By Dr Duncan Houston
Insulinoma is a tumor of the insulin-producing cells in the pancreas. It releases insulin when blood sugar is already low, potentially depriving the brain of the energy it needs.
The condition is uncommon in dogs and very rare in cats. Episodes of weakness or unusual behavior deserve investigation, even when a pet seems normal afterward. Most treatment research concerns dogs, so a cat's care should not simply follow a canine protocol.
Quick Answer
Insulinoma can cause low blood sugar, called hypoglycemia, leading to wobbliness, confusion, collapse or seizures. Collapse, seizures or impaired awareness require immediate veterinary contact and emergency assessment. Diagnosis combines blood glucose and insulin measurements with other investigations; surgery and medical care are chosen according to the pet's condition and the tumor's extent.
What insulinoma means in dogs and cats
These tumors have the potential to spread, particularly to lymph nodes and the liver. They should be treated as potentially malignant, even if imaging finds only a small pancreatic mass. Dogs are usually diagnosed in middle or older age. Feline cases are too uncommon to assume the same treatment response or survival as dogs. The MSD Veterinary Manual's insulinoma guidance explains these species differences.
Recognizing signs and choosing the right urgency
Signs may include trembling, hindleg weakness, staggering, unusual dullness, collapse or seizures. Episodes can occur around activity or missed meals, but their timing varies. Looking well between episodes does not rule out a serious problem.
| What you notice | What it may mean | Action and timing |
|---|---|---|
| Seizure, collapse, inability to stand or reduced awareness | Dangerous hypoglycemia or another emergency | Call an emergency vet immediately; arrange safe transport as directed. |
| Brief weakness or wobbliness followed by apparent recovery | An intermittent blood sugar problem or another illness | Contact your vet today. Recurrent or persistent signs need immediate advice. |
| A diagnosed pet is comfortable and behaving normally | Current control may be adequate, but recurrence remains possible | Continue the prescribed plan and scheduled monitoring; report any new episode promptly. |
Emergency: what to do during a suspected blood sugar crisis
Call the emergency clinic immediately if your pet collapses, has a seizure or cannot respond normally. Tell them about any known insulinoma, diabetes medication or possible toxin exposure.
- During a seizure, clear nearby hazards, keep the surroundings quiet and time the episode. Do not restrain your pet or put your fingers near their mouth.
- Do not force food, water, syrup or oral medicine into a seizing, unconscious or poorly responsive pet. They may choke or bite involuntarily.
- If your pet is fully alert and swallowing normally, follow their veterinarian's written rescue instructions or the emergency clinic's live advice. Do not improvise a sugar dose.
- Ask the clinic how to move your pet safely. Improvement after food or prescribed rescue treatment does not remove the need for assessment.
PDSA's seizure first aid guidance supports protecting pets from injury and keeping away from their mouths.
How vets investigate insulinoma
A vet checks glucose and, where possible, measures insulin in a sample collected at the same time as confirmed hypoglycemia. Insulin should fall when glucose is low, so even a result inside the laboratory's normal range can be inappropriate. One normal glucose reading between episodes does not exclude insulinoma.
Do not withhold food at home to provoke an episode or improve a test result. Ask for specific feeding instructions before appointments. Any testing that risks hypoglycemia needs veterinary supervision.
Other causes include severe liver disease, infection, some other tumors and excessive insulin medication. Addison's disease is another consideration in dogs. Sample-handling problems can also produce misleading glucose results. Weakness and seizures have additional neurological or cardiac explanations, so symptoms alone cannot identify the tumor.
Ultrasound can miss small insulinomas. In dogs, contrast CT can help locate a tumor and investigate spread; a negative scan cannot settle every case. Tissue examination can confirm the tumor type. The review of canine insulinoma diagnosis and treatment explains the limitations of blood tests and imaging.
Treatment and recovery
Severe hypoglycemia needs stabilization before longer-term decisions. Hospital care may include carefully monitored glucose treatment and seizure control.
Surgery: Removing the affected part of the pancreas may offer the best chance of sustained control in a suitable patient. The surgeon also assesses possible spread. Surgery does not guarantee cure. Afterward, monitoring looks for persistent low glucose, high glucose or diabetes, and pancreatitis. Vomiting, abdominal pain, poor appetite or renewed weakness require prompt contact with the surgical team. The American College of Veterinary Surgeons' insulinoma guidance describes these options and complications.
Medical care: A tailored feeding and activity plan may be combined with medicines such as a glucocorticoid or diazoxide. These may be needed before surgery, after recurrence or when surgery is unsuitable. Meal frequency, drug choice and monitoring must suit the individual animal. Feline decisions require particular care because published evidence is limited.
Selected anticancer treatments may be discussed with an oncologist, especially for dogs with progressive disease. Evidence and adverse effects vary; there is no universally effective chemotherapy regimen for dogs and cats.
Outlook and quality of life
For dogs, staging describes disease confined to the pancreas, spread to nearby lymph nodes, or distant spread. Extent of disease, glucose control and other illnesses influence the outlook.
A multicenter study of 116 dogs with insulinoma found surgery was associated with longer survival, while metastasis was associated with a poorer outcome. This retrospective comparison cannot predict an individual pet's lifespan, and its results should not be applied to cats.
Discuss comfort, appetite, enjoyable activity, episode frequency and the burden of treatment. If crises become difficult to control, your vet can help reassess treatment or plan palliative care.
Your practical care plan
- Keep a record of episodes, meals, medicines and activity. Take a video only when it is safe and does not delay help.
- Ask for a written feeding, medication and emergency plan, including what to do if your pet refuses food or vomits.
- Keep emergency contact details accessible and ensure everyone caring for your pet understands the plan.
- Attend agreed glucose checks and other follow-up appointments. Discuss changes before adjusting medicines, exercise or food.
Common mistakes and prevention
Avoid prolonged fasting, strenuous activity against veterinary advice, routine sugary treats as treatment, and copying another animal's medicines. Do not give insulin to treat insulinoma; it can lower glucose further. Never assume apparent recovery means the underlying problem has resolved.
There is no established way to prevent this tumor. A suitable complete diet, regular veterinary care and early reporting of changes support general health; they cannot guarantee prevention. Once diagnosed, consistent care aims to reduce hypoglycemic episodes and preserve comfort.
Frequently Asked Questions
Can cats get insulinoma?
Yes, but it is very rare. A specialist may help confirm the diagnosis and adapt treatment without assuming canine outcomes apply.
Can normal blood tests rule out insulinoma?
A single normal glucose result may miss intermittent hypoglycemia. Your vet decides whether repeat or paired glucose and insulin testing is needed.
Should I fast my pet before an insulinoma appointment?
Ask the clinic first. Do not deliberately miss meals to trigger low blood sugar; the team must plan any necessary fasting safely.
Is insulinoma curable with surgery?
Surgery can improve control, but residual disease, spread or recurrence may require further treatment. Ask about your pet's findings rather than relying on a fixed survival estimate.
A clear diagnosis and a plan that everyone at home understands can make this condition more manageable. Work with your veterinary team to balance glucose control, treatment choices and your pet's daily comfort.
For help understanding the next questions to ask about your pet's care, ASK A VET™ offers supportive information. Suspected hypoglycemic emergencies need immediate hands-on veterinary care.
The ASK A VET™ Tracker logs live location and activity trends, so a change in routine never goes unnoticed.
Every ASK A VET article is written and reviewed by qualified veterinarians.
