Happy Wednesday, everyone!  I was sitting on our back patio a few nights ago watching Jake watch a spider crawl in front of him.  This gave me an idea for a blog post on spiders and What To Do If Your Dog Gets Bit By A Venomous Spider.  Fortunately, Jake didn’t make a big deal about his little friend, and fortunately, the little spider was not poisonous.  But what does a non-venomous bite look like?  

Non-Venomous Bites

Most of the spiders found in the North Providence area can’t produce enough venom to harm your dog or you. Their bites appear as small red bumps, similar to mosquito bites, and cause hardly any irritation to your dog. They can be treated in several natural ways, primarily focused on relieving itchiness. Some dogs may not even notice any irritation at all.

Most spider bites won’t cause significant harm to your dog. The venom of most household spiders is either too weak or delivered in such a small quantity that it doesn’t cause a severe reaction. However, there are some spiders whose bites can pose serious risks to dogs. According to VCA Animal Hospitals, “The two groups of spiders responsible for most medically significant spider bites include the widow spiders (Latrodectus spp., including the black widow spider) and the recluse spiders (Loxosceles spp., including the brown recluse).” Below are a few of the most common dangerous spiders that can bite dogs, and why they are so harmful.

If your dog gets bitten by a venomous spider, it’s essential to act quickly. Spider venom can be very dangerous depending on the species (e.g., black widow, brown recluse). Here’s what you should do:

1. Stay Calm and Keep Your Dog Calm.  
Stress can speed up the spread of venom.
Keep your dog as still and quiet as possible.

2. Identify the Spider (If Possible)
If you saw the spider, try to take a photo from a safe distance.
Please don’t attempt to catch it unless you’re sure it’s safe.
Note the spider’s size, color, and markings.

3. Look for Symptoms of a Venomous Bite
Some symptoms may appear immediately or within a few hours.

Black Widow Spider

A black widow spider is a small, venomous arachnid known for its glossy black body and distinctive red markings. Here’s a detailed description:

Physical Description:
Color: Shiny black (females), sometimes dark brown (males or juveniles).
Size:
Females: About 1.5 inches (38 mm) including the leg span.
Males: Much smaller, about half the size of females.
Markings:
Females typically have a red or orange hourglass-shaped marking on the underside of the abdomen.  Some may have additional red or white spots or streaks on the upper side.
Shape: Round, bulbous abdomen and long, thin legs.

Habitat:
Found in dark, secluded, undisturbed areas:
Woodpiles, sheds, garages, basements, under outdoor furniture, and crevices.
Common across North America, especially in warmer climates.

Behavior:
Generally non-aggressive and bites only in self-defense.
Constructs irregular, tangled webs close to ground level.
Female black widows are more venomous than males.

Venom:
Neurotoxic: affects the nervous system.
Bites can cause severe muscle pain, cramps, and systemic effects in both humans and animals.
Rarely fatal, but urgent medical or veterinary attention is required, especially for children or small pets.

Brown Recluse Spider

A brown recluse spider is a venomous spider best known for its necrotic bite and reclusive behavior. It’s often confused with other brown spiders, but it has some distinct traits.

Physical Description:
Color: Light to medium brown, sometimes yellowish-tan.
Size:
Body length: About ¼ to ½ inch (6–12 mm), with legs extending up to 1 inch.
Markings:
Notable dark violin-shaped marking on the upper back (cephalothorax), with the neck of the violin pointing toward the rear.
Eyes:
Most spiders have eight eyes, but the brown recluse has six eyes arranged in pairs (dyads): one in the front and one on each side.

Habitat:
Native to the Midwestern and Southern United States.
Prefers dark, undisturbed places:
Closets, basements, attics, cardboard boxes, behind furniture, under sinks.
Often found indoors more than outdoors.

Behavior:
Shy and non-aggressive; bites usually occur when it’s trapped against the skin (e.g., in clothes or bedding).
Builds irregular, loosely woven webs in hidden spots—not used to catch prey.
Nocturnal hunter—comes out at night to feed.

Venom:
Necrotic toxin: causes cell and tissue death around the bite.
Bite may be painless at first, but develops into:
Redness, blistering
An open sore or ulcer with a dark center
Possible fever, chills, nausea
In rare, severe cases, systemic symptoms or large skin necrosis may occur.

Brown Recluse Bite Symptoms:

Red or purple blister at the bite site
Skin ulceration or necrosis (tissue death)
Fever, lethargy
Vomiting
Muscle pain

4. Seek Emergency Veterinary Care
Please contact your vet or an emergency animal hospital right away.
Venom can cause serious or fatal complications without treatment.
Treatment may include antivenom, pain management, IV fluids, antibiotics, or wound care.

Treatment for Spider Bites in Dogs

Treatment for spider bites can vary depending on the severity of the bite and whether venom was involved. Here are some typical treatments your vet might use:

Antivenom: For dogs bitten by black widow spiders, antivenom may be administered to neutralize the venom. This medication is given intravenously (IV). (Brown recluse spider bites are treated with supportive care, as there is no available antivenin in the United States.)

Pain management: Pain relief medication is often prescribed to keep your dog comfortable, especially if the bite is causing significant discomfort.

Wound care: If the bite has caused tissue damage or ulceration (which is common with brown recluse bites), your veterinarian may provide wound care to help the area heal and prevent infection.

Intravenous fluids: In severe cases where systemic symptoms, such as weakness, fever, or muscle tremors, are present, your dog may require IV fluids to stay hydrated and stabilize their condition.
Surgery: In very rare and extreme cases, such as severe necrosis from a brown recluse bite, surgery may be required to remove the dead tissue.

5. Do Not Attempt Home Remedies
Do not use ice, alcohol, or try to suck out the venom.
Do not give human medications unless directed by a vet.

6. Monitor Your Dog Closely
If you’re en route to a vet, continue to monitor for worsening symptoms.
If breathing slows, gums turn pale, or your dog collapses, seek immediate advanced care.

References:  

Interested in more posts like this? Check them out here:

How To Protect Your Dog From Venomous Snakes

What To Do If Your Dog Has Been Stung By A Bee