One of my longest-standing clients is also one of my favorites. He’ll consider anything I say—but a smart question is always sure to follow. That’s an admirable trait he’s honed to perfection in recent years as a result of his own illness—one which culminated in a kidney transplant about a year ago.

After dealing with the plethora of specialists he’s been subjected to (it’s like herding cats, he says) a trip to the vet must seem like a walk in the park. Still, he takes me to task every time—and I appreciate it—really.

Last week his geriatric Doxie-mix came down with some bizarre neurologic symptoms.

His 15 year-old brain decided it might best like him to turn in circles to the right. Tie him up on a leash to a doorknob and watch him turn the line into a tightly wound bungee cord (after about one or two hundred turns to the right). It’s dizzying. And that’s no doubt how he feels, too.

At first we thought this was a classic case of vestibular disease. That’s when older pets suffer an aberration in their balance system, causing a vertigo sensation and the feeling that down is up and vice versa. Consequently, they tend to roll about, their eyes quiver in a characteristic pattern, and those who can stand, do so with head tilted and a propensity for perpetual perambulation.

Usually they get better. But Doxie’s condition just got worse. Next step: Is this an infection affecting his nervous system? A toxin? A tumor in or around his brain?

The safest way to determine that? Lots and lots of labwork. Then check his brain with an MRI or CT scan before doing more invasive tests (like a spinal tap, which can often make things lots worse in the event of a tumor).

The expenses just seemed extreme to this owner, and, in his estimation, all the treatment options seemed more or less the same, regardless of the disease state. I couldn’t much argue, given that, at this point, more labwork was like taking stabs in the dark—and because he’d already put his foot own against any invasive approaches (like spinal taps or surgery).

So I did my best: I set about to treating with doxycycline (an antibiotic useful for bacterial, parasitic or tick-borne diseases) and prednisone (an anti-inflammatory corticosteroid).

Within a few days, Doxie was well on his way to normal dogdom. We may never know what caused the problem, or indeed, whether we’ve even cured him. Time will tell.

Problem is, today this owner’s other geriatric charge, a sixteen year-old poodle mix, came down with the same symptoms. Head tilted, falling over when walking in a circle, etcetera. Though I can’t rule out that both dogs might have come down with the same vestibular symptoms due to separate disease processes, the strange flavor of Doxie’s distress was equally matched to Moxie’s.

And here’s where things get tricky. This is an owner who’s loaded up on organ anti-rejection drugs. Though he’s careful not to handle his cats’ litterboxes and to wash his hands after handling all his pets, there’s always the possibility of disease transmission. If this is an infection or toxin, the same agent might easily infect an immunosuppressed person. This changes everything—a lot.

And here’s where I put my foot down: All that labwork we thought we could dispense with earlier? Forget about declining it. Toxoplasma, Prototheca, Neospora, Blastomycosis, everything…a full panel of the expensive zebras we never look for outside of the specialist’s place or without a very high index of suspicion.

That CSF tap and MRI? It’s on the table again, if just to find something, anything that might rule out the big, bad bugs. Don’t agree? Sign right here… Better yet, go see the specialist. Yours and theirs. Sign right here again…and again…

I know this all sounds remarkably paranoid, but I’m just not used to handling the imminent possibility of human death as a result of pet illness. The closest I come on a regular basis comes when I present the issue of toxoplasmosis to pregnant women and explain how children need to be kept 100% clear of pet feces until intestinal parasite treatment is complete. My AIDS patient clients and transplant recipients always get extra attention, but this situation? It’s special.

I don’t know how human docs do it. It all seems so stressful. But maybe that’s just my training. In vet school, these issues get hammered into us over and over again so that it’s clear that the mission to prevent spread of disease from animals to humans (zoonotic disease) is priority number one. Indeed, the veterinarian’s oath we take at graduation hits a powerful note that invokes our mission to protect public health.

All this may sound strange to those of you who see us vets as animal doctors pure and simple. But the truth is, there’s a lot of ground to cover between human and animal medicine—and someone’s got to be charged with picking up that zoonotic slack. Your general practitioner should do it. Your infectious disease specialist should do it. But when all else fails, sometimes it’s your vet that does it.