The Animal Poisons Helpline is occasionally contacted about pets that have mouthed or ingested caterpillars. Most problems that arise from these exposures are due to the tiny hairs (setae), spines, or quills may be covering a caterpillar’s body. These hairs or spines are connected to glands that can produce a toxin. As part of the caterpillar’s defence strategy, when animals come into contact with these stinging hairs or spines, they can break off into the skin, releasing a tiny dose of toxin in the process.

Doratifera vulnerans, more commonly known as the Australian cup moth, is a common culprit of caterpillar envenomations in Australia. Doratifera vulnerans, which translates to “bearer of painful gifts”, produce larvae which are endowed with dozens of spines laced with a highly potent venom. Found along Australia’s east coast, including in Sydney, Canberra and Brisbane, the spines of this caterpillar are retracted at rest and everted when the animal is disturbed.

Many syndromes have been described from caterpillar exposures, most commonly following ingestion or mouthing by companion animals. Such exposures may result in drooling, difficulty swallowing and irritation of the lips and mouth. These effects are highly variable in severity and all appear to occur secondary to embedded caterpillar hairs. In severe cases, caterpillar exposures can result in allergic reactions including anaphylaxis which may be life threatening without veterinary intervention. Spontaneous abortions have also been documented in mares ingesting certain types of caterpillars.

As a general rule, brightly coloured caterpillars with spines, bristles, or a fuzzy appearance might be venomous. The Animal Poisons Helpline can be useful in these cases and can provide an immediate risk assessment to determine if veterinary assessment is required or if home management may be appropriate.

The Animal Poisons Helpline provides free advice to pet owners in Australia and can be reached on ☎️ 1300 869 738 (AU)
,0800 869 738 (NZ), 3106 4216 (SG), (917) 722-5958 (US) or +1917-722-5958 (CA) . If you are a member of a veterinary team in Australia or New Zealand, you can join the Animal Poisons Centre For Vets Facebook group which is regularly updated with toxicology tidbits and poisoning trends. We thank the Western Australian Department of Primary Industries and Regional Development for supporting this post.