Persistent Diarrhea in Adult Cat


I have an otherwise perfectly healthy fixed male cat who for the last six months or so has had persistent diarrhea. He's been examined for parasites, has had cortisone shots and has been put on an anti-allergen diet. So far, nothing has made any difference. I've been giving him Metamucil--jellified and mixed with his food--which has helped a little, but only to the extent that what comes out of him has some consistency, rather than being just liquid. He still has no control and leaves little puddings wherever he goes. Kaopectate hasn't helped, either. Any suggestions???


Whenever it is possible, it is best to get a specific diagnosis for the cause of the persistent diarrhea and then to treat that cause. This isn't always possible, though. These are the things that we do in these cases to try to figure out what the cause of the problem is, so that you can see what has and hasn't been done yet.

We check fecal examinations for parasites, just as your vets have done. It is helpful when a parasite is identified and can be specifically treated for. When we don't find anything on a fecal examination and diarrhea persists we usually go ahead and treat for several of the possible parasite infections, just to be sure they aren't present. We like to use fenbendazole (Panacur Rx) dewormer, because it kills hookworms, roundworms and giardia, which are three of the common parasites. Giardia can be really hard to find on fecal exams, which is why we think it is reasonable just to treat for it to rule it out.

Early in the diagnostic process it is a good idea to check a complete blood count (CBC) and chemistry panel to try to be sure that some problem like kidney disease or liver disease is not contributing to the diarrhea. For cats over nine or ten years of age it is a good idea to check a total thyroxine (T4) value, as well. Hyperthyroidism can cause persistent diarrhea in some instances.

After treating for parasites we usually try two different dietary manipulations to see if they will help. If the cat will eat Hill's w/d (tm) diet, we usually try it. This is a low fat, moderate fiber diet and it will sometimes work to resolve chronic diarrhea. When this works it usually works quickly, so we try it first. If this does not work, then we try a diet that helps eliminate the possibility of food allergies. The best diet for doing this is probably Hill's z/d (tm) diet since it is thought to be truly "hypoallergenic" due to the hydrolyzed protein in it. However, there are alternatives to this diet that use proteins from unusual sources, such as duck, rabbit or deer which are not common in cat foods. It is usually necessary to feed these diets for six to eight weeks to be sure that food allergies are not the cause of the diarrhea. Adding fiber, as you are doing, does work for some cats. Our experience is that it works better when the diet is also low fat, though.

Once we get past the above steps, there is a decision to make. At this point, it is necessary to go to a "trial and error" approach or to consider obtaining biopsy samples of the intestines and possibly the pancreas and liver. Biopsy of the intestinal tract can be done in conjunction with endoscopic examination, which is less invasive than surgery. To obtain pancreas and liver samples surgery is usually necessary, though. I think that endoscopic examination and biopsy is the ideal next step but the cost and/or availability can limit access to this diagnostic test.

If we are going to use a trial and error approach I usually try metronidazole first but other vets like a different order. If it is successful I usually want to try sulfasalazine (Azulfidine Rx) when owners can readily give pills. If not, I might consider using injectable corticosteroids, usually methylprednisolone acetate (DepoMedrol Rx). In some cases, but not too often, we try to control the diarrhea using medications such as loperamide ( Immodium AD tm) or diphenoxylate (Lomotil Rx) for a few days.

For some reason, just stopping the diarrhea seems to help some patients recover. Either that, or some patients coincidentally get better after we use these medications for a few days. Since chronic diarrhea does sometimes stop on its own, especially in young and young adult cats, this is a possibility.

We are not adverse to going back to the beginning and starting this whole process over again when we are not having much success with treatment. For some reason, repeating the lab work sometimes shows a problem that wasn't there the first time or a cat will respond to a treatment we have already tried once, when it didn't the first time. While I can't always explain why these things occur, it is worth repeating some of the steps when therapy isn't working.

If you get really frustrated consider asking your vet to refer your cat to an internal medicine specialist or to a veterinary college. These folks tend to see the really difficult cases of things like diarrhea more frequently than general practitioners and sometimes there is something in that experience that makes it easier to recognize a particular problem.

Learn more about Cat Diarrhea Treatment at Home.

Chronic Diarrhea


Ferdinand was rescued by an agency, tested negative for FIV and leukemia, dewormed, altered, and vaccinated. The problem is, he has always had loose stools. When I first got him the stools were big, soft, and foul smelling. On 11/28 I brought him in to my vet who did not see anything wrong in the stool (or any other health problems) but prescribed flagyl for one week. The flagyl did not lead to marked improvement. The vet looked at Ferdinand's stool again and did not see anything but prescribed a course of Albon and Droncit in case there were parasites that did not show up in the lab tests. These medications seemed to make his diarrhea much worse, to the point where it was liquid, messy, his rectum looked very sore, and he left spots accidentally around the house. On 12/12 the vet instructed me to give him Kaopectate and also gave him a cortisone shot which seemed to help.

I switched their food to Nutramax on 12/17 but the situation declined as Ferdinand's cortisone shot wore off. His diarrhea returned with even more flatulence. On 12/22, the vet put Ferdinand on another course of Flagyl and started us on an 8-week trial of Prescription Diet formula z/d (dry food). I also gave him Kaopectate for 2 days. Two weeks have passed and I have not noticed any change except perhaps that Ferdinand's stool does not smell foul. It is still extremely loose (has no form) and he goes with some urgency at least 3 times a day. I am wondering about the z/d food. I've learned that most vets in my area don't use it yet because it is so new. What do you think of z/d? As for Ferdinand, is there a chance that his diarrhea will improve within 8 weeks if there has been no improvement after 2 weeks? The vet says that if there is no improvement after 8 weeks, the next step might be to do a scope of his insides. Do you agree? What could I learn from this test, and is it worth it?


We have not used z/d (tm) diet in our clinic, yet. However, we have used Purina's HA and LA (tm) diets which are similar, but not identical. We have only used these diets in dogs but of the dogs we have tried to use the diets for, two have had vomiting that occurred when they were on the diet and then stopped when it was withdrawn. I am not sure why this happens but the diets are different in composition from anything that a pet may have eaten before, so perhaps it is just the dietary change itself that leads to these problems. I do think it is a good idea to try a hypoallergic food trial in this type of case and z/d is a good choice as it is clearly hypoallergenic, which is not always the case with the novel protein diets, such as d/d (tm). It takes a minimum of 3 to 4 weeks to determine if hypoallergenic diets will help and your vet's suggestion of 8 weeks is a common recommendation since some cats do respond much later than others to these diets.

I think that I would probably try a few other things prior to considering endoscopic examination, but if they did not work, it is a good choice for obtaining a diagnosis.

The things that I would try are a low fat diet (we use Hill's w/d (tm) diet, but there may be others) and the Iams Low Residue (tm) diet. These diets should be OK for Olive, too. It is important to change from one food to another slowly, so the process of trying these diets may take several weeks. Our experience has been that the low fat diet helps pretty quickly, usually within a few days, when it works. We have not used the low residue diet for diarrhea but I have seen anecdotal reports of success doing this. We have had a couple of cats who got better when dewormed with fenbendazole (Panacur Rx), so we usually try it, too. Sometimes we use loperamide (Immodium AD tm) for a few days to see if it will control diarrhea. Once in a while, if the diarrhea can be stopped it will continue to stay away. There is a small chance of causing excitable behavior in cats when using loperamide. Lastly, we have some patients that seem to respond to either famotidine (Pepcid AC tm) or ranitidine ( Xantac Rx) administration.

As long as Ferdinand feels OK and continues to maintain his weight, it is reasonable to pursue treatment options. If he starts to show signs of being ill, exhibits weight loss or anything else that worries you, then it would be better to pursue a diagnosis. The best way to get a diagnosis is to obtain biopsy samples of the intestines and most vets and cat owners feel that endoscopic examination is a better way to obtain these specimens than exploratory surgery.

Learn some of the causes of Chronic Diarrhea in Cats.

Read more: Diarrhea in Cats and Kittens - VetInfo