Page 947 - Problem-Based Feline Medicine

43 – THE CAT WITH ATAXIA WITHOUT WEAKNESS 939

Ivermectin toxicosis has resulted in generalized Prognosis
ataxia, tremor, weakness, incoordination and miosis in
With metronidazole toxicity, a complete recovery is
a kitten.
possible after discontinuation of the drug if the signs
Griseofulvin therapy resulted in ataxia in a 12-week- are not severe.
old kitten.
● Clinical signs remained static up to 4 months after
Prevention
the initial presentation.
Avoid exposure to these products.
Aminoglycosides, administered either systemically or
topically, may cause vestibular signs including vestibu-
lar ataxia (cat leans, drifts, falls or rolls to side of the IDIOPATHIC ENCEPHALOPATHY*
head tilt), head tilt and nystagmus.
● Streptomycin and gentamicin have the most pro- Classical signs
nounced effects on the vestibular receptors, while
● Ataxia, paresis, and “head shaking” in
neomycin, kanamycin and amikacin preferentially
young cats up to 3 years old in the UK.
damage auditory receptors.
● Ataxia of the pelvic limbs was the initial sign.
Chlorhexidine solution used to clean the external ear
may result in vestibular signs.
Pathogenesis
Diagnosis Pathogenesis is unknown, although a viral etiology was
suggested but not proven.
Serum concentrations of metronidazole will be in the
toxic range if measured soon after clinical signs Wallerian degeneration was noted primarily involving
begin. the spinocerebellar pathways and the ventral funiculus
● If there is a delay in collecting blood for drug of the spinal cord.
concentrations after the initiation of clinical
signs, serum concentrations of metronidazole may
Clinical signs
decrease into the normal range even as the clinical
signs remain persistent. An encephalomyelopathy of young cats reported in the
United Kingdom had clinical signs of ataxia, paresis
Diagnosis of other toxicities is supported by a history
and “head shaking”.
of exposure.
Cats 3–12 months old were affected, however, the dis-
Differential diagnosis ease was seen in cats up to 3 years of age.

Other diseases causing signs of vestibular disease Ataxia of the pelvic limbs was the initial clinical sign
include otitis interna, middle ear polyps in cats, and noted.
neoplasia (squamous cell carcinoma of the middle ear).
These can usually be differentiated from toxicity on the Diagnosis
basis of history, otoscopic examination and imaging of
Diagnosis was made at necropsy.
the bulla.

Treatment Differential diagnosis
Diseases causing peripheral vestibular disease should be
There is no specific treatment for metronidazole toxicity.
considered including otitis interna and middle ear polyps.
● Discontinuation of the drug is imperative. A com-
plete recovery is possible.
Treatment
No specific treatment is available for the other
toxicities. No treatment was attempted.