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Dr. Kara
Dr. Kara, Veterinarian
Category: Cat
Satisfied Customers: 18147
Experience:  Over 20 years of experience as a veterinarian.
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My cat had vaccination booster 2 weeks ago and a week later

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my cat had vaccination booster 2 weeks ago and a week later she developed a lump on her shoulder blade so i took her back to vet, he said give it a few weeks 3 4 to see if it goes down he also said there was a chance that it could turn cancerous i am worried sick and need more advise what is the likely hood of this happening? and should i wait up to 4 weeks? will it grow rapidly if cancer and what are the things to look out for?
Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am very sorry to hear that your kitty received her booster vaccination a couple weeks ago and has now developed a lump. Of course this would make you concerned. Some cats will have an inflammatory response to a particular vaccine as it is seen as foreign material by the body. Most commonly we see them with Rabies vaccines or the leukemia vaccine, but it can happen with any vaccine. We see firm swellings usually a few days to a few weeks after the vaccine. Usually by warm compressing them they resolve on their own over time.Ideally we would aspirate the lump to look for signs of infection. If infection is present the abscess should be lanced and drained and she should be on antibiotics. If these are inflammatory granulomas then an anti-inflammatory can be prescribed to hasten their resolution. Very rarely (1 in 1,000 to 1 in 10,000) these can become cancerous so if the lump isn't resolving over the next several weeks it should be removed surgically. It takes time for these inflammatory nodules to turn cancerous, and waiting for 4-6 weeks or so to see if it resolves won't allow it time for that to occur.In short most of these inflammatory nodules resolve and don't become an issue, but they always bear a close watch.Please let me know if you have any further questions.Please let me know if you have any further questions.
Customer: replied 2 years ago.

thank you for you quick reply so what you are saying is its not cancer at this stage and waiting is the best thing to do is this a common thing for lumps to appear after boosters? it was felv by the way when you say 1 on 1,000 or is it 1 in 10,000 which is it?

Yes, it isn't cancer at this point. It is an inflammatory reaction that may become cancerous later, but it is worth giving it time to see if it can resolve because most of them do resolve and do not become cancerous.While it isn't common to see an inflammatory nodule after a vaccine, it happens enough that it is something quickly recognized and we simply advocate a close eye and don't panic.There have been various studies to try and track how often these vaccine associated tumors (sarcomas) come up and the studies have come up with different statistics. The statistics range anywhere from 1 in 1,000 to 1 in 10,000. True incidence is probably somewhere between those numbers. Either way that tells it is a pretty rare occurrence, so try not to get too worried yet.I usually aspirate them, measure them and have the kitty come back in about a month. If the nodule gets smaller then I continue monitoring. If it's getting bigger or staying the same size then I recommend surgery.
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