[brytlea]

I have not paid much attention to them (don’t have any cats, sorry!) altho I do recall that there was talk of cancer at the site of some cat vaccination or other. Sorry I don’t know more about it.
susie

[AnAmericanMother]

It was the flea shot that had some incidents of necrosis and skin cancer at the injection site. Our cats had it (because we have indoor/outdoor dogs even though our cats are indoor only) and had no problems. One did die of lung cancer years later after the shots were discontinued, but it had nothing to do with skin cancer at the site of the injection, and unfortunately Siamese cats seem to have a genetic component for cancer in any event. :-(

A long time ago, there were similar problems with injectable ivermectin (worm medicine) in horses. It also tended to colic the horses if they had a large parasite load, because it killed every worm instantly and the horse's digestive system took a big hit of dead and decaying parasites all at once . . . so they took it off the market and substituted an oral paste.