Use of phenytoin to treat horses with Australian stringhalt.
Abstract: Five horses with Australian stringhalt were treated with 15 mg/kg phenytoin orally for 2 weeks. During the second week of the trial, 3 of the horses were given an additional dose of 10 mg/kg phenytoin. The response to treatment was clinically assessed by grading the severity of the gait abnormality at the walk, trot, turning and backing twice daily. There was a significant (P less than 0.05) improvement in the gait abnormality when pre-treatment values were compared with the mean of the last 3 assessments before treatment stopped. When reassessed 2 weeks after treatment ceased, there remained a significant (P less than 0.05) improvement compared with pre-treatment values at the trot and on backing, but not at the walk or turning. Surface electromyographic recordings were made weekly from the long digital extensor muscle, and there was a change to a near normal recording by the end of treatment. Plasma phenytoin concentrations were monitored during the trial, and the dose rates used achieved a steady state with a mean plasma level of 37 +/- 7 mumol/l. There was wide variability between plasma concentrations in different horses, although there was no difference in absorption between administration of the phenytoin as a paste, or when it was mixed in the feed. Although mild tranquilization was seen after treatment, there were no clinical, haematological or biochemical signs of toxicity from the phenytoin therapy.
Publication Date: 1991-07-01 PubMed ID: 1929987DOI: 10.1111/j.1751-0813.1991.tb03210.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigated the use of phenytoin to cure five horses affected with Australian stringhalt, a neurological disorder leading to noticeable gait abnormalities. The treatment resulted in a considerable improvement in the gait abnormality, although variations were observed in different movements, and the effectiveness was indicated by electromyographic recordings.
Experimental Procedure
- The study was performed on five horses with a diagnosed condition of Australian stringhalt, a disease causing abnormal gait in affected horses.
- These horses were treated with an oral dosage of 15 mg/kg phenytoin for a period of two weeks.
- During the second week, three horses received an additional 10 mg/kg dosage of phenytoin.
- The horses’ response to the treatment was monitored meticulously by grading the severity of the gait abnormality when walking, trotting, turning and backing, twice daily.
Results of the Treatment
- The improvement in gait abnormality was significant (indicated by P less than 0.05) when compared with pre-treatment values and the mean of the last three assessments before stopping the treatment.
- The horses were reassessed two weeks after discontinuation of treatment, and it was found that the significant improvement had been retained in trotting and backing, but not in walking and turning.
- Electromyographic recordings of muscle activity from the long digital extensor muscle supported these findings, showing a change to near normal by the end of the treatment period.
Measurement of Plasma Phenytoin Concentrations
- Throughout the trial, plasma phenytoin concentrations were measured, demonstrating that the prescribed dose rates resulted in a steady average plasma level of 37 +/- 7 mumol/l.
- There was high variability in plasma concentrations between separate horses, however, no difference was noted in absorption when comparing the administration of phenytoin as a paste or mixed within their feed.
Side Effects and Toxicity
- Though mild tranquilization was noticed post-treatment, the study did not observe any clinical, hematological, or biochemical signs of toxicity related to phenytoin therapy.
Cite This Article
APA
Huntington PJ, Seneque S, Slocombe RF, Jeffcott LB, McLean A, Luff AR.
(1991).
Use of phenytoin to treat horses with Australian stringhalt.
Aust Vet J, 68(7), 221-224.
https://doi.org/10.1111/j.1751-0813.1991.tb03210.x Publication
Researcher Affiliations
- Department of Agriculture, Victorian Institute of Animal Science, Attwood.
MeSH Terms
- Administration, Oral
- Animals
- Electromyography / veterinary
- Horse Diseases / drug therapy
- Horses
- Muscles / physiopathology
- Muscular Atrophy / drug therapy
- Muscular Atrophy / veterinary
- Neuromuscular Diseases / drug therapy
- Neuromuscular Diseases / veterinary
- Phenytoin / administration & dosage
- Phenytoin / blood
- Phenytoin / therapeutic use
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