Why spider bites are dangerous
Black widow and brown recluse spiders inject neurotoxic and necrotic venom.
The venom destroys tissue and disrupts nerve signals, causing severe pain and muscle tremors.
Dogs are more likely to bite or sniff spiders, resulting in oral and facial swelling.
Cats may be bitten while hunting, leading to similar localized and systemic signs.
Why speed matters
Delaying care significantly worsens outcomes. Some signs appear hours or days later, so "looks fine right now" is not a reason to wait.
Signs to watch for
- Sudden swelling and redness around the bite site, often on the face or limbs
- Visible puncture wounds or a small blister at the bite area
- Shivering, muscle twitching, or tremors within minutes to hours
- Difficulty breathing or rapid breathing if venom affects respiratory muscles
- Weakness, collapse, or inability to stand
- Excessive drooling and pawing at the mouth if bitten orally
What to do right now
- Call your vet or the nearest emergency animal hospital immediately.
- Do not attempt to suck out venom or cut the wound.
- Keep the pet calm and restrict movement to slow venom spread.
- If safe, identify the spider or take a photo for veterinary reference.
- Bring the pet in for evaluation; antivenom or supportive care may be needed.
If your pet shows any of the signs above, go to the nearest emergency vet now and call ahead.
The step-by-step response, from the first minute to the vet visit, is in our Spider Bites in Dogs and Cats: What to Do emergency guide.