Pancreatitis is a disorder of the pancreas wherein it fails to properly perform its roles as the producer of digestive enzymes. More specifically, the enzymes are still produced, but the pancreas loses its unique ability to handle them effectively and so they break down before they're delivered to the parts of the body where they're needed. Instead of digesting food, they break down the tissue in and around the pancreas itself.
Pancreatitis can have a number of causes, and is usually the result of several causes coalescing. Diets that are high in fat may lead to obesity, which is a major contributing factor to the development of the disease. In addition, certain medications used to treat other diseases may increase the risk that a dog will contract pancreatitis, including corticosteroids and azathioprine.
Though it's a fairly common disease among many dogs, especially the Miniature Schnauzer, pancreatitis is very infrequently seen in cats. That said, it usually manifests in dogs that are at least middle-aged, and especially in those that are overweight and get little exercise. Though it occurs frequently in both sexes, there is a slight leaning towards prominence in females. It's often difficult to diagnose the disease because the signs and symptoms tend to vary wildly, but in general, most dogs will appear to be suffering some type of pain, even though there's usually no apparent cause. In certain cases, dogs will become prone to frequent vomiting and depression might set in, causing the dog to isolate his or herself in one area and become opposed to any kind of physical activity or interaction. Often the appearance of such symptoms is very sudden and must be treated as an emergency if and when they do arise.
A dog that does end up diagnosed with pancreatitis will need to undergo various types of treatment. First and foremost, a fasting of all food should occur for 1-3 days as this seems to result in the pancreas either shutting down or significantly decreasing the production of the digestive enzymes that have become harmful to your pet. You might have the inclination to try and entice your dog to eat by offering him or her treats, but doing so in this case will only make the problem worse as piquing their appetite will stimulate the pancreas. During this time, your dog will remain on fluids to prevent dehydration and drugs to help manage the pain he or she is feeling. In general, a bout of pancreatitis can be managed by undergoing this type of "resetting" of the digestive system and after a day or two of observation, most dogs will be able to return home so long as they appear to be behaving and eating normally again. Certain changes in diet and exercise may have to be enacted though, in order to prevent future (and possibly more severe) outbreaks.