My dogs have diarrhea with mucous. What's causing it and what to do?
Hi there! Although dogs can get diarrhea from worms, there are other reasons why, including bacterial infections, or even dietary indiscretion (eating something out of the ordinary that they shouldn't), that can cause it. From the description of the mucous, it could very well be colitis - or inflammation of the colon or large bowel.
Also, fleas carry tapeworms, so sometimes the over the counter de-wormers don't take care of those.
You can try a fast of 12 hours of no food, and very little water. After that period of time, 1/3-1/2 of their normal portion of food in the form of boiled or steamed lean protein such as chicken breast or ground turkey (no sauce or seasoninng) can be introduced. If the diarrhea seems like it's improving, or it stops, every 12 hours you can increase the portion little by little until it's back to the normal portion of food.
If the diarrhea is not improving, both dogs should be evaluated by their veterinarian. It is important to make sure that the dogs are not getting too dehydrated from the diarrhea (as even though they may be drinking, they lose way more fluid than they can take in sometimes with diarrhea). The veterinarian can also give them some medications to help with the diarrhea, like, for example, some antibiotics to help re-balance the bacterial populations in the gut.
At any time, if vomiting starts in addition to the diarrhea, I always advise to have the pet(s) evaluated immediately, because this can indicate an intestinal blockage, or a severe gastrointestinal infection or diffuse inflammation. All of those issues need to be addressed immediately.
If the diarrhea does improve with the bland diet, I always advise to feed it until there is 48-72 hours of normal, solid stools. Then, you can transition the dogs back to their normal diet, gradually, over the course of 5-7 days (as switching too quickly can actually cause diarrhea). You can find a food transition guide here:
https://www.hillspet.com/dog-care/nutrition-feeding/how-to-transition-my-dogs-food
Best of luck!
Updated on September 23rd, 2025