Dr. Patty Khuly
|February 28, 2022
The brown recluse spider may be uniquely attractive to spider-watchers, but if you're a dog parent, you'll want to be extra careful when it comes to this arachnid. A brown recluse bite on a dog tends to be painful and possibly dangerous. What's more, clinical signs of a brown recluse spider bite in dogs can be hard to identify — particularly, early on. Let's take a closer look at what these spiders do and how to help your dog if they've been bitten.
As its common name suggests, this spider is brown in color and generally reclusive. As noted by the Merck Veterinary Manual, the distinctive "violin-shaped marking" on this spider's cephalothorax (upper body) is one of few features that makes this spider identifiable. However, this reclusive spider typically doesn't hang around long enough for a positive ID.
The brown recluse tends to avoid humans and dogs, whenever possible, but will bite when disturbed. Measuring 1 to 1.8 centimeters in length from the tip of its tiny head to the end of its bulbous abdomen, with longer legs measuring 2 to 3 centimeters, this creature's bite is notoriously destructive to the skin of both humans and dogs. The poison this spider wields is considered a formidable venom. While it can be merely painful at the outset, it can lead to tissue death and ulceration, sometimes in an area several times larger than the spider itself.
The brown recluse spider can be found in a wide geographic range. It lives in the Midwest section of the U.S., from Colorado and New Mexico in the west to Northern Georgia in the east. It also lives throughout southern portions of the U.S. and up the Mississippi into Wisconsin.
While the bite is somewhat distinctive, clinical signs of a brown recluse spider bite in dogs may initially be mistaken for a wide variety of other bites and stings. Your dog may also show no clinical signs that they were bitten or display non-specific signs, such as limping or shaking.
Clinical signs of a brown recluse spider bite in dogs include the following:
Less common signs of a brown recluse bite on a dog include systemic effects from the venom, including:
Some dogs may also experience damage to red blood cells, which can lead to anemia and hematuria (blood in the urine). This typically occurs within the first 24 hours after a brown recluse bite on a dog. While rare, the venom of a brown recluse can enter a dog's bloodstream and lead to renal failure, gangrene, blood clotting problems and dangerously severe destruction of red blood cells.
Due to the localized pain or itchiness of the lesion, most dog parents will observe the bite early on in the process. Veterinarians will usually home in on the bitten area and may have to shave the fur around it to observe any telltale signs.
Initially, other bites — including the bites of ticks, scorpions, other spiders, dogs, cats and wildlife — can sometimes be mistaken for this bite. Once the characteristic bull's-eye and eschar appear and underlying tissue sloughing takes place, however, a spider bite (if not specifically a brown recluse bite) is the inevitable suspicion.
In some cases, brown recluse bites can cause variations in red blood cells, certain white blood cells and platelets. Blood in the urine is also a possibility. Therefore, a complete laboratory analysis can be helpful to make a definitive diagnosis.
Treatment of a brown recluse spider's bite is aimed at treatment of the lesion itself. Antibiotics, pain relievers, corticosteroids and topical treatments to maintain hygiene, relieve pain, and limit both inflammation and infection are the mainstays of treatment.
Early on, cold packs can be helpful. Dapsone is considered the medication of choice to lessen the local and systemic effect of these bites, but it must be administered early in the process. Recovery can be slow if severe tissue damage has occurred — several weeks, at least. Surgical intervention may be required to remove necrotic or infected tissues as their presence can delay healing. This is especially crucial when gangrene is a serious possibility.
Preventing brown recluse bites on a dog should be aimed at limiting your pet's ability to root in the underbrush off of hiking paths or while camping in the wilds of areas known to be home to these spiders. If you live in an area where brown recluse spiders are native, or you notice clinical signs of a brown recluse spider bite in dogs, contact your vet immediately to get the care your dog needs.
Dr. Patty Khuly is an award-winning veterinarian known for her independent thinking, her spirited pet advocacy, her passion for the veterinary profession, and her famously irreverent pet health writing.
Dr. K is an honors graduate of both Wellesley College and the University of Pennsylvania School of Veterinary Medicine. She received her MBA at The Wharton School of Business as part of the prestigious VMD/MBA dual-degree program. She now owns Sunset Animal Clinic, a veterinary practice in Miami, Florida.
Fewer calories for less active dogs
Over 70% of dogs lost weight within 10 weeks when fed this nutrition. Delicious food in a large bite size.
Hill's Science Diet Sensitive Stomach & Skin Small & Mini dry dog food is tailored nutrition for Small & Mini dogs while being gentle on stomachs. Nourishes skin & promotes a lustrous coat.
Science Diet's breakthrough nutrition supports ultimate digestive well-being & healthy microbiome
Supports energy & beautiful coat. Helps keep immune system, joints, heart & kidneys healthy
Over 70% of dogs lost weight within 10 weeks when fed this nutrition
Science Diet's breakthrough nutrition supports ultimate digestive well-being & healthy microbiome
Hill's Science Diet Healthy Cuisine Variety Pack
Vital nutrients to support 5 essential building blocks for lifelong health
Chicken & Vegetables recipe with great taste and precisely balanced nutrition to help your puppy build immunity and strong bones
Clinically proven kibble technology to reduce plaque & tartar build-up
For the unique nutritional needs of mature Small & Mini Dogs
Delicious roasted chicken paired with tender vegetables in a succulent stew
Over 70% of dogs lost weight within 10 weeks when fed this nutrition
Supports energy level and beautiful coat in mature dogs
Over 70% of dogs lost weight within 10 weeks when fed this nutrition
Science Diet's breakthrough nutrition supports ultimate digestive well-being & healthy microbiome for dogs age 7+
Science Diet's breakthrough nutrition supports ultimate digestive well-being & healthy microbiome
Hill's Science Diet Sensitive Stomach & Skin dry dog food is gentle on stomachs while nourishing skin & promoting a lustrous coat.
First-time foster parents: Learn about the process of fostering a puppy or dog, including how to prepare, challenges & rewards that come with it.
Are you curious why your dog feels the need to pee on everything? Learn what dog marking is, why dogs do it, and what you can do to reduce this behavior.
Do you think you might have an overweight dog? Learn the signs of dog obesity, as well as causes, potential effects and tips for prevention.
Apartment living with a herding dog can be a challenge. Discover these indoor activities for herding dog breeds that can make sharing a small space easier.
Learn to recognize the signs of congestive heart failure in dogs so you can give your dog the best chance of a longer, healthier life.
Read about two diabetic alert dogs' stories and how they help notify their owners when their blood sugar is out of range.
A deaf dog may now live a quieter life, but he's still the active, loving pup you once knew! Discover how to care for and communicate with your dog.
Learn about the pregnancy cycle in dogs, including how long they are usually pregnant and details about each trimester.
Learn why grapes & raisins are poisonous for dogs, how to manage the situation if they've eaten them, symptoms to watch for, and when to go to the vet.
Learn about different types of dog foods, why your dog might actually like certain ones over others and questions to ask your vet about dog food taste.
Every puppy should get a health check-up at six months by a veterinarian to make sure he is healthy. Learn what to expect at your puppy's health check.
Gather the following puppy supplies to prepare your family for all the fun (and commitment) that comes with being a dog parent.
Learn the benefits of starting to train your puppy at an early age, preventing a wide variety of problems and promoting good behavior.
Learn the underlying causes behind excessive dog farting, signs that gas problems may be a larger health concern, and how to help manage these issues.
Learn why your dog's muzzle might be going gray earlier than expected, including whether it's just a sign of aging, stress, or an underlying health issue.
Learn how to recognize signs of depression in your dog, the underlying reasons he might be feeling down, and what you can do to help lift his spirits.
Learn whether or not dogs truly have best friends, including information on their loyalty to humans and behavioral tendencies to support the idea.
Learn all about your dog's odd sleep behaviors, including snoring, twitching, running in his sleep, and what they all mean.
Discover how urinary tract diseases like urolithiasis manifest in dogs, and what you can do to help prevent this disease in your dog.
Learn facts and precautions about dogs and drinking pool water, including what types are most hazardous and what to do if your dog drinks too much.
Our low calorie formula helps you control your dog's weight. It's packed with high-quality protein for building lean muscles, and made with purposeful ingredients for a flavorful, nutritious meal. Clinically proven antioxidants, Vitamin C+E, help promote a healthy immune system.
Our low calorie formula helps you control your dog's weight. It's packed with high-quality protein for building lean muscles, and made with purposeful ingredients for a flavorful, nutritious meal. Clinically proven antioxidants, Vitamin C+E, help promote a healthy immune system.
©2025 Hill's Pet Nutrition, Inc. As used herein, denotes registered trademark status in the U.S. only; registration status in other geographies may be different. Your use of this site is subject to the terms of our Legal Statement. About our Ads. Cookie Consent Tool