Brain Tumors in Dogs

Brain Tumors in Dogs: Symptoms and Treatment Options

Brain tumors in dogs are neoplastic masses or abnormal cell growth in the brain. Brain tumors in dogs are primary, secondary, or metastatic. Primary tumors are the first neoplastic mass. Secondary tumors form in other parts of the body and spread to the brain. Metastatic tumors are one of the cancer types in dogs where the tumor spreads to the brain. Meningioma and glioma are the main primary tumors. 

Brain tumors are caused by complex combination of genetics and environmental factors such as diet, exposure to pollutants, and traumatic events. Age and breed are the main risk factors for brain tumors in dogs. 

Symptoms of brain tumors in dogs include seizures, mentation or behavioral changes, head tilt or tremors, circling, ataxia, hypermetria, paresis or hemiparesis, blindness, and nystagmus. The location of the tumor dictates the clinical presentation. 

The treatment for dog brain tumors is medication, surgery, radiation, and chemotherapy used alone or combined. CBD oil is an excellent addition to the anti-cancer treatment strategy, while boosting the immune system does not help prevent or treat cancer. The prognosis for brain cancer in dogs is guarded to poor. 

What is brain tumor cancer in dogs?

Brain tumor cancer in dogs is a newly formed or neoplastic mass in the brain. Tumors of the brain are benign and malignant or cancerous. 

Brain tumors are classified as primary or secondary. Primary tumors arise from the brain or its cover layers (meninges). Secondary brain tumors develop in other parts of the body and then spread to the brain through invasion or metastasis. 

Brain tumors affect the brain by pressuring and destroying healthy neurons and nervous tissues. The effects depend on the tumor type, size, and location.   

The most common brain tumor in dogs is meningioma, and the second common is glioma. Brain tumors are rare compared to other cancer types in dogs

What are other terms for brain tumor cancer in dogs?

Other terms for brain tumor cancer in dogs are meningioma and glioma. The names describe the origin cells of the tumor. Meningioma stems from the membranes covering the brain and glioma from the deeper brain tissues. 

Veterinarians use different names, such as astrocytomas or oligodendromas, based on the exact type of cells involved in the tumor. Deciphering brain tumor terms is challenging, and it is best to consult a vet for clarification. 

How does brain tumor cancer develop in dogs?

Brain tumor cancer develops in dogs when cells start dividing abnormally and without control. The cells turn tumorous in the brain or elsewhere in the body and travel to the brain. 

Brain cancer develops when dogs are over five years old, and the signs of a brain tumor depend on its type, size, and location. 

There is no clear answer to the question, “Why do dogs get brain tumors?” A complex interaction of genetic and environmental factors contributes to the head dog brain tumor development. 

How common is brain tumor cancer in dogs?

Brain tumor cancer is relatively common in dogs, accounting for 2 to 5% of primary brain tumor cancers. The top three brain tumor cancers are meningioma, glioma, and choroid plexus tumors. 

Primary brain tumors account for 2 to 5% of all canine cancer cases, reports a study, "Canine Primary Intracranial Cancer: A Clinicopathologic and Comparative Review of Glioma, Meningioma, and Choroid Plexus Tumors," published in Frontiers in Oncology in 2019. 

Brain tumors are infrequent in puppies and cats. Primary brain tumors in cats make up less than 2% of all feline cancer diagnoses, according to an article "Brain Tumors in Cats" published by PetMD.

Which breeds are more prone to developing brain tumor cancer?

The breeds more prone to developing brain tumor cancer are listed below. 

  • Bulldogs: English and French Bulldogs are predisposed to gliomas or brain tumors originating from the brain or the spinal cord.  
  • Boston Terriers: Boston Terriers have a higher than-average risk of developing gliomas, primarily oligodendrogliomas and astrocytomas. 
  • Boxers: "Boxers have a 25-fold increased risk for developing primary brain tumors," says a study, "Utilizing the Dog Genome in the Search for Novel Candidate Genes Involved in Glioma Development," PLOS One in 2016. 
  • Golden Retrievers: Golden Retrievers are prone to meningiomas or brain tumors stemming from the membranes surrounding and protecting the brain.

What does brain tumor cancer in dogs look like?

Brain tumor cancer in dogs looks like an abnormal mass within the brain tissue. The specific appearance depends on the tumor type. 

Meningiomas are homogenous, well-circumscribed, and with broad bases. Gliomas appear very similar to normal brain tissues. Choroid plexus tumors are small, red, and ulcerative masses. 

What are the main types of brain tumors found in dogs?

The main types of brain tumors found in dogs are listed below. 

  • Meningiomas: Meningiomas arise from the meninges and are the number one primary brain tumor in dogs. The meninges are the layers of tissue that lie beneath the skull and protect and cover the brain. Meningiomas are generally benign. 
  • Gliomas: Gliomas are tumors arising from glioma cells, which surround and support the neurons. Dogs have three types of gliomas, including astrocytomas, oligodendromas, and undefined gliomas. 
  • Choroid Plexus Tumors: Choroid plexus tumors originate from the choroid plexus, which lines the brain's ventricles and produces cerebrospinal fluid (CSF). The fourth ventricle is dogs' most common location of choroid plexus tumors (CPT).
  • Other Primary Brain Tumors: Rare primary brain cancers are ependymoma, germinoma, and embryonal tumors. Ependymomas stem from the lining of the brain's fluid-filled spaces, germinomas from germ cells, and embryonal tumors from remaining cells from early development. 
  • Secondary Brain Tumors: Hemangiosarcoma, pituitary tumors, lymphosarcoma, and metastatic carcinomas are common causes of secondary (metastatic) brain tumors, says a study "Secondary intracranial neoplasia in the dog: 177 cases (1986-2003)," Journal of Veterinary Internal Medicine in 2008.

What are the causes of brain tumor cancer in dogs?

The causes of brain tumor cancer in dogs are listed below. 

  • Genetics: Brain cancer is prevalent among certain breeds, such as Bulldogs, Boxers, and Retrievers, suggesting a genetic component. 
  • Environment: Diet, traumatic events, and exposure to pollutants and carcinogens in the environment contribute to brain cancer in dogs. 
  • Germs: Infectious diseases caused by bacteria and viruses are believed to play a role in the complex development of brain tumors.

Is there a genetic predisposition to brain tumors in certain dog breeds?

Yes, there is a genetic predisposition to brain tumors in certain dog breeds. Brain cancer occurs more frequently in some dog breeds, and specific types of brain tumors are prevalent in particular breeds. 

Meningioma is widespread in dolichocephalic dogs like Italian Greyhounds, Great Danes, and Dachshunds. Glioma has a high incidence among brachycephalic breeds such as Boxers, Bulldogs, and Boston Terriers.

What are the symptoms of brain tumor cancer in dogs?

The symptoms of brain tumor cancer in dogs are listed below. 

  • Seizures: Dogs with forebrain tumors experience uncontrolled electrical impulse release in the brain, causing seizure episodes. 
  • Circling: Compulsive walking in circles and an inability to follow a straight trajectory are symptoms in dogs with forebrain tumors. 
  • Head Tilts: Dogs with tumors in the hindbrain or vestibular system tilt the heads to one side as if they are listening to something on the floor.  
  • Intentional Head Tremors: Dogs with brain tumor cancer are prone to shake their heads when intent on something but do not tremor when relaxed.  
  • Blindness: Tumors in the forebrain cause acute blindness in dogs, which affects one or both eyes depending on the tumor type. 
  • Nystagmus: Nystagmus is abnormal eye movement or eye darting, a symptom of a brain tumor affecting the vestibular system. 
  • Loss of Coordination: Wobbly or uncoordinated walking, medically termed ataxia, is a symptom of brain tumors of the hindbrain. 
  • Hypermetria: Hypermetria or dramatic goosestepping is taking unnecessarily large steps, and it is a symptom of a brain tumor on the cerebellum. 
  • Paresis or Hemiparesis: Paresis (weakness) and hemiparesis (weakness in the limbs on one side of the body) are common symptoms of a brain tumors in dogs
  • Behavioral Changes: Sudden and unexplained behavior changes, like withdrawal, clinginess, or irritability, are signs of brain tumors in dogs
  • Altered Mentation: Brain tumors, in certain cases, alter a dog's mentation status, making the dog more tired or dull than usual.

When do symptoms of brain tumor cancer typically occur in dogs?

Symptoms of brain tumor cancer typically occur in dogs when the growth starts pressuring the brain. The symptoms depend on the tumor's location and the affected part of the brain. 

Different brain parts have different functions, resulting in a unique clinical manifestation. The number one brain tumor symptom in dogs is seizures. Brain cancer must be considered in all dogs over the age of five presenting with seizure episodes. 

What are the risk factors for brain tumor cancer in dogs?

The risk factors for brain tumor cancer in dogs are listed below. 

  • Breed: Certain breeds, such as Boxers, French and English Bulldogs, Boston Terriers, Golden Retrievers, and Doberman Pinschers, have an increased risk of brain tumor cancer. 
  • Age: The risk of brain tumor increases in dogs over five years of age, although the median age of brain tumor cancer in dogs varies.

Are older dogs more at risk for brain tumors?

Yes, older dogs are more at risk of brain tumors. Age is a significant risk factor for cancer in dogs. Primary and secondary brain tumors occur in middle-aged to older dogs over the age of five. 

Median ages at the time of diagnosis for dogs with gliomas, meningiomas, and CPT are 8 years, 10.5 years, and 5.5 years, respectively, according to a study “Postmortem Evaluation of 435 Cases of Intracranial Neoplasia in Dogs and Relationship of Neoplasm with Breed, Age, and Body Weight,” Journal of Veterinary Internal Medicine in 2013. 

Neuroepithelial tumors of glial, neuronal, or embryonal origin are seen in younger dogs in rare cases. 

What are the complications of brain tumor cancer in dogs?

The complications of brain tumor cancer in dogs are listed below. 

  • Seizure Episodes: Seizures are a major brain tumor complication and are debilitating to the dog and distressing for the owner. 
  • Blindness: Acute vision loss is a common complication of brain tumors. Some dogs regain vision after the pressure on the brain is relieved. 
  • Trouble Walking: The inability to walk in a straight line, trouble keeping balance, and lack of coordination frequently accompany brain tumors in dogs. 
  • Extreme Fatigue: Pronounced fatigue that prevents dogs from participating in everyday activities is a potential complication of certain brain tumors. 

Where can you seek a diagnosis for brain tumor cancer in dogs?

You can seek a diagnosis of brain tumor cancer in dogs at the vet’s office. The veterinarian performs a physical and neurological exam. The dog is referred to a neurologist based on the findings. 

Brain tumors are complex and require specialized attention. The veterinary neurologist is able to differentiate the tumor type and recommend treatment options. 

How is brain tumor cancer diagnosed in dogs?

Brain tumor cancer is diagnosed in dogs with neurologic examination, thoracic X-rays, brain CT or MRI, and blood work. 

The neurological examination helps determine the tumor's location. Thoracic X-rays are used to check for lung metastasis. MRI and CT scan the brain, with MRI being the diagnostic method of choice, but it is more expensive and less available than CT. 

Brain tissue biopsy is risky and rarely performed in dogs. Blood work is ordered to evaluate the dog’s health status. 

What is the typical prognosis for a dog diagnosed with a brain tumor?

The typical prognosis for a dog diagnosed with a brain tumor is guarded. The outcome depends on the tumor’s type and size and the treatment. 

The prognosis is worse for dogs with untreated brain tumors. A better prognosis is expected for dogs with brain tumors managed with multiple approaches. 

Brain tumors are life-threatening on their own, through metastasizing, or because they pressure the brain tissue. The treatment goal is to delay tumor growth and keep the dog comfortable. 

How long can a dog survive with brain tumor cancer?

A dog with brain tumor cancer can survive for two to 30 months. The median survival time depends on the tumor location and type of treatment. 

Tumors of the lower region of the brain are associated with shorter life expectancies compared to tumors in the upper region. 

Dogs managed with supportive care live for two to four months. Surgery extends the lifespan for six to 12 months, while surgery combined with radiation for six to 30 months. 

Radiation slows down the dog brain tumor progression time, giving an extra seven to 24 months of life. Chemotherapy prolongs a dog’s life expectancy for seven to 11 months. 

What are the treatments for brain tumor cancer in dogs?

The treatments for brain tumor cancer in dogs are listed below. 

  • Medications: Steroids help slow down the tumor growth, reduce brain swelling, and keep the dog comfortable. Antiepileptics control seizures. Medications are used alone or combined with other treatments. 
  • Surgery: Surgery is performed on dogs with surface tumors like meningiomas. Dogs with gliomas are suitable for surgery because of the tumor’s location. The goal of the surgery remove the tumor without damaging the healthy brain tissue. 
  • Radiation: Radiation treatment shrinks tumors, which helps improve the dog’s condition but does not destroy the tumor. Brain tumors managed with radiation recur within a year. Mouth ulcers, ear infections, and nausea are common side effects of radiation. 
  • Chemotherapy: Chemotherapy is rarely used to treat brain tumors in dogs because the dog’s brain is protected by a network of blood vessels. The network prevents drugs (chemotherapeutics) from penetrating. 

How effective is surgery in treating brain tumors in dogs?

Surgery is moderately effective in treating brain tumors in dogs. Dogs with tumors on the brain’s surface, such as meningiomas, are surgical candidates. The tumor, however, tends to recur. 

Surgical treatment is not an option for dogs with tumors in the deep brain tissues, like gliomas. The risks of damaging the healthy brain tissues outweigh the potential surgery benefits. 

Can boosting the immune system of dogs help fight brain tumors?

No, boosting the immune system of dogs cannot help fight brain tumors. Brain tumors interact with the immune system, but the exact link has yet to be determined.  

A study, “Immunohistochemical Evaluation of Immune Cell Infiltration in Canine Gliomas,” published in Veterinary Pathology in 2021, reports that high-grade gliomas contain a high number of regulatory T lymphocytes (Tregs)

Tregs are immune cells that prevent autoimmune diseases. Brain tumors recruit Tregs to defend them against immune system attacks, making immunity work in their favor. 

Immunotherapy for dogs with cancer is to train the immune system to recognize and attack cancer cells instead of boosting the immune system.

Can CBD oil help dogs with brain tumors?

Yes, CBD oil can help dogs with brain tumors. CBD, or cannabidiol, is a hemp plant extract with non-psychoactive and health-boosting properties. 

Cannabidiol blocks cancer growth and spread, acting directly against the brain tumor. Combined with chemotherapy and radiation, CBD boosts their effectiveness.  

CBD reduces inflammation and swelling, relieving the pressure on the brain. Cannabidiol helps with brain tumor symptoms through its antiepileptic and relaxing properties. 

Talk to the veterinarian to safely incorporate the treatment CBD oil into the anti-tumor strategy. CBD is suitable for daily use in dogs of all ages.   

Is there a way to prevent brain tumors in dogs?

No, there is no way to prevent brain tumors in dogs. The cause of cancer is poorly understood, limiting prevention options. 

A healthy lifestyle is believed to reduce the risk. A healthy lifestyle for dogs includes a balanced diet and daily exercise. Routine veterinary checkups help catch brain tumors early.