Think You Found a Spider Bite on Your Dog? Here’s What to Do
Step one: Don’t freak out. 
By Kristi Valentini August 11, 2021 Advertisement Pin FB More Tweet Email Send Text Message Print 
dog with spider bite running in yard towards camera Credit: Karan Kapoor / Getty
Just like with people, spider bites on dogs can be serious depending on the type of spider. If you suspect your dog was bitten by one of these eight-legged creatures, don't stress: Life-threatening spider bites aren't all that common. Most of the time, spider bites simply cause itching or irritation similar to other types of insect bites. Read on to learn what you can do to relieve your pooch's discomfort at home and when it's time to see a veterinarian.
What Do Spider Bites Look Like on Dogs?
Most spider bites won't look different than any other insect bite, Brian Roberts, DVM, a board-certified veterinary criticalist and regional medical director for VCA Animal Hospitals, says. Typically, what you'll see is a pink or red bump unless your dog has an allergic reaction, which would result in hives and a swollen face. However, a bite by the venomous brown recluse spider causes a lesion that changes color over time.
Signs and Symptoms of Venomous Spider Bites
It's usually hard to spot spider bites on dogs because of their fur. And even if you see a venomous spider on your pet, you may not notice any symptoms for hours or days after your dog was bitten.
"There are tens of thousands of species of different spiders. But there are really only two that we worry about in the U.S. The bites from a black widow or a brown recluse can cause significant injury," Roberts says. Here are the signs of a venomous spider bite from one of these varieties.
Brown Recluse Spider Bite
The bite of a brown recluse is often painful. So when bitten, your dog may yelp or later be seen licking or biting at the area. The venom these spiders emit helps them digest their prey, Roberts explains. So it causes skin and muscle cells to die, resulting in tissue damage.
Initially, the bite is red and swollen. Then the tissue starts to die, beginning from the bite location and spreading out from there. The center of the lesion will change in color from pink to darker red or black and then white as venom progresses outward. Sometimes it takes on a bullseye appearance or even blisters. Your dog may also vomit and act lethargic.
Black Widow Spider Bite
Usually, there's no pain associated with a black widow bite in dogs, says Roberts. You won't see a red bump or any sort of local reaction. But if the spider has injected its neurotoxin, symptoms will develop later and include muscle pain and spasms, difficulty walking (drunk walking), paralysis, and tremors. Your dog may also drool, vomit, or have diarrhea. If left untreated, a black widow bite can be deadly.
How To Treat Spider Bites On a Dog
If you're wondering why your dog is so itchy or keeps nipping at something on his body, spread the hair and have a look at it. If there's a red bump or a bite mark, clean it with soap and water. You can also wash your furry pal with a soothing oatmeal shampoo to help soothe the irritation. Then watch your pup for any side effects that may indicate he was bitten by a venomous spider.
Note: Don't ice the bite. "There's been no studies showing that icing does anything. With certain bites, it can actually make it worse," Roberts warns. "For example, the toxin from the brown recluse spider damages tissues. The way tissues are repaired is through blood flow. If you ice that area, you're actually creating more tissue that the venom can affect."
If you notice signs of a venomous spider bite or your dog keeps biting or scratching the area, it's time to see a veterinarian. Even if it wasn't a brown recluse or black widow spider bite, skin that's been broken open by scratching or biting can become infected.
Your veterinarian can administer anti-itch medication such as a steroid and may also recommend an antihistamine or antibiotic, if the wound is infected. Your pup may get an e-collar too to keep him from going after the affected area.
Venomous spider bites definitely require medical attention. Dogs who get bitten by black widows can receive the antitoxin at a veterinary clinic. No antidote exists for brown recluse spider bites. But your veterinarian can provide supportive care, which may include removing damaged tissue.
Preventing Future Spider Bites
There are a few ways to prevent spider bites on dogs. First, make sure your yard is free of debris and apply a bug spray for dogs to keep pests away. If you live in a place where there are lots of spiders, consider a monthly preventative medication too.
"The topical ones that contain pyrimethamine, like SimpleGuard, protect against biting insects," Roberts says. "They don't specifically say spiders, but they stop fleas, ticks, biting flies, sandflies, and lice. So I would imagine those medications would work against spiders too."
The good news is that in most cases, spider bites are merely a nuisance. With a few precautions you and your four-legged friend can keep on enjoying the great outdoors.
