Question

I own a teenage Lipizzan gelding that weighs approximately 1,000 lb (455 kg). He is fed 1.5 lb (0.68 kg) of a high-fiber concentrate, 15 lb (8 kg) of Dengi Totally Timothy, and pasture when seasonally available. I have owned him for seven years, and he has always had chronic loose manure. It is almost liquid when he is stressed or anxious. I have tried various supplements, but nothing seems to work. I have even put him on metronidazole, which clears up the problem but only till he’s finished the medication. He is an easy keeper, eats what is put in front of him, partakes in no stable vices, and has never experienced colic in my care.

Answer

I understand your frustration with your gelding’s loose manure. It seems that if he responds to metronidazole, an antibiotic that treats anaerobic bacteria and protozoa, that perhaps it is a certain microbe in the colon that may be causing the problem. 

The only thing I can suggest is to see if a change in the pH of the colon will make a difference by making the environment less hospitable for that pathogen (raise the pH). Kentucky Equine Research (KER) developed a product that moderates the pH of the hindgut called EquiShure. Typically this product is recommended for horses on high-grain diets, but it has made dramatic changes in horses on high-forage diets with specific issues as well.