Ahhh, gastrointestinal diseases. We see lots of these in cats. Vomiting, diarrhea and not eating are probably the most common symptoms that we see in cats daily. There are so many causes of GI upset in cats that we will just touch on some of the most common ones, including intestinal parasites, intestinal bacterial overgrowth (IBO), food allergies/intolerances, inflammatory bowel disease (IBD), foreign bodies, chronic constipation, and cancer.
Intestinal parasites. Very common in cats that go outside and cats that have had fleas. Unfortunately, these are not always easy to diagnose. The simplest to diagnose and one of the most common intestinal parasites we see are roundworms. They will show up in most standard fecal floats. We can also find whipworms and hookworms in fecal floats, but they are not as common. Coccidia is another fun little intestinal protozoal parasite, but cats don't shed their eggs consistently, so they are not always found in a fecal float. Tapeworms are the other most common intestinal parasite that we see, but they are very hard to find. They almost never shed eggs in the stool, so usually we have to rely on actually seeing the tapeworms on the rear end, which look like little grains of moving rice.
Less common, but very hard to find, is giardia and tritrichomoniasis. These are protozoal parasites that we need a fresh fresh fecal sample to do smear on, and if we are lucky, we will see them moving under the microscope. If not, we can have a fluorescent antibody test done to find giardia antibodies, which is a little pricey, and for tritrichomoniasis, we might get lucky and be able to grow them in a special culture pouch, but not always. And then of course, there is toxoplasmosis. This doesn't usually cause intestinal disease, but this is the one that they warn pregnant women about in regards to changing litterboxes during pregnancy. This requires a special blood test to find. No one dewormer will get all intestinal parasites, which is why we generally want to at least look at the stool to see if we can find eggs or the organisms themselves.
Most of these parasites are spread by fecal-oral contamination - stepping on another animal's stool, then grooming the paws and ingesting it, such as sharing a litterbox, or by eating grass that some animal has defecated on up to 2 years earlier, because that is how long some eggs can exist in the environment. Tapeworms can also be spread by eating contaminated fleas. Doesn't that just sound yummy. The good news is that virtually all intestinal parasites are treatable, it is just a matter of finding which parasite it is, to give the most effective dewormer.
Intestinal Bacterial Overgrowth, or IBO. This commonly occurs secondary to some type of intestinal upset, including stress or other intestinal diseases. There is normally a ton of bacteria in the intestinal tract. Most of this bacteria aids in digestion - it helps to break down the food coming through. But some of these bacteria serve no good purpose at all, other than waiting to cause disease. Now this "bad" bacteria is usually kept in check by the "good" bacteria. But, due to multiple causes, the "bad" bacteria on occasion can grow out of control, resulting in diarrhea and or vomiting, depending on where in the intestinal tract the infection is.
We will generally treat IBO with antibiotics. Antibiotics though, can sometimes be so effective, that not only do they wipe out the "bad" bacteria, but they also wipe out the "good" bacteria, basically causing more problems, so we try to target the bacteria with specific antibiotics that are less likely to affect the "good " bacteria. This is also where probiotics come in. Probiotics are "good" bacteria that we feed to cats to try and restore normal balance to help keep the "bad" bacteria in check. It is a delicate balance to restore everything back to normal. Sounds like a bad B movie, doesn't it. Oh, the joys of diarrhea in cats.
Food allergies. We see this in all ages of cats. Even cats as young as 6 months of age can develop food allergies. Food allergies stimulate an immune response that results in inflammation, which can result in vomiting and nausea. Initially, this just causes the cat to not feel good. However, over time, the chronic inflammation in the intestinal tract can lead to inflammatory bowel disease and even intestinal cancer. So, best to nip it in the bud. There are certain food allergies that are a little more common. We will commonly see carbohydrate allergies in young cats, kind of like a cat Celiac disease. This is easy to fix, we put the cats on a high protein low carb diet. In older cats, fish is a common allergen. But, cats can be allergic to any ingredient found in their cat food, and they generally need to have been exposed to it for a while previously to develop an allergy to it. Cats cannot be allergic to something they have never been exposed to.
There are two ways that we commonly use to diagnose food allergies in cats. The first is to try a hypoallergenic diet trial. There are several prescription diets that contain ingredients not found in any over the counter cat food. We switch your cat to that diet exclusively for 4-6 weeks, and if the symptoms go away, then we know we have a food allergy. We don't know to what, but your cat can stay on the hypoallergenic diet indefinitely. The other way is to test for food allergies, either by drawing blood and having the serum tested for antibodies to certain ingredients, or by doing a skin scratch test. There is a lot of controversy as to the effectiveness of food allergy testing, but we at All Feline have had pretty good luck with it.
Inflammatory Bowel Disease, or IBD. This is unfortunately all too common in cats, it is not easy to definitively diagnose, and treatment for it can have some undesired side effects. IBD is a chronic inflammatory condition in the intestinal tract, and sometimes stomach as well. It can affect a small area, or the entire length of the GI tract. It is characterized by higher than normal levels of white blood cells, specifically lymphocytes, plasma cells, neutrophils, or eosinophils in the walls of the intestine. Over time, this chronic inflammation results in thickening of the intestines and scar tissue development, which inhibits absorption of calories and nutrients. In later stages, cats will eat continuously, but just waste away because they can't absorb what they need from the food. This can be triggered by intestinal parasites, food allergies, chronic IBO, food intolerances, chronic stress, or what we call idiopathic, which means we have no idea of the cause.
The only way to definitively diagnose IBD without a doubt is to do full thickness biopsies of the intestines. Endoscopic biopsies can be done, but since they are not full thickness, they are less likely to yield an accurate answer. To do full thickness biopsies requires full blown abdominal exploratory surgery. So, is surgery is not feasible, we will treat presumptively.
The gold standard of treatment is steroids and/or immunosuppressants - specifically a drug called chlorambucil. Steroids have a high risk of diabetes with long term high dose administration, and chlorambucil can cause anorexia and bone marrow suppression. It is also very pricey. However, they are the two most effective drugs for IBD, and if we don't keep the inflammation under control, then your cat can develop scar tissue, thickened intestines, and in some cases, it can progress to intestinal lymphoma. We may also try a hypoallergenic diet, or low residue diet just in case a food allergy is what started the IBD. There are other meds we may use in conjunction, but steroids and immunosuppressants are the big guns.
Just recently, we have also started using another method for treating IBD. We haven't really used it in enough cats for long term to really know if it is going to work as well or better than steroids, but initial results have been very promising, and that is to switch your cat to a raw food diet. The thought process behind this is that cats were designed to eat raw food - in the wild they would be catching mice, rabbits, etc. and eating them raw in their entirety. They weren't designed to eat corn, rice, eggs, etc., and so commercial cooked food results in antigenic stimulation, which results in intestinal inflammation. Now, as discussed on the diets page, you cannot make a homemade raw food diet that is safe for your cat and is nutritionally balanced unless you are working with a veterinary nutritionist. In the wild, cats will eat all of the animal - bones, liver, muscle, spleen, etc. There are some commercial raw food diets, and a few of the companies have been experimenting with a high pressure 'pasteurization' system designed to kill bacteria and parasites, but keep the nutrients intact. These are the diets that we are starting to try with cats with IBD, and have had a few good results so far. That doesn't mean it would work for your cat, but when looking at a lifetime of medications, it doesn't hurt to try, just make sure to work with your veterinarian on it. You also have to get your cat to eat it, which is a whole other ball game.
Foreign bodies. An article was recently published in a veterinary journal about some of the most unusual things removed from cats and dogs stomachs. The winner for cats was a cat that had over 100 hair bands removed from the stomach. Now, this was unusual. But it is not unusual for cats to eat strange things that they cannot digest. At All Feline, we have surgically removed string, yarn, pieces of phone cord, a dime, many pieces of plastic and rubber toys, mini blind cord ends, hairbands, a fish hook, and of course hairballs that were too large to vomit. This is primarily a young cat problem, but even some older cats will do it as well.
If you have a cat that likes to chew on things, or you seem to be missing things, and suddenly your cat starts vomiting and can't keep anything down, the first thing we will want to do is an x-ray to look for a foreign object. Unfortunately, not everything ingested will show up on an x-ray, only thick plastic and metal. So, we look for hints. Unusual gas patterns in the intestines. Dilated intestines to a certain point, then empty. Stomachs that seem distended even though your cat hasn't eaten anything for a day or two.
If we are suspicious, but not sure, we may want to run some barium through your cat. This is a liquid contrast agent that we syringe feed to your cat, and then we take a series of x-rays to watch it go through. If it get stuck somewhere, or we see a space filling defect, good chance there is a foreign object. Sometimes we are highly suspicious, but just can't seen anything, especially with stomach foreign bodies that haven't plugged up the intestines yet. In this case, we may ask to just go in and do an exploratory surgery. On the off chance that we don't find a foreign object anywhere in the GI tract, as long as we are in there, we will take biopsies to look for IBD or pancreatitis as a cause of the vomiting.
Chronic constipation. This tends to happen more in older cats, but some breeds can be predisposed to it, especially the Manx breed, and it can develop in cats of all ages. In older cats, it usually happens from losing more moisture through the kidneys as a result of chronic kidney disease, which means that there is less moisture in the stool, and the feces become hard and dry. Arthritis is another cause in older cats, it hurts so much to squat, that cats don't do it as much, and the stool builds up. In younger cats, it can be idiopathic, that lovely medical word that means we have absolutely no idea of the cause. Over time, the colon muscles can stretch from the stool building up in it, and in the final stages, your cat develops what is called megacolon. This is not a good thing, and the only fix, if the muscles are completely stretched out, is to remove the colon, and attach the small intestine to the anus, which then has the potential for chronic diarrhea.
If we think your cat has constipation issues, we will first want to rule out underlying diseases such as kidney disease. If we cannot find a reason, then we will want to start your cat either on a fiber supplement or a stool softener. Fiber helps pull moisture into the stool, but it can also bulk it up to some extent. Fiber is very effective in early stages of constipation, but in later stages, can actually cause more damage once the colon muscles start to stretch since it can make the stool even bigger. At that point, we go to a stool softener and/or a drug that increases intestinal motility. Most cats will do very well on these drugs, and can live a normal life as long as we can prevent the colon from stretching more.
Cancer. The most common type of cancer that we see by far in the GI tract is lymphoma. This can be as a progression from IBD, or just develop on its own. Lymphoma can respond to some extent to chemo, but it is not a cure, and in most cases, we will treat your cat with what is called palliative meds - meds to make your cat feel better, but not fix the disease, which usually consist of high dose steroids and/or immunosuppressants. At some point though, you may have to make a decision whether or not to keep going.