Encephalitis in Dogs
Encephalitis refers to inflammation of the meninges and brain parenchyma caused by infection or toxic factors. In a broad sense, encephalitis includes various brain infections and encephalopathies.
[Etiology] Purulent encephalitis is mostly caused by pyogenic bacteria, head trauma, spread of nearby purulent foci, or hematogenous metastasis from systemic pyemia. It can also be caused by the migrating larvae of certain parasites entering brain tissue, resulting in parasitic encephalitis.
Non-suppurative encephalitis is mostly seen secondary to infectious diseases, such as canine distemper and rabies. Bacterial diseases can also cause encephalitis.
[Symptoms] Clinical signs vary depending on the location of inflammation in the brain. When the inflammatory focus is far from the cerebral cortex and relatively small in extent, the clinical signs are mild, with disturbance of consciousness being prominent. The affected dog may show restlessness or marked depression, and may even fail to recognize its owner. Some dogs bark continuously, run aimlessly, and collide with obstacles, while others circle or back up, and may have localized or generalized clonic convulsions. Depressed animals hold their heads down, keep their eyes half-closed, remain motionless when facing obstacles, respond slowly to external stimuli, assume abnormal postures, and have generalized muscle flaccidity and weakness; some affected dogs lie down and are lethargic.
When inflammation extends to the deep brain or there are inflammatory lesions in the deep brain, it can cause generalized paralysis or incomplete paralysis, incoordination of the limbs, ptosis, dilated pupils, and paralysis of the optic nerve, masseter muscle, pharyngeal muscle, larynx, and tongue. The dog lies motionless and completely loses responsiveness to external stimuli.
Most dogs with encephalitis have an elevated body temperature, and in the later stages they completely lose their appetite.
[Treatment] Eliminate inflammation, sedate, reduce intracranial pressure, and prevent brain edema.
(1) Sulfadiazine sodium injection 50 mg/kg body weight, intravenous injection, 2 times/day. Penicillin 50,000 units/kg body weight, intravenous or intramuscular injection; gentamicin 40,000 units/kg body weight, intravenous or intramuscular injection, 2 times/day.
(2) For sedation, chlorpromazine 1-2 mg/kg body weight, or phenobarbital sodium 5-10 mg/kg body weight, intramuscular or intravenous injection, 2 times/day.
(3) Mannitol injection 1-2 g/kg body weight, 25% glucose injection 5 mL/kg body weight, mixed and given by intravenous injection.
(4) Place the affected dog in a clean, well-ventilated kennel, keep it quiet, and provide nutrient-rich food.