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Ask a Vet: What Do You Do When Your Cat Is Stung or Bitten?

What are treatment options for cats who've been stung or bitten by snakes or black widow spiders? One popular remedy, shockingly, is illegal.

 |  Mar 18th 2014  |   3 Contributions


The good folks at Catster HQ forwarded a question from an anonymous cat lover. Here it is:

I need to know info on cat emergency help, for future reference. Lizzie is a dilute calico cat and she is fine now, but just in case it should happen again, I need to know what I should I do if we have a repeat incident.

Yesterday she was sitting on the porch railing watching the three of us chatting. My friend was standing near her when he was suddenly attacked by a wasp. He waved it off and got off the porch. Lizzie was not so lucky. The pissed-off wasp nailed her nearly in the eye. Bless her heart, her eye swelled shut immediately and teared horribly. We kept a very close watch on her the rest of the day ready to drive like the proverbial bat to the vet if necessary.

I know with dogs I can give them Benadryl and I know the dosage for dogs. But we have six cats and I vaguely remember you aren't suppose to give it to cats. Is this true? If you can give it, what dosage? Children's? If not what could I give? We also give 
Benadryl for snake bite. What do you give cats for snake bite?

Photo of Dr. Eric Barchas by Liz Acosta

Today we're going to talk about wasp stings and snake bites in cats. Yikes! While we're at it, we might as well include another creepy-crawly: black widow spiders.

Bees, wasps, hornets, and yellow jackets have complex venoms that cause pain and histamine release. In addition, histamine itself is a component of many bee, wasp, and yellow jacket venoms.

Histamine, in case you're wondering, is a molecule that occurs naturally in the body. When it is released by the cells containing it, it causes swelling, itching, and redness. Histamine is what makes a mosquito bite itch. Histamine is what causes noses to run and eyes to water in cases of hay fever. Severe release of histamine into the bloodstream can lead to vomiting, diarrhea, intestinal ulceration, low blood pressure, anaphylaxis, and death.

Cats react to bee stings (and the stings of the other insects mentioned above) in one of two ways. Most cats suffer from localized pain and swelling at the site of the sting, such as poor Lizzie developed after the wasp stung her. This is normal, and may last for a day or two. Although Lizzie was stung on the face, cats are most frequently stung on the foot when they hunt for or step on stinging insects.

Some cats are especially sensitive to bee stings. These cats develop the generalized histamine release that can lead to vomiting, diarrhea, collapse, anaphylactic shock, and even death.

Adorable? Yes. But also in danger of encountering a bee. Tabby kitten by Shutterstock.com

Since histamine plays such a crucial role in bee, wasp, hornet, and yellow jacket stings, it is not surprising that diphenhydramine (also known as Benadryl), which is an antihistamine, is used to treat them. When I treat a cat for such a sting, I administer roughly one milligram of diphenhydramine per pound of body weight by intravenous or intramuscular injection. I also sometimes prescribe the same dose orally. (In cases of shock, epinephrine or steroids may also be necessary.) Such treatment usually leads to resolution of symptoms within hours.

Here's the rub for our anonymous questioner: Unless your vet has specifically prescribed diphenhydramine for you to use in your cat, its use in the cat is illegal. Furthermore, it is illegal for your vet to send you to the pharmacy to pick up Benadryl, or for me to recommend that you administer Benadryl to any of your pets at home (and I therefore admonish you not to do it). Granted, if a person were to administer 1 milligram of diphenhydramine per pound cat weight after a bee sting, it likely would prevent symptoms from developing. And that person probably wouldn't get caught. But it's illegal, so it must not be done.

Why is it illegal? There are some valid reasons. For instance, many products that contain diphenhydramine also contain pseudoephedrine or acetaminophen. If a person were to accidentally administer such a product to her cat, then life-threatening toxicity would develop.

But the illegality actually stems primarily from a more basic issue: bureaucracy. The Food and Drug Administration (FDA) prohibits the use of any medication in a manner that is not consistent with its labeling. If you read the label on a bottle of Benadryl, you will see that there is no mention of its use in cats. Therefore, for Benadryl (or any medication) to be used legally in cats, a new label, i.e., a prescription label, must be provided. Veterinarians are required by law to issue a prescription for any medication, including human over-the-counter products, that is to be used in cats. Believe it or not, most vets don't know this, and many of them risk their licenses on a regular basis as a result.

But I have digressed. We have discussed the treatment for bee, wasp, yellow jacket, and hornet stings. What about envenomation from snakes or black widow spiders?

Rattlesnake photo by Tigerhawkvok

I am happy to say that snakebite is relatively rare in cats. In those rare instances, rattlesnakes are most likely to bite cats in the U.S. Although dry bites are possible, cats that suffer envenomation may develop swelling, tissue necrosis, blood clotting abnormalities, and neurological irregularities. Antihistamines such as Benadryl do not directly treat snake envenomation, and there is nothing that can be done at home for cats who are bitten by rattlesnakes.

Treatment for rattlesnake bites includes supportive care, intravenous fluids, pain killers, and sometimes antibiotics. These treatments should occur at a veterinary facility. Antivenom use is controversial. One recent paper recommended its use in cats. Another, published at almost exactly the same time, found that antivenom did not significantly affect mortality, but did predispose cats to a condition (called type 1 hypersensitivity) that increased mortality tenfold. Fortunately, both papers found low mortality rates for cats afflicted by snakebite.

Sadly, cats bitten by black widow spiders generally do not fare as well. They are extremely sensitive to the spider's venom. Black widows are found throughout the U.S. (except for Alaska), and they are prevalent in areas of human habitation. Their bite leaves almost no mark, so it can be difficult to diagnose cats who have been envenomated unless the owner witnesses the incident.

Two words: Serious danger. Black widow photo by Steve Ryan

Black widow spider venom is a neurotoxin. Benadryl has no direct impact on cats bitten by black widows, and no home treatments are effective. Symptoms of black widow spider envenomation include severe pain (with marked vocalization), severe GI upset, paralysis, drooling, seizures, and staggering. Death often occurs as a result of respiratory paralysis. Treatment must occur at a veterinary facility and is symptomatic: pain control, antiseizure medications, and intravenous fluids are administered. There is an anti-venom for black widow spiders that is considered safe for use in cats, but it is not commonly available.

Prevention is better than treatment for all of the bites and stings discussed in this post. Indoor cats are much less likely to encounter bees and wasps, and almost certain not to encounter snakes. Black widows are most common outdoors, but may spin webs inside under furniture or appliances. Such areas should be checked regularly for evidence of the spiders.

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