Brain Tumors in Dogs & Cats
Brain tumors are among the most common causes of new-onset seizures in older dogs and cats. Because the brain is entirely encased in bone, there is no way to directly examine it — making MRI the essential diagnostic tool for identifying brain tumors, characterizing their type, and guiding treatment decisions.
At Sage Veterinary Imaging, our 3-Tesla MRI provides the highest-resolution brain imaging available in veterinary medicine. Contrast-enhanced MRI reveals tumor location, size, boundaries, relationship to critical brain structures, and characteristics that help predict tumor type — all of which directly inform whether surgery, radiation, or medical management is the best approach.
SVI offers advanced mri services at our centers in Round Rock, Texas; Spring, Texas; and Sandy, Utah.
Brain Tumors at a Glance
What Are Brain Tumors in Pets?
Brain tumors in dogs and cats can be primary (arising from brain tissue or meninges) or secondary (metastatic spread from tumors elsewhere in the body). Primary brain tumors are more common, with meningiomas and gliomas accounting for the majority of cases.
Meningiomas arise from the meninges (coverings of the brain) and are the most common brain tumor in both dogs and cats. They are typically well-defined, strongly contrast-enhancing masses that compress the brain from outside. In cats, meningiomas are often surgically resectable with good outcomes. In dogs, location determines surgical accessibility.
Gliomas (astrocytomas, oligodendrogliomas) arise from the brain tissue itself and are particularly common in brachycephalic breeds (Boxers, Boston Terriers, Bulldogs). They tend to be infiltrative, making complete surgical removal more challenging. MRI characteristics help distinguish low-grade from high-grade gliomas, which impacts prognosis.
Other brain tumors include choroid plexus tumors (which can cause hydrocephalus), pituitary macroadenomas (which cause hormonal dysfunction and mass effect), and lymphoma (which may involve the brain primarily or as part of multicentric disease).
Signs & Symptoms of Brain Tumors
Brain tumor signs depend on tumor location and size. They are typically progressive over weeks to months, though seizures can appear suddenly.
🚨 When to Seek Emergency Evaluation
Cluster seizures (multiple seizures within 24 hours), status epilepticus (a seizure lasting more than 5 minutes), sudden blindness, or acute inability to walk warrant emergency veterinary evaluation. These signs can indicate rapid tumor growth, brain herniation, or severe cerebral edema requiring immediate treatment.
How MRI Diagnoses Brain Tumors
MRI is the only imaging modality that provides sufficient soft-tissue contrast to visualize brain tumors in detail. CT shows the skull well but provides limited brain parenchyma detail. X-rays are unable to evaluate the brain at all.
What Our 3T MRI Reveals
Tumor location and size — MRI precisely maps the tumor relative to critical brain structures, ventricles, and the brainstem, determining surgical accessibility.
Tumor characteristics — Enhancement pattern, signal intensity, and margins help predict tumor type. Meningiomas show strong, uniform contrast enhancement with a broad dural attachment (“dural tail sign”). Gliomas are typically intra-axial with variable enhancement.
Mass effect and herniation — MRI shows how much the tumor is displacing normal brain tissue and whether life-threatening brain herniation is occurring.
Secondary changes — Peritumoral edema, hydrocephalus (from CSF obstruction), and hemorrhage within the tumor are all visible on MRI and affect treatment decisions.
Multifocal disease — MRI of the entire brain identifies whether tumor is solitary or multifocal, which dramatically impacts treatment options and prognosis.
MRI vs. Other Imaging for Brain Tumors
MRI
Gold standard. Shows tumor type characteristics, brain parenchyma detail, enhancement patterns, edema, and herniation.
CT
Shows skull and calcified tumors. Limited soft-tissue brain contrast. Useful adjunct for surgical planning of skull-based tumors.
X-Ray
Cannot visualize the brain. Only shows secondary skull changes in rare, advanced cases.
Which Breeds Are Most at Risk?
Breeds at Higher Risk
Boxers, Boston Terriers, and English Bulldogs have the highest rates of gliomas. Golden Retrievers are predisposed to multiple brain tumor types. Domestic Shorthair cats are the most commonly diagnosed with meningioma. Siamese cats have elevated brain tumor rates. Large-breed dogs including German Shepherds have higher rates of meningioma. Any dog or cat over 5 years of age with new-onset seizures should be evaluated for a brain tumor.
What to Expect During a Brain MRI
Brain MRI studies typically take 45–75 minutes under general anesthesia. Multiple specialized sequences are acquired, including T1-weighted, T2-weighted, FLAIR, and contrast-enhanced images. Contrast enhancement is essential for brain tumor evaluation because it reveals the tumor’s blood supply and helps characterize tumor type.
Results are interpreted by a board-certified veterinary radiologist the same day. For cases with acute neurological deterioration, preliminary findings are communicated immediately to your veterinarian or neurologist. If CSF analysis is needed, it can be collected under the same anesthesia.
Dr. Jaime Sage, DVM, MS, DACVR
Dr. Jaime Sage is the founder of Sage Veterinary Imaging and a board-certified veterinary radiologist (DACVR) with advanced expertise in diagnostic MRI for companion animals. Dr. Sage personally interprets complex cases and works closely with referring veterinarians to ensure every imaging study delivers clear, actionable diagnostic answers.
Her published research on MRI in veterinary medicine — co-authored with Dr. Patrick Gavin, a pioneer in the field — has contributed to advancing the standard of care for pets requiring advanced diagnostic imaging.
Why Choose Sage for Brain Tumor Diagnosis
Schedule a Brain MRI
If your pet has new seizures, behavioral changes, or progressive neurological signs, brain MRI can identify the cause and guide the most effective treatment plan.
Brain Tumor Imaging FAQ
Get Answers for Your Pet
If your pet is showing neurological signs that could indicate a brain tumor, advanced MRI can identify the problem and guide effective treatment. Visit one of our locations to get started.