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My cat's steroid shot isn't stopping her itching. Dosage or allergies?

Updated on September 23rd, 2025

Pet's info: Cat | American Shorthair | Female | spayed | 11 years and 3 months old | 10 lbs

My cat has an autoimmune disorder. She scratches herself until she breaks the skin and gets an injection of depomedrol (a steroid) every 2-4 months to treat it. It usually works like a charm. Recently at this new vet though, they gave her the injection and it seems to be wearing off. Her old vet said she was getting 1cc of the shot and her new vet gave her 20ml this past time. 20ml seems like a lot. What is going on? Is it just because of the weather change that she's so itchy?

1 Answer

Most Helpful Answer

Megan, DVM, CVA

Answered By Megan, DVM, CVA

Veterinarian

Published on April 3rd, 2018

Poor Maggie. I think there has been a misunderstanding. They probably gave 20mg (milligrams) which is equal to either 0.5mL (milliliters) or 1.0mL of depo-medrol depending on the concentration your vet carries. The general dose that most vets use is 20mg depomedrol per cat every 8 weeks as needed. I seriously doubt anyone would give 20mL of this drug.

Also, it could be wearing off quicker if there are more allergens causing her skin to act up. With it being the changing of the seasons, this very well could be the issue. Also make sure she is on a high quality flea preventative. One flea bite can cause a major allergic reactions in cats with her problem. If she needs another depomedrol shot, I would talk to your vet and see if they would be willing to repeat the injection as early as 6-8 weeks during high allergy season. You could also start giving her benadryl twice a day. See link below. I hope this helps!

https://www.petcoach.co/canigive/cat/benadryl/#!
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