Terro ant baits are not considered highly toxic to pets, but they aren’t completely safe either. The active ingredient, borax, has a low toxicity level in small amounts, meaning a dog or cat that licks a little bait will likely experience only mild stomach upset. However, the amount consumed, your pet’s size, and the physical bait station itself all factor into how serious the situation could become.
What’s in Terro Ant Bait
Terro’s liquid ant baits use borax (sodium tetraborate decahydrate) as their active ingredient. Borax is a naturally occurring mineral compound, and it’s far less potent than many synthetic insecticides. The bait works by mixing borax with a sugary liquid that attracts ants. That same sweet smell can also attract curious pets.
The concentration of borax in each bait station is relatively small, designed to kill insects that weigh a fraction of a gram. A 30-pound dog, by comparison, would need to consume a significantly larger quantity before reaching a dangerous dose.
How Much Borax Is Actually Dangerous
Borax becomes toxic to animals at doses above roughly 0.5 grams per kilogram of body weight, according to the Merck Veterinary Manual. To put that in perspective, a 10-kilogram (22-pound) dog would need to ingest at least 5 grams of borax to reach that threshold. A single Terro bait station contains a very small volume of liquid, so one station alone is unlikely to deliver a toxic dose to a medium or large dog.
More detailed toxicology data from the National Pesticide Information Center shows that the lethal dose in dogs is above 974 mg of borax per kilogram of body weight. That’s a substantial amount. But dogs appear to be more sensitive to borax than rats or mice, so the margins aren’t as wide as they might seem for very small dogs or cats. A 5-pound Chihuahua faces considerably more risk from the same amount of bait than a 70-pound Labrador.
Long-term exposure matters too. Chronic ingestion of boron compounds, even at lower levels, has been linked to reproductive damage in dogs, specifically testicular changes. This isn’t a concern from a single accidental exposure, but it reinforces why you shouldn’t leave bait stations where pets can access them repeatedly.
Symptoms to Watch For
If your pet gets into a Terro bait station, the most common reactions are gastrointestinal: vomiting, diarrhea, and sometimes bloody stool. Smaller dogs and cats tend to show more pronounced symptoms because the same amount of borax represents a larger dose relative to their body weight.
More serious warning signs include uncontrollable drooling, persistent coughing, or refusal to eat. If you notice any of these, your pet needs veterinary attention quickly rather than a wait-and-see approach. Lethargy and signs of abdominal pain (whining, restlessness, a hunched posture) also warrant a call to your vet or the Pet Poison Helpline.
The Plastic Station Is Its Own Risk
The borax gets most of the attention, but the plastic bait station housing can be just as dangerous, particularly for dogs that chew aggressively. If your dog crunches through the plastic casing and swallows sharp fragments, those pieces can lodge in the stomach or small intestine and create a gastrointestinal obstruction.
Foreign body obstructions are veterinary emergencies. Signs include repeated vomiting, loss of appetite, abdominal pain, dehydration, and lethargy. Most obstructions require surgery to remove the object, and if the plastic has perforated or damaged the intestinal wall, the affected section of intestine may need to be surgically removed as well. This is a far more urgent situation than mild borax ingestion, and it’s the risk that pet owners most often overlook.
How to Use Terro Safely Around Pets
The simplest approach is placement. Put bait stations in locations your pet physically cannot reach: behind appliances, inside cabinets, on high shelves, or behind baby gates. Terro also makes enclosed bait stations that are harder (though not impossible) for pets to open compared to the open liquid drops.
If you’re dealing with an ant problem in areas your pet frequents, consider placing the bait at night when pets are confined to a bedroom or crate, and removing it in the morning. Check stations regularly for signs of tampering, teeth marks, or displacement. If a station goes missing, assume your pet found it and look for chewed plastic around the house.
For households with small dogs, cats, or puppies that investigate everything with their mouths, outdoor placement along the home’s exterior perimeter is often a better strategy. The ants encounter the bait before entering the house, and your pets stay separated from the stations entirely.