Spider Bite on Dog (Symptoms & Treatment)

Dogs have a penchant for exploration and frequently encounter the natural world in ways that can sometimes put them at risk. Among the myriad of indoor and outdoor encounters, spider bites stand out as a concern for many pet owners. While most spider bites are harmless, certain spider species can pose a threat to your dog. 

Understanding the symptoms and potential risks of a spider bite on a dog is essential for ensuring their health and well-being. Early recognition and treatment can be the key to preventing severe complications and ensuring a speedy recovery for our furry friends. 

• Spider Bite Symptoms on Dogs
• Types of Spider Bites
• Treating Spider Bites on Dogs
• Allergic Reactions
• FAQs
• Final Notes

Spider Bite Symptoms on Dogs 

When a spider bites a dog, the reaction can vary significantly based on the type of spider, location, and depth of the bite, and the dog's own immune system. While many spider bites cause minimal issues beyond localized skin irritation or swelling, some spiders are venomous and can cause more severe symptoms. 

Common spider bite symptoms on dogs to watch out for include the following: 

• Localized redness and swelling: The most common reaction to a spider bite is a red, swollen area. The size can vary depending on the spider and the dog's reaction. 
• Pain: Some dogs might exhibit signs of pain, especially when the bitten area is touched. 
• Fever: If your dog is reacting strongly to the bite, they may experience a fever. 
• Muscle or joint pain: Certain spider venoms can cause muscle or joint pain, leading to limping or reluctance to move. 
• Tissue necrosis: Bites from certain spiders, like the brown recluse, can lead to necrosis — tissue death — in the surrounding area. This is a more severe symptom and requires immediate veterinary attention. The necrotic area can grow larger, turning black. 
• Systemic effects: Some venomous spiders can cause more widespread symptoms, such as tremors, seizures, paralysis, and death.¹

Types of Spider Bites 

Spiders have varying degrees of danger associated with their bites. While most spiders possess venom, only a few can cause clinical harm to mammals because of their ability to penetrate the skin and the potency of their venom. The primary spiders of concern in the US are the widow and brown spiders.²

Brown recluse spider bites

The brown recluse is recognized by its violin-shaped marking. These spiders are common in the central and southern US, but they've been found outside those locations. Brown recluse spider venom contains enzymes that can lead to tissue necrosis. 

Initially, there might only be slight redness or itching, but within hours, a blister can form, which later may turn necrotic. Systemic effects are rare, including fever, vomiting, and more severe reactions.² Other symptoms include: 

• Anemia
• Lethargy and weakness
• Slowed clotting, with increased bruising
• Kidney and liver damage¹

The Chilean recluse is another type of brown spider with potent venom. Akin to the brown recluse in appearance, it has a brown body with a black line. Though its natural habitat is in South America, the Chilean recluse has found its way to parts of the United States, particularly the Los Angeles area. There have also been reports in locations such as Florida, Massachusetts, and Kansas.¹

One thing to note is that the venom of the Chilean recluse is more toxic than the brown recluse and has caused several human fatalities.¹

Widow spider bites

Widows are found worldwide and are known for their characteristic markings. The black widow, for instance, has an iconic hourglass pattern and is the most common in the US. The black widow's venom is among the most potent and affects neurotransmitter release, leading to muscle cramps, agitation, and more. Black widow spider bites on dogs are painful; symptoms can manifest within minutes, peaking around 8 hours.² Other symptoms may include: 

• Whining and crying
• Tremors
• Difficulty breathing
• Vomiting or diarrhea
• Stomach cramps
• Increased heart rate 
• Seizures
• Paralysis
• Death¹

Of course, throughout the world, there are more widow spiders than the black widows. The red widow spider is closely related to the black widow. Distinguished by its orange-red upper body and black abdomen with bright red markings, the red widow carries an unmistakable appearance. 

Restricted primarily to the palmetto scrubland sand dune habitats of central and southern Florida, its bite contains less venom than the black widow but is highly potent, especially to smaller dogs.¹

The brown widow is another relative in the widow family that can cause an emergency if it bites your dog. It's typically smaller than black widows, exhibiting a brown body, elongated legs, and a distinctive orange or red marking on its abdomen. 

The brown widow has a presence in regions like Hawaii, Southern California, and the Gulf states but has been spotted in areas like Georgia and South Carolina.¹ While the venom of the brown widow can rival or surpass the toxicity of the black widow's venom, it usually injects significantly less during a bite.¹

Other types of spider bites

Remember, spider bites can vary in severity, depending on the species of spider involved. While some spider bites won't affect your dog, others are venomous, and others can cause painful bites, but it's unlikely their venom will significantly affect your dog. 

The wolf spider, for instance, is a common spider that may bite if provoked. A wolf spider bite on a dog can result in redness, swelling, and pain at the bite site, but they're not considered to be dangerously venomous to dogs. However, because of their size, their bites can be quite painful and cause localized discomfort.³

Treating Spider Bites on Dogs 

If a venomous spider bites your dog, they require immediate care. Unfortunately, there's no antivenom available in the US for a brown recluse spider bite on dogs. Instead, wound care, cool compresses, and certain medications may be used to help reduce the extent of the necrosis.²

Antivenom is available for widow spider bites but is used selectively. Treating widow spider bites on dogs primarily consists of supportive care and managing pain and cramps. The prognosis is mostly positive, with recovery occurring over several days.²

Generally, spider bites on dogs can range from mild to severe, depending on the species and amount of venom injected. Recognizing the symptoms early and providing appropriate care can prevent complications and ensure your pet's well-being. 

Even if the bite appears mild, it's essential to consult with a veterinarian as soon as possible. They can provide definitive diagnosis, advice, and, if necessary, treatment options. 

As always, prevention is the best treatment. Be aware of the areas where dangerous spiders are prevalent. Regularly check and clean your dog's kennels, bedding, and other favorite spots. You can also consider regular pest control treatments, especially if you live in an area known for harmful spiders.¹

Allergic Reactions 

Like insect bites and bee stings, some spider bites can cause allergic reactions or look like them by causing localized swelling, itchiness, pain, and redness.⁴ However, there's a difference between an allergic reaction and a spider bite. 

If your dog is experiencing an allergic reaction due to a spider bite, you might notice: 

• Localized swelling and redness: The bite site may become increasingly swollen, and the surrounding skin may turn red.
• Pain: Depending on the severity, the bite can be painful to touch. 
• Difficulty breathing: In severe allergic reactions, a dog may experience respiratory distress or swelling of the throat.
• Swelling: If your dog is allergic to bees or spider bites, they may exhibit swelling in areas far from the bite site, such as the face, ears, or lips.⁴

An allergic reaction to a spider bite can develop rapidly after the bite, often within minutes to an hour. On the other hand, symptoms from a spider bite, particularly venomous ones, might develop more gradually. 

In general, spider bites have more localized symptoms. However, certain spiders can cause systemic symptoms that look like allergies or other illnesses.⁴

If you believe your dog is having an allergic reaction due to a spider bite or any other reason, contact your veterinarian immediately for assistance. 

FAQs

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

If a spider has bitten your dog, you may notice swelling, redness, or a visible bite mark. The dog might also exhibit signs of pain, itchiness, or lethargy. If you suspect a more severe spider bite or your dog's symptoms worsen, consult a veterinarian immediately. 

What does a spider bite look like on a dog?

A spider bite on a dog typically appears as a small, red, swollen area, which might have a puncture mark at the center. The skin around the bite can become warm and tender to the touch. Depending on the type of spider, there may be additional symptoms. 

How do you know if your dog has been bitten by something?

If your dog has been bitten by something, you may notice localized swelling, redness, or a puncture mark. The dog might also show signs of pain, lick the area excessively, or display changes in behavior. An easy way to tell if your dog has been bitten is to look at spider bites on dog pictures online and try to match any marks you find on your dog. However, the only way to know whether a spider has bitten your dog is to consult a vet. 

Final Notes 

Spider bites on dogs can be concerning. While most spiders are harmless to dogs, there are specific species that, when they bite, can pose significant health risks. Recognizing the signs of a spider bite early is crucial. Symptoms like redness, swelling, and systemic effects can be indicators of venomous bites. Treatment varies depending on the spider species involved and the severity of the bite.