In my last post, I talked about venomous snake bites. Today, something a little less scary (for most folks, at least)… spider bites.
I should start out by saying that after the great majority of spider bites, owners won’t have the slightest idea that anything is amiss.
Your dog might be a little itchy around the bite site, but rather quickly that subsides and life returns to normal. What I’m going to talk about are those thankfully relatively rare occasions in North America when spider bites present a serious risk to health.
The Black Widow
When I practiced in southern Virginia, I saw a few dogs that I suspected had been bitten by black widow spiders. They exhibited the typical symptoms of this spider’s venom, which is a neurotoxin.
The dogs all had muscle rigidity, tremors, and were in pain. I treated them symptomatically (e.g., fluids, pain relievers, muscle relaxers, and the like) and they all recovered. This is the most common scenario when the individual that is bitten is fairly large. When petite dogs, cats, or other small animals are bitten by a black widow, the muscles necessary for breathing are more likely to be affected, which can lead to death. In these cases, a human black widow antivenin is available, but it may be prohibitively expensive for some veterinary patients.
Black widows reside primarily in warm areas with mild winters, but they have been found as far north as Canada.
The Brown Recluse
The brown recluse spider lives in the midwestern and south-central regions of the United States. Its bite contains a toxin that destroys tissue, leading to pain and sometimes large wounds that develop days after the bite occurred. Treatment depends on the severity of damage but may include antibiotics, pain relievers, and surgery to remove devitalized tissues and deal with open wounds. Affected dogs may also require symptomatic treatment for nausea and fever.
Secondary Infections and “Hot Spots”
Any injury to the skin, including bites from benign species of spiders, can become infected and/or irritated, particularly if a dog licks, chews, or scratches at the area. Relatively mild itchiness may respond to an oral antihistamine and/or topical anti-inflammatories. More severe symptoms respond best to a short course of a corticosteroid. An antibiotic ointment or spray may be all that is necessary to resolve a superficial skin infection, but oral antibiotics are often required in more advanced cases (particularly if your dog tends to lick topical preparations off before they can be effective!). If an abscess develops, surgery to drain it and deal with devitalized tissue may also be necessary.
If you suspect that your dog has been bitten by a spider, keep an eye on him.
Just as is the case for people, most canine spider bites don’t require medical attention. But if your dog acts sick or develops a lesion at the bite site, it’s time to call your veterinarian.