Not All Pets Are the Same: Why Species Matters for Pet Toxins

One of the most fascinating and challenging aspects of veterinary medicine is that we don’t treat just one type of patient. Unlike human medicine, veterinary care spans many species, each with unique anatomy, physiology, bodies and behaviors. These differences mean that what is safe for one species may be dangerous, or even fatal, for another. Understanding species sensitivities is especially important when it comes to pet toxicology and everyday exposure risks.

Size = Opportunity

When a pet ingests a medication intended for people, even a single dose can represent a massive overdose relative to their size, making poisoning much more likely. Compounding this risk is behavior: dogs and cats are closer to the ground, naturally curious and often explore new or dropped items with their mouths. Many also eat whatever they can get their paws on or have grooming behaviors that increase exposure to potentially harmful substances.

Dogs vs. Cats

Beyond size and behavior, physiology and metabolism play a major role in species-specific toxicity. For example, cats are deficient in certain enzymes that allow other types of animals to tolerate and process substances differently and at varied amounts. Some toxins that affect cats differently are:

• Lilies. Cats are particularly sensitive to lilies, including those in the Lilium and Hemerocallis species, which cause kidney failure.
• Acetaminophen and aspirin, as well as other medications. If ingested, they can cause vomiting, excessive drooling, lethargy, breathing problems or discolored gums.
• Garlic and onion can cause vomiting, lethargy and pale gums.

Dogs are particularly sensitive to items like:

• Xylitol, a common sugar substitute that is found in many sugar-free gums, candies and baked goods. Xylitol can cause low blood sugar levels and liver damage in dogs when ingested.
• Grapes and raisins contain tartaric acid, which is speculated to be the toxic component for dogs. Exposure to grapes and raisins can lead to kidney damage.

Medications Are Not One-Size-Fits-All

Flea, tick and heartworm prevention products are another common source of accidental poisoning among species. These medications must always be used exactly as directed and only on the animal they are made for. Here are some common ingredients found in parasite preventatives that could be dangerous for certain species:

• Permethrin: Products containing permethrin are safe for use in dogs but can cause severe tremors and seizures in cats.
• Fipronil: Fipronil is a common ingredient in many heartworm preventatives and is safe for most mammals when used properly. However, rabbits are highly sensitive to fipronil based preventatives. With exposure to fipronil, rabbits can develop lethargy, trouble walking and seizures, with many cases being fatal within 2-4 days of exposure.
• Ivermectin: Specific dog breeds, such as Collies and Australian Shepherds (among others), often have a genetic sensitivity to ivermectin, a medication used primarily to treat infections caused by parasitic worms or mites. While doses found in heartworm preventatives are safe when used as labeled, other forms require conservative and careful dosing in those breeds. Ivermectin toxicity can cause serious neurologic signs (lethargy, seizures, trouble walking), cardiorespiratory depression (low blood pressure, inadequate breathing), and blindness. Extreme caution is recommended when deworming large animal species (cattle, horses) in the presence of dogs. Ivermectin toxicity is also possible if dogs scavenge and ingest the feces of animals that were recently treated.

Birds and Airborne Toxins

Some animals can be harmed more easily based on how they come in contact with a toxin. Birds, for example, are excellent at moving air through their lungs. While this is beneficial for flight, it also makes them especially sensitive to airborne toxins such as carbon monoxide or fumes from overheated nonstick coatings on items such as cookware (polytetrafluoroethylene - Teflon™).

What if an exposure occurred?

It is best to always refer to a veterinary professional when it comes to giving your pet any medications. And if you’re uncertain about a certain food or products, check the ASPCA Poison Control page for more information and resources to help keep your pet safe.

If you believe your pet has been exposed to a toxin, ingested or received a veterinary product that was not labeled for their species, or if you notice any symptoms of illness – immediately seek veterinary care or contact ASPCA Poison Control at (888) 426-4435