Pancreatitis and Other Disorders of the Pancreas in Dogs
The pancreas is an organ that has 2 main functions: endocrine and exocrine. The endocrine pancreas produces the hormones insulin and glucagon, which regulate blood sugar levels. The exocrine pancreas produces enzymes that are essential for the digestion of complex dietary components such as proteins, triglycerides, and complex carbohydrates. The exocrine pancreas also secretes large amounts of bicarbonate, which buffers stomach acid.
Disorders of the exocrine pancreas are discussed here, because they relate to digestion. Endocrine functions of the pancreas are discussed in the Hormonal Disorders chapter.
Pancreatitis is the most common exocrine pancreatic disease in both dogs and cats. It can be short- or longterm, depending on whether or not the disease has permanently damaged the pancreatic tissue. Both forms can be severe.
For most cases of pancreatitis no specific cause can be identified. However, eating trash, large amounts of table scraps, or other inappropriate food is believed to be a common risk factor in dogs. Severe trauma or surgery can lead to pancreatitis. Use of some drugs may also be linked to pancreatitis.
In the initial stages of disease, the secretion of pancreatic juice decreases. This is followed by a series of steps that lead to activation of pancreatic enzymes inside the pancreas, rather than in the intestinal tract. The enzymes begin to digest the pancreas itself, causing damage within the pancreas and triggering inflammation, which leads to damage in other parts of the body. Loss of appetite, vomiting, weakness, abdominal pain, dehydration, and diarrhea are the most common signs reported in dogs with severe pancreatitis.
A thorough history (including any dietary indiscretions) combined with vomiting and abdominal pain may suggest a diagnosis of pancreatitis. Blood tests may be used by your veterinarian to confirm the diagnosis, along with abdominal x‑rays, ultrasound, or exploratory surgery, if needed.
Treatment for pancreatitis includes careful monitoring and supportive veterinary care. Hospitalization may be required. Early intervention will help prevent complications. If the cause is known, specific treatment may be started. Resting the pancreas by restricting all food or water by mouth for 3 to 4 days is recommended when the dog is vomiting. Severely ill dogs are given intravenous fluids. Pain medication is usually given because the animal is assumed to have abdominal pain.
In mild cases of pancreatitis, dogs will usually be switched to a low-fat diet and low-fat treats. Pancreatic enzyme supplementation may help in cases when abdominal pain is present or for animals with consistently poor appetites, which may be the only indicator of abdominal pain. Patients with mild, longterm pancreatitis should be monitored for potential complications, such as exocrine pancreatic insufficiency (see Pancreatitis and Other Disorders of the Pancreas in Dogs : Exocrine Pancreatic Insufficiency) and diabetes mellitus.
The outlook in mild cases is good, but the outlook in severe cases of pancreatitis is poor. About half of dogs with severe pancreatitis may die.
Exocrine pancreatic insufficiency is a syndrome caused by insufficient production and secretion of digestive enzymes by the pancreas. Deterioration of the structures that produce pancreatic enzymes is the most common cause of this syndrome in dogs. This can either be due to the slow decline of cells that produce the enzymes in German Shepherds or due to destruction resulting from longterm pancreatic inflammation in other breeds. Less common causes are tumors that lead to obstruction of the pancreatic duct. German Shepherds with exocrine pancreatic insufficiency are usually young adult dogs, while dogs with exocrine pancreatic insufficiency due to other causes are usually middle-aged to older and can be of any breed.
Pancreatic enzymes play a critical role in the assimilation of all major dietary components, and a lack of pancreatic digestive enzymes leads to problems with digestion and to malabsorption (see Disorders of the Stomach and Intestines in Dogs : Malabsorption). The lack of nutrients also causes weight loss and may lead to vitamin deficiencies. Animals with exocrine pancreatic insufficiency caused by longterm pancreatitis may develop diabetes mellitus.
Signs most commonly reported are excessive eating, weight loss, and diarrhea. Vomiting and loss of appetite are sometimes seen, but these may be a sign of a concurrent condition. The feces are most commonly pale, loose, and voluminous and may be foul-smelling. In rare cases, watery diarrhea may be seen. Diagnosis can be made using a blood test that indicates a decrease in the functional capacity of the exocrine pancreas.
Most dogs with exocrine pancreatic insufficiency can be successfully treated by supplementing each meal with pancreatic enzymes (powdered or from fresh tissue). Follow your veterinarian’s directions for this dietary supplement carefully. Avoid providing too much or too little and follow the schedule prescribed. Be sure to report any bleeding from the mouth to your veterinarian. This adverse effect can often be eliminated by lowering the enzyme dose. When signs have improved, it may be possible to gradually decrease the dose.
If enzyme supplementation alone does not resolve the condition, vitamin B12 (cobalamin) deficiency may be a possible cause. Cobalamin deficiency is seen in about half of dogs with exocrine pancreatic insufficiency. Dogs with vitamin B12 deficiency can be given this vitamin by injection. Other vitamin deficiencies have also been reported.
Most dogs can continue eating their normal food, but a highly digestible, low‑fiber, moderate-fat diet can be useful in those that do not respond satisfactorily to treatment. It is important to avoid radical changes in diet, however.
In most cases, exocrine pancreatic insufficiency is the result of an irreversible loss of pancreatic tissue, and a cure is rare. However, with appropriate enzyme supplementation and monitoring, dogs with this disorder usually gain weight quickly, pass normal stools, and can live a normal life.
Cancers of the exocrine pancreas can be either benign or malignant. Pancreatic adenomas are benign (nonspreading) tumors. Pancreatic adenocarcinomas are the most common malignant tumor of the exocrine pancreas in dogs. A few other types of cancer have also been reported in the pancreas.
A diagnosis may be made based on a combination of blood tests, x-rays, biopsy, or exploratory surgery as appropriate.
Benign tumors of the pancreas can lead to the displacement of organs in the abdominal cavity. However, these changes cause no signs in most cases. In rare cases, the tumor can obstruct the pancreatic duct and cause deterioration of the remaining exocrine pancreas, leading to exocrine pancreatic insufficiency (see Pancreatitis and Other Disorders of the Pancreas in Dogs : Exocrine Pancreatic Insufficiency).
Pancreatic adenomas are benign and theoretically do not require any treatment unless they cause signs. However, because the tumors are often found during surgery and the appearance of both benign and malignant tumors is similar, removal of the affected pancreatic tissue is usually recommended. The outlook in these cases is excellent.
Adenocarcinomas may lead to death of part of the cancerous tissue if the tumor outgrows its blood supply. This causes local inflammation, which can lead to signs of pancreatitis. Malignant tumors may also spread to neighboring or distant organs.
Many dogs show no signs until late in the disease. Some dogs have signs that suggest inflammation of the pancreas. Jaundice may be seen if bile duct obstruction develops. Signs related to spread— such as lameness, bone pain, or difficulty breathing—have also been reported in some cases of pancreatic adenocarcinoma.
Pancreatic adenocarcinomas are usually not detected until the disease is advanced and the cancer has already spread. In those few cases when it appears the cancer has not yet spread, your veterinarian may attempt surgical removal. However, it is difficult to completely remove such tumors and surgery is often unsuccessful. Both chemotherapy and radiation treatment have shown little success in human or veterinary patients with pancreatic adenocarcinomas. Thus, the outlook for dogs with pancreatic adenocarcinoma is grave.
A pancreatic abscess is a collection of pus, usually near the pancreas, which is considered a complication of pancreatitis (see Pancreatitis and Other Disorders of the Pancreas in Dogs : Inflammation of the Pancreas (Pancreatitis)). Signs may include vomiting, depression, abdominal pain, loss of appetite, fever, diarrhea, and dehydration. In some animals, a mass in the abdomen can be felt. Dogs may respond favorably to surgical drainage of the abscess. However, the risks and expense of surgery may outweigh the benefit, unless there is clear evidence of an enlarging mass or bacterial infection. Your veterinarian will make a surgical recommendation based on your dog’s specific condition, overall health, and related considerations.
A pancreatic pseudocyst is a collection of sterile pancreatic fluid enclosed by a wall of tissue. Signs are similar to those of pancreatitis. Vomiting is the most consistent sign. The cysts can be seen by using ultrasound. Use of a long needle to draw fluid from the cyst can provide fluid for analysis and diagnosis. Drawing fluid is also a method of treating such cysts. Surgery may be needed if the dog has signs that persist or if the pseudocyst does not decrease in size.