a difficult disease: pancreatic cancer in pets
The pancreas is a delicate, small organ with a super huge job. Not only does it produce insulin, which keeps our blood glucose levels stable, but it produces a number of other hormones and digestive enzymes that help our small intestines absorb nutrients and digest food.
Luckily, pancreatic cancer is rare in pets. But when it strikes, it is devastating. Of the pancreatic cancers that affect our pets, pancreatic adenocarcinoma, insulinomas, and gastrinomas are the three most common.
Causes of pancreatic cancer in pets
Pancreatic adenocarcinomas usually arise from the pancreatic duct system. These tumors cause necrosis and inflammation, which leads to more local inflammation of the pancreas. In turn, this leads to signs of pancreatitis. Clinical signs of pancreatic adenocarcinoma are vague and non-specific. They include weight loss, loss of appetite, fever, lethargy, abdominal pain and distention, and vomiting and diarrhea. A host of other illnesses can cause similar signs, so extensive testing will likely be required for a definitive diagnosis.
Gastrinomas are pancreatic tumors that produce excess gastrin, a hormone responsible for stimulating the cells of the stomach to produce gastric acid. Increased levels of gastric acid can cause gastrointestinal ulceration and perforation. Clinical signs are related to high gastric acid levels and gastrointestinal ulceration and include bloody vomit, bloody stool, pale gums, decreased appetite, and weight loss.
Insulinomas are pancreatic tumors that produce excess insulin, causing dangerous drops in blood sugar. Clinical signs relate to hypoglycemia but can also extend to some behavioral changes. Shaking, muscle tremors, weakness, collapse, and seizures can all occur.
Luckily all of these cancers are rare in dogs and very rare in cats. But unluckily for those diagnosed, treatment options are quite limited. Add in to the mix that by the time these cancers are diagnosed, 80% of cases have already metastasized to other organs and we get a very bleak prognosis.
But we are not without hope – there are some options for treatment. Surgery can be pursued if the tumor is localized, though it is often difficult to remove all cancerous cells. Because of the delicate nature of the pancreas, surgery has a tendency to promote pancreatitis due to the mere handling of the organ, so post-operative pancreatitis is common.
Adenocarcinomas are generally unresponsive to chemotherapy and radiation, so these are not usually pursued. Pancreatic adenocarcinomas carry a very poor to grave prognosis for this reason, and pets will often succumb within weeks of diagnosis.
Patients with gastrinomas will benefit from some medications in addition to surgical removal of the tumor. H2 blockers (like Pepcid or Zantac), intravenous fluids, and gastroprotectants aim to minimize the clinical signs, and survival times range from one week to eighteen months post-surgery.
Insulinomas in dogs are rarely benign, whereas in humans, up to 90% of cases are. In dogs (and very rarely cats), treatment of malignant insulinomas requires surgery, medical management, or dietary management, and some cases require a combination of two or more treatment modalities. A recent study showed a median survival time in dogs of about two years when treated with surgery versus a little over six months when treated with medical therapy alone.
Again, we are lucky that malignant pancreatic tumors are rare in our pets. If your pet has been diagnosed with pancreatic cancer, you and your veterinarian will come up with a treatment plan that is right for your pet and your family. In some cases, that might be aggressive treatment and in other cases, humane euthanasia might be best. An open dialogue with your veterinarian is key to finding the right answer for your family, and of course, having pet insurance will allow you forget about the potential costs of treatment and to make whatever decision is right for you.