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Dog - German Shepherd 2 year and 9 month old spayed female
Abnormal gait which rapidly developed over a few days
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Cerebellum, pons and medulla
This dog exhibits a cerebellar-vestibular ataxia with abrupt and excessive limb protraction especially in the pelvic limbs and a loss of balance. The balance loss implicates a vestibular system abnormality which could relate to dysfunction of the vestibular components of the cerebellum or the vestibular nuclei in the pons and medulla.
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Metronidazole toxicity
The differential diagnosis includes inflammations caused by viral, protozoal, fungal, bacterial agents or autoimmune disorders. Neospora caninum has a predilection for the cerebellum in young adult dogs. Neoplasia is less likely at this age. Dermoid or epidermoid cysts occur most commonly in the caudal cranial fossa. Of the various possible toxins, metronidazole is a strong consideration based on this anatomic diagnosis. A feature of this toxicity is the occurrence of bizarre clinical signs of a cerebellar-vestibular dysfunction. One unique expression of this dysfunction is observed when the patient is abruptly picked up or makes a sudden attempt to catch its balance. At that moment the patient will suddenly abduct all of its limbs and assume a position as if it was going to plane. One brief episode of this occurs towards the end of the video when the dog stumbles and falls. Abnormal nystagmus is common with this toxicity but was not observed in this dog. Further questioning of the owner revealed that for the past 40 days this dog had received 750mg of metronidazole twice daily for a presumptive gastrointestinal infection. The normal dose is 15mg/kg twice daily. Metronidazole toxicity is seen in patients on excessive doses and/or extended regimens of the medication. Withdrawal of the drug and treatment with valium markedly improved the clinical signs in this patient. We thank Drs. Catherine Hegarty and Thomas Ross from Colonial Animal Hospital of Ithaca NY for the use of this case and the video.
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