Encephalitis in Dogs - Signs, Causes & Treatment
Read on to find out what causes it, the symptoms to watch out for and how tick protection can help.
The word ‘Encephalo’ means brain and ‘itis’ means inflammation, so together encephalitis simply means inflammatory disease of the brain. Sometimes it affects the spinal cord too, which is known as myelitis, and the membranes of the brain and spinal cord, which is known as meningitis.
Encephalitis can happen on its own, but it may be a symptom of other diseases affecting the brain and spinal cord, such as a viral or bacterial infection.
Any breed of any age can be affected by encephalitis, but young and middle-aged dogs are most at risk.
Encephalitis is not actually a disease, it’s more often a symptom of something else. This means it can happen for many reasons. However, the causes of encephalitis can be grouped into two categories: 1) Those caused by infection; 2) Those not caused by infection where the cause is unknown (also known as idiopathic). The latter is much more common.
Causes of infectious encephalitis
- Tick-borne diseases, such as Lyme disease, Tick Borne Encephalitis (TBE) and Ehrlichiosis
- Viral diseases, such as canine distemper
- Single-cell parasites, such as Toxoplasma gondii and Neospora caninum
- Fungal infections, such as Cryptococcosis
- Bacterial infections
- Infection from foreign bodies, e.g. grass seeds
Causes of non-infectious (idiopathic) encephalitis
When something is known as idiopathic, it just means that a cause cannot be found. In the case of non-infectious or idiopathic encephalitis it’s thought that it could be triggered by autoimmune disease – this is when the body’s immune system is ‘faulty’ and mistakenly starts to attack healthy tissues. As a result, the dog’s immune system attacks the brain.
Signs of encephalitis usually appear suddenly and get rapidly worse. They are a sign of a medical emergency so if you suspect your dog has encephalitis, you should take them to your vet or veterinary hospital right away.
Symptoms to watch out for:
- Loss of coordination
- Behaviour changes such as depression or lack of responsiveness
- Head tilt
Encephalitis can only be diagnosed by your vet. To begin with they’ll ask you for a detailed history of your dog’s health to understand if there are any clinical signs of encephalitis. They’ll want to know when the symptoms first appeared, their frequency and severity, and a history of anything else abnormal, for example if they were recently bitten by a tick.
There are various tests that can be done to diagnose encephalitis, including:
- Spinal tap - This is when spinal fluid that surrounds the brain and spinal cord is tested. An increase in protein and white blood cells in this fluid can indicate encephalitis.
- MRI / CT Scan - This scans the tissues in the brain to check for inflammation and rule out other brain diseases, such as a tumour
Your vet may also run routine tests such a blood tests, analysis of urine and X-rays, to rule out other causes. Even if these test results are normal, your dog could still have encephalitis.
Treatment of encephalitis depends on the underlying cause, if any, of the inflammation. Initially, your vet will treat your dog to reduce the severity of the symptoms and stop the condition from worsening. At this stage they may require hospitalisation and intensive care.
Medication will depend on the type of encephalitis that your dog has and their individual health. Some dogs respond well to medication, but others do not respond well or have relapses.
Treatment options for infectious encephalitis
- Antibiotics and antifungals to treat any infection
- Anticonvulsants if your dog is having seizures
- Steroids to treat inflammation
- IV fluids and supportive care, depending on the health of your dog
Treatment options for non-infectious encephalitis
- Steroids, to reduce inflammation
- Immunosuppressive medications to reduce the effect of the ‘faulty’ immune system and stop it attacking the brain tissues
Note, when non-infectious encephalitis is caused by an autoimmune response, there is no cure and in some cases the condition can re-occur and will need to be treated again. Suppression of the immune system helps stop it attacking the brain’s tissues.
The outcome of encephalitis is very hard to predict as it depends on the type of encephalitis that your dog has, how early it is diagnosed and your dog’s response to treatment.
Your vet will be able to advise you on your dog’s individual case.
Encephalitis is rarely contagious. The exception is when the condition is caused by canine distemper, where the virus is transmitted by direct contact between dogs, or by rabies which can be transmitted to humans via infected saliva.
Prevention of non-infectious encephalitis
Unfortunately, there is no way to protect against idiopathic or immune-mediated encephalitis since it is thought to be caused by the body’s ‘faulty’ immune system mistakenly attacking healthy tissues. The best way to protect your dog’s health is to get it diagnosed early and agree a treatment plan with your vet.
Prevention of infectious encephalitis
Though uncommon, there are ways to protect your pet from infectious encephalitis:
- Protect against tick bites: Ticks can carry diseases such as Tick-Borne Encephalitis (TBE) and Lyme disease. With their inquisitive nature and bodies that are low to the ground, dogs are more likely to come in contact with infected ticks than humans. For this reason, it’s vital to protect your dog against ticks, particularly in areas where they are endemic.
- Vaccinate: Protect against diseases such as canine distemper virus by making sure your dog’s vaccinations are up-to-date.
- Be vigilant: Always get unusual symptoms, such as behaviour changes, checked by a vet – it’s better to be safe than sorry!
Here are 6 tips to keep your dog safe from tick bites and tick-borne diseases.
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