What causes lethargy and loss of appetite in a 1+ old cat on a new diet for food allergies?

Two months ago my cat developed diarrhea and started vomiting. The vet took her off canned food and replaced her dry (Iams) with prescription foods. She didn’t like either flavor and now she’s on Science Diet. She is eating it but not with her old appetite. She doesn’t look as well groomed as usual, there’s a lack of animation to her face, she’s not active anymore, doesn’t greet us when we come home–all her old tricks appear gone. The vomiting stopped when we stopped the wet food. Her bowels appear pretty much back to normal. Why is she still not herself? She is an indoor cat, spayed, adopted from a shelter when she was approx. 6 mos. old. She doesn’t appear to have lost significant weight. She was always such a love and played with everyone. It is heartbreaking to see her like this.
EDIT: In answer to one of the responses, I did gradually mix in the food with the first two vet prescribed substitutes. When we got to the Science Diet, she ate a piece that accidently dropped on the floor so I went whole strength. At first, she was eating it but now it no longer appeals to her. Thank you for your responses.
EDIT II: FYI–Since adopting our cat, we had always given her Iams, both wet and dry, which I thought was the best commercial brand I could get. I did break down last night and give the girl some tuna and at least she seems to be speaking to me again. 😉 Thank you again for all your suggestions. I think I may give her some homemade food and see how that works.
EDIT III: I’ve made an appointment with another vet for tomorrow.
EDIT IV: Visit to the vet #2 today went very well–she was more responsive. Our cat was running a fever (105+ degrees) and her colon appeared ‘thickened’. The vet did not feel any blockage. She gave the cat a shot of penicillin and B-12. She also gave us a 10 day treatment of an antibiotic which the vet #1 had given us (but for only 5 days) which had worked very well. Once she went off the medication the symptoms came back and that’s when vet #1 diagnosed it as a food allergy. Vet #2 doesn’t seem to share that opinion. She thinks the original infection (vomiting and diarrhea) was only suppressed and when the medication was stopped it continued and has now developed into its present state. Our cat had lost close to 2 pounds so she recommended putting her back on her original food to get her to eat again. I gave it to her at dinner and she did eat. We are also running a complete set of bloodwork. We should have the results tomorrow. Taking her back tomorrow for a temp check.

12 thoughts on “What causes lethargy and loss of appetite in a 1+ old cat on a new diet for food allergies?

  1. for god sake get her off this junk food the vets advise. they are pushing a promotion not in the cats best interest. most pet food is full of crap and creates allergy problems. instead buy a good quality food. or feed your cat good human food. rice, bolied chicken, etc that with perk them up. dont buy science plan or iams (iams are one of the worlds largest animal testers-evil) dont trust the vet when it comes to recommendations. your cat is trying to tell you whats wong. i speak from experience. my dog has the same problems with allergies and weight. i switched hes food to human (obviously basic food groups) and he dropped tons of weight and is fighting fit again. hope this helps

  2. it could be that she is not used to the new food all of a sudden what you should of done is take her normal food and slowly add the perscription foods to her food until thats all she eats and do the same thing to the science diet i might be wrong with cats but call your vet before you do it again to make sure it can be mixed together you do this so their bodies can get used to the new food that will be coming in *~ Hope this helps! ~*

  3. she is not happy. Science diet is fine and dandy but, not all cats are the same. give her some fresh fish steamed with white rice. lots of water on alternate days. maybe that might help. good wishes to kitty.

  4. My cat won’t touch Iams or Science diet at all! The poor cat probably wants something else to eat!

    Try something else, it’s not worth it to watch her suffer like this when it’s just a matter of changing the food.

    Sometime I even just give my cats some people tuna, but I mash it up good, so there are no big chunks. Try a little at a time, see what happens. Salmon is good also.

    My little cat sometimes vomits when she swallows big chucks of food, but when I mash it up a little, there is no problem. Both of my cats have diarrhea when I give them milk, so I don’t do that now.

    Good luck (and go with the pet-owner’s instict) you know your cat better than your vet, if this isn’t working, try another vet or try some other food.

  5. My cat was allergic to chicken, for the first year of her life the vet told me to feed her chicken.
    My husband tried her on different tinned food once we worked out the food that was causing the problem she was fine.
    My cat had the runs and not vomiting.
    My she cat went to live at my mums as my mum had a mice problem. She is happier there no kids to bother her. lol

    My other cat was sick tonight but that was because he stole some liver and it doesn’t agree with him.
    have put my cat on indoor dry cat food which Go kat do he seems quite happy on it.

    I found it was trial and error.

    The cat is obviously not very happy at the moment and she is trying to tell you.

    Good luck I hope you find a solution soon.

  6. I am right in sync with jesselvr and keely here. And I would like to know what the prescription diet is for. Have they told you the cat has IBD (those are symptoms of that)?

    I give my cats a homemade (with a supplement powder) of raw turkey and chicken. So you need to look into homemade diets. Go to: http://www.littlebigcat and read Dr. Jean Hovfe’s article “Easy Homemade Diets for Cats and Dogs.” Dr. Hovfe is a past president of the Amer. Assoc. of Holistic Vets.

    I have not read this article as I am happy with the diet I use. Cat diets are trickier than dog diets because dogs are omnivores like us and they can eat lots of veggies, potatoes and cooked meat. Cats cannot eat cooked meat because the cooking destroys taurine which is essential to cat health.

    I will take the time too to read of Dr. Hovfe’s article. There is a long article there too on commercial cat foods.

    I am a fervent advocate for improving the food that cats eat. I hope that reading the articles at littlebigcat will help you to make a descision to seek out the best diet for your kitty.

    Veterinarians are not knowledgeable about cat nutrition. They have no credit courses in that in their education. They receive “seminars” put on by the food companies.

    According to one of my vets UC Davis in CA now has a small animal nutritionist on the staff of their veterinary school. So future vets will have the benefit of this improved education.

    I belong to a Yahoo group “Holisticat”. A large percentage of the members feed their cats homemade diets so you can get ideas and help in making a switch with your cat.

  7. A suggestion – try the good-quality cat foods, and the home recipes, and advice, listed on http://www.catinfo.org. Actually taking your cat off canned food per se may have been an error (although the specific canned food you fed her may have been really problematic). Dry food does cause dehydration, because cats don’t have the drive to drink enough water to satisfy their needs – and the dry food absorbs some of that when it enters their body. I have switched my cat to all-canned food diet recently (being very, very, very careful what canned food I get him), and he is drinking the same amount of water as when on kibbles. The water content in kibbles is up to 10%; in canned food there are about 70-80% water. I think you can guess what a difference it makes.

    But the junk they put into canned food… it’s reasonable to accept that it can upset a cat’s bowels. Get good-quality food, whatever you decide (canned or kibbles), or, best of all, if you have the time, prepare you cat’s food yourself. The recipes don’t seem all that difficult to do, overall – I am waiting for a bit of decrease in heat (currently I cannot stand the thought of turning my stove on) to try some of the recipes…

    Also, I recently discovered a brand of superpremium kibble food called Advance (www.affinity-petcare.com; http://www.advancepetfood.com.au) for more info; it seemed to agree quite well with my kitty – before I realized the problem of dehydration, that is. Giving him that food according to the instructions made him more active and sociable than he had been before (he accepted Whiskas OK, but this food made me realized how much better a good brand of food makes the cat feel).

  8. Did the vet do blood tests on your cat? My mum’s cat developed some similar symptoms and was found to have a kidney problem (she was also a rescue cat), and has been put on medication as well as special food for that problem. Six months later, the blood tests say that she still needs the medication – probably always will – but she is keeping on top of it, and is her old self again.

    I am not saying that your cat has the same problem, but if the treatment is not working, I would want to get a second opinion and some more tests. What about vitamin shots?

  9. [email protected]

    Take her to another vet; she needs help, and all vets are not cat-friendly. She sounds very depressed and unwell considering her age- try again, and good luck to you both, you must be very worried.

  10. I’v got six cats all vary in what they like, so I tend to feed them cat biscuits, canned food & whiskas nuggets, when I had one very pooley with cat flue I gave them cooked chicken, beef, corned beef any thing they would eat, the vet gave me satchets but told me to put tuna etc anything smelly so they could smell it, if they can’t smell they do not want to eat. Best for the future, I hope you have a happy cat soon.x

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