Mysterious weight loss in my cat?

Question

I have two 6 year old male (neutered) house cats (brothers) that I've had since they were 8 weeks old. Since about May, one of them (Harry) has been going outside at night for a few hours, sometimes all night. He has never been allowed to do this before, but I have been allowing it lately because he enjoys it so much. Ever since I've been allowing him out though, he has been losing weight at an alarming rate. Last year at this time he weighed about 10 lbs. Now he weighs 6.5 lbs. I can feel ribs and backbone, hip bones and chest bones sticking out all over, way more than before. My other cat (Patch) who does not go outside ever, is actually overweight and weighs 12 pounds.

So Harry is eating, drinking, pooping, peeing and active. Besides being let outside, the only other thing different that has happened to him is he's been getting into my gerbil cages and killing and eating the gerbils. He did this to 5 of my gerbils until I finally figured out how he was getting them out and put a stop to it.

So I am just at a loss for explaining his dramatic weight loss apart from his increased night time activity and possibly acquiring worms outside or from my gerbils. I cannot see him getting worms from my gerbils because my gerbils are healthy and do not show signs of infection. Plus, I've raised them in the same cage since they were pups and have never exposed them to raw meats or outside parasites.

Does anyone have any suggestions for why my cat has been losing weight? I am worried about him and am considering taking him into the vet if he doesn't start gaining. I have put a stop to his night time outings. All positive advice is welcome!

Answer 1

could be thyroid disease.

Answer 2

Probably a parasite. Likely a tapeworm.

Answer 3

anytime a cat loses over 30% of his weight with no apparent explanation it is cause to take him to the vet.  Soon.

Answer 4

He definitely needs a trip to the vet. There are so many things that it could be - most of those listed already - and I would not take any chances.  Get him to the vet, tell the vet everything that's been going on, and do it ASAP.  Whatever it is, you need to try to get it while it's treatable (hopefully it is), hasn't done too much damage, and hopefully hasn't infected your other cat.  You might consider taking them both in.  If it's leukemia, your other cat is at risk.

Answer 5

Stop considering and take action!

Something is seriously wrong & only a through examination & tests by a vet can determine the cause. He needs a blood panel to check for infection, virus & organ function. He also needs a fecal sample run to check for intestinal parasites. As he has been allowed free run outside he should also be checked for FeLV, FIV, FIA & FIP.

It could be as minor as a serious case of worms or as serious as liver or kidney failure - you will never know w/out testing.

Answer 6

I would suggest taking him to a vet.  There are many illnesses that he can contract from being outside including Feline Leukemia (which is highly contagious to other cats).  My cat lost a lot of weight and started breathing heavily.  Unfortunately, she had a lot of fluid in her chest and we lost her last April.  The best thing to do is get it checked out as soon as possible.

Answer 7

Is he eating or has he lost appetite?Cats can get feline lukemia outside that will cause them to loose weight.But then he just may been very active when he goes outside,Just notice if he is eating.

Answer 8

Hey may have gotten internal parasites from something he ate or drank outside.  You should take him to a vet.