A 16 year old 15.2hh Thoroughbred cross Connemara leisure horse gelding was recently diagnosed with Cushing’s syndrome (PPID) and the owner is worried about feeding him enough without risking laminitis because he’s not a good doer. He lost some weight last winter, and was fed hay and a scoop of mix twice daily. He had some early stage symptoms of PPID including mild laminitis and is now on medication to control the PPID and is sound and free of symptoms.
Horses with PPID need a good quality diet, but with controlled intake of sugar and fructans (known as water soluble carbohydrates or WSC). Good quality forage with a low WSC content should be sourced (ideally under 10% WSC) and fed ad lib. Well-made haylage can be a good choice because its usually low in WSC but with good levels of energy and protein. If hay is fed, ideally have it analysed. Soaking good quality hay for 12 hours – usually done to reduce WSC – is not ideal because it will reduce the energy and protein too much.
Good quality (but low WSC) forage fed ad lib will help reduce reliance on compound feed, but the horse may well still need some concentrate to help him maintain weight over winter. A low starch, high digestible fibre and oil-rich compound feed should be fed, or low starch straights, e.g. micronized linseed, unmolassed sugar beet with cooked soy bean meal or flakes for extra good quality protein. If the straights option is fed, or less than the full recommended amount of the compound is required, feed a multi-vitamin and mineral supplement as well.
PPID-affected horses benefit from extra antioxidants, and feeding vitamin C daily is worthwhile. Don’t suddenly stop feeding vitamin C because this is harmful – if you run low then gradually decrease until you restock.
If the forage is under 8% protein, ideally feed a source of good quality protein such as cooked soy bean meal or flakes, to ensure the horse receives enough essential amino acids. Soy beans are the richest vegetable source of the most important essential amino acid, lysine.
Watch the good grass during spring and autumn and ideally restrict, supplementing with forage of a known nutrient content (to avoid high WSC intake).