Help, my Pet has Diarrhea!

By | August 19, 2017

One of the most common reasons pet owners seek the help of a veterinarian is because their pet has diarrhea. Whether it is a regular occurrence for a pet with an over sensitive digestive system or a one off event, it always signifies that something is not right and requires action to firm those stools up again. This article explains in simple terms some of the more common causes of diarrhea in dogs and cats, and how best to deal with the problem.

OK, so you have noticed your pet has diarrhea. The first question to ask yourself is to describe the nature of the feces. The consistency, color and even smell of the feces gives the veterinarian vital clues as to the cause. Here are some questions to ask yourself, so that you are well prepared to answer any questions your veterinarian might ask if you end up seeking his/her advice.

1. How long has your pet had diarrhea for? Has your pet suffered from episodes of diarrhea in the past? If yes, there may be a dietary intolerance to deal with and therefore specific foods to avoid.

2. Is your dog/cat bright and well or depressed and lethargic? If the latter is true, more urgent diagnostics and treatment may be necessary.

3. How is your pets appetite? If your pet is still eating it is a good sign that the cause of the diarrhea is a simple one that is easy to fix.

4. Is the diarrhea watery or just slightly loose? If it is very watery then it suggests fluid is being actively secreted into the intestines, and there is more of a danger from your pet suffering from dehydration due to fluid loss.

5. Has there been any vomiting at all? If your pet has been vomiting too then the disease is affecting the front end of the digestive tract (esophagus, stomach and small intestine) in addition to the back end (small intestine and large intestine). This could be due to something your pet has eaten, or due to toxins in the bloodstream that make the animal feel nauseous.

6. Is there any blood in the diarrhea? Blood can take on two forms; bleeding into the small intestine results in black feces as the blood is partly digested by the time it reaches the anus. Bleeding into the large intestine or rectum leads to reddish feces, with more fresh looking blood. The nature of the blood and the color of the stool tells us the location of the problem. Puppies and kittens commonly have streaks of blood in their feces; this is often no major cause of concern. Copious blood in the feces however is a huge worry and needs immediate veterinary investigation to check for nasties such as anticoagulant toxicity, severe infections and tumors.

7. Which of these two descriptions best fits the diarrhea: A) your pet is producing huge amounts of explosive diarrhea a couple of times a day at most, or B) your pet is straining to defecate and passing small amounts of mucus covered diarrhea 4 or more times during the day. If the answer is A, the small intestine is the source of the problem whereas if the answer is B, the large intestine is where the disease is. This is also important in how the diarrhea is treated.

8. Could your pet have swallowed an object that is lodged somewhere? This is far more common in dogs, particularly those that play with sticks and toys, or those that are given bones to chew. However it does happen to cats occasionally, with things such as elastic, string or cotton. If your pet has swallowed something that is stuck it will usually be vomiting first and foremost, and off its food. An object stuck in the intestine somewhere will often cause diarrhea though, which can lead to rapid dehydration. This scenario requires urgent veterinary attention, for xrays and possible surgery.

Common causes of diarrhea in dogs and cats

1. Intestinal parasites. Make sure your dog/cat is wormed with a licensed veterinary product every 3 months to prevent an infestation building up and causing diarrhea and weight loss.

2. Bacterial infections. Arguably the most common cause of diarrhea in pets. Many animals are by nature scavengers and will gobble up things they find lying around outside, some of which might be harbouring nasty bacteria that cause vomiting and/or diarrhea. Certain bacteria are worse than others; the 3 ones to worry about are E. coli, Salmonella and Campylobacter as these can be passed to humans. However, bacterial infections are usually easily treated by a course of antibiotics. Veterinarians usually prescribe a non specific broad spectrum antibiotic to start with, and if the stools do not firm up then a swab is taken to determine the species of bacteria involved and which antibiotics it is sensitive to.

3. Viral infections. Though quite rare nowadays in the USA and UK due to widespread vaccination, viral infections are often more deadly than their bacterial counterparts. One of the better known and most deadly ones in dogs is Parvovirus, which causes an explosive foul smelling bloody diarrhea, usually with vomiting, and severe dehydration. Since antiviral drugs are seldom used in veterinary practice, treatment usually focuses on keeping the dog hydrated via an intravenous drip, and treating any secondary bacterial infections with antibiotics.

4. Dietary intolerance. Also widely known as food allergy, this is a hypersensitivity reaction to certain ingredients in a pets diet. Certain breeds are more prone to it than others, and it can occur in pets that have been fed the same diet for years but suddenly develop an allergy to one of its ingredients. The symptoms can either be diarrhea, though the animal usually remains bright with a good appetite throughout, or itchiness, in particular licking at the paws. Diagnosis is either via a blood test sent to a specialised laboratory to measure antibodies to different ingredients, or by conducting a strict dietary trial and feeding nothing but chicken and rice for 6 weeks, with no treats at all. Long term resolution is identifying the ingredient responsible and eliminating it from the diet.

5. Inflammatory bowel disease. This is an inflammation of the wall of the intestines, usually due to a defective immune system. It is characterised by a long history of intermittent or constant diarrhea that is non responsive to antibiotics or a dietary trial. Diagnosis is best achieved by taking biopsies of the intestines and having the tissue samples examined by a pathologist. The disease cannot be cured and is often managed with low dose steroids and/or a prescription diet.

6. Liver disease. This tends to occur more in older animals and is easily diagnosed via simple blood tests. There are medications to lessen the symptoms, and a low protein, high fibre diet is advised.

7. Hormonal imbalances. Disease of the adrenal or thyroid glands can cause diarrhea. These can be diagnosed via blood tests and treated appropriately.

8. Cancer. This is unlikely to occur in young animals. There are a number of different types of cancer that can cause diarrhea, all of which have different prognoses. Early identification and surgical removal of some types may be curative, but if they have already spread via the lymphatic system the outcome is poor.

What you should do

If your pet has recently developed diarrhea (and/or vomiting) and seems depressed, lethargic or flat, contact your veterinarian immediately.

If your pet is off his/her food completely, or is unable to hold down water, contact your veterinarian immediately.

If your pets diarrhea (or vomit) contains a large amount of blood or is very dark looking, contact your veterinarian immediately.

If you suspect your pet has a high temperature or is dehydrated, contact your veterinarian immediately.

If none of the above apply, first of all starve your pet for 24 hours. Make sure plenty of water is available during this period (not too cold), but no food at all. Once your pet has been starved for 24 hours, offer him/her a small amount of chicken and rice. If it is eaten, continue feeding small amounts of chicken and rice 3 times a day for the next 5 days. This bland diet will be gentle on the digestive system as your pet recovers. The majority of cases of sudden onset diarrhea will respond to this protocol.

Dr Matthew Homfray is one of the veterinary pet experts at Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.