Black Widow Spider Bites in Dogs
Key takeaways
A black widow spider bite is uncommon in dogs. This type of envenomation is caused by any spider of the Latrodectus genus; five species are native to the United States with the black widow being the most common.
- The amount of venom injected determines the severity of symptoms and dry bites (bites without envenomation) are possible
- Symptoms can begin immediately but may take up to eight hours to fully appear, including pain, tremors, restlessness, abnormal breathing, abdominal rigidity, and in severe cases seizures and paralysis
- If the bite was witnessed, diagnosis is self-evident
- If needed, other diagnostics include blood work, urinalysis, and diagnostic imaging
- Treatment involves administration of the antivenom (if available), pain management, and medications for muscle spasms
- Prognosis is generally good and the antivenom is not always needed; more severe cases may take several weeks to completely clear
Connect with a vet to get more information about your pet’s health.
A closer look: Black Widow Spider Bites in Dogs
Black widow spider bites are overall uncommon in dogs. In regions where widow spiders are not present, there is no concern. However, if it is a possibility that a bite has occurred, several factors need to be considered. Dogs are more resistant to the venom than other species, but the exposure can still be painful and distressing to experience for the dog. In some cases it can still be lethal so it is always best to seek veterinary care when venom injection is suspected. As the exposure to a black widow spider bite is not always observed, dogs showing signs of sudden paralysis or seizures require emergency veterinary attention.
Connect with a vet to get more information
Risk factors
Black widow spiders can be found in both tropical and temperate climates.
Severity can depend on the amount of envenomation relative to body size. In cases of larger doses, symptoms can include seizures and paralysis. This is more common in smaller breeds as smaller doses may trigger more serious reactions.
Possible causes
The cause of the condition is a bite by a widow (Latrodectus spp.) spider. These species occur worldwide with five species present in the United States. The black widow is the most common species in the US. Black widows are most commonly found in dry, dark areas including attics and basements, and females tend to be larger and more venomous than males. The venom is very potent by volume when compared to other types of spider.
Main symptoms
The symptoms of a black widow bite are more likely to be systemic than localized and can include;
Initially
- Painless
- Limited or no local reaction
Testing and diagnosis
If the spider bite is witnessed, diagnosis may be self-evident but additional tests may be run to determine the extent of envenomation and to direct treatment.
If envenomation is suspected, there are a number of tests that can be done in addition to a physical examination. These are mostly to eliminate other causes with similar symptoms. Testing may include
- X-rays
- Ultrasound
- Blood work
- Urinalysis
Steps to Recovery
Treatment once a black widow bite is confirmed is administration of the antivenom. Supportive treatment for symptoms include pain management (ice/cold compress, opioids) and medication to reduce muscle tension and spasms (sedatives).
The prognosis is generally good with treatment and some cases may not require antivenom administration, although this produces the most rapid resolution of symptoms. Severe cases may take several weeks to fully resolve.
Prevention
The best method of prevention outdoors is to keep dogs on a leash, especially in forests and other dry, dark areas where the spiders are more likely to be. In the home, prevention can include keeping dogs away from dry, dark areas, awareness of the presence of spiders, and extermination if an infestation is suspected.
Black widow spider bites are not contagious.
Is Black Widow Spider Bites in Dogs common?
Black widow spider bites are uncommon in dogs.
Typical Treatment
- Antivenom
- Pain management
- Muscle spasm medication/sedatives
