Sick cat two weeks after vaccinations

Question
Hello Dr. Jennifer,

My seven year old cat Snoopy received his annual booster shots 16 days ago. In one hind leg he received the comprehensive shot for D-Fvr, Rabies, and Fecal, and in the other hind leg, a Leukemia shot. They aren't new to him because every year he gets these vaccinations -- however, he's never had them administered as two shots before, if that means anything.

Since these shots two weeks ago, Snoopy hasn't been the same. His appetite has decreased as well as his energy. I finally took him to the vet yesterday when he began wimpering as he walked. The doctor gave him a careful examination including X-rays and (preliminary) blood works. He stated that Snoopy is obviously sore and dehydrated (and has lost 15 oz in two weeks) but other than that, the tests results rendered no other information. The doctor chalked up Snoopy's sickness to a negative reaction to his shots. Snoopy was administered an anti-inflammatory shot and milky liquids (Rebound Liquid Diet) by the doctor, and I was given these as well to admininster to Snoopy at home.

Snoopy seemed like his old self again yesterday right after that vet visit, but today he's back to being very lethargic and uninterested in his food or liquids.

My question is, can vaccinations really cause this bad of a reaction on some cats? Also, how worried should I be for my cat's current condition? Can he bounce back at any time, or can he just wither away? Lastly, if he really is having a negative reaction to his shots, what is the system or organ most affected i.e. muscular, renal, cardiovascular etc?

Thank you for any feedback or insight!

All the best,

Judi

Answer
Judi,

Most cats have no problems after vaccines.  Many will spike a small fever and be lethargic for a day or two.  And a few have severe reactions.  In this case, I would recommend DISCONTINUING any future vaccines except Rabies as required by law, and before that is given, pre-treat with Benadryl and Dexamethasone or Prednisone.

I would recommend a trip back to the vet...a SQ fluid treatment as well as a B12 shot and a repeat steroid injection would be indicated at this point.

As far as systems affected, it is the immune system that is the problem.  Some times they will be a bit sore at the muscle around where the injection was given.  But there should not be any complications with his organs.

Good luck,
Dr. Fry