Diarrhea is very common in pets. In fact, it is one of the more frequent reasons for a veterinary visit. Whether regularly occurring for a pet with a sensitive gut or a one-time accident, diarrhea always signals that the digestive system is not functioning normally. Let’s explore causes of diarrhea in cats and dogs, and the best approach to dealing with it.
When You First Notice Diarrhea
The first question to ask is what is the color and consistency of your pet's diarrhea, as this often gives the veterinarian vital clues in determining the cause. Here are some questions your veterinarian will very likely ask you if and when you take your pet in to see them:
- How long has the diarrhea been present?
- Has there been any history of diarrhea in the past?
If the answer is yes to previous bouts of diarrhea, there could well be a dietary intolerance at play and so prevention may point to avoiding specific foods.
- Is your pet depressed & lethargic or bright & well in themselves?
More urgent care may be necessary if your pet is depressed and lethargic.
- Is your pet's appetite normal?
If appetite is still normal, most likely the cause of the diarrhea is lower down the gut (e.g., colitis).
- How firm is the stool? Is it very watery or just loose?
If the stool is very watery then there is more risk of your pet suffering from dehydration due to loss of fluids.
- Has your pet been vomiting, too?
Vomiting in addition to diarrhea is more suggestive of the front of the gut being affected such as the stomach and small intestine. Involvement of the stomach and intestines is referred to as gastroenteritis.
- Does the diarrhea contain any blood?
Blood can appear in diarrhea in two ways: small intestine bleeding will result in black feces (the blood being partially digested by intestinal enzymes so it looks a little like ground coffee). Large intestine bleeding often results in red-tinged feces, with fresh looking blood streaks. Therefore, we can partially identify the location of the problem by the nature of the blood and color of the diarrhea.
It can be common for puppies and kittens to have little streaks of blood in their feces but it is worth checking with your veterinarian if you notice any. A larger quantity of blood in the feces requires immediate veterinary care, however.
- Which description is the best fit for your pet's diarrhea?
- A. Large amounts of diarrhea a few times a day, or
- B. Small amounts of diarrhea (covered in mucus) and multiple bouts of straining
- Is there any chance your pet could have swallowed an object (foreign body) that has got stuck somewhere?
Foreign bodies are more common in dogs (think sticks, toys and bone fragments), but we do see them in cats sometimes. When we do, it is often elastic, string or cotton (referred to as a linear foreign body), which tend to pleat the intestines together.
If your pet has ingested something inappropriate that is now stuck, you will usually notice vomiting and retching. The abdomen is often painful and your pet will certainly be off their food. Needless to say, if this is suspected, it is an emergency and your veterinarian should be spoken to straight away.
What Commonly Causes Diarrhea in Cats and Dogs?
- Intestinal Parasites
Use a veterinary-licensed dewormer regularly to prevent build up. Worms can cause diarrhea, weight loss and general ill health.
- Bacterial Infection
Many pets scavenge and will eat up things they find on their travels. These items, like spoiled foods, may harbor bacteria that will cause diarrhea (and often vomiting, too).
Some bacteria are worse than others; the main ones to worry about being E. coli, Salmonella and Campylobacter, as not only will they make your pet very sick, they can also be passed to humans. Veterinarians will likely collect a stool sample to determine the species of bacteria involved to help them choose which antibiotic to use.
- Viral Infection
Widespread vaccination has reduced the incidence of viral infection in pets in the U.S. The most commonly known virus affecting dogs is Parvovirus. This causes a bloody diarrhea that is often foul smelling and explosive in nature, as well as vomiting (and subsequently severe dehydration and anemia). Treatment focuses on reducing symptoms and maintaining hydration via intravenous fluids and antibiotics. Newer antiviral drugs are being trialed and assessed.
- Dietary Intolerance, Reactions and Allergies
These all share common symptoms and are a challenge for your veterinarian to diagnose. Symptoms include diarrhea (the pet usually remains bright with a good appetite throughout), flatulence and itchiness (licking at the paws is very common). Diagnosis can be difficult, involving testing to assess antibody response to different ingredients and strict diet trialing of a novel protein. A dietary trial involves feeding nothing but one single protein source (e.g. chicken) and rice for six weeks, with no treats at all (commercially prepared foods are available for this).
Lactose intolerance has been a common finding in dogs and gluten sensitivity has been reported in Irish Setters. In most cases of adverse dietary reactions, it is the result of a sudden change in diet. Longer-term improvement is achieved if the ingredients causing the problem are completely eliminated from the diet.
Food allergy is a hypersensitivity response to specific ingredients in the pet's food. Some breeds are more prone to it than others are. Vets can see it when a pet has been fed the same diet for years on end and then they suddenly develop an allergy to one of the ingredients.
- Inflammatory Bowel Disease
Inflammatory bowel disease is usually due to a defective immune system. It is characterized by history of intermittent or constant diarrhea that is unresponsive to antibiotics or a dietary trial. Intestinal biopsies are taken to help diagnose this condition. This condition is usually managed with low-dose steroids and/or a prescription diet.
- Liver Disease
Liver disease occurs more commonly in older animals and diagnosis involves blood testing and ultrasound. Medications are prescribed to reduce symptoms, and a low-protein, high-fiber diet is usually advised.
- Hormonal Imbalances
Adrenal or thyroid gland disease can cause diarrhea. Other symptoms related to these diseases will help guide your veterinarian to a diagnosis.
There are a few different types of cancer that can cause diarrhea, all with varying prognoses. Removal after early identification of some types by surgery may be curative. Outcome is generally poor, however, if the cancer has already spread via the lymphatic system.
What Should I Do If My Pet Has Diarrhea?
You should contact your veterinarian immediately if:
- diarrhea has developed recently and your pet seems depressed or lethargic.
- your pet is off their food completely, or is unable to hold down water.
- your pet’s diarrhea contains blood or is very dark looking.
- if your pet has a high temperature or is dehydrated.
- vomiting and diarrhea are occurring.
If none of the above applies, it may be reasonable to starve your pet for 24 hours, making sure plenty of water is available during this period, but no food at all. Once your pet has been starved for 24 hours, bland food such as well-cooked chicken (boiled and skinless with no seasoning) and plain boiled rice (no seasoning) can be offered. Hills i/d® and Royal Canin Digestive Low Fat are commercially prepared alternatives that can be used.
If the food is eaten, keep feeding the bland diet in small amounts, three times a day for the next five days. This bland diet will be gentle on the digestive system as your pet recovers.
Some recommend the use of probiotics such as Nutramax Proviable or Purina’s FortiFlora®.
No over the counter medications (e.g., Imodium) intended for human use should be given to your pet. Kaopectate is especially toxic to cats.
Please note that if you are at all concerned, you should speak to your veterinarian. We cannot provide complete guidance for all scenarios within the constraint of an article. We always recommend giving your veterinarian office a quick call to check on the right course of action.