My cat has a lump after being vaccinated

Our question this week was:

Dear Dr Debra – My tonkinese mix cat was vaccinated 1 month ago. Two weeks later lump developed. We decided to have it removed. He is just a year old. We have had him since 5 wks old. Should we have waited longer for surgery? We are very afraid and didn’t want to lose him.

Thank you

Christine Aakjar


Hi – thanks for your email. Sorry to hear about your cats lump after vaccinate. The recommendations are as follows:

A swelling, nodule or mass under your cat’s skin in a region of the body that was previously used for injection or vaccination should be taken very seriously. If this occurs, you should schedule an appointment with your veterinarian to have your cat examined and the mass evaluated. This approach is recommended especially if the mass has persisted for 3 or more months, is larger than 2 cm (just under one inch) in diameter, or if you notice that the mass has been increasing in size during the one month after injection or vaccination. Have your veterinarian examine your cat as soon as possible in this situation.

An article that might be helpful to you is Injection-Site Sarcoma (Vaccine-Site Sarcoma).

If it has only been two weeks, personally I think this is a little premature to do surgery. The most important thing that IF surgery is done to be very aggressive – even have a board certified surgeon do it. IF this tumor is the “worst – case scenario” – aggressive margins with a surgeon gives the best long-term prognosis.

Best of luck!

Dr. Debra

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