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208 Breeds, 422 Health Conditions  |  Find a Vet

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Spider Bites View In Dogs

First Aid Condition

First aid health condition




Condition Overview

Spiders would rather avoid most pets altogether, but they will bite cats and dogs if they feel threatened. Most spider bites are more uncomfortable than dangerous and can be treated in the same manner as bee or wasp stings to relieve the pain and reduce the swelling.


Bites on pets are usually hidden by fur, and often, the spider will be gone by the time symptoms appear. Signs of distress can develop as soon as 30 minutes after the bite, but some venomous bites won't cause problems until up to 6 hours after the encounter. Your pet may shiver uncontrollably or run a high fever (over 104F). As the poison spreads throughout her body, she can go into shock or even develop paralysis.


Almost all spiders are venomous, but only a few can actually penetrate the skin with their bites and also have enough venom (and venom that is potent enough) to cause serious illness.


Diagnosis can be made by evaluating symptoms and identifying the bite site.


First aid helps control the spread of the venom, but your pet will need immediate medical attention. If your pet has a non-poisonous spider bite, first aid is usually all that is necessary.

For Poisonous Bites

  1. Restrict your pet's movement until you get to the vet - Running around or even walking will increase her circulation and make the venom in her system travel more quickly. The reaction can go from bad to worse if the venom reaches her heart or brain.
  2. Keep the bitten area below heart level - This also slows the spread of the venom.
  3. Wash the bite wound - Use cold water and soap to get rid of the bacteria on the skin surface. This reduces the chance of secondary infection.
  4. Apply cold packs to the bite - This will help numb the pain and reduce swelling. Cold also helps decrease blood flow in the area, slows the spread of venom, and can prevent some tissue death. Place a cold, wet washcloth against the injury first, then apply the cold pack as you travel to the vet.
For Non-Poisonous Bites
  1. Remain on the side of caution - If you have seen a spider bite your pet, and it doesn't fit any of the poisonous spider descriptions (in the Prevention section below), it is probably not poisonous. However, if you aren't sure, call your vet right away.
  2. Keep him from moving - Restrict your pet's movement for 2 - 4 hours.
  3. Wash the wound - Use cold water and soap to get rid of bacteria on the skin surface and reduce the chance of secondary infection.
  4. Ice it - Hold a cold, wet washcloth to the wound, then apply a cold pack for 10 - 30 minutes several times a day.
  5. Watch for infection - Monitor your pet closely for signs of infection, which include fever, discharge of pus, and a red, swollen area that is hot to the touch and painful. If you see any of these signs or if your pet is acting strangely in any way, go to your veterinarian immediately.
For allergic reactions - Your pet may have an allergic reaction to spider venom. If you see any of the following symptoms, take her to the vet right away: breathing difficulty, diarrhea, skin swelling, weakness, or collapse.


Identifying Poisonous Spiders - It can be hard to know if your pet has been bitten unless you actually see the spider. It is helpful to know if deadly spiders live in your part of the world, and if so, how to identify dangerous spiders by the way they look and where they live.

Widow Spiders - The widow spiders may be the most common and deadly type of venomous spiders in the United States. They are about the size of a blueberry and have bright red hourglass designs on their undersides, although this shape varies according to species and individual. Widows bite only when accidental contact is made with the skin. 3 species of widow spiders are shiny and black: the southern widow, the western widow, and the northern widow. The southern widow is most commonly found in the south eastern United States, west to central Texas and Oklahoma, and north to New York state. It builds it's web in cool, dark places, such as under woodpiles and beneath trash. The southern widow's hourglass marking is shaped more like an anvil.

The western black widow like to inhabit abandoned rodent holes, but like other widows, it can be found in any urban or suburban setting, even in downtown settings. This spider is the common black widow of the western United States. Although its distinctive marking is usually a perfect hourglass shape, it can be divided into two separate parts in some individual spiders of this type.

The third black widow, the northern widow, prefers to live in wooded areas. Stone walls and tree stumps are other favorite habitats of this species. It usually has an hourglass marking that is divided into 2 long, separate markings. The northern widow is found in extreme southeastern Canada, throughout New England, and south all the way to northern Florida.

There are other species of widow spiders in the united states that are not black. The brown widow is most commonly found in southern states. It can vary in color but is usually brown to gray, and its marking is a complete hourglass. Brown widows can be found in almost any kind of building. The red widow, which can also be orange in color, is typically found only in central and southern Florida and possibly Louisiana. Its hourglass is usually a single elongated marking. This spider lives in sandy, scrub-pine areas.

Widow spider venom is a neurotoxin and causes severe, painful cramps in all the large muscles. it can also sometimes cause paralysis. More info about Widow spiders.

Brown Spiders - There are at least 10 species of brown spiders, but the brown recluse spider is the most common, followed by the Missouri brown spider. Most brown spiders have violin-shaped markings on their thoraxes, so they are often referred to as fiddle-back spiders. They are found all over the United States. Brown spider bites usually kill the surrounding tissue, and without prompt treatment, a tiny bite can develop into a massive ulcer that can take months to heal. The venom can also cause severe blood disorders that won't appear until 3 - 4 days after the bite. More info on Brown Spiders.

Tarantulas - The largest and hairiest North American spiders are found in the southern and southwestern states, including the dry and warmer parts of southern California, and they can have a leg span of 4 inches or more. Most tarantulas are shy and avoid contact with pets and people. The bite is not considered terribly toxic, but some pets can develop an anaphylactic reaction to tarantula bites. More info on the Tarantula.


Pets bitten by widow spiders will often remain weak or have partial paralysis for several days. You may need to carry your pet to the yard or litter box until she regains her strength. Keep food and water within easy reach.

Pets may receive intravenous pain medication like morphine at the hospital after a black widow bite. Depending on how severe the muscle contractions are, you may need to give oral muscle relaxants or seizure-control medicine at home.

Bites from brown spiders often develop into massive sores that can spread, and you will need to give antibiotics prescribed by your veterinarian for up to several weeks to fight secondary infection. A drug called avlosulfon (Dapsone), which is used in humans to treat leprosy, may also be prescribed for up to 25 days.

When the spider bite causes tissue necrosis, water therapy can help heal the wound. Flood the area with pressurized water from a hand-held shower head or a hose nozzle, 2 - 3 times a day. This will clean away dying flesh, massage the tissue, and increase blood circulation to the area, which promotes healing. Your veterinarian will show you the best way to do this.

Show Sources & Contributors +


The First Aid Companion for Dogs And Cats

Publisher: Rodale Inc, 2001

Website: http://www.rodalebooks.com/

Authors: Amy D. Shojai, Shane Bateman DVM

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