Insulinoma in Dogs: Low Blood Sugar, Warning Signs and Treatment
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By Dr Duncan Houston
A dog who becomes wobbly after exercise and then seems better after eating still needs assessment. Temporary improvement does not explain why blood glucose fell, and another episode can be more serious.
Insulinoma is one possible cause of recurrent low blood glucose. It is different from diabetes and requires a carefully planned approach.
Quick Answer
An insulinoma is a pancreatic tumour that releases insulin inappropriately, causing blood glucose to fall. Signs can include weakness, trembling, confusion, seizures and collapse, sometimes after fasting or activity. Collapse or seizures require emergency care; diagnosed dogs need a vet-directed feeding schedule, medication plan and clear instructions for a low-glucose episode.
Why does low glucose cause these signs?
The brain relies on a steady energy supply. Excess insulin moves glucose out of the bloodstream even when levels are already low. Episodes can be intermittent, so a dog may look normal between them. Canine insulinomas can spread, but the extent of disease and its behaviour vary.
How do vets establish the diagnosis?
Blood glucose and insulin are assessed together. Insulin should be suppressed when glucose is low; a result within the laboratory's normal range can still be inappropriately high in that situation. A single insulin measurement without the paired glucose does not establish insulinoma.
The Merck Veterinary Manual explains this diagnostic relationship. Ultrasound or CT helps identify pancreatic lesions and possible spread, but a small tumour may be difficult to see. Surgical tissue examination can provide definitive confirmation.
What else can cause low blood glucose?
Too much injected insulin, xylitol poisoning, severe infection, liver disease, some other tumours and poor reserves in very young animals are important alternatives. Fainting or neurological disease can resemble a low-glucose episode. Do not deliberately fast a dog at home to reproduce signs.
How urgent is it?
| Signs | Action |
|---|---|
| Brief weakness that has resolved | Contact a vet today and describe the episode. |
| Trembling, wobbliness or confusion | Seek urgent veterinary advice; follow the established rescue plan if there is one. |
| Seizure, unconsciousness or collapse | Attend an emergency clinic immediately. |
When is this an emergency?
Seizures or collapse need immediate treatment even if the dog improves temporarily. Do not force food, drink or syrup into an unconscious or convulsing dog's mouth. Keep hands away from the teeth and call the clinic for first-aid instructions while arranging transport. If a vet has prescribed a sugar-based rescue plan, follow its exact instructions; this is a temporary measure, not definitive care.
What treatment is available?
Surgery may remove the pancreatic tumour and assess nearby tissues. Medical management uses diet and medicines, such as those that reduce insulin effects or support glucose production. The American College of Veterinary Surgeons outlines medical and surgical options.
Small, regular meals and avoiding prolonged fasting are commonly part of care. Meal composition, activity and medicines must suit the individual. Repeated sugary snacks are not a balanced long-term solution. Recurrence can occur after surgery, so follow-up remains important.
Your home plan
- Keep meal and medication times consistent, including arrangements for work or travel.
- Ask what to do if a meal is missed, vomiting occurs or appetite drops.
- Use controlled activity rather than strenuous exercise until advised otherwise.
- Record episodes, recovery and any glucose readings obtained under veterinary guidance.
- Keep emergency contacts and written rescue instructions accessible to everyone caring for the dog.
Common mistakes and prevention
- Waiting because a dog improves after food.
- Fasting at home for a test without instructions.
- Changing steroid or other medication doses independently.
- Assuming one normal scan rules out a small tumour.
There is no established way to prevent insulinoma. Preventing avoidable glucose crises through consistent care is the practical goal.
Frequently asked questions
Is insulinoma the same as diabetes?
No. Insulinoma produces excess insulin and low glucose; diabetes generally involves inadequate insulin action and high glucose.
Can surgery cure it?
Surgery can improve control, but recurrence or spread is possible. Staging and follow-up guide the outlook.
Can a normal insulin result exclude it?
No. The result must be interpreted alongside glucose measured at the same time.
The most useful protection is a clear plan for meals, medicines and emergencies, supported by regular reassessment.
Explore ASK A VET™ for information to help understand your dog's treatment. Seizures and collapse need emergency care.
