Your pet can get meningitis and encephalitis PDF Print E-mail
News - Rubrieke
Monday, 27 August 2012 18:54
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Dr Liesel van der Merwe is a small animal medicine specialist. Send her your questions: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .


Dr Liesel van der Merwe

Dogs and cats can get meningitis and encephalitis (“breinvliesontsteking”) just like people. I will briefly discuss the different presentations as I have just had two amazing cases recover at the practice against all odds.

In humans, especially in young children, bacterial meningococcal encephalitis and meningitis are very contagious. Pets don’t suffer from a contagious form. Bacterial meningitis is rare in dogs and cats and occurs in very young puppies and kittens from umbilical infections or in animals with chronic severe middle ear infections - where the infection can get into the blood vessels supplying the brain.

Tick-borne diseases, such as tick bite fever, can cause joint and meningeal inflammation. Toxoplasmosis, an infection transmitted in cats’ faeces and undercooked meat, can also infect the brain tissue. The underlying infection as well as the brain inflammation needs to be treated in these cases.

In some animals viruses, such as canine distemper virus in dogs and feline infectious peritonitis in cats, can cause meningitis as part of the generalised disease process. These viruses cannot be treated. In dogs the condition may stabilise but in cats it is fatal. 

The majority of infections in dogs and cats are immune mediated. This means that there is no evidence of infection and it looks as if the body is reacting against its own tissues and seeing them as foreign. Symptoms are inflammation and swelling.

Meningitis is diagnosed using the symptoms, a CSF tap and maybe even a MRI. A CSF tap is similar to a lumbar puncture in humans except we use a gap in the vertebra high in the neck and we anaesthetise the patients for the procedure. The spinal fluid we collect is analysed for the type of inflammation and infection. Inflammation of the brain can also be seen on a MRI, but we only use this if we suspect additional problems or specific types of encephalitis where other damage occurs.

Dogs generally have combinations of signs: neck pain, lameness/paresis/weakness, head tilted to one side, walking in circles, decreased mental alertness, dilated pupils, blindness and seizures.

Certain breeds are more susceptible. Young (six to nine months old) large breed dogs such as Rottweilers, weimaraners and boxers often get non-infectious meningitis which causes severe neck pain and fever without any neurological signs. This responds to prolonged treatment with immunosuppressants.

The other common age group affected are young to middle-aged adult small breed dogs, such as dachshunds, Yorkshire terriers, Pugs, miniature Pinschers, Maltese, and small crossbreeds with terrier or poodle heritage. Development of the neurological signs can be sudden or gradual over a few days to weeks and may initially come and go.  

The CSF tap checks that inflammation is present but cannot be used to make a final diagnosis. To do this a tissue sample or biopsy is required, which is not something done in general practice or even in university veterinary hospitals.

The severity of the disease can only be predicted by the response to treatment and whether relapse occurs or not. In mildly affected animals the medication can be tapered and stopped after three to six months. In more severely affected patients medication is lifelong and multiple drugs need to be used. In a small percentage of cases the medication is not really effective.

In the initial stages of the disease the animals are often placed in a short drug-induced coma to allow their brains to rest and heal. Once the worst swelling is under control they are woken. The brain and nerve tissue heal slowly and severely affected dogs almost have to learn everything from scratch.

If we see improvements every day, we just need to keep them eating, drinking, urinating, defecating, give them physiotherapy and enough time to heal. Dogs generally recover fully or with slight damage. Some retain a head tilt although their balance normalises. 

Meningitis is more rare in cats; the cause being generally infectious and often viral. Their prognosis is much more guarded.

 

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