Brain Tumor in Dogs: Exactly What You Need To Know

By Chelsea Hunt-Rivera / June 4, 2018
Brain tumor in dogs

Perhaps the most terrifying news that a dog owner can receive is that their beloved four-legged companion has a brain tumor. Without even knowing any additional information, as humans, we know just how destructive, fast-growing, and horrific brain tumors can be and how quickly they can turn both of your worlds upside down.

As pet owners and dog lovers ourselves, we know that there’s no right thing to say. There’s nothing that we can do to reverse the diagnosis that you may have just received. However, through this article, we hope to be able to be a source of information for any pet owner who may find themselves facing an impossibly hard time.

dog with brain tumor

What is a Brain Tumor in Dogs

A tumor of any kind is an abnormal growth of cells. Therefore, a brain tumor is any intracranial tumor that develops from abnormal growth of cells and uncontrollable cellular division in the brain. Canine brain tumors are typically found in the brain itself, but can commonly appear in the skull, the cranial nerves, the meninges (the brain envelopes), or the pituitary and pineal gland.

Veterinarians usually diagnose brain tumors in older dogs. Additionally, certain canine breeds tend to be at a predisposition for developing specific types of brain tumors.

Symptoms of and treatment for the brain tumour will vary based on the location and whether it is a primary tumor or secondary tumor.

Types of Brain Tumors

A brain tumor in dogs will either be classified as a primary brain tumor or a secondary brain tumor.

Primary Brain Tumors

If your veterinarian diagnoses your dog’s brain tumor as primary, it means that the cancer originates within the brain’s cells and its membranes. Additionally, primary brain tumors affect certain breeds of dogs more so than others. It is imperative for dog owners to be aware of the specific risk factors that their pup may face based on their breed. (We’ll get into that momentarily)

The most common primary brain tumors are as follows:

  • Meningioma brain tumor
  • Glioma tumor
  • Choroid plexus papilloma
  • Pituitary adenoma
  • Adenocarcinoma

Secondary Brain Tumors

Conversely, a secondary brain tumor originates from cancer cells in another area of the body that has spread to the brain through a process that veterinarians refer to as metastasis. The tumor can also develop from an adjacent non-nervous system tissue which extends into the brain tissue (I.e. the nasal cavity).

  • Hemangiosarcoma
  • Mammary carcinoma
  • Melanoma

Sadly, due to the fact that secondary tumors originate elsewhere, by the time they are diagnosed as brain tumors, the cancer cells have spread throughout the body. Because of the magnitude of spreading, the prognosis for dogs diagnosed with secondary brain tumors is typically not very positive.

Symptoms of Brain Tumor

symptoms of brain tumor in dogs

Clinical signs of a brain tumor in dogs may resemble the symptoms of several other conditions. In particular, early signs of brain tumors may develop in ways that pet owners aren’t exactly able to pinpoint. Some dog owners say that their pup seemed a bit “off.” Due to the fast nature of brain tumor growth, it is imperative for pet owners to recognize any time that they see behavioral changes in their dog, no matter how small.

Pets notoriously hide whenever they are in pain. Therefore, many serious and life-threatening health conditions do not receive a diagnosis until it is too late.

Pet owners must ensure that they are aware of their dog’s “normal” day-to-day habits and act accordingly if anything changes. It can ultimately be the difference between life and death in a situation such as a brain tumor.

Brain Tumor Warning Signs

  • Seizures (Experts suggest that seizures are the most common early clinical sign of a brain tumor in dogs)
  • Depression
  • Head tilting
  • Loss of balance/ “drunken” walk
  • Cranial nerve deficits
  • Decreased vision or loss of vision
  • Difficulty swallowing
  • Voice change (more vocalization than usual and/or hoarseness)
  • Weakness and lethargy
  • Strange behaviors (such as aggression)
  • Gain or loss of appetite
  • Vomiting
  • Weight loss

Clinical Signs of Brain Tumor in Late Stages

  • An overall continuation of persistent early-stage symptoms
  • Reclusive or solitary behavior (even social dogs will hide to avoid attention from both humans and other dogs)
  • Confusion
  • Vomiting
  • Pacing
  • Walking in circles
  • Pressing against a hard surface (often times pressing their heads against the surfaces)
  • Worsening weakness leading to an inability to stand
  • Worsening seizures
  • Paralysis
  • Coma

Critical Stage Brain Cancer Symptoms

Dogs in critical stages of brain cancer will often exhibit the following clinical signs:

  • Difficulty breathing
  • Continued seizures (many of which will lengthen in time and the amount which they occur)
  • Uncontrollable vomiting
  • Uncontrollable diarrhea
  • Sudden collapse
  • Excessive bleeding (the bleeding can be internal or external or both)
  • Crying and whining out of pain (again, dogs do not often show pain so this is a critical sign)

What Causes Brain Cancer

chemical toxins

The definite cause of brain tumors in dogs and cats is still relatively unknown, even with progressive research on the topic. However, experts tend to agree that a few factors seem to come into play. These factors include:

  • Environmental toxins
  • Dietary factors
  • Genetic predispositions
  • Chemical toxins
  • Weakened immune system

Breeds at a Higher Risk for Dog Brain Cancer

Generally speaking, some canine breeds tend to be at a greater predisposition for developing brain tumors.

These breeds include:

  • Boxer
  • Golden Retriever
  • Doberman Pinscher
  • Scottish Terrier
  • Old English Sheepdog

Additionally, there are certain breeds that are at a predisposition of developing specific types of brain tumors.

For example, brachycephalic breeds (characterized by their flat-faced and short-nosed appearance) tend to be more prone to develop gliomas. Gliomas are tumors that are located in the interstitial tissue of the central nervous system. The brachycephalic dogs at a higher risk of developing such tumors are Boxers, English Bulldogs, and Boston Terriers.

Conversely, dolichocephalic breeds (characterized by their long noses and faces) tend to be at a higher risk of developing meningiomas. Meningiomas are brain tumors that develop in membranes covering the brain. Veterinarians often diagnose meningiomas in breeds such as Golden retrievers and Collies (among others).

While brain tumors have the ability to develop in dogs of any age, they are more common in dogs over the age of five years old.

Diagnosing Brain Cancer

diagnosing brain tumors in dogs

Generally speaking, dogs who do not have a previously diagnosed brain condition who have a sudden onset of neurological symptoms are often suspected of having a brain tumor.

Your veterinarian will conduct full physical and neurological exams. These tests will also involve a complete blood count (CBC) and x-rays of the chest and abdominal areas. The blood tests and x-rays will determine whether the cancer cells and/or additional tumors have spread to other parts of the dog’s body.

In the vast majority of cases, a veterinarian will perform an MRI (magnetic resonance imaging ) or CT scan (computerized tomography) in order to accurately diagnose a brain tumor in dogs. This is primarily due to the fact that soft tissue brain tumors are unable to be seen with simply an x-ray of the skull.

Typically, an MRI or a CT scan will be able to determine the type of brain tumor based on its appearance. However, a definite diagnosis of the type of tumor is only possible by taking a sample of the mass either when it is removed through surgery or by taking a surgical biopsy. Many times, total removal, even with advanced surgery, is not possible if the tumor is deep within the dog’s skull. Therefore, a sample of the tissue will be removed for evaluation.

Furthermore, it is highly possible for brain masses to develop due to infections. These masses commonly resemble tumors. Therefore, taking a biopsy is incredibly important in order to make an accurate diagnosis and determine the cells involved.

Finally, the biopsy will also be able to provide the veterinarian knowledge on the malignancy of the tumor.

Treatment of Brain Tumors in Dogs

Treatment for the brain tumor will vary based on whether the tumor is primary or secondary in addition to varying in regards to where the tumor is located.

The most common treatment methods of brain tumours in both dogs and cats are surgery, radiation therapy, and occasionally chemotherapy.

The primary objective of the three types of treatment is to eradicate the tumor whenever possible. If total removal of the tumor is possible, your veterinarian will perform surgery as soon as possible.

If surgical removal is not possible due to the location of the tumor, radiation therapy and chemotherapy may be used in order to shrink the size of the tumor. Radiation therapy may also be advised following surgery prevent regrowth of the tumor.

While chemotherapy is still used on a case by case basis, more often radiation therapy is the preferred method. This is due to the blood-brain barrier limitations that chemotherapy drugs have. The blood-brain barrier limits the effectiveness that the drug is able to have.

Medication may also be prescribed in order to help reduce the symptoms that the tumor may be causing the dog. The veterinary medicine includes anti-seizure medications and drugs to reduce pain and intracranial pressure.

Brain Tumor in Dogs: A Final Thought

healthy dog

At the end of the day, canine brain tumors can be horrific for pet parents to think about. While you can’t necessarily prevent your beloved pooch from the developing a brain tumor, it is absolutely possible for dog owners to make sure they are implicitly aware of the early clinical signs. Recognizing behavioral changes in your pup and making sure to act according can save your dog’s life.



About the author

Chelsea Hunt-Rivera

Chelsea Rivera is a Dedicated Pet Parent who loves to create amazing content for pet owners and is helping change pet wellness as the Head of Content for