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Seizures in exotic pets (Proceedings)

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Aug 01, 2009

When presented with a seizuring dog or cat, the steps to take are familiar to most veterinarians. However, with a non-traditional species, even knowing where and how to administer treatments presents a challenge, as well as what might be common etiologies. With a little additional familiarity, any practitioner can effectively treat any seizuring patient.

The most important aspect to remember, regardless of species, is to first control the seizures, and return the patient's body temperature and vital parameters to normal. As with any animal, prolonged seizures may result in permanent deficits, but the extent of these deficits cannot be assessed for several days. Supportive care may be required during that time, including fluid therapy, nutritional support, and sometimes even management of the sedated or debilitated patient, including turning the patient, lubricating eyes, and physical therapy.

In any seizuring patient, check blood glucose, and administer a dextrose bolus if necessary. If vascular access is not readily available, or if the animal is actively seizuring, proceed as you would in any other species. Administer diazepam, 0.5-1.0 mg/kg. Administer intravenously if possible, but this may be a challenge in exotic patients. As an alternative, administer rectally (or cloacally) or orally, as diazepam is readily absorbed across mucous membranes – use double the intravenous dose for this route. Diazepam can also be administered intramuscularly, but it is poorly absorbed via this route. Absorption of intramuscular medications in birds is almost as rapid as intravenous, but slower in other species. The dose may be doubled if necessary. Alternatively, administer midazolam intramuscularly at 0.5-2.0 mg/kg.

If a single dose of diazepam is not effective, repeat up to three times. Diazepam can be administered via continuous intravenous or intraosseous infusion. Start at a rate of 1.0 mg/kg/hr diazepam added to intravenous fluids. If cerebral edema is suspected, administer mannitol, 0.5-1.0 g/kg IV over 20 minutes, and consider administering a single dose of prednisolone sodium succinate or methylprednisolone sodium succinate, 10 mg/kg IV, or dexamethasone sodium phosphate 1-2 mg/kg IV. (Do not administer steroids repeatedly in most exotic species, as they are highly susceptible to the immunosuppressive effects of steroids. Exception: ferrets.) Once seizures have stopped for 12-24 hours, taper the valium infusion slowly over the next 12-24 hours. If valium does not control seizures, begin a constant rate infusion of phenobarbital, 2-10mg/kg/hr. This can be given in conjunction with the diazepam; monitor for respiratory depression. If patients are unresponsive, add dextrose to the IV drip, as many of these small patients will rapidly become hypoglycemic if not eating. Once controlled, depending on etiology, oral phenobarbital can be used for long term seizure management. Potassium bromide can also be used for seizure control. Check blood levels of phenobarbital within 2-3 weeks of starting therapy; potassium bromide levels may not reach a steady state for 60-90 days. Adjust dosages based on blood levels.

Common causes of seizures in exotic pets by species

Rabbits

Hypoglycemia

Most common in juveniles with diarrhea or anorexia, very rare in adults even when anorexic. Treat with intravenous dextrose 50% slowly to effect, followed with a 5% IV dextrose drip until patient is eating. Address underlying causes.

Encephalitozoon cuniculi

Juvenile or adult. Rather than true seizures, actually causes head tilt (may be severe), rolling, torticollis, vestibular signs,. However, owners often describe their pets as seizuring. Onset may be acute or gradually progressive. Protozoal infection may occur as juvenile, but animals generally are asymptomatic; clinical signs may appear at any time. Linked to immunocompromise in other species. Avoid steroids. Treat with supportive care, pad cage, meclizine, syringe feeding and eye lubrication if necessary. Treatment with albendazole or fenbendazole may control shedding, but will not eliminate the organism, and can cause toxicity. Prognosis: varies, but is independent of severity of clinical signs.

Pasteurella multocida

Probably overdiagnosed as a cause of clinical signs in neurologic rabbits, but may spread to the central nervous system and cause either abscess formation or meningitis. Treat with supportive care, antimicrobials. Fluoroquinolones are beneficial in many cases and are readily available in most practices.

Otitis media/interna

Rarely, a severe case of otitis or even ear mites can be so disturbing that the rabbit may fall over and become ataxic, giving the appearance of seizures. Diagnose and treat as in other species.

Other

Toxins, toxoplasmosis, metabolic disturbances – uncommon. Treat as in any companion species. Avoid steroids whenever possible. Idiopathic epilepsy can exist. Baylisascaris procyonis infections can occur in rabbits with contact with raccoon feces, and will cause progressive neurologic signs and death. There is no antemortem test or treatment.