It was maybe 10 years ago I was on the telephone with a veterinary specialist updating me about a very sick cat I had referred. “She’s doing a little better,” the specialist reported. “Still not eating much but at least the vomiting has stopped.” She paused. “You know, these triaditis cases can go either way.”
Luckily the fancy veterinarian on the other end of the line couldn’t see the mystified expression on my face. Triaditis? What was triaditis? In 20 years of practice I had never heard of it. The older I get, the less I know, and I have no problem acknowledging when I am clueless… but this time I opted for listening quietly, while making a mental note to look it up later.
Triaditis. A cool word that literally means “inflammation of three.” Three what? Well, in people it refers to inflammation at a specific area of the liver called the “portal triad” which contains three structures — the proper hepatic artery, hepatic portal vein, and bile ducts. But we’re talking about feline triaditis. The term first came into use in veterinary medicine some time in the late 1990s to describe a condition in cats involving concurrent inflammation of the pancreas, biliary system in the liver, and small intestines. Learning that the name was coined long after I graduated from vet school made me happy: I had not in fact slept through a complete series of lectures about an entire disease.
Triaditis is not so much one disease as an acknowledgment of a cat’s unique anatomy. Unlike dogs, in cats the duct from the pancreas and the common bile duct from the liver join together, then empty into the intestines. Thus the three systems are intimately connected and prone to simultaneous inflammation. Say, for example, there are some bad bacteria in the intestines. Say some of that bacteria back into that combined duct. From there it can then travel to both pancreas and liver. The result may be an inflamed pancreas (pancreatitis), inflamed biliary system in the liver (cholangitis or cholangiohepatitis), and inflamed intestines (inflammatory bowel disease.) Voila. Triaditis.
Bacterial infection is just one of the proposed initiating causes but is actually relatively uncommon. Other underlying etiologies might include dietary, viral, allergic, or autoimmune. More often than not, we can’t determine exactly what starts the problem and the clinical signs vary widely, depending on which systems are most severely affected Let’s discuss each aspect individually.
Pancreatitis.The pancreas has two main jobs — it excretes enzymes for digesting food, and it dispenses insulin for regulating blood sugar. When the pancreas gets inflamed, dogs almost always show abdominal pain and vomiting, but kitties don’t. In cats, symptoms are variable, vague, and nonspecific. Signs may include loss of appetite, vomiting, lethargy, fever or abnormally low body temperature, abdominal pain, rapid breathing, or diarrhea. But some cats with pancreatitis don’t show any clinical signs. Radiographs and blood tests may support a diagnosis of pancreatitis, but they may also be normal. Ultrasound can be helpful, but depends a lot on the skill of the person doing the imaging. Treatment is primarily supportive care tailored to the individual cat’s specific presentation. It may include intravenous or subcutaneous fluid, good nutrition (using surgically implanted feeding tube if necessary), pain medication, anti-vomiting drugs, antacids, antibiotics, and/or vitamin injections.
Next we have cholangitis (inflammation of the bile ducts) or cholangiohepatitis (inflammation of the bile ducts and liver.) These are most commonly caused either by bacterial infection or immune-mediated disease. Symptoms may include loss of appetite, vomiting, diarrhea, dehydration, abdominal pain, enlarged liver, fluid in the abdomen, jaundice, and, rarely, fever. Blood tests are often helpful in diagnosis but definitive diagnosis usually requires biopsy. Treatment depends on the cause, and may include antibiotics, steroids, and medications to stimulate bile flow. Supportive care may include fluids and nutritional supplementation. Occasionally surgery is indicated for bile duct obstruction.
Finally we have inflammatory bowel disease (IBD), a condition in which the lining of the gastrointestinal tract becomes irritated and thickened, compromising normal function. Symptoms may include vomiting and diarrhea (sometimes with mucous or blood). Officially the diagnosis of IBD is used to describe a condition in which no specific cause can be found. Diseases such as food allergy, bacterial infection, or intestinal parasites must be ruled out. Definitive diagnosis requires tissue biopsies from several areas of the intestines. In some cases of IBD, just changing to special hypoallergenic diets, using either “novel” or hydrolyzed proteins that do not stimulate the immune system, may alleviate the vomiting and/or diarrhea, but most cases require medication to suppress the inflammation. In the worst cases, chemotherapeutic drugs may be needed to control the problem.
As you can see, pancreatitis, cholangiohepatitis, and IBD can present with similar symptoms. Does kitty have one, two, or all three problems? Definitive diagnosis relies on multiple organ biopsies, something we rarely get to do. There is still controversy in the veterinary community about whether triaditis is “real.” Studies where biopsies (or postmortems) are done suggest that many different disease processes are occurring in cats, and then being lumped together as triaditis. Despite many studies and statistics looking at the links between inflammatory disease in these three separate systems, no one is in complete agreement. According to one source, over 80 percent of cats with cholangiohepatitis also have intestinal inflammation, and 50 percent have pancreatic lesions. Bacterial infection is found in only a few of the cases. Often immune-mediated inflammation is the only factor identified. Sometimes cancer is eventually located at one of the sites.
The bottom line is that a diagnosis of “triaditis” doesn’t really identify either the cause of a cat’s disease nor help the veterinarian decide on potential therapies or prognosis. Some specialists are now also looking at kidney involvement in some of these cases and proposing that triaditis is a misnomer, suggesting “feline inflammatory disease” as a more appropriate term. I’m waiting for the next specialist to use this new moniker. This time I’ll be ready.