What to Do When Your Cat or Dog Has Chronic Constipation, Diarrhea, or Indigestion

1 Why Gut Flora Balance Matters

Veterinarian Amy Dicke notes that 60 to 80 percent of a pet’s immune system is located in the digestive tract, so how well the gut functions has an outsized effect on overall immunity.

The gut is not only where nutrients are broken down and absorbed; it is also a critical barrier that keeps harmful bacteria, toxins, and pathogens in the intestinal lumen from invading the body.

In short, once the microbial balance is disturbed, pets are likely to develop a range of digestive complaints and become more susceptible to infection.

2 What Throws the Microbiome Off Balance

Diet plays a major role in shaping the gut flora. The three macronutrients (protein, fat, and carbohydrate) along with dietary fiber all influence which bacteria thrive.

In the wild, cats are obligate carnivores and dogs are primarily meat-eaters that also forage selectively for beneficial foods, such as mice, which supply lysine. Modern pets eat mostly processed kibble and canned foods, which brings regularity but can also lead to a monotonous diet, while table scraps and hard-to-digest grains add further imbalance.

It is worth noting that stress, emotional upset, ongoing medication, and a naturally lower bacterial count can also disrupt the microbiome, so changing the whole diet is not always the answer.

3 How Probiotics Help Restore Gut Health

Probiotics are beneficial live bacteria that, when consumed as a supplement, help maintain a healthy microbial balance. Research shows they can be effective for managing gastrointestinal disease in pets.

Common, well-studied strains include Bifidobacterium, Lactobacillus acidophilus, and other Lactobacillus species. In one 2017 study of 249 dogs with gastrointestinal disease, 83 with viral diarrhea, 69 with bacterial diarrhea, 38 with parasite-related diarrhea, 45 with chronic diarrhea, and 14 with constipation, targeted treatment plus oral probiotics produced a marked improvement and high recovery rate.

However, simply eating foods that contain these strains is no guarantee of benefit, because most bacteria are killed by the strong acid in the stomach, and only acid-resistant strains survive to reach the gut.

4 Choosing a Probiotic That Actually Works

Probiotics also lose activity at high temperatures, which is why many foods that claim to contain them have no real effect.

For that reason, choose a high-activity probiotic that is both heat-stable and acid-resistant. If the bacteria die before they reach the intestine, the supplement cannot do its job.