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Abstract

Objectives

To investigate changes in CSF concentrations of inhibitory and excitatory neurotransmitters in dogs with confirmed idiopathic epilepsy, and to evaluate them with regard to the clinical characteristics of the sample population and of the seizures.

Animals

13 (8 male and 5 female) drug-naive dogs with an initial generalized seizure, 6 (4 male and 2 female) drug-naive dogs with an initial partial seizure, and 10 clinically normal (5 male and 5 female) control dogs.

Procedure

At least 24 hours after the last observed seizure, CSF was collected aseptically from the cisterna cerebellomedullaris, and a portion was immediately aliquoted into vials, placed on dry ice, then stored at −80 C. The CSF glutamate (GLU) and γ-aminobutyric acid (GABA) concentrations were estimated by use of HPLC with electrochemical detection. Cerebellomedullary cisternal CSF glutamate and GABA values were analyzed in dogs with noninduced idiopathic epilepsy. Comparisons were determined for differences attributable to weight, sex, age at first seizure, seizure type, and total time of past seizure history.

Results

Mean (range) age at onset of the first seizure was 3.33 (0.1 to 11), 3.5 (0.1 to 11 ), and 3.25 (0.5 to 9) years for all dogs, dogs with initial partial seizure, and dogs with initial generalized seizure, respectively. Low GABA and high GLU values were found in the CSF of epileptic dogs, and were independent of time elapsed between the first observed seizure and CSF sample collection. The GABA value was inversely related to body weight in epileptic dogs, independent of age. Changes in GABA and GLU concentrations were not related to seizure type.

Conclusions

Altered GABA and GLU values in CSF might be indicative of a state of chronic overexcitation in the brain of dogs with primary or idiopathic epilepsy.

Clinical Relevance

CSF GABA and GLU may serve as important markers in epileptic dogs for potential response to antiepileptic drugs. (Am J Vet Res 1997;58:451–456)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To measure impedance audiometric values in clinically normal dogs that were sedated or anesthetized, evaluate effects of ear flushing on tympanometric measurements, and determine effects of performing acoustic reflex testing in a sound-attenuated room.

Animals—35 mixed-breed and purebred clientowned dogs and 21 laboratory-bred Beagles.

Procedures—Tympanometry and acoustic reflex testing were performed on 27 mixed-breed and purebred dogs under isoflurane anesthesia in a non–sound-attenuated room and 21 Beagles under sedation in a sound-attenuated room. Tympanometry was performed on 8 mixed-breed dogs under halothane anesthesia before and after ear canal flushing.

Results—Among impedance audiometric values, ear canal volume and compliance peak were smaller in Beagles than in mixed-breed dogs; differences among other values were not detected. Ear canal volume was dependent on body weight. Differences were not found for tympanometric values measured before and after ear canal flushing.

Conclusions and Clinical Relevance—Results of this study established reference range values for impedance audiometric measurements in clinically normal dogs under isoflurane anesthesia or sedation. Acoustic reflex testing does not need to be performed in a sound-attenuated room. The ear canals of clinically normal dogs can be flushed prior to performing tympanometry without altering the results. Impedance audiometry may be a useful noninvasive procedure for the diagnosis of otitis media in dogs. (Am J Vet Res 2000;61:442–445)

Full access
in American Journal of Veterinary Research

Summary

On initial evaluation for onset of seizure disorders at nonreferral veterinary practices, 50 previously healthy dogs were enrolled in a study to determine the probability of identifying a specific cause for the seizures. Treatment was not administered prior to entry of dogs in the study. On the basis of antemortem and postmortem test results, 22 dogs (44%) were classified as having primary epileptic seizures (pes; idiopathic or without identifiable cause), 23 (46%) had secondary epileptic seizures (ses; identifiable intracranial cause), and 5 (10%) had reactive epileptic seizures (res; metabolic or transient noxious cause). Forty-one dogs (82%) had 2 or more seizures before evaluation, with 37 (90%) of these dogs classified as having epilepsy on the basis of an underlying chronic brain disorder. For these 41 dogs, 17 (41%) had pes, 20 (49%) had ses, and 4 (10%) had res. Among the 9 dogs (18%) with nonrecurring seizures, 5 had pes, 3 had ses, and 1 had res. Generalized seizures were the most common first-observed seizure type associated with all etiologic classifications in all dogs with recurring and nonrecurring seizures.

Diagnosis of ses was statistically more probable when the dog was less than 1 or more than 7 years old at the first seizure, when the first seizure was a partial seizure, or when the first seizure occurred between midnight and 8 am. A diagnosis of res was statistically more probable only when the interval between the first and second seizure was brief (≤ 4 weeks). A diagnosis of pes was statistically more probable when the dog was between 1 and 5 years of age at the first seizure, when the dog was a large breed (> 15 kg), when the seizure occurred between 8 am and midnight, or when the interval between the first and second seizure was long (> 4 weeks).

Free access
in Journal of the American Veterinary Medical Association

Objective

To characterize clinical features, diagnostic evaluation, and treatment outcome for dogs with generalized tremors.

Design

Retrospective case series.

Animals

12 white purebred and 12 nonwhite mixed-breed and purebred dogs.

Procedure

Medical records of dogs examined for tremors between January 1984 and July 1995 were reviewed. History, signalment, abnormalities on physical and neurologic examinations, results of diagnostic testing, and diagnosis were recorded for each dog. Results were divided into the following 3 categories on the basis of the cause of the tremors: inflammatory, noninflammatory, and idiopathic. Cause was determined by results of CSF analyses or a history of toxin exposure.

Results

The only noninflammatory cause of generalized tremors identified in these dogs was mycotoxin ingestion. Steroid-responsive tremor syndrome had developed in 22 of 24 dogs, half of which had abnormal results of CSF analyses. Most dogs were young adults between 1 and 5 years old. More than half of the dogs were nonwhite mixed-breeds and all weighed < 15 kg (33 lb). Eighty percent of the dogs responded to immunosuppressive treatment within 3 days.

Clinical Implications

Inflammatory and noninflammatory causes for generalized tremors in dogs result in similar clinical signs, so a logical diagnostic and treatment approach is needed. Steroid-responsive tremor syndrome should be considered in small- to medium-breed, young adult dogs, regardless of coat color. A rapid and complete response to immunosuppressive treatment is expected. (J Am Vet Med Assoc 1997;211:731–735)

Free access
in Journal of the American Veterinary Medical Association