October 16, 2014
From the Desk of Dr. Voorheis
Ok, enough about growing vegetables in water tanks and hiking long distance to fulfill a lifelong dream. It was fun sharing those things with all of you but we’ve got veterinary medicine to talk about! And today we will dive into a timely topic here at WBAH, pancreatitis.
The pancreas is a complex gland that performs many vital functions in both a human body and in the body of our furry critter friends. Anatomically, it lies next to the greater curvature of the stomach and the portion of the small intestine called the duodenum. It performs both exocrine and endocrine functions. Endocrine function means it makes hormones. Many of you are familiar with one of the hormones the pancreas makes which is Insulin. If the pancreas stops making insulin, you become a type 1 diabetic. Type 1 diabetics are dependent on daily insulin injections. This is true for humans and animals alike. The pancreas makes other hormones as well such as glucagon, somatostatin and pancreatic polypeptide. These hormones are secreted by specific cells scattered in the pancreas called islet cells. The endocrine function of the pancreas will be the subject of another blog because there is so much to say on that subject. This blog will be a bit more compact and concentrate on exocrine function. Endocrine and exocrine functions are intertwined and work in tandem with each other. The close association of endocrine and exocrine cells in the pancreas allows them to coordinate digestion and metabolism which is a good thing. But it also means the two are linked together when things go wrong.
The exocrine function of the pancreas is to secrete digestive enzymes and bicarbonate. These enzymes are produced by cells called the acini. The pancreas secretes all of the enzymes and enzyme precursors necessary for the digestion of proteins, fats, and carbohydrates. These are secreted as proenzymes and are converted to the active form once they reach the intestine. “Digestion” of the pancreas is prevented because these enzymes are secreted in the proenzyme form. Pancreatic lipase works to break down dietary triglycerides (fats) into substances that can be absorbed. Lipase needs bile salts in order to be activated. The bicarbonate is secreted because the digestive enzymes require an alkaline pH to work. Still with me?
Anatomically, the pancreas has ducts that serve to transport the digestive enzymes into the intestine. In the dog, there are usually two pancreatic ducts and in the cat there is usually one and it joins with the bile duct before entering the duodenum. In addition, the bile duct, transporting bile from the liver into the intestine, travels through the pancreas to reach the intestine. In the normal animal, pancreatic secretion is triggered by the thought of food and the stomach filling with food, and most importantly by the presence of fat and protein in the small intestinal lumen.
Pancreatitis is the inflammation of the pancreas. It can be defined as acute pancreatitis and chronic pancreatitis. Acute pancreatitis is recognized more often in dogs and chronic pancreatitis recognized more often in cats. Think of pancreatitis as the disease that occurs when digestive enzymes that are meant to be “dumped in” to the intestinal lumen, instead are activated within the pancreas itself. Pancreatitis affects far more organ systems than just the pancreas too. The gastro-intestinal tract is affected; heart and lungs can be affected, the liver can be affected, and in severe cases we can see activation of the coagulation cascade. In cats, pancreatitis is often associated with inflammatory bowel disease and cholangitis and cholangiohepatitis which are liver diseases. It can be seen with any breed of dog or cat. In the dog, Miniature Schnauzers, Miniature Poodles and Cocker Spaniels are over-represented. In cats, it is seen more often in DSH (domestic short-haired) and Siamese. In the dog, they present with primarily GI tract signs. (Vomiting, anorexia). In the cat, the signs are vague, and non-specific. A painful abdomen is common in dogs. Sometimes we appreciate a painful abdomen in cats, but not always. Cats will often present with weight loss. Since is more often an acute disease with dogs, weight loss is not a common complaint. With the advancement of tests specific to diagnose pancreatitis in both dogs and cats, the diagnosis is achieved readily. The treatment can be both straight forward and challenging.
So what causes pancreatitis? There are a number of causes. In the dog, it is often linked to ingestion of a high fat meal. However, it can be caused by pancreatic trauma, certain medications, pancreatic duct obstruction or high levels of blood calcium. In the cat, throw in certain infections such as toxoplasmosis, FIP and extensions of feline liver diseases and IBD (inflammatory bowel disease). There are sometimes when we diagnose pancreatitis and have no known reason or cause. By far the most common cause is feeding a high fat meal to a dog. Giving a dog the “table scraps” (the fat we don’t eat on our steak for example, or chicken skins) is often in the history of a dog with acute pancreatitis. Another reminder to not feed your dog table scraps.
We know we see a higher incidence of the disease in obese pets or in dogs that have concurrent disease such as Cushing’s disease or Diabetes Mellitus. As usual, dogs and cats don’t come in with a sign that says – my pancreas hurts, or better yet “I’ve got pancreatitis”. The symptoms they arrive with are identical to signs seen with a number of other disease conditions such as GI disease (gastritis, gastroenteritis, foreign body, gastric ulcers), liver diseases without jaundice, Addison’s disease, inflammatory kidney diseases, uterine infections, prostatitis and others. A careful history will eliminate some of these but xrays, laboratory work and ultrasound may be necessary to diagnose pancreatitis and eliminate these other diseases.
Pancreatitis in the dog is almost always managed in the hospital setting. These guys need aggressive IV fluid therapy and pain management. In addition, we use IV anti-emetic agents to help control the vomiting. Often these drugs are administered as a CRI (continuous rate infusion). We “rest” the pancreas. Not feeding the dogs for a 24 hour period of time. We will try to introduce safe foods as soon as possible. Depending on the severity of the disease, sometimes a J-tube is placed (a tube that by-passes the portion of the intestine the pancreas is adjacent too). Some of these animals need extended hospitalization, most do not. Many of these dogs are managed long term by dietary fat restriction.
Chronic pancreatitis is a far more challenging condition and is one that seems to affect our feline friends. Many of these cats have other associated conditions. These conditions need to be managed in order to manage the pancreatitis. Some, but not all, of these cats will respond to a low fat diet. Some, but not all, respond to the addition of pancreatic enzymes in their food. Some of these cats require potent anti-inflammatory medications to control both their pancreatitis and other associated conditions. These guys are treated on an individual basis, based on their specific needs. They are indeed a challenging group. It is not unusual for cats to also develop diabetes mellitus as a result of their chronic pancreatitis. I consider feline pancreatitis amongst the more challenging diseases I treat because of the difficulty and the chronic nature of the condition.
So much more can be said about Pancreatitis but I think this is a good place to stop so that I don’t send anyone into a state of crossed eyes and confusion.
Next blog in two weeks will be on Diabetes Mellitus. Until then…….