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Insulinoma in Dogs

What Is Insulinoma in Dogs?

Insulinoma in dogs refers to a pancreatic tumor that tends to be malignant and has typically spread by the time it’s identified. This tumor comprises cells that generate excessive insulin, leading to hypoglycemia or low blood sugar levels.

Normally, when a dog eats, insulin is released to facilitate the breakdown of sugar (glucose) in food. As blood sugar levels drop, the brain signals the pancreas to halt insulin production through hormonal cues. However, in insulinoma, the abnormal cells forming the tumor don’t respond to these hormonal signals. Consequently, they persist in producing insulin, resulting in dangerously low blood sugar levels.


Symptoms of insulinoma in dogs primarily manifest as hypoglycemia, characterized by abnormally low blood sugar levels, typically below 40, whereas normal levels range between 80 and 120.

Clinical indications of low blood sugar include:

  • Marked lethargy or decreased energy levels
  • Unsteadiness or a wobbly gait
  • Episodes of collapsing
  • Seizures
  • Paleness of the gums
  • Nausea


The causes of insulinoma in dogs remain unidentified. This condition is most commonly observed in middle-aged and older dogs of larger breeds. While it’s rare, insulinomas can also occur in younger dogs.


To diagnose insulinoma, veterinarians employ a comprehensive approach. Initially, they conduct a thorough physical examination to identify clinical signs, though this alone may not provide a definitive diagnosis.

Subsequently, a blood diagnostic panel is conducted to investigate the underlying causes of the observed clinical signs, with low blood sugar serving as a crucial indicator. If blood glucose levels are below 60, the veterinarian proceeds to measure insulin levels. Elevated insulin concentration coupled with low blood sugar confirms the presence of insulinoma. Another blood test, the insulin to glucose ratio, may also be conducted to corroborate the diagnosis.

Further diagnostic procedures may involve ultrasound and CT scans, which utilize sound waves and x-ray images, respectively, to visualize internal organs and locate the tumor. While CT scans are more effective, both ultrasound and CT scans are valuable for examining surrounding lymph nodes and the liver for signs of metastasis.

Histopathology, involving the analysis of tissue cell samples, is considered the definitive method for diagnosing insulinoma. Samples from lymph nodes, the liver, and the spleen are assessed for signs of cancer spread. Radiographs of the chest and abdomen are also utilized to detect metastasis, such as lung lesions.

Stages of Insulinoma in Dogs

Insulinoma in dogs often involves malignancy, where cancer cells have already spread to other parts of the body. This occurrence is prevalent, affecting over half of canine patients at the time of diagnosis.

The stages of insulinoma in dogs are as follows:

  • Stage I: In Stage I insulinoma, the cancer remains localized within the pancreas. There is no evidence of cancer in other organs or lymph nodes.
  • Stage II: Stage II insulinoma indicates some infiltration of cancer cells into surrounding tissues, typically observed in a lymph node within the vicinity.
  • Stage III: Stage III insulinoma signifies that the cancer has spread to adjacent organs and lymph nodes.


The primary treatment for insulinoma in dogs is surgical removal of the tumor, considered the most effective approach. This procedure eliminates the cells responsible for clinical symptoms and enhances the chances of survival. Even in cases of Stage III insulinoma, surgery is recommended to improve the dog’s quality of life.

Prognosis of Insulinoma in Dogs

The prognosis of insulinoma in dogs is heavily influenced by the extent of metastasis present at the time of diagnosis and the type of treatment administered. Surgical intervention combined with additional medical therapy offers the most extended survival period. In Stage I and Stage II cases, this can extend up to 1.5 years. However, Stage III cases typically have a survival time of around 6 months.

Living and Management

Recovery and management of insulinoma in dogs involve a comprehensive approach aimed at ensuring the dog’s comfort and well-being. While medical management doesn’t offer a cure, it focuses on maintaining normal blood glucose levels and slowing tumor growth through medication, supplements, and dietary adjustments.

Medications that either raise blood glucose levels or decrease insulin production are commonly utilized. Prednisone, for instance, is frequently prescribed to inhibit insulin release while promoting glucose production in the liver. Diazoxide and octreotide are other medications available to help regulate blood glucose levels effectively.

Supplements like Nutri-Cal and Karo syrup are recommended for managing hypoglycemia episodes, providing a rapid increase in blood glucose levels during crises. They may also be administered preventively by giving small doses throughout the day.

Diet plays a crucial role in medical treatment. Feeding the dog multiple small meals throughout the day helps prevent spikes in glucose intake, thereby reducing insulin production. Prescription diets for diabetic dogs typically include foods with complex carbohydrates to minimize postprandial glucose spikes. Examples of recommended prescription diet foods are Purina Pro Plan Veterinary Diets EN Gastroenteric Fiber Balance and Royal Canin Veterinary Diet Adult Glycobalance.

Insulinoma in Dogs FAQs

Can insulinoma be cured in dogs?

Insulinomas are highly malignant and cannot be completely cured. The most effective approach involves surgical removal of the tumor followed by ongoing medical management. This combination offers the best outcomes both qualitatively and quantitatively. Medical management should be continued for the dog’s lifetime post-tumor removal.

What if I cannot afford surgical treatment?

If surgery is not feasible, the primary aim is to ensure the highest quality of life for your pet. Adjustments in diet along with medications can help maintain optimal blood glucose levels, thereby alleviating clinical symptoms. While life expectancy may be shortened without surgery, it’s still possible to provide a good quality of life for your dog.

Are there other causes for hypoglycemia?

Yes, hypoglycemia can stem from various other diseases. These may include, but are not limited to, hypoadrenocorticism, other pancreatic cancers, certain liver disorders, and severe infections. Additionally, insufficient nutrition, particularly in small breeds, can also lead to hypoglycemia.

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