Brain Parasites in Dogs

Brain Parasites in Dogs - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What are Brain Parasites?

When a dog has a brain infection, this is often known as encephalitis. There are two main types of inflammation of the brain which causes encephalitis, which are infections and idiopathic. Infections of the brain which can lead to encephalitis include parasites, fungi, bacteria, and viruses. Parasites within the brain are common causes of this inflammation, and can be dangerous to the dog’s health if they are not diagnosed and treated quickly.

In neurological disease, the brain and spinal cord are affected. Encephalitis is often used to describe a nervous system disease, as this typically affects the brain of the dog. When parasites invade the dog’s brain, they spread very rapidly and cause a myriad of symptoms. A parasitic infestation in the brain can be life-threatening. This type of brain infection, known as parasitic encephalitis, is a serious condition which causes the dog to develop abnormalities in the central nervous system as the brain swells and the spinal cord becomes infected due to a variety of parasites.

Brain parasites in dogs can be caused by several different types of parasite infestation within this organ. With brain parasites, encephalitis, or swelling of the brain occurs. This typically alerts dog owners that medical attention is needed.

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Symptoms of Brain Parasites in Dogs

Your dog may have a variety of symptoms with brain parasites. They may range from mild to severe, depending on how long he has been infected. Symptoms may include:

  • Depression
  • Staggering
  • Walking around in circles
  • Head tilting
  • Head pressing
  • Loss of muscle movement in the face
  • Dizziness
  • Weakness


There are several types of parasites that can negatively affect your dog’s central nervous system by infesting in his brain and spinal cord. Different brain parasites include:

  • Taenia
  • Toxocara canis
  • Dirofilaria immitis
  • Balamuthia mandrillaris
  • Ancylostoma caninum
  • Coenurus spp
  • Toxoplasma gondii
  • Neospora caninum
  • B. columnaris

Causes of Brain Parasites in Dogs

Brain inflammation due to parasites, also known as parasitic encephalitis, is caused by parasites entering the dog’s body. Causes include:

  • Parasites can enter the ears and nasal openings
  • Parasites can enter through injuries or bites
  • Parasites gain entry within the bloodstream of the canine when entering through an opening
  • Migration of parasites into the central nervous system
  • The dog spends time in stagnant water, swallowing the water

Diagnosis of Brain Parasites in Dogs

If your dog is being affected by the symptoms above, make an appointment with your veterinarian. Once you reach your veterinarian’s office, he will take a closer look at your pet’s symptoms. He will do a complete physical examination, as well as blood testing, urinalysis, and biochemistry profile. This will give your medical professional some baseline data to go by before he performs any other tests.

He may ask you questions pertaining to your dog’s symptoms, such as when they began. Information about the environment and lifestyle of your companion will be noted, as will ask any other questions he feels are necessary in order to help him understand what may be the issue. 

Your veterinarian may then do other tests, such as imaging of the chest, ultrasound of the abdominal area, and aspirations of his lymph nodes  to look for any infections that are causing his encephalitis. The main mode of diagnosis to diagnose your dog’s encephalitis is by performing a spinal tap.

The fluid that surrounds the spinal cord in the brain is known as spinal fluid, or cerebrospinal fluid. This fluid can be tested to gather information on what is happening in your dog’s nervous system. If your dog has a significant increase in white blood cells, your dog will be diagnosed with the encephalitis. Your veterinarian will determine if your dog’s overall health and condition will allow for a low-risk spinal tap.

An MRI may be performed to rule out other causes of neurological disease, and in order for the veterinarian to identify parasites within the brain, several other tests will need to be performed. Histopathology of the brain in several different stains will need to be conducted, namely Trichrome, Calcofluor fluorescent, or Fungi-Fluor stains, which are effective ways to identify parasites in the brain. Sediment in the urine may also be a key factor of this condition.

Treatment of Brain Parasites in Dogs


Your veterinarian may prescribe a medication to treat the parasites if he feels your dog’s condition is treatable. Drugs that may be effective in mild cases of parasitic encephalitis are fenbendazole, ivermectin, or thiabendazole. Depending on your dog’s particular diagnosis, as well as the type of parasite involved, your veterinarian will choose the best medication possible for your loved one.

Anti-Seizure Drugs

Other medications may be given if your dog is suffering from seizures. Medications include diazepam or phenobarbital. If your dog is having a great deal of inflammation, a steroid may be given to reduce any swelling.

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Recovery of Brain Parasites in Dogs

Unfortunately, treatment methods for moderate to severe parasitic encephalitis are limited. This can be a fatal condition if it is not diagnosed in a timely manner.

If your dog has a mild condition, your veterinarian will prescribe the proper medication. Once home, it will be very important to follow your veterinarian’s advice and instructions on administering the medication to your dog. It will also be important to monitor your dog for any changes or new symptoms that arise.

Your veterinarian will want to see your dog for several follow-up appointments to check his progress. During these rechecks, more tests will be performed to see if he is recovering. In this condition, prognosis is very guarded, and your veterinarian will be honest with you and communicate with you as to his chances of survival.

Brain Parasites Questions and Advice from Veterinary Professionals


Siberian Husky



One Year


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0 found this helpful

My pet has the following symptoms:
Seizures, Drooling, Crying In Pain
Vet cannot give any diagnosis. There is a slight increase in EBC and Eos.

July 13, 2020

Answered by Dr. Michele K. DVM

0 Recommendations

Thank you for your question. Unfortunately, without more information, it is impossible for me to comment on what might be going on. It may be best to have a referral to a neurologist, if this problem is not resolving. Your veterinarian would be able to give you that referral if needed. I hope that all goes well for your dog.

July 13, 2020

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1 Year


1 found this helpful


1 found this helpful

My pet has the following symptoms:
We have a little chihuahua/dachshund mix, on an island that we regularly visit with our dog several squirrels have been diagnosed with brain worms transmitted from raccoons. Could this parasite be transmitted to our dog?

June 19, 2018

Answered by Dr. Michele K. DVM

1 Recommendations

I'm not sure what type of parasite the squirrels have been diagnosed with, as there are a few that can affect the brain. In general, I would say yes, the parasite could be transmitted, possibly by inhaling the parasite, eating feces contaminated with the parasite, or drinking stagnant water where the parasite may be living. It may be a good idea to keep Coco away from this island, or keep him on a leash to prevent contact if possible.

June 19, 2018

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