title: “Canine Brain Tumors: What GPs Should Know About Gliomas, From Suspicion to Treatment” slug: canine-high-grade-glioma date: 2026-02-01 source_lecture: “Lecture 43: Canine High Grade Glioma” presenter: “Associate Professor of Veterinary Neurology and Neurosurgery, University of Minnesota” status: verified word_count: 834
Canine Brain Tumors: What GPs Should Know About Gliomas, From Suspicion to Treatment
An 8-year-old French Bulldog presents with new-onset seizures. No prior seizure history. Neurologic exam between episodes is unremarkable. The owner asks: what is wrong with my dog?
For brachycephalic breeds over five years old with new-onset seizures, a brain tumor belongs at the top of your differential list. According to a veterinary neurosurgeon and glioma researcher presenting at VetOnIt CE, the question is not whether to suspect a tumor. It is what to do next.
Which Dogs Get Gliomas?
Gliomas are intraxial brain tumors arising from glial cells within the brain itself. They are one of the two most common primary brain tumor types in dogs, alongside meningiomas. About half of all brain tumors in dogs are primary, and the other half are metastatic.^1^
The breed predisposition is striking. Brachycephalic breeds, particularly Boxers, Boston Terriers, French Bulldogs, and English Bulldogs, are disproportionately affected. The presenter reports that up to 50% of canine gliomas occur in these four breeds alone. Given the current popularity of these breeds in the United States, the presenter suggests that gliomas may now be more common than meningiomas in the general dog population.
Dogs are typically at least 8 years old at diagnosis, although French Bulldogs and Boxers tend to develop tumors at a younger age.
When Should You Suspect a Brain Tumor?
Seizures are the most common presenting sign for dogs with forebrain tumors. The presenter notes that while published literature suggests about 50% of brain tumor dogs present with seizures, their clinical experience places the number higher.
Not every seizure means cancer. Age and breed matter enormously. A young Australian Shepherd with seizures? Idiopathic epilepsy is far more likely. An adult Boxer with new-onset seizures? The presenter reports that research has shown essentially all Boxers over five with new-onset seizures have brain tumors.
For forebrain lesions, look for propulsive circling toward the lesion with contralateral postural reaction deficits and absent menace response on the opposite side.
Time as a Diagnostic Test
Not every client can pursue an MRI. Geography, finances, anesthesia concerns, or simple preference may rule it out. The presenter offers a practical alternative: time as a diagnostic test.
Dogs with brain tumors who are neurologically normal between seizures will eventually develop progressive deficits, typically within six months. Dogs with idiopathic epilepsy remain normal between episodes for life. This distinction can guide the conversation without advanced imaging.
When MRI is pursued, gliomas are usually identifiable. In ambiguous cases, cerebrospinal fluid analysis can help distinguish tumors from inflammatory conditions.
Treatment: What Actually Works?
The prognosis varies dramatically by treatment choice. Here is what the published data shows:
Palliative care (prednisone alone): Median survival of 30 to 60 days.^2^ Prednisone reduces inflammation and can temporarily improve neurologic signs. The presenter starts at 0.5 mg/kg and recommends including a taper plan on every prescription.
Lomustine chemotherapy: Median survival of approximately 138 days, significantly better than palliative care alone (P = .003).^3^ Side effects include neutropenia (46% of dogs), anemia, and hepatotoxicity. Worth considering as an add-on to palliative management.
Surgical resection alone: The presenter reports a median survival of approximately 66 days. Surgery is not a standalone treatment for gliomas because complete resection is impossible. These tumors send microscopic projections into surrounding tissue, and the presenter considers gliomas a whole-brain disease.
Radiation therapy: The strongest standalone option. Conventional (fractionated) radiation therapy is associated with a median survival exceeding 500 days.^4^ Stereotactic radiation therapy offers approximately 200 days. The presenter, a neurosurgeon, states plainly: if forced to choose one modality, they choose radiation therapy every time.
Emerging Research: Immunotherapy and Beyond
The University of Minnesota Canine Brain Tumor Program, now in its 17th year, is investigating immunotherapy combinations. The presenter reports that autologous tumor lysate vaccines combined with a novel CD200 immune checkpoint inhibitor (CD200AR-L) achieved a median survival of 381 days in enrolled dogs (excluding French Bulldogs, who responded poorly).
A key research finding: French Bulldogs respond significantly worse to immunotherapy than Boxers and Boston Terriers. Published transcriptomic analysis confirmed that French Bulldog tumors differ substantially at the genetic level, with only 15.9% overlap in differentially expressed genes compared to other breeds.^5^ This suggests different breeds may ultimately need different treatment strategies.
Sonodynamic therapy (5-ALA combined with focused ultrasound) has shown results comparable to stereotactic radiation in French Bulldogs specifically, offering a promising alternative for the breed that responds poorly to immunotherapy.
Talking to Clients About Survival
The presenter offers one final piece of guidance: be careful with numbers. A median survival time means 50% of dogs lived longer. Telling a client “your dog has three months” can lead to premature euthanasia decisions. Speak in ranges, prepare clients for variability, and encourage them to evaluate treatment options based on both best-case and worst-case scenarios alongside cost and quality of life.
Watch the full two-part lecture, including video examples of neurologic exams and detailed discussion of novel therapies.
References
- Miller AD, Miller CR, Rossmeisl JH. Canine primary intracranial cancer: A clinicopathologic and comparative review of glioma, meningioma, and choroid plexus tumors. Front Oncol. 2019;9:1151. PMID: 31788444.
- Moirano SJ, et al. Survival times in dogs with presumptive intracranial gliomas treated with oral lomustine: A comparative retrospective study (2008-2017). Vet Comp Oncol. 2018;16(4):459-466. PMID: 29797768.
- Moirano SJ, et al. Vet Comp Oncol. 2018;16(4):459-466. PMID: 29797768.
- Magalhaes TR, et al. Outcome After Radiation Therapy in Canine Intracranial Meningiomas or Gliomas. In Vivo. 2021;35(2):1117-1123. PMID: 33622909.
- Arnold SA, Low WC, Pluhar GE. Breed-Associated Differences in Differential Gene Expression Following Immunotherapy-Based Treatment of Canine High-Grade Glioma. Animals (Basel). 2024;15(1):28. PMID: 39794971.