Vet Talk

Arachnophobes, Start your Engines!

What do you do if your pet is bitten by a spider?

September 2, 2019 (published)
Illustration courtesy of Depositphotos

I can still hear the shrieks from my stepdaughters’ bedrooms on the other side of the house because someone spotted a spider. Always taking the opportunity to explain to them that spiders are an important part of the ecosystem, I would corral what would usually be a wolf spider or daddy long legs safely into a container for transport and rehoming somewhere outdoors.

Having concluded with a bittersweet sigh that it’s not going to happen as often anymore because the youngest just left for college, I’ve reluctantly stepped down from my family post as spider wrangler. What will they do when I am not there to corral the spider for them? I suspect they’ll manage or enlist someone else to help, although I won’t be one bit surprised when I get the late evening phone call, “Help, there’s a spider!

Spider Fun Facts

  • Technically, spiders are not insects or bugs, they’re arachnids. The Arachnida group also includes scorpions, ticks, and mites. The distinguishing feature is that they typically have eight legs and eight eyes (sometimes six eyes), while insects from the group Insecta have six legs and who knows how many eyes. The term bugs, however refers to hemipterans (Hemiptera group) which includes other creatures like bed bugs and cicadas.

  • Charlotte from the book Charlotte’s Web is a barn spider.
  • The condition of being bitten by a spider has a cool name: arachnidism.
  • translucent spider was discovered not too long ago in an Indiana cave. Yes, Indiana, not India.
  • Spiders will generally only bite if cornered or provoked. They don’t like humans any more than most people like them but they do like the messes we leave behind in our homes (hoarders beware!) and the dark spaces under and behind our furniture.

  • Technically, almost all spiders are venomous since they have glands for injecting venom, but only a tiny few are of medical significance.

  • Because so many people are irrationally afraid of spiders, they make great fodder for scary movies such as Arachnaphobia ("Eight legs. Two fangs. And an attitude." 1990); see sidebar below to see how often movie makers try to make a buck off our fears.

Good Spiders

All spiders aren’t bad and some are even considered to be pets. They're not interested in us and they catch and eat lots of pests in the house, including flies, mosquitoes, midges, etc., pests you would prefer not to have as guests in your house. Here are several I consider to be good spiders with one note worthy exception.

Yellow Garden Spider

In addition to Charlotte’s kind, this spider is also an orb weaver. They can be a little frightening at first glance if you’re not prepared, but they do more good than harm by catching and eating other insects. I wouldn’t want one in the house but I typically leave them undisturbed if I see them in the yard. With Halloween around the corner, their showy webs will be an original addition to your usual outdoor decor.

Wolf Spider

These are some pretty impressive spiders and tend to get big. Ranging in color, they can be black, brown, grey, or a combination of these colors. The wolf spider is a diurnal species (active during the day) and you are more likely to see them out and about without the web; web spinning isn’t worth their time as they have great vision.

Tarantula Spider

The tarantula is a low-maintenance pet for some, but dog and cat owners beware! The bite of a tarantula can be lethal to a dog or cat. Keeping your pet tarantula safe from your other pets, in an out-of-reach containment with a secure lid, should be sufficient.

Simple Tips to Avoid Spiders (Safety Tip: Don't Hide in the Closet)

Keep your closets and under-bed spaces free from clutter. Some spiders are nocturnal, so any dark places such as cabinets, closets, or cluttered spaces make great homes for spiders. After de-cluttering your home, you’ll be ready for a garage sale!

Keep the contents of your garage to a minimum, lawn trimmed short, and outdoor shrubs, bushes, and trees neatly trimmed to let the light in. Tall grass and dense landscaping are a safe haven for spiders.

Wear gloves when doing activities around the yard such as clearing tree branches and bagging fall leaves.

If you are seeing a lot of spiders, you can call a bug control specialist capable of treating a spider infestation. 

Venomous Spiders 

Black widow spiders inject a potent neurotoxin, which affects the nervous system as well as the nerves near the bite site. The venom delivered from the female’s large fangs may cause painful muscle cramping, irregular breathing patterns, anxiousness, weakness, and partial paralysis. In dogs and cats, the venom can be life-threatening. Symptoms may last for several days and can sometimes be fatal, particularly to cats. Only the female has the red hourglass mark; the males are considered non-toxic because they have smaller fangs. Treatment includes anti-venom, muscle relaxants, intravenous fluids, anti-seizure medications, pain medications and symptomatic supportive care.

Brown recluse spiders on the other hand, inject a necrotoxin. This toxin causes necrosis, a.k.a. tissue death, of skin and potentially of tissue that is below it (e.g., muscle). Signs of a bite are intense itchiness and redness of the skin as well as a “bull’s-eye” lesion, characterized by an inner pale ring and outer red ring. The resulting lesion from the bite leaves a crater after the dead tissue has been removed. There is a huge variability of the potency and quantity of venom injected, so cases can be mild or life-threatening if there is damage to the liver and kidneys. No anti-venom is available, but strong supportive care measures may be needed, including wound care.

A combination of any of the signs above along with observing a small bite wound or prior history of your pet chasing after and even eating a spider raises the suspicion of a spider bite. With the latter, a pet may not have a visible bite wound as it could be out of sight (i.e., somewhere in the mouth). In this scenario, the pet may exhibit pain from in or around the mouth and possibly have trouble chewing or using their tongue.

Incidentally, I stumbled across a simple test used to help diagnose brown recluse spider bites in humans, which is based on detecting cooler skin around a potential bite site, simply by touch. Could this also be a quick and useful test to aid diagnosis in pets?

You’ve spotted a spider inside and other than scream, you’re not sure what to do. Here are some options:

  • Just let the spider be (they're not interested in us and catch/eat lots of pests in the house, including flies, mosquitoes, midges, etc.).

  • If you’re sure it’s not a venomous ("poisonous") spider, you can catch and rehome it outside, especially if someone inside is afraid of it. We do not recommend that you do this with bare hands or with venomous spiders due to the risk of a bite.

  • Use your vacuum cleaner hose with the long tube attachment to suck up the spider and quickly empty the contents of the waste bin into the trash or outside so it can’t escape or crawl up your arm.

  • If it’s a venomous spider, the bottom side of a shoe or rolled-up newspaper should do the trick, or even a tennis raquet (if you are Woody Allen).

  • If it’s not a venomous spider but you’re convinced it shouldn’t live (even though we encourage you to let it do so) you can corral it into a closable container and simply place it in the freezer. Freezing spiders is a slower but slightly less traumatic way for them to die.

Bites from nonpoisonous spiders usually only cause mild reactions but it depends on the individual that has been bitten. Rarely, humans can have an allergic reaction to the venom of nonpoisonous spiders. A secondary infection at the bite site can occur as well.

Finally, if you’re worried a spider has bitten your pet because you’ve discovered a small bite-like wound or your pet is experiencing characteristic signs, don’t delay calling your veterinarian. Immediate treatment may prove to be life-saving because death is a potential outcome of a venomous spider bite. For the most part, however, spider bites are just a little annoying, like the spiders themselves.


September 29, 2019

I have two cats and an arachnophobic wife... These two cats are her protectors.we moved into a house on a lake in n.e. Texas and ended up sleeping in a tent pitched in the middle of the living room. This was because the house was utterly and completely infested with brown recluse spiders.ive done the research and have no problems identifying the bug and I'm no stranger to it's bite. Being one of the most common spiders in you house (at least where I live) its bite is one if the most rare. And when bitten, it may or may not be so bad as the spider can vary in poison amount and poison potency. Anyhow. My wife is so afraid of spiders or any other insects(carpet fuzz,dustbunnys,shadows)that we are not allowed to even speak the words.whether or not she needs the help of professionals or not is is up for debate. Our two cats which I'm too embarrassed to say their names, adore my wife. So much so that over the years of living here ,even after eliminating the infestation, actually hunt for spiders at night mostly but especially before bedtime almost making a show of it. The crazier part of it is they hunt these spiders and eat them. It doesn't matter what kind they are how big or small and yes, how poisonous they are. May be that they have just been lucky and never been bitten by the right one. But I swear, they actually love eating them more so than the expensive treats we buy for them. They actually fight over the spider hunt and the quick meal afterwards. There was a time when my wife called me on my cell...I was upstairs she was downstairs trapped in her bathroom because of a snake in the hallway. So I ran down there to find two crazy looking cats and a snake that was stripped halfway down its tail of everything but it's vertabrae. The snake was very much still alive .. it was a baby snake, cottonmouth,about a foot and a half long. I cut its head off threw that and the remains in a jar.and did a once over on the cats they were fine though I did feel a few really small knots or lumps here or there on them . Legs, face limbs and so on but watched them for several hours to decide that they where fine. We went outta town for the evening and came home the next day to find the cats hiding in separate corners sick and very lathargic. I was surprised because they were eating and playing after the half day of watching them before we left. By now all the lumps and bumps they received from that evil little snake had swollen into huge hot bulges of misery. I rush them to the vet and he was surprised to see how many bites there were between the two and how they weren't as affected as badly as expected. He gave them some shots and said I would definitely need to bring them back for treatment of worms. Said eating the a** end of a snake was some nasty choice in fingerfoods.but the cats survived rather quickly and have decided spiders good . Snakes... No good.i worry about what will my wife do if and when she looses these cats. Those cats saved her life. But back to spiders..... Did you know that brown recluse are the only spider with six eyes. That's the for sure way but not the only way, to identify these spiders. But who wants to put their face that close to a spider to count its eyes?;no thank you...

Aine Hawthorn
September 6, 2019

I am not entirely convinced that the 'trick' of detecting cooler skin around the bone is diagnostic for a recluse bite; it seems like that would be true for any lesion with arteritis as the underlying pathogenesis. Recluse bites are very frequently over diagnosed, and if you are outside their native range (the midwest for reclusa, and some minor species that less frequently end up in houses along the southern southwest US border), then it is almost certainly NOT a recluse bite. This is a better description of the bite itself, at least in humans:

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