Most tarantula species kept as pets in North America pose little lethal risk to dogs, but certain wild species, particularly in Australia, can absolutely kill a dog. The answer depends on the species of tarantula, the size of the dog, and whether the encounter involves a bite or contact with the spider’s barbed defensive hairs.
Australian Tarantulas Are Deadly to Dogs
The clearest evidence of tarantulas killing dogs comes from Australia. A study published in PubMed documented seven cases of dogs bitten by Australian tarantulas (species in the Phlogius and Selenocosmia groups, sometimes called “barking spiders” or “whistling spiders”). All seven dogs died, some in as little as 30 minutes to two hours after being bitten. Researchers concluded that the venom of these spiders is far more toxic to dogs than it is to humans. In two of the seven cases, the dog’s owner was also bitten and survived with relatively mild symptoms.
This is a striking difference in vulnerability. The same venom that causes pain and swelling in a person can shut down a dog’s system rapidly. If you live in Australia or in regions where large wild tarantulas are present, a bite to your dog is a genuine emergency.
Pet Tarantulas in North America
The tarantulas most commonly kept as pets, such as Chilean rose, Mexican red-knee, and curly hair tarantulas, have venom that is relatively mild. For most dogs, a bite from one of these species is comparable to a bee sting: painful, potentially causing localized swelling, but not life-threatening on its own. A small dog or a dog with an allergic reaction could face more serious consequences, but fatal outcomes from North American or Central American pet tarantula bites are not well documented in veterinary literature.
That said, “not usually fatal” does not mean harmless. Dogs are curious and tend to investigate tarantulas with their noses and mouths, which puts them at risk for bites to the face, tongue, or throat. Swelling in those areas can obstruct breathing, especially in small or flat-faced breeds like pugs and bulldogs.
Urticating Hairs Are a Hidden Danger
Bites are not the only concern. Most New World tarantulas (those from the Americas) defend themselves by flicking tiny barbed hairs from their abdomens. These hairs, called urticating hairs, are designed to embed in skin and mucous membranes, causing intense irritation. When a dog sniffs or mouths a tarantula, these hairs can lodge in the eyes, nose, mouth, and throat.
In the eyes, these barbed hairs can penetrate the cornea and cause a condition called keratitis, a painful inflammation that worsens over time. Research from the National Center for Biotechnology Information describes cases where the hairs migrated deeper into the cornea, making removal difficult and sometimes risking perforation. Dogs cannot communicate the specific discomfort, so owners may not notice the problem until significant damage has occurred. Signs include pawing at the face, squinting, redness, and excessive tearing.
If inhaled, urticating hairs can irritate the airways and trigger swelling. In a small dog, this could potentially compromise breathing. If swallowed in large quantities, the hairs can inflame the lining of the mouth and digestive tract.
Signs Your Dog Encountered a Tarantula
Dogs that have been bitten or exposed to urticating hairs may show a range of symptoms depending on the type of contact:
- Bite symptoms: Localized swelling, pain, limping (if bitten on a paw), whimpering, excessive drooling, or lethargy. With highly toxic species, rapid weakness, vomiting, or collapse can follow.
- Urticating hair exposure: Intense scratching or pawing at the face, swollen eyes or muzzle, sneezing, coughing, difficulty breathing, or visible redness around the mouth and nose.
- Allergic reaction: Facial swelling that spreads rapidly, hives, vomiting, difficulty breathing, or collapse. This can happen with any species and any size of dog.
What to Do After an Encounter
If you suspect your dog has been bitten by or exposed to a tarantula, keep the dog calm and try to prevent it from rubbing or pawing at the affected area. An Elizabethan collar (cone) can help with this. Applying a cool compress to a bite site several times a day can reduce swelling. Do not give your dog any medications without contacting a veterinarian first, as the appropriate treatment depends on the type and severity of the reaction.
If your dog shows signs of a severe allergic reaction, facial swelling that spreads, labored breathing, or sudden weakness, treat it as an emergency. These symptoms can escalate quickly. For dogs in Australia bitten by native tarantulas, the timeline is especially urgent given how rapidly fatal outcomes occurred in documented cases.
If urticating hairs have lodged in your dog’s eyes, a veterinarian will need to examine the cornea and may need to remove accessible hairs individually. Topical medications to reduce inflammation are typically part of the treatment. Hairs that have penetrated too deeply may need to be monitored rather than surgically removed, as extraction can sometimes cause more damage than leaving them in place.
Keeping Dogs and Tarantulas Separate
If you keep a pet tarantula, the simplest prevention is making sure your dog never has unsupervised access to the enclosure. Tarantulas that escape or are handled outside their tank create opportunities for exactly the kind of nose-first investigation dogs are prone to. Even a tarantula that doesn’t bite may kick urticating hairs when startled, and a curious dog pressing its face close is a perfect target.
For dogs that spend time outdoors in areas where wild tarantulas live, encounters are harder to prevent. Tarantulas in the American Southwest are most active during warm months, especially during mating season in late summer and fall when males wander in search of females. Keeping your dog on a leash during evening walks in tarantula territory reduces the chance of a surprise encounter in low light, when both tarantulas and dogs tend to be more active.