More than 46,000 spider species have been documented worldwide, and nearly all of these species possess venom glands for subduing prey. Of the 113 spider families worldwide, only 23 are of medical and/or veterinary importance. Generally, if the bite of a certain spider species is not harmful to a human, then it will probably not be harmful to a dog either.

The harm that a spider bite can cause to a dog varies by the species of spider that inflicted the bite, as well as the size and age of the dog bite victim. For the most part, medical professionals only mention black widow and recluse spider species as being dangerous to dogs. In the northeast US, recluse spider species cannot be found, and while the northern black widow’s habitat range extends well into eastern Canada, black widows are rarely spotted in the northeastern coastal states.

According to numerous case reports and research studies, tarantulas pose a health threat to dogs, as their venom causes severe inflammation, and if a bite is not promptly treated by a veterinarian, death can result. Of course, tarantulas are also absent in the northeast, but there exists some evidence that yellow-sac spider bites can be physically harmful to dogs, just as they can be to humans in rare cases. Yellow-sac spiders are abundant in the northeast where they are known for invading houses and biting humans without provocation.

The topic of spider envenomation in canines is relatively understudied in the scientific community, but anecdotal evidence indicates that wolf spiders may pose a health threat to dogs. Numerous wolf spider species are abundant in the northeast where they often wander indoors accidentally due to their habit of constantly skittering around residential lawns in search of prey.

Not long ago, a woman living in Massachusetts discovered that her dog had fallen ill in response to a suspected wolf spider bite. Two or three days after the woman herself sustained a wolf spider bite while sleeping next to her dog, she noticed that her dog was lethargic and unwilling to eat. The woman took her dog to a veterinarian after finding a spider bite on the dog’s shoulder that appeared identical to her own bite. After an examination, a veterinarian put the dog on antibiotics to treat the necrotizing bite wound. Eventually, the woman’s dog recovered, but a nasty scar remained.

Persistent licking of bite wounds is one of the most common ways in which pet owners first realize that their dog had sustained a spider bite. Although dogs spend a lot of time outdoors, they rarely sustain spider bites that require veterinary attention, and this is especially the case in the northeast where spiders of veterinary importance are scarce. To put it simply, the northern black widow is the primary arachnid threat to dogs in the northeast, but yellow-sac spiders and wolf spiders should be considered when a seemingly harmful spider bite is found on a dog in the region.

Have you ever found a spider bite on your dog?