Know the neurological signs. Ask why they are happening. Seek investigation when they are progressing.
A brain tumour is an abnormal growth of cells within or affecting the brain.
Brain tumours can be primary, meaning they arise from tissues within or around the brain, or secondary, where cancer originating elsewhere in the body spreads to the brain.
Examples of primary brain tumours include meningiomas, gliomas, ependymomas and choroid plexus tumours. Meningiomas are the most commonly reported primary brain tumour in cats and dogs, while gliomas are also an important form of intracranial neoplasia.
What signs can a brain tumour cause?
The signs depend heavily on where the abnormality is located, how large it is, how rapidly it is changing, and how it affects surrounding brain tissue.
Possible neurological signs can include:
- Seizures or seizure-like episodes
- Circling, particularly repeatedly in one direction
- Head tilt or abnormal head position
- Loss of balance or coordination
- Falling or stumbling
- Weakness
- Changes in walking or posture
- Disorientation or appearing confused
- Changes in behaviour or personality
- Abnormal vocalisation or behaviour
- Changes in vision or apparent blindness
- Altered awareness or responsiveness
- Difficulty eating or performing previously normal activities
- Progressive neurological deterioration
These signs do not automatically mean an animal has a brain tumour.
Many neurological diseases can produce similar signs. The important question is:
Why is this happening?
When neurological abnormalities are new, severe, recurring or progressively worsening, veterinary reassessment is important.
How are brain tumours diagnosed?
A neurological examination can help a veterinarian determine whether signs may originate from the brain and approximately which region may be affected.
But examination alone cannot establish that an animal has a brain tumour.
Advanced imaging may be required.
MRI is a major diagnostic tool for suspected intracranial disease.
MRI can identify the location, size and characteristics of a brain lesion and the effects it is having on surrounding brain tissue. Contemporary veterinary literature describes MRI as integral to the diagnosis and management of brain tumours in dogs and cats.
CT can also identify some intracranial abnormalities and may be appropriate in particular circumstances, although MRI generally provides greater soft-tissue characterisation of the brain.
But an MRI image is not always the final diagnosis.
This distinction is extremely important.
MRI can sometimes provide a strong presumptive diagnosis, but different tumours—and even non-cancerous inflammatory or other brain diseases—can share imaging characteristics.
Definitive identification of tumour type may therefore require examination of tissue by a veterinary pathologist.
What happens after a mass is discovered?
Further investigation depends on the individual animal and may include:
Neurological examination → MRI/CT → blood tests and other investigations → assessment for disease elsewhere → specialist interpretation → biopsy/histopathology where appropriate
The veterinary team may also investigate whether the lesion could represent something other than cancer.
The diagnostic pathway should be tailored to the animal rather than automatically applying the same tests to every patient.
Can brain tumours be treated?
Sometimes.
Treatment and prognosis vary considerably depending upon:
- Tumour type
- Location
- Size
- Whether surrounding brain tissue is affected
- Whether the tumour can be surgically accessed
- Whether cancer is present elsewhere
- The animal's age and general health
- Severity of neurological impairment
- Available treatment options
Treatment can include combinations of:
Medication
Corticosteroids may sometimes be used to reduce inflammation and swelling surrounding an intracranial mass.
Anti-seizure medication may be required when seizures occur.
These medications generally manage consequences of the disease rather than physically removing the tumour.
Surgery
Some tumours can potentially be surgically removed or reduced.
Location is crucial: a tumour accessible from the brain's surface may present a very different surgical situation from one deep within or involving critical structures.
Radiation therapy
Radiotherapy may be used for some brain tumours, either independently or alongside other treatment.
Other oncological treatments
Chemotherapy and newer therapeutic approaches may be appropriate for particular tumour types, and veterinary neuro-oncology continues to develop.
Modern treatment therefore cannot accurately be reduced to one universal prognosis or treatment pathway.
Quality of life matters
A diagnosis does not always mean that treatment will be possible—or that treatment will be the kindest option.
But diagnosis still matters.
Knowing what is happening can help a family and their veterinary team understand:
Can this be treated?
What is the likely prognosis?
Can symptoms be controlled?
Is the animal comfortable?
What might happen next?
Would treatment meaningfully improve quality of life?
When might euthanasia become the kindest decision?
Sometimes diagnosis opens the door to treatment.
Sometimes it provides something equally important:
the information needed to prevent unnecessary suffering.
When should I seek veterinary help?
Seek prompt veterinary advice if your pet develops a new neurological abnormality—particularly if it is severe, recurring or worsening.
Signs such as seizures, collapse, circling, significant loss of balance, sudden behavioural or awareness changes, apparent blindness, inability to walk normally or rapidly progressive neurological deterioration warrant veterinary assessment.
If your animal is already receiving treatment but continues to deteriorate, tell your veterinary team clearly what has changed and ask:
“Does this deterioration change the working diagnosis or mean further investigation or specialist assessment is now needed?”
That is not diagnosing your own animal.
It is asking whether the available explanation still fits the evidence.
The Every Pet Deserves a Diagnosis message
You know what is normal for your animal.
You may not know why something has changed—and you shouldn't be expected to diagnose it yourself.
Your role is to notice, document and report the change.
The veterinary team's role is to assess, investigate and determine the appropriate diagnostic pathway.
Record unusual behaviour where possible. Keep videos of neurological episodes. Note when symptoms started and whether they are becoming more frequent or severe.
And when an animal continues to deteriorate despite treatment:
Ask why.
A symptom is not a diagnosis.
A treatment response is information.
Progressive deterioration deserves reassessment.
Every Pet Deserves a Diagnosis
Educational information only. This resource does not diagnose individual animals or replace examination and advice from a veterinary surgeon. Animals experiencing acute or severe neurological signs may require urgent veterinary care!
