Dr. Sarah Wooten
|July 19, 2021
With over 3,000 types of spiders in the U.S. and more than 45,000 around the world, including the brown recluse, you may be concerned about one of those spiders potentially biting your favorite furry friend. Most spider bites on dogs only cause localized redness and swelling and do not require veterinary care. However, there are a few species of spiders whose bites can be life-threatening in dogs. Learn more about which spiders pose a greater threat, how to identify a spider bite on a dog and what to expect during a visit to your veterinarian.
There are 11 species of spiders indigenous to the United States, and out of these, two main species of venomous spiders to be aware of are:
Spider bites may vary depending on the type of spider. For example, brown recluse spiders contain a venom that causes a local skin reaction in humans. There is no consensus on what these bites look like for dogs, but known clinical signs in humans include:
On the other hand, black widow spiders have a venom that contains a compound called alpha-latrotoxin which is a strong neurotoxin. But according to the sixth edition of The 5-Minute Veterinary Consult, 15% of black widow bites do not contain venom and don't cause any signs other than some redness around the bite. If there is only mild envenomation, signs may not show up for weeks. If a dog is heavily envenomated by a black widow, clinical signs may include:
If you suspect that there's a spider bite on a dog, call your vet immediately. If your dog is already showing clinical signs, call your vet and let them know that you're coming; you may get redirected to a local emergency hospital if your vet can't see you. If you can, carefully bring the spider in a jar with you.
If you notice a bite wound, lightly apply an ice pack. Remember, when dogs are fearful or experiencing pain, they can bite. Use these tips from Fear Free Happy Homes to learn how to handle a dog that is afraid or in pain, and above all, stay calm and breathe.
If your vet recommends it, you can give your dog an antihistamine orally, like Benadryl, before you leave the house. Ask your vet for the correct dosage.
Your vet will take your dog's vitals and conduct a full physical examination. Try to give them as much information as you can, as well as the spider if you have it. Depending on the type of spider suspected, laboratory testing and hospitalization may be recommended.
If your vet suspects that your dog has been bitten by a brown recluse, there is not much to be done initially. Bites by these types of spiders typically take a long time to heal — as long as six to eight months. Most of the care will be done at home; therefore, it's important to keep the wound clean and maintain regular contact with your vet, even if it is just weekly phone call updates. If a deep ulcer forms, then your vet will likely prescribe antibiotics to prevent a secondary bacterial infection. If your dog is in pain, pain medication will be prescribed.
If the wound becomes large with a dead area in the middle, your vet will likely recommend surgical removal of the dead tissue, and a skin graft may be required to help your dog's skin heal. If your dog is very sick, your vet may recommend hospitalization with IV fluid therapy. In rare cases, blood transfusions are required. After a brown recluse bite heals, a scar is usually left behind.
If a black widow bite is known or suspected, an antivenom is available and recommended. Your vet may hospitalize your dog, administer antivenom and fluids through an intravenous catheter, monitor for any allergic reactions to the medicine and treat any muscle spasms.
Spider and other common bug bites can be prevented by maintaining regular pest control around your property and in your home. If you live in an area where these spiders are known to reside, be sure to keep your dog out of woodpiles.
Dr. Sarah Wooten graduated from UC Davis School of Veterinary Medicine in 2002. A member of the American Society of Veterinary Journalists, Dr. Wooten divides her professional time between small animal practice in Greeley, Colorado, public speaking on associate issues, leadership, and client communication, and writing. She enjoys camping with her family, skiing, SCUBA, and participating in triathlons.
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