Original Question: I went to the vet and my puppy received a dosage of Revolution for fleas. After that his scratching got worst and he got bumps on his stomach and ears. I don’t know what to do to stop this reaction or could it be something else? I have applied cortisone to try to calm his itching. - Melissa
So I’ll start off by saying that Revolution contains the active ingredient called selamectin and it’s primarily used to treat and prevent flea infestations, although it’s also active against some other parasites as well. And like any drug there’s a small risk of side effects and it really does sound like this puppy has had an allergic reaction to the Revolution that’s caused itchiness and hives.
Of course it could be that the dog was also stung by a bee or had an insect bite or something at a very similar time and that’s caused the reaction. So we can’t say for certain that it was the Revolution, although I’m not a big fan of coincidences and that would have to be up there in the concerns.
Now, while an allergic reaction is a possibility, there are other potential side effects to selamectin and that includes, going off food, drooling, vomiting, and diarrhea. You can even get labored breathing, twitching and even seizures if we’re having an allergic reaction to any kind of product or insect bite. These side effects are considered very rare and generally affect less than 1 in 10,000 animals so it’s not very common.
Treatment of an allergy really depends on how severe it is and that can include a number of different things. It can include antihistamines and so that can be antihistamine tablets and also steroids and that can be by injection, tablets, and creams. If we’re having a severe allergic reaction, then adrenaline is going to be the thing to give. So just like with people who have peanut allergies, for example, they’ll carry an EpiPen around and that contains adrenaline which is for the treatment of severe reactions. So in the same way if we’ve got a dog or a cat who’s having a severe allergic reaction, then adrenaline may be something that we need. Although it’s very rare that that’s the case and the best treatment is going to be based on an examination of the patient by the vet to see what works best. Also if we know that a dog has had allergies, so if we’re talking about something like a bee sting and they just get a little bit of itchiness and a bit of hives, then it would be appropriate to have some treatment on hand to give without needing to necessarily consult with your vet provided that that was doing the job and things weren’t getting worse despite giving that treatment.
Now what do we do with this puppy? I think that’s based on the vet’s examination. It doesn’t sound like it was a severe enough reaction to need any more serious intervention and injections, but there are a number of things that can be given. We also want to avoid this happening in the future. So it might be a good idea to avoid this class of drug in the future in this specific puppy. Talk to your vet about which other products are appropriate and that’s really going to depend on where you are in the world, depend on which parasites are present in your local area and what the disease risk is for diseases that are carried by parasites as they are different. Parasites can be fleas, it can be ticks, it can be sandflies and diseases can be things like heartworm Leishmania, and Lyme disease.
So there’s a number of different things to consider and depending on all of those risks will determine what the best class and the best product to use in your specific individual dog in your specific individual area.
I hope this helps.
Dr. Alex Avery