The Most Dangerous Poison: The Unknown

There's no readily available toxin panel like you see on TV. TV lied to you.

Published: October 05, 2015


We all learn in different ways, and veterinarians are no different. We learn by example, by experience, and by trial-and-error (sometimes several different ways at once). In veterinary school, most learning follows the classic didactic method of “Here’s this disease, here’s how you diagnose it, here’s how you fix it,” at least in the last two clinical years.  The first couple of years of vet school are usually all spent figuring out what the knee bone is connected to, how drugs work, and which wine pairs best with Twinkies.

It’s hard to teach a negative, hard to teach what something isn’t, or what do to when faced with an unknown. We usually go from here’s this thing to now let’s fix it. When faced with what the hell is this thing, we often short circuit and stand there looking like someone just drank the last of the milk and put the empty carton back in the fridge. Sorta slack-jawed and empty.

I can think of lots of circumstances where I’m faced with a blank canvas in terms of a patient’s illness and have to work hard just getting to where the learning usually begins: here’s this thing. We’re usually still light years away from now let’s fix it. But that process isn’t usually taught well in school or in life. It’s a skill you develop after being out in practice for a bit. I think one of the main places that this phenomenon rears its head is in the world of toxicology: treating animal poisons.

In school, most toxicology classes present the relevant poison du jour, go through all the fun ways it can kill you, and then discuss the antidote and treatment options. It’s all quite tidy and organized and lulls you into the comforting fantasy that toxicology cases usually play out on a predictable and pre-planned course.

They don’t.

I fully expected my first toxicology case in practice to come through the door with a poisoned pet in one hand and the box or bottle of what poisoned them in the other. All I had to do was figure out the right supportive care or find the proper antidote, and Bob’s your uncle, the patient was healed and could go back to digging up the garden or peeing on the fresh laundry or whatever. I assumed I would usually know what I was treating and only had to align tab A with slot B and the universe would be made whole. Boy, was I wrong.

Sometimes, you do get lucky and know what the pet got into: the rat poison just put out today, the spilled bottle of pills from this morning, the jug of antifreeze tipped over in the garage. Those are the easy ones. I’ve found the most frustrating and dangerous poison to be the one you don’t know – the pet comes in with clinical signs that could be caused by a hundred different poisons and there’s no readily available clues to help us determine what’s killing them. The clock is ticking and I feel like a bleeding idiot because all I can do is supportive care.

I can practically hear you screaming “but, doc, what about all those toxicology tests and drug screens you hear about on Grey’s Anatomy and ER and Quincy and just about every medically-themed TV show of the past half century?”

As if.

Yes, there are toxicology tests, and some of them are easy. The antifreeze test is pretty easy, those over-the-counter illicit drug tests that my parents use to test me for drugs in high school work okay, and there’s a smattering of other ones available. But here’s the rub: there are millions of toxins out there. There might just be tests for most of them, but there’s no readily available “toxin panel” like you see on TV.

Yes, TV lied to you. I’m sorry. Take a moment if you need to.

Welcome back.

You just can’t send a blood or urine sample off to the lab and have it come back with a report telling you exactly what is poisoning the pet. I’ve been asked about this from many hundreds of pet owners over the years. In some cases, you can send stomach samples or blood and have certain labs tell you whether there is a toxin there or not, but that’s different. That’s not casting a wide net and saying “what is the poison?” That’s narrowing the field and saying “is this poison present?” Make sense?

If you’re lucky enough to know what the poison is, if it’s that scenario with the poisoned pet under one arm and the box or bottle of poison under the other, then usually you’re first in the mode of decontaminating the pet. Getting them to vomit it up, wash it off their fur or otherwise get it out of their system. Hopefully you can get them to rid themselves of enough so that you won’t be faced with actually treating the poison.

But if the ingestion is unseen – happens behind the couch, some pile of rotting something out on the back 40, in the dark back corner of the unused woodshed – then you miss the chance to decontaminate and the poison spreads its leathery wings, sinks it dark and jagged claws into tender flesh, and the clinical signs show up. The only two parties in the entire of the universe who know which of the 75 million poisons it is are the pet and the poison and neither one is saying boo.

The most common poison that I’ve actually seen and treated is the unknown toxin. And it usually sucks. Sometimes a clue will peek out of the medical mire and help nudge you along the path to a diagnosis: kidney values elevating on blood tests or low calcium hinting that antifreeze is the culprit, or strange and unexplained bleeding telling you that it’s rat poison. But in lots of cases, you just have a sick cat or dog seizing and convulsing the night away with nary a clue what’s causing it.

There are general supportive measure that we can take for any sick pet, regardless of whether we think a poison is involved or not. We can give fluids to ensure hydration and organ function; we can keep blood pressure, blood sugar, and body temperature in the normal range; we can stop seizures with valium; and treat pain. When we don’t know what poison is causing problems, or even if it is poison causing problems, we try and set the stage for the body to fend off the crisis and get back to normalcy and health. Obviously, knowing what the poison is can confer a huge advantage in treatment, but all is not lost if we don’t know. It’s just much more frustrating and uncertain when the toxin is unknown.

In any medical case, the unknown is dangerous, but with poisons what you don’t know can kill you.

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