How much testing is too much testing?

Learning from Ophelia and Juliet.

Courtesy of Pixabay.

To test or not to test? That is the question — whether veterinary medicine or human. Does that cough warrant an x-ray? Should we biopsy that lump? My knee hurts. Do I need a Lyme test? What about screening people for ovarian or prostate cancer? Too much testing can lead to a lot of false positives. False positives can lead to unnecessary worry, unnecessary invasive diagnostics, even unnecessary treatments. But whether in a person or a pup, without tests, serious diseases can be missed.

Take Ophelia, the hound dog. Born in Tennessee, she was transported north by a pet rescue agency to Massachusetts when just over a year old. On arrival, she was vaccinated, tested for heartworm and tick-borne diseases, spayed, dewormed for intestinal parasites, given flea and tick control and heartworm preventive medication, and put up for adoption. Ophelia weighed in at 40 pounds and was heartbreakingly scared. The first time I visited her at her new home (she was way too skittish for a car trip to my office), she panicked. Seriously. Her owner tried holding her, but Ophelia flew from her mother’s arms and slithered beneath a very low bed. We had to remove the mattress and dismantle the bed to fish her out, poor thing.

Each visit she got a little better. We tried not to overstress her, limiting our poking and prodding at each encounter in hopes of calming her fears. When the time came when I would normally run another heartworm test, Ophelia was still a bundle of anxiety. I managed to give her necessary vaccinations before she fled our ministrations, at which point I opted to delay further tests, rather than emotionally traumatizing her with additional restraint for a blood draw. I figured she was low risk for heartworm. She rarely went outside. She had been tested prior to her adoption, and her new owner gave heartworm medication monthly like clockwork. I wasn’t worried. We would catch up with everything in one fell swoop at her annual physical.

By the time that rolled around, Ophelia was better adjusted. Her mother held her fairly easily for a thorough exam and vaccinations. I drew blood, even trimmed her toenails. I was very happy … until completing the blood test. Ophelia had heartworm. She had almost certainly been infected a year ago back in Tennessee, where heartworm infections are far more common than on Martha’s Vineyard. Then why was that first test done by the rescue agency negative? Simple. It takes six to nine months after an infected mosquito bites a dog until heartworm larvae reach adulthood, and our test depends on the presence of adult worms for a positive result. The worms in Ophelia’s heart were immature at the time of her initial test. Voilà! False negative. It’s not that the test failed. It was just too soon to diagnose the infection. Then I compounded the problem by not pushing harder to repeat it in a timely fashion. To test or not to test? I should have tested, no matter how nervous Ophelia was.

Then there was Juliet. This beautiful longhaired cat was less than a year old when her owners noticed occasional bouts of altered breathing. Over a six-month period, they had seen three episodes where Juliet made a dry heaving motion. “Like gagging up a hairball?” I asked, noting her luxurious coat. “No, not like that,” they replied. They described an inspiratory sound that would last about 10 seconds, then stop. They also noted that when running around, she would sometimes breathe unusually fast. Juliet had been seen by other veterinarians for an upper respiratory infection, common in kittens, and a history of sneezing. The owners also liked to burn incense, and it was suggested that might be irritating her. A good thought, for sure. I’ve seen both cats and dogs have significant respiratory reactions to incense, open fireplaces, scented candles, even wood-burning stoves. But when the owners stopped burning incense, the symptoms did not resolve, so they came to me for a second opinion.

My first reaction was that Juliet looked a perfectly healthy young cat, and the history did not sound too concerning. Was this much ado about nothing? A case of overly worried parents? Or maybe Juliet had feline asthma? That could explain her symptoms. Watching her on the exam table, maybe she was breathing a tiny bit hard. But cats sometimes do that when stressed. I listened to her heart and lungs. Could that be a slight heart murmur? Yes, I think it was. Was it? It was subtle. Hard to hear. But, hmmm, yes, I think it was. Maybe. I was still kicking myself for not having done that heartworm test on Ophelia sooner. Since this couple was worried, and because I thought Juliet had a heart murmur, albeit a very small one, I suggested radiographs. Honestly, I didn’t expect to see much, but when the films were done, they revealed a little fluid around Juliet’s lung on the right side, called pleural effusion, and a classic “Valentine” shaped heart, typical of the cardiac condition called hypertrophic cardiomyopathy. A visit to a veterinary cardiologist later that week confirmed the diagnosis.

Now I can tell you plenty of stories with the opposite results, i.e. tests done that did not lead to diagnoses. To test or not to test? Finances are frequently a concern for pet owners, and veterinarians are too often accused of “being in it for the money” and doing unnecessary and expensive procedures. I think the reality is that most of us just want to keep up with the rapidly changing standard of care in veterinary medicine and provide the best we possibly can. We are always walking a tightrope between not wanting to miss anything, and not wanting to run needless tests. Juliet is now in an array of cardiac medications. Ophelia? We confirmed the heartworm infection with a second sample sent to an outside laboratory and had begun treatment. Now we just hope that all’s well that ends well.