The black widow spider gets its name from the practice of the female devouring the male after mating. But the female black widow is a threat to more than just her erstwhile mate. The female carries enough neurotoxin venom to injure or kill a small pet. Males, on the other hand, are rarely encountered (for obvious reasons) and are smaller. Incidentally, the practice of eating the male is common in many types of spiders.

Black widow spiders range from about half-inch to one inch in size and are typically shiny black. They have a distinctive red hourglass area on their stomachs. Black widows typically inhabit warm, dry areas, such as those found in the southern and southwestern parts of the United States, although they have been found as far north as Canada. They prefer dark crevice-like environments, such as woodpiles and holes.

The best way to prevent a bite is to limit your pet's access to areas that may house black widow spider nests. Black widows are not aggressive; they normally only bite defensively. Pets tend to be bitten when they invade a nest.

What to Watch For

After a bite, your pet may experience extreme pain in the area around the bite. Nausea and swelling may follow. Other signs to look for include:

Muscle tremors

Rigid muscles

Paralysis

Difficulty breathing

Spasms

A bite can kill your pet. Death is usually caused by paralysis of the muscles and nerves associated with breathing.

Home and Veterinarian Care

If you suspect your pet has been bitten by a poisonous spider, do not place a tourniquet above the bite. This won't stop the spread of venom and may severely compromise the circulation in that area of the body. Keep your pet quiet and calm, and take him to your veterinarian immediately.

Because there is no blood test that can detect black widow venom, your veterinarian will make a diagnosis based on the potential access to black widow spiders and a physical exam to check for muscle rigidity, spasms and possible breathing difficulty.

Your veterinarian will administer medication to try to relax the muscles and help with breathing. Your pet will likely be hospitalized and given intravenous fluids. Although there is an antivenin (an antidote) available for people, the cost is often prohibitive in a veterinarian setting. With treatment, dogs usually survive black widow spider bites but cats, however, do not always fare so well.

Preventive Care

As noted earlier, the best way to avoid bites is to keep your pet away from areas that may contain black widow spiders. Thoroughly investigate your lawn and garden for these spiders. If you discover any, contact an exterminator to remove them. The venom is also dangerous to humans, so take care when working in the area.