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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.

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

English Shepherd
2 Years
Mild condition
1 found helpful
Mild condition

Has Symptoms


My dog is a healthy, playful 2 year old english sheperd and has had 3 seizures in the last 2 days, has never had them before, and seems to only happen when he is sleeping. Can this be a symptom of parasites?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2152 Recommendations
There are various causes for seizures including neurological issues, poisoning, head trauma (may have occurred months ago), tumours, infections, parasites among other causes; you should have Koko examined by your Veterinarian to determine a cause since the different causes have different treatments or management options. Regards Dr Callum Turner DVM

is pheno a solution for dogs epillepsy

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10 Years
Moderate condition
0 found helpful
Moderate condition

Medication Used


My female mastif is 10yrs and has a large lump over the right side of her head (from back of eye to ear)some days it swells and her eye is closed .The lump goes up and down within the day but is mostly visible. The vet has tried to get fluid from the mass but to no avail she's also been on antibiotics .Her appetite is normal perhaps drinks more water, she does drink and swim in our dam .

Dr. Michele King, DVM
Dr. Michele King, DVM
679 Recommendations
Thank you for your email. WIthout examining Flute, I'm not able to shed much light on what might be going on with her, but your veterinarian should be able to get a fine needle sample or biopsy to determine what the lump might be, and how best to treat it or remove it. I hope that you are able to figure out what is causing the lump!

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Australian Shepherd
3 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

very unseattled

My dog has itching in the anus for years. After several anti parasitic infections, she was finally diagnosed with skin problems in the base of the tail. For about 6 months se started with head tilting and for about 2 weeks she has been really unsettled, she wants to go out in the garden and back again all the time, she wakes me up at night and is really unsettled. Otherwise she eats properly and her stools are firm.

Dr. Michele King, DVM
Dr. Michele King, DVM
679 Recommendations
Thank you for your email. Without examining Lucky, I can't determine what might be going on with her, but I'm not sure that those signs are associated with her skin problems that she had before. If she has had a head tilt for 6 months and seems unsettled, it would probably be best to have her examined by your veterinarian to try and determine the cause of what is happening with her and see if there is a treatment that can help her. I hope that she is okay.

Can humans get it

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10 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Dialated pupils

My dog recently began eating uncontrollably about a week ago. She's been lethargic, twitching, and "distant" when you look into her eyes. What could it possibly be?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2152 Recommendations
There are a few different causes for an increase in appetite which may include malabsorption disorders, parasites, infections, hormonal conditions among others; the dilated pupils may be related or a separate condition, if the pupils are related a neurological issue like tumour or other cause may be the cause. Your Veterinarian will be able to determine the underlying cause and whether the dilated pupils and the increase in appetite are related. Regards Dr Callum Turner DVM

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