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Dog Oncology & Endocrine · Vet-Reviewed Guide

Insulinoma in Dogs: The Tumor That Causes Low Blood Sugar

DB
Medically reviewed by Dr. Daniela Betz
Reviewed 8 September 2026

Insulinoma is a rare but important tumor that does the opposite of diabetes, it floods the body with insulin and crashes blood sugar. Because the signs look neurological, it's often misread until someone connects the dots.

Insulinoma is a tumor of the pancreas that overproduces insulin, causing dangerously low blood sugar in dogs. Signs include weakness, wobbliness, disorientation, collapse, and seizures, often after fasting or exercise, and they can be mistaken for a neurological problem. It's diagnosed by your veterinary team and sits at the intersection of endocrine disease and cancer, with treatment directed by your vet and often an oncologist.

About Palladia (toceranib): this is a prescription medication your veterinarian can prescribe. Read our guide, or ask us if you need help sourcing it.

What insulinoma is and does

It is a tumor of the insulin-making cells in the pancreas. Diabetes is too little insulin. Insulinoma is the reverse: too much. That extra insulin drives blood sugar dangerously low. The low blood sugar causes the symptoms. That is why the signs come and go. Fasting or exercise often triggers them. [1]

The signs (and why they're misread)

Signs include weakness, unsteadiness, and disorientation. A dog may seem glazed or vacant, collapse, or have seizures. These often follow a period without food, or exercise. These signs look neurological. So insulinoma is often mistaken for epilepsy or a brain problem at first. The clue is checking blood sugar during an episode. [2]

Diagnosis and expectations

To diagnose it, a vet documents low blood sugar with high insulin. Imaging then helps find the tumor. Insulinoma is both an endocrine disease and a cancer. So a veterinary oncologist is often involved. Treatment may combine diet strategies to steady blood sugar with other care. Your team sets the plan for your dog.

Where a pharmacy fits

Diagnosis and treatment are directed entirely by your treating veterinarian and oncologist. If they prescribe a medication we carry as part of the plan, we can supply it in collaboration with your team. We never diagnose or set doses.

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Frequently asked questions about insulinoma in dogs

What are the signs of insulinoma in dogs?

Weakness, wobbliness, disorientation, collapse, or seizures, often after fasting or exercise, from low blood sugar.

Is insulinoma the same as diabetes?

It's the opposite, insulinoma makes too much insulin (low blood sugar), while diabetes involves too little (high blood sugar).

Who treats insulinoma?

Your veterinary team, often with an oncologist, since it's both an endocrine and a cancer condition.

Veterinary review. This guide was reviewed for clinical accuracy by Dr. Daniela Betz. Guidance is clinician-governed; we never state a dose.

Related endocrine conditions

Cushing’s disease in dogs · Cushing’s symptoms · Cushing’s life expectancy · Addison’s disease · Hypothyroidism · Diabetes symptoms

Sources & References

  1. Merck Veterinary Manual — Endocrine system
  2. PubMed — canine insulinoma