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dog looking at a garden spider

The essentials

  • Spider bites on dogs are usually harmless — While some pups will have allergic reactions to spider bites, the good news is most pups will survive.
  • Clinical signs of spider bites vary — Depending on the species, a spider bite may cause side effects like stinging, pain, redness, vomiting, diarrhea, and muscle tremors.
  • Black widow and recluse spider bites are the most problematic — You’ll want to consult a veterinarian if either of these types of spiders bite your dog. Though death is rare, the spiders inject enough venom to cause side effects that typically need veterinary care.

Bug bites are not fun for humans or their furry friends. Typically, itchy mosquito bites or spider bites cause just some discomfort. However, some species of spiders can cause more severe reactions when they bite, particularly in small dogs or pets with allergies.

Knowing the tell-tale signs of a spider bite on dogs can help pet parents seek prompt medical advice, increasing the likelihood of successful treatment and healing.

How harmful are spider bites on dogs?

Most spider bites on dogs are not dangerous at all. Still, it’s a good idea to be aware of them so that you can monitor your dog and seek medical treatment if your pet is experiencing serious side effects.

Notably, two species of spiders, the black widow and recluse, produce enough venom to trigger problems like diarrhea, rapid heart rate, tremors, and, rarely, kidney failure .

Besides the type of spider that bit a dog, many factors play into which dogs are at the highest risk for more severe outcomes. A dog’s size, age, and the size of the bite may all affect the need for treatment. Monitoring your pet for irregular behavior that could be spider bite symptoms and seeking emergency care can reduce the harm caused by spider bites.

Symptoms of a spider bite on a dog

It’s challenging to identify and diagnose a spider bite definitively. The only way to accurately diagnose a spider bite is to find the precise spider that bit the dog — a tall feat, as you can likely imagine. Instead, a vet will usually base a diagnosis on clinical signs in an animal, such as:

  • Redness or itchiness around the bite site
  • Small red bumps
  • Tremors, spasms, or seizures
  • Severe pain around the area (may present as whining)
  • Breathing difficulties
  • Drooling
  • Vomiting
  • Diarrhea
  • Increased blood pressure and heart rate
  • Fever
  • Lethargy

Sometimes, a blood test can diagnose black widow spider bites. In rare cases, a dog may experience severe symptoms, including seizures, paralysis, kidney failure, or death.

Non-venomous spider bites

There are more than 48,000 spider species in the world. Most of these species are venomous spiders — even the daddy long legs. However, most don’t inject enough venom to cause serious harm to a dog (or cat, for that matter) because their fangs aren’t long or sturdy enough to penetrate the skin of an animal.

In these cases, spider bite symptoms are similar to other insect bites and may include bumps, redness, and itchiness. Though potentially pesky, non-venomous bites will typically go away on their own without harming a pet.

👉 Bumps, sores, and increased itchiness can also be a sign of other medical issues, like a bacterial infection, so the best thing to do is to seek veterinary attention if you’re concerned.

Venomous bites

Venomous bites are a medical emergency that require care from veterinary experts. Knowing what these spiders and their bites look like can help you keep your pet at a safe distance and know when it’s time to seek immediate vet care following a potential or known bite.

  • Black widow bites. Black widow spiders are found in every state in the United States except Alaska. Female black widow spiders are the largest and most venomous, hallmarked by shiny, round black bodies with a red or orange hourglass on their bellies. About 15% of black widow bites are “dry bites,” meaning without envenomation. The remaining 85% of black widow bites are venomous, but most dogs won’t develop severe clinical signs. Redness, swelling, cramping, GI upset, muscle tremors, and agitation are clinical signs.
  • Brown recluse bites. Brown recluse spiders are yellow-brown with markings resembling a violin. Their bites aren’t initially painful, but brown recluse spider venom can be harmful. Stinging, redness, and blisters at the bite site are often the first symptoms. The blister may evolve into a “bulls-eye” mark, which can progress to cause tissue damage and is an indication to seek immediate vet care. Kidney and clotting abnormalities are rare but possible.

The trouble with spider venom

When a more dangerous spider like a black widow or brown recluse penetrates a dog’s skin with enough venom, it can cause or trigger some of the most severe symptoms.

Spider venom comes from specialized secretory cells in what’s known as the venom gland . When enough venom is injected, a dog may experience various clinical signs ranging from mild to life-threatening. This venom causes symptoms to develop, including swelling on and around the affected area, tissue damage, fever, breathing problems, high blood pressure, kidney dysfunction, and even death.

Though death only happens in the most severe cases — even from black widow or brown recluse spider bites — prompt medical care from a team of veterinary experts is the best way to improve your dog’s prognosis.

6 home remedies

Non-venomous spider bites (usually) can be treated at home so long as there’s no sign of infection. However, there are some caveats. You’ll want to call the vet ASAP if you notice a black widow or brown recluse bite, as those are dangerous but not typically fatal with prompt veterinarian treatment.

  1. Basic treatment. If your pup doesn’t seem to be showing signs of illness or discomfort, the spider bite is likely benign (it will be in most cases). Start by cleaning the area using plain soap, water, and a cold compress or ice pack. If you notice any swelling around the area, elevate the limb.
  2. Potato poultice. That’s right, we said it. Slice up a potato and put the pieces into a cloth. Apply it on the bite to help reduce inflammation.
  3. Baking soda. There is a simple paste you can make by mixing water with baking soda. This step will speed up the healing process.
  4. Turmeric powder and olive oil. Create this mixture and rub it on the spider bite to help with inflammation. Turmeric is a superstar treatment (it can also be ingested) that has many other benefits for dogs.
  5. Salt. This step is great for venomous bites. Wash the affected area with warm water and sprinkle a bit of table salt with lukewarm water onto a clean cloth. Rub it on the bite to effectively soak up some of the venom. Minimize the dog licking the salt to avoid salt toxicity.
  6. Skin balms. Check out our two favorite balms, Skin Soother and Musher’s Secret Paw Protection Natural Dog Wax, to calm the irritation.

👉 If the affected area doesn’t seem to be improving after several days, call your vet. 

Treating venomous spider bites

Your veterinarian is the best resource for how to treat a brown recluse bite on a dog — ditto for a black widow bite (or any spider bite). Treatment options will vary depending on the type of spider that bit your dog.

Black widow bites can be treated with a medicine known as antivenin or antivenom. The medication is injectable and must be given while the dog is in the hospital for the bite. It can cause severe reactions in some dogs, so this route is usually reserved for the most severe spider bite cases. Pain relief medication, IV fluids, and muscle relaxers are other treatments that may help. Your pet may need to be hospitalized for two to three days following a black widow spider bite, and it can take weeks or months to heal completely.

Brown recluse spider bites mostly require monitoring — there’s no antivenin as these bites are very rarely fatal. Treatments to manage symptoms include antibiotics, pain relief, and treatment of the affected area. In the most serious cases, a dog may need blood transfusions or surgical treatment. It can take up to two months for a pup to fully recover.

Frequently asked questions

How do you tell if your dog has been bitten by a spider?

It’s challenging to know whether a spider has bitten a dog unless the exact insect is found and tested. Vets typically use clinical signs to diagnose a bite. Redness, itchiness, and small red bumps are common signs of spider bites on dogs. A dog may develop a fever, become lethargic, and even experience seizures in more severe cases.

How do you treat a spider bite on a dog?

It depends on the severity. A dog spider bite may include at-home treatments like cleaning the affected area with soap and water and applying a cold compress. The most severe venomous spider bites may require pain medication, antivenom, IV fluids, blood transfusions, and surgical treatment.

Can a spider bite kill a dog?

Rarely. Spider bites are usually harmless to dogs, though they may cause discomfort, such as itchiness. If a black widow or brown recluse spider bites your dog and injects enough venom, they may experience more serious symptoms like a fever, lethargy, tissue damage, and kidney failure. Call your vet if your dog is experiencing severe symptoms or if you believe they were the victim of a black widow or brown recluse spider bite.

What types of spiders are harmful to dogs?

Brown recluse and black widow spiders are the two types of venomous spiders considered most dangerous to dogs. Unlike other spiders, these two species are able to inject enough venom into a dog’s skin, causing more severe symptoms and warranting prompt medical care.

How can I prevent my dog from getting bitten by spiders?

Keep your home and yard free of spider webs. Spiders like to hide in wood or leaf piles, so minimizing those in your home and yard is also helpful. Try to keep a safe distance from spider webs when out and about with your pup. Your vet may be able to recommend dog-safe insect repellents.