Visiting Veterinarian : Summer on Martha's Vineyard can't prevent pet illness
Jaws, a middle-aged black-and-white cat, is a seasonal resident, so I see him less frequently than my year-round patients. But this summer, he put in an appearance soon after arriving on the Island.
"Right before we left home, he began looking slightly bloated," his owners reported. Once they had unpacked and settled in, they noticed his tummy was even more distended. A normally fastidious cat who goes outside to do his business, Jaws also had a bowel movement in the house, extremely unusual behavior for him. When he started seeming off-balance climbing stairs, the family scheduled an exam.
At my office, it was obvious something was seriously wrong. Although Jaws had lost only a small amount of weight since last year, looking carefully, I noticed that most of his body was very thin. Only his abdomen was big and fat. Tapping it with my finger, I felt a wave of liquid rebound.
"His belly is full of fluid," I sighed, knowing this usually meant something exceedingly bad. "Let's start with a quick tap to see what's in there."
The most likely possibilities paraded through my mind as I shaved a spot on his belly, scrubbed it, and positioned my needle and syringe. Certain types of heart disease can lead to clear, straw-colored effusion in the abdomen. So can liver disease, and cancer. Then there's Feline Infectious Peritonitis (FIP) caused by a coronavirus infection. FIP fluid is more viscous, almost like saliva, and often contains flecks of solid white material. Well, we'd know more in a minute. I popped the needle in and withdrew a milliliter of fluid. Thin. Opaque. Pure white. It looked just like milk. Jaw's belly was full of chyle.
Chyle is another name for lymph or lymphatic fluid, specifically lymph containing lots of fat. Lymph fluid normally accumulates in the body between cells. As muscles contract and relax, lymph is passively pumped and channeled into lymphatic vessels which eventually go to the lymph nodes. These nodes filter impurities, mounting an immune response to anything foreign, like bacteria, viruses, or cancer cells. That's why we get "swollen glands" with certain illnesses. Chyle is lymph that is white because of fat absorbed from the intestines after digestion of food. Normally, lymphatic fluid recycles back into the blood stream, but if something interferes with that flow, it can build up in abnormal places.
"Jaws has chyloperitoneum," I reported. The internal lining of the abdominal cavity is called the peritoneum and for some reason the official medical term for this condition is chyloperitoneum (not chyloabdomen), a fancy word that just means "belly full of chyle," but doesn't explain why. "In all honesty, I've seen abnormal chylous effusions before, but always in the chest, never in the abdomen."
That's called chylothorax — a collection of chyle in the space between the lungs and chest wall. Although it can occur in animals of any age or breed, in dogs, it is most prevalent in middle-aged Afghan hounds and young Shiba Inus. In cats, older Oriental breeds are most frequently affected. Presenting signs relate to the constrictive action of the fluid around the lungs — difficulty breathing, coughing, muffled heart sounds. Although chylothorax may be caused by tumors, heart disease, or trauma, the vast majority of cases have no known underlying cause and are simply classified as "idiopathic chylothorax."
In cases where we can identify an underlying cause, definitive treatment depends on treating the primary problem, but for idiopathic chyothorax there are two options — conservative medical approach, or surgery. When I was in veterinary school, many moons ago, we were taught that chylothorax was usually caused by traumatic rupture of the thoracic lymphatic duct. Turns out this is not the case, but surgical ligation of the duct (combined with an additional procedure called a periocardectomy) is still the treatment of choice for idiopathic cases and has great success rates. If surgery is not an option, patients can often be maintained by draining the fluid as needed to keep them comfortable. Low-fat diets and a supplement called Rutin available at health food stores may help minimize chyle build up and idiopathic chylothorax may eventually resolve spontaneously.
Feline chyloperitoneum was a new one for me. A search of my veterinary database unearthed a small number of cases. Underlying causes reported included cancer, pancreatitis, inflammatory bowel disease, trauma, FIP, and biliary cirrhosis. Not good stuff.
"Let's drain all this fluid," I suggested. "Then take X-rays." Jaws lay on his side, nervous but compliant, as long as we gently rubbed behind his ears. Using a butterfly catheter, three-way stopcock, and a big syringe, we removed seven hundred milliliters. That's almost three cups of chyle. We took radiographs, sent the fluid for analysis, ran blood tests. Other than confirming that Jaws had chyloperitoneum, we found no underlying disease process. We referred him for an ultrasound, which also failed to pinpoint the cause.
"The specialists say we might need exploratory surgery to make a definitive diagnosis," I told the owners.
Jaws's family opted for conservative medical treatment. "Low fat diet, Rutin, and supplementation with stuff called medium chain triglycerides is recommended for chylothorax," I said, sharing the results of my research. "We might as well try those, too."
His owners were game, but less than two short weeks later, we had a new development when Jaws returned to have his abdomen drained again. Three and a half cups worth. The fluid looked different than previously. Less milky. Flecks of black tissue. After the fluid was removed, I felt his tummy. This time, the diagnosis was evident. A palpable mass in his intestines almost as big as a baseball. Without a doubt, an aggressive cancer.
Once again, his owners considered their options, including surgery, but with the very guarded prognosis, decided to take him home for however long he has left. When his time comes, and it will probably be soon, we will say good-bye, but for now Jaws is enjoying his last summer, one beautiful Vineyard day at a time.