Pumpkin or psyllium for a dog’s loose stools?

Psyllium in dogs

22 police dogs with chronic idiopathic large-bowel diarrhea were given psyllium husk at four tablespoons a day for a month: 50% responded very well, 40% well and 10% poorly; defecations fell from 3.5 to 2.9 a day and 90% had consistent stools (Alves et al., 2021). A follow-up trial of 30 dogs compared psyllium at 16 g a day with fecal microbiota transplant over 30 days and found a similar effect, with the transplant working faster (Alves et al., 2023). An older series of 37 dogs given Metamucil at a median two tablespoons a day with a highly digestible diet reported a very good to excellent response in most (Leib, 2000), and a retrospective study of 32 dogs with chronic enteropathy whose total dietary fiber was raised to 4.7 g per 100 kcal found the median fecal score fall from 4.5 to 2 with 87.5% improved (Ford-Hrymak et al., 2026).

Psyllium in cats

The cat evidence is for constipation. A multicenter randomized blinded trial of 49 constipated cats compared a 6% psyllium diet with a 0.5% diet: diet failure was 26.9% against 73.3% (p=0.0005) (Rochon et al., 2026). In 9 healthy cats a 6% psyllium diet produced more bowel movements (p=0.0052), a higher fecal score and more stool wet weight than cellulose (Keller et al., 2024), and in 66 constipated cats on a psyllium-enriched diet 93% and 82% improved on the two measures (p<0.001) (Freiche et al., 2011). These trials used diets with psyllium built in; a powder added to food supplies the same fiber at whatever dose the label gives.

Pumpkin

Searches for pumpkin in dogs or cats returned a protein-digestibility study of pumpkin press-cake in eight dogs, ethnobotany surveys and parasite work, and no trial of pumpkin on stool quality in either animal (Godgluck et al., 2025). That is an absence of trials, not a trial that failed: pumpkin is a soluble and insoluble fiber source and the products built on it are used the same way. It means the products with pumpkin alone have no evidence to point to, while products that pair pumpkin with psyllium can point to the psyllium trials for that ingredient.

Which to choose

For loose stools in a dog, the trials used psyllium at doses from about two to four tablespoons a day in working and pet dogs, so a product that states its psyllium content per serving is the one that can be dosed against them. For a constipated cat, the trials used a diet at 6% psyllium; a psyllium-containing powder is the closest supplement. Pumpkin-only powders are a fiber source with owner reports behind them and no trial. Start any fiber at half the label dose for a few days; a sudden fiber load produces gas in dogs as it does in people, and a dog or cat straining without passing stool, passing blood, or off water is a vet visit.