Canine insulinoma: symptoms, diagnosis, treatment and prognosis – Canine insulinoma is a neoplasm located close to or inside the dog’s pancreas. The pancreas is a secretory organ responsible for two main functions: exocrine gland and endocrine gland.
The exocrine portion of the pancreas produces digestive enzymes that allow the dog to process proteins, carbohydrates and fats. These enzymes enter the duodenal portion of the small intestine through a small duct where they interact with the food particles that come out of the stomach.
The endocrine portion of the pancreas is located in different groups of cells present within the pancreatic tissue known as Langerhans islets. These cells produce several hormones, the most important of which, for the purposes of the topic in question, is insulin.
insulin it can be defined as the “truck” that “transports” sugars, mainly glucose, from the bloodstream into the body’s cells where they are used as “fuel” which supplies energy to the body, especially to the brain.
When blood sugar levels rise, following a meal or in response to a stressful situation, insulin is released to supply the sugars present in the blood to the cells.
When Langerhans islets become cancerous, increase in number and also increase the hormonal levels that they produce, in particular the insulin levels of the dog. When the dog’s bloodstream receives an abnormally high amount of insulin, the available blood sugars are carried by the bloodstream into the cells causing a marked reduction in the dog’s blood sugar. This condition is known as hypoglycemia.
In response to hypoglycaemia, the dog’s body releases a quantity of hormones called catecholamines. These hormones attempt to counter hypoglycemia by mobilizing the sugars and sources of sugar available.
Canine insulinoma is almost always malignant and often metastatic.
The average age at which insulinoma can develop in dogs it is around 9 years old. The dogs most commonly affected are those of medium-large size.
Insulinoma dogs exhibit a variety of symptoms, including:
- Ataxia (lack of coordination)
- Mental dulling
- Visual changes
- Seizure crisis
These symptoms are the result of insulin-induced hypoglycaemia.
Formulating the diagnosis of insulinoma requires several elements.
The persistent presence of hypoglycaemia is highly suggestive. The evaluation of multiple blood samples (fasting and non-fasting) may be required.
A comparison of the insulin and glucose levels detected in the same blood sample may suggest the presence of insulinoma. In this case, insulin levels are higher than normal and glucose levels lower than normal.
For diagnostic purposes, the identification of a named value may be useful “Modified insulin-glucose ratio”. This test compares the amount of insulin present in the bloodstream compared to glucose levels. The outcome could reveal a “normal” insulin value and abnormally low glucose levels.
L’diagnostic imaging it cannot always be of help in the diagnosis of this neoplasm. Abdominal ultrasound of the pancreas is generally not useful because of the small size of these cancerous lesions. However, ultrasound examination is useful in evaluating other tissues for the presence of metastases.
There direct visualization of the pancreas during abdominal surgery, it is considered the most effective method for the diagnosis of insulinoma. During the operation, the surgeon provides a gentle palpation of the pancreas in search of any abnormal growths. To further facilitate visualization of the pancreas, a 1% solution of methylene blue mixed with saline is injected intravenously. Insulinoma cells will “absorb” the chemical compound while the surrounding tissues do not.
Canine insulinoma metastasize?
Yes, there is a high probability that insulinoma will extend to other body regions of the dog. The areas most affected by metastasis include:
- Regional lymph nodes
As metastatic tumors grow in size, they often interfere with the functionality of the surrounding structures and organs. For example, if the tumor develops close to or near the duodenum, it can lead to blockage of the flow of digestive enzymes from the pancreas and / or bile from the gallbladder. Both of these situations compromise the dog’s health.
Canine insulinoma be treatable?
Yes, this tumor is treatable.
In the early stages of the pathological process, it is important to treat hypoglycaemia by administering small meals during the course of the day in order to promote the stabilization of the dog’s blood sugar. Medicines, such as corticosteroids, can be used to increase blood sugar. Diazoxide can be used to inhibit insulin secretion.
In most cases, treatment will involve surgical removal of the insulinoma. It is of paramount importance to control hypoglycaemia during and after surgery. Since the surgeon needs to manipulate the pancreas, the dog will need to be monitored for a possible onset of acute pancreatitis. There pancreatitis can be fatal.
If hypoglycaemia persists even after surgery, the prognosis is not the best. This would indicate that a portion of the insulinoma is still present and the use of chemotherapy therapy.
There are several drugs that can be used to counteract these tumors and their possible metastasization. Streptozocin directly attacks beta cells, but can have toxic side effects.
The main objective of the treatment is to stabilize the dog’s blood sugar and avoid hypoglycaemia. If the dog experiences seizures due to hypoglycaemia that cannot be controlled by feeding and / or drugs, the use of a drug such as phenobarbital may be necessary.
In most cases the prognosis for dogs with insulinoma varies from reserved to poor. This tumor is almost always malignant and metastatic. The chances of survival vary from 6 to 24 months once the diagnosis is confirmed. Surgery, chemotherapy and diet can reduce the effects of increasing insulin and the consequent decrease in blood sugar.