By Dial A Vet Veterinary Team
Spiders get blamed for a lot of mystery lumps on dogs, but confirmed spider bites are uncommon, and in Australia a dog that suddenly becomes wobbly or collapses after time in the yard is more likely to have met a snake. That matters, because snakebite needs antivenom fast. Of the spiders, the redback is the one most likely to make a dog genuinely unwell, causing intense pain, restlessness, muscle tremors, and drooling. Funnel-web venom is extremely dangerous to people, yet dogs and cats appear far less sensitive to it. This guide covers what spider bites look like, what else they can be confused with, and when to go to a vet.
Key takeaways
- Most suspected spider bites on dogs turn out to be insect stings, abscesses, allergies, or other skin problems.
- Redback bites can cause severe pain, tremors, drooling, vomiting, and weakness. These dogs need a vet.
- Sudden collapse, wobbliness, dilated pupils, or red or brown urine points to snakebite, which is an emergency.
- Keep your dog still and calm and get to a vet. Do not cut, suck, or apply ice packs to a suspected bite.
- Never give human pain relief.
Spiders that matter for dogs in Australia
- Redback spider (Latrodectus hasselti): a glossy black spider with a red stripe on the back of the abdomen, found under outdoor furniture, in sheds, and around pot plants. Its venom affects nerves and muscles.
- Funnel-web spiders: large, glossy black spiders of eastern Australia. Life-threatening to people, but dogs and cats are thought to be relatively resistant. Any bitten pet should still be checked.
- White-tailed spiders: often blamed for skin ulcers, but research does not support them as a common cause of skin death. Most bites cause only local pain.
- Mouse spiders and large huntsman: can give a painful bite with local swelling.
Signs of a spider bite
Local signs: a red, swollen, painful spot, sometimes with a small puncture, licking at the area, or limping.
Signs of redback envenomation:
- Severe pain, crying, or restlessness that seems out of proportion to the wound
- Muscle tremors, twitching, or a rigid belly
- Drooling, vomiting, or panting
- Weakness or wobbliness
- Rapid heart rate
Is it a spider bite or something else?
- Snakebite: sudden weakness or collapse (sometimes with an apparent recovery), dilated pupils, trembling, drooling, vomiting, bleeding, or dark urine. Often no visible wound. See snake bites on dogs.
- Bee or wasp sting: sudden yelp, swelling, sometimes hives. See bug bites and stings on dogs.
- Paralysis tick: change in bark, wobbly back legs, breathing changes.
- Abscess: warm, painful swelling a few days after a fight or a grass seed injury.
- Allergic reaction: hives, facial swelling. See anaphylactic shock in dogs.
What to do right now
- Keep your dog as still and calm as possible. Carry small dogs.
- If you saw the spider and it is safe, take a photo or trap it in a sealed jar. Do not risk being bitten.
- Gently wash a visible bite with clean water.
- Call your vet or emergency clinic and head in if your dog shows anything beyond mild local soreness.
- Do not cut the wound, suck it, apply a tourniquet, or give human medicines. Do not apply heat.
When to see a vet
Emergency, go now: any weakness, collapse, wobbliness, dilated pupils, tremors, vomiting, drooling, breathing changes, or dark urine. Also any suspected funnel-web bite.
Same day: a painful, swollen area that is getting bigger, a bite on the face, or a small dog that is unsettled after a suspected bite.
Can usually be monitored: a small red bump in a bright, comfortable dog. Call a vet if it grows, oozes, or does not improve within 48 hours.
How vets typically help
A vet will examine your dog, look for a wound, and work out whether the signs fit a spider bite, snakebite, tick paralysis, or another problem. Blood and urine tests, including a snake venom detection kit in some cases, help with this. Redback envenomation is treated with pain relief, muscle relaxation, and supportive care, and antivenom is available for significant cases. Local bites are managed with wound care and comfort measures. Infected wounds may need extra treatment.
Prevention
- Wear gloves and check under outdoor furniture, play equipment, and pot rims for redback webs.
- Keep sheds, garages, and woodpiles tidy and off-limits to dogs.
- Shake out dog beds and blankets that have been left outside.
- In funnel-web areas, check pools and garden beds after summer rain.
- Keep grass short to reduce snakes as well as spiders.
FAQ
Can a redback bite kill a dog?
Deaths are uncommon, but small dogs and puppies can become very unwell. Treatment is effective, so get your dog seen if signs develop.
How long after a spider bite do signs appear?
Local pain is usually immediate. Redback signs can develop over several hours. Snakebite signs can be delayed, so do not wait if your dog seems off.
Do white-tailed spider bites cause flesh-eating ulcers?
Studies in people have not supported this, and the same is thought to apply to dogs. A skin ulcer needs a vet to look for other causes.
Should I give my dog an antihistamine?
Only if your vet tells you to. Antihistamines do not treat redback or snake venom.
Talk with a vet
If you have found a sore lump and are not sure what caused it, a vet at Dial A Vet can look at photos and help you decide on the next step. Any weakness, collapse, or wobbliness means going straight to an emergency clinic.
References
- Merck Veterinary Manual. Spider and scorpion bites and stings to animals.
- Australian Museum. Redback spider and funnel-web spider fact sheets.
- Australian Venom Research Unit (University of Melbourne). Spider bite first aid.
- RSPCA Australia Knowledgebase. My pet has been bitten by a snake, what should I do?
Disclaimer: Educational only. This page does not replace an examination by a veterinarian. Weakness or collapse after a suspected bite is an emergency.