Visiting Veterinarian : For Martha's Vineyard vets, diagnosing is like solving a puzzle
Making a medical diagnosis on an animal is a lot like doing a jigsaw puzzle. A cat can't tell us, "I ate tinsel and my tummy hurts." A dog can't say, " I twisted my ankle chasing squirrels." When a pet is ailing, veterinarians and owners have to put together bits and pieces of information until we have enough to reveal the big picture.
We begin, as all good jigsaw puzzle solvers do, with the corners and edges, i.e., history and physical examination. This gives us the fundamental framework. Next, we use various diagnostic tools, ranging from basic blood tests to advanced technology, to fill in the middle.
Some puzzles are simple — just a few big pieces and we're done. For instance, middle-aged cat eating voraciously but losing weight with a palpable thyroid nodule and elevated thyroid hormones. Case solved. That cat has hyperthyroidism. Easy as a My Little Pony puzzle.
Try another one: tick-covered dog with fever, swollen joints, and a positive Lyme test. Any self-respecting Islander can solve that one. But then there are the harder cases. The thousand piece puzzles — like Ravensburgers.
Ravensburger is a 15-year-old poodle who has generally been in good health. Getting her poodle-do done at the groomer last week, her stylist noticed one hind foot was swollen, and pointed this out to the owner who called me immediately. I nonchalantly booked her an appointment later in the day, not expecting anything major. When Raven arrived, we began collecting corner pieces.
"When did you first notice the problem?" I asked, noting Raven's body temperature was 103.1, slightly higher than the normal range of 101.0 to 102.5. The elderly dog had been having difficulty negotiating stairs for quite some time, but the swollen foot was just discovered today. "How is she feeling otherwise?" I asked, lifting the foot and gently squeezing. One little piggy, two little piggies, three little....
Ravensburger was feeling fine. "She's deaf," her owner mentioned. I nodded. Not surprising at her age. "Her vision also seems to be getting worse," she continued. "I took her to another vet about her eyes this summer. They prescribed drops and ointment," she concluded.
I nodded again, a bit distracted. The swelling of the foot was unusual, an uncommon fluid build-up called "pitting edema." This was no simple infected toe or sprained ankle. Time for a thorough physical exam, head to tail.
To compensate for my middle-aged memory, I always do my exam in the identical order so not to overlook any system. Ears, okay. Eyes next. Pushing her fluffy pom-pom of fur away from her face, I shone a bright light in her eyes. There, in her right eye, a haze of red. Blood in the anterior chamber. Definitely not normal. Her other eye, also abnormal, had a cataract and cloudy cornea. "Call the other vet and get those previous records, please," I shouted to my secretary. Knowing how her eyes had looked four months ago would help us establish the significance and chronicity of what we were seeing today. I proceeded with my routine, rolling up her lip to look at her gums. My heart sank.
Petechia and ecchymosis. Petechia - from the Italian petecchie meaning "skin eruptions" or "measles." Petechiae are flat, pinpoint red dots caused by bleeding in the skin. Ecchymosis - from the ancient Greek meaning "I pour out," refers to larger areas of bleeding that cause skin discoloration, i.e., bruising. Now if Raven had been hit by a car or fallen down the stairs that might explain small hemorrhages dotting her mucous membranes and bleeding into her eye, but all she did was visit a kind, gentle groomer. I examined the rest of her skin carefully. Sure enough, under that black curly fur were multiple, large bruises. The puzzle pieces were beginning to form a picture — the picture of a dog with a bleeding disorder.
When a normal animal or person gets cut or bruised, a series of clotting mechanisms make bleeding stop. Otherwise, a child with a skinned knee or a dog with a torn toenail would continue bleeding indefinitely. Congenital problems such as hemophilia are inherited abnormalities in which the body does not make proper clotting factors. Since Raven had lived 15 healthy years without any bleeding issues, this was unlikely. Eating anticoagulant rat poison can also cause hemorrhage, but these cases more typically manifest as massive bleeds into the lungs or abdomen, and Raven had no history of access to rodenticides.
The most likely cause for petechia and ecchymosis in a dog of Raven's age is thrombocytopenia — a deficiency of the tiny blood cells called thrombocytes or platelets that are necessary for proper clotting. A complete blood count (CBC) provided another puzzle piece. Sure enough, Raven's platelet count was dangerously low.
Low platelet counts may be the result of inadequate production (such as with bone marrow cancer), excessive consumption (such as in the life-threatening condition DIC — disseminated intravascular coagulation), or increased destruction by the immune system. Immune-mediated thrombocytopenia may be secondary to many diseases, from cancer to tick-borne infections to lupus, but most often happens spontaneously for no obvious reason. If Raven were five instead of fifteen, or if money grew on trees, we might complete the puzzle with a battery of expensive tests. We might send her to a specialty hospital for blood transfusions and round-the-clock intensive care. But considering her advanced age, and the fact that, despite her abysmally low platelet count, Raven appeared to feel fine, her owner understandably opted for outpatient empirical treatment. We started her on corticosteroids and antibiotics, with the caveat to treat her like a hemophiliac, cognizant that she could fatally hemorrhage at any time. A week later, Raven's platelet count has increased, though still well below normal, and the petechia and ecchymosis are resolving. We are continuing treatment and hoping for the best. A significant number of cases of spontaneous immune-mediated thrombocytopenia will resolve with treatment and not recur, but many others die or are euthanized, despite all intervention. That final piece of the puzzle remains missing. Only time will tell.