameness in horses. Kinetic gait analysis may also be applied for quantification of equine hind limb gait abnormalities as well as confirming lack of lameness and ataxia in soundness examinations.
Objective—To investigate risk factors for development of equine protozoal myeloencephalitis (EPM) in horses.
Animals—251 horses admitted to The Ohio State University Veterinary Teaching Hospital from 1992 to 1995.
Procedure—On the basis of clinical signs of neurologic disease and detection of antibody to Sarcocystis neurona or S neurona DNA in cerebrospinal fluid, a diagnosis of EPM was made for 251 horses. Two contemporaneous series of control horses were selected from horses admitted to the hospital. One control series (n = 225) consisted of horses with diseases of the neurologic system other than EPM (neurologic control horses), and the other consisted of 251 horses admitted for reasons other than nervous system diseases (nonneurologic control horses). Data were obtained from hospital records and telephone conversations. Risk factors associated with disease status were analyzed, using multivariable logistic regression.
Results—Horses ranged from 1 day to 30 years old (mean ± SD, 5.7 ± 5.2 years). Risk factors associated with an increased risk of developing EPM included age, season of admission, prior diagnosis of EPM on the premises, opossums on premises, health events prior to admission, and racing or showing as a primary use. Factors associated with a reduced risk of developing EPM included protection of feed from wildlife and proximity of a creek or river to the premises where the horse resided.
Conclusions and Clinical Relevance—Development of EPM was associated with a number of management-related factors that can be altered to decrease the risk for the disease. (J Am Vet Med Assoc 2000;217:1174–1180)
Objective—To investigate risk factors for use in predicting clinical improvement and survival of horses with equine protozoal myeloencephalitis (EPM).
Design—Longitudinal epidemiologic study.
Animals—251 horses with EPM.
Procedure—Between 1992 and 1995, 251 horses with EPM were admitted to our facility. A diagnosis of EPM was made on the basis of neurologic abnormalities and detection of antibody to Sarcocystis neurona or S neurona DNA in CSF. Data were obtained from hospital records and through telephone follow-up interviews. Factors associated with clinical improvement and survival were analyzed, using multivariable logistic regression.
Results—The likelihood of clinical improvement after diagnosis of EPM was lower in horses used for breeding and pleasure activities. Treatment for EPM increased the probability that a horse would have clinical improvement. The likelihood of survival among horses with EPM was lower among horses with more severe clinical signs and higher among horses that improved after EPM was diagnosed.
Conclusions and Clinical Relevance—Treatment of horses with EPM is indicated in most situations; however, severity of clinical signs should be taken into consideration when making treatment decisions. Response to treatment is an important indicator of survival. (J Am Vet Med Assoc 2000;217:1181–1185)
Objective—To identify risk factors for equine protozoal myeloencephalitis (EPM) among horses examined at 11 equine referral hospitals.
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.
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)