Vestibular disorders of dogs and cats (Proceedings) - Veterinary Healthcare
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Vestibular disorders of dogs and cats (Proceedings)


CVC IN BALTIMORE PROCEEDINGS


Neoplastic

Primary and Secondary (metastatic). Neurological signs are progressive. Tumors are usually found within the brainstem (gliomas, ependymomas, metastatic tumors) or involving the cerebellomedullary angle or surface of the brainstem (meningiomas, neurofibromas, choroid plexus tumours, lymphosarcoma). Diagnosis often requires advanced imaging and either surgical or CT guided needle biopsy. Treatment is often palliative and may include corticosteroids to reduce peritumoral edema. Surgical excision or debulking is generally more difficult in the brainstem compared to the superficial areas of the cerebrum, but is done regularly at UC Davis with good outcomes. Radiotherapy and chemotherapy may also be done depending on tumor type and location. Prognosis is generally guarded, but reasonable periods of remission/reduction of clinical signs can be achieved. It is VERY important to include a good minimum data base including metastasis check thoracic radiographs and abdominal imaging to rule out metastatic disease.

Nutritional

Thiamine deficiency. Generally seen in cats fed all fish diets (fish contains thiaminase). Thiamine deficiency causes spongy necrosis and hemorrhage of grey matter. Vestibular signs may be present early in the disease with progression to seizures, dilated pupils, cervical ventroflexion and death. Diagnosis is based on history, clinical signs, decreased blood thiamine and transketolase activity and response to therapy. Treatment is supportive with thiamine supplementation and diet management. Successful treatment is possible in the early stages.

Infectious

1. Bacterial: Uncommon. Extension of otitis media-interna. Treat with surgery and long term antibiotics, ideally based on culture and sensitivity results.

2. Viral.

A. Canine distemper virus: Dogs, sealions, lions, tigers affected. May or may not exhibit systemic signs. Diagnosis antemortem is difficult and is based on history, clinical signs, CSF analysis, serology and PCR. Treatment is supportive. Prognosis is guarded.

B. Feline infectious peritonitis: Nervous system lesions often affecting ependymal surfaces and meninges. May be associated with uveitis. Usually chronic progressive illness. A variety of CNS signs may be seen including vestibular disease. Diagnosis antemortem is difficult. History, coronavirus titres, MRI, increased serum globulin and often markedly abnormal CSF (Markedly raised protein with monocytic pleocytosis). Treatment supportive, may be transient response to corticosteroids. Prognosis poor.

C. Rabies: Can manifest with almost any neurological syndrome, however behavioral signs and ataxia are most common. Diagnosis is post mortem. There is no treatment. Suspect animals must be quarantined. Death normally occurs within 10-15 days.

D. d. West Nile Virus?

3. Protozoa

A. Neospora/Toxoplasmosis: Relatively uncommon infection causing vestibular signs in cats (toxo) and dogs (neospora and toxo). Respiratory and ocular signs may be more common. Myopathy may be seen in young dogs. Diagnosis antemortem may be difficult as serology can be difficult to interpret. PCR may be helpful in diagnosis. Treatment is with potentiated sulphonamides or clindamycin. Prognosis guarded once neurological signs are apparent.

4. Mycotic

A. Several mycotic agents cause granulomatous disease of the CNS in cats and dogs.

B. The more common agents include:

• Cryptococcus neoformans

• Coccidiomycosis immitis

• Blastomycosis

• Histoplasmosis

C. Cryptococcus is the only common agent, particularly in California. Involvement of the respiratory tract is common. Diagnosis is based on demonstration of the organism in CSF and serology. Treatment includes amphoteracin and the "azole" derivatives, particularly fluconazole. Prognosis with CNS involvement is poor.

Parasitic

Aberant migration and growth of parasites within the CNS is rare in dogs and cats.

Rickettsia

Rarely involves the CNS.


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Source: CVC IN BALTIMORE PROCEEDINGS,
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