Equine Cushing’s Syndrome
Horses, like humans, are living longer, healthier lives and as a consequence, certain age related diseases are becoming more prevalent. Equine Cushing’s Syndrome (ECS) is a disease of the endocrine system caused by an abnormality of the pituitary gland situated at the base of the brain. A characteristic of Equine Cushing’s Syndrome is the production of excessive amounts of the hormone cortisol which negatively impacts on the horse’s ability to effectively regulate blood pressure/cardiac function and protein/carbohydrate/fat metabolism.
Equine Cushing’s Syndrome (ECS) has been documented to affect more than 10% of horses over 15 years of age (McGowan, 2003). While the condition is known to affect all horses, ponies have been reported to be more likely to develop ECS (McGowan, 2003).
Equine Cushing’s Syndrome in Horses
- Increased appetite which may be combined with weight loss
- Abnormal fat distribution (particularly above orbits of the eyes)
- Excessive thirst/urination
- ‘Cresty’ appearance
- Thick coat and failure to shed
Feeds…Can I or can’t I?
It is important to differentiate between non-structural carbohydrates (NSC’s) and structural carbohydrates (SC’s) ie; fibre. Non-structural carbohydrates constitute the majority of carbohydrates found in cereal grains such as oats, corn and barley and are commonly referred to as starch or sugar. Conversely, structural carbohydrates constitute the majority of carbohydrates found in forage products such as hay which also make up the bulk of plant structure and contain little available starch or glucose and are commonly referred to as fibre.
The below NSC values provide a measure of the amount of starch and sugar contained in a forage, grain or mixed feed:
What can be done to prevent the occurrence and/or minimize the severity of these symptoms?
Nutrition is critical. The provision of high starch feeds which contain high amounts of the sugar fructan and feeds high in NSC’s should be closely monitored or avoided. Additional management strategies to be employed include the following;
- Closely monitor body condition score (BCS) and ensure your horse is not carrying unnecessary excess weight as this may also predispose your horse (particularly aged horses) to insulin resistance, therefore becoming more susceptible to laminitis.
- Choose fibre for energy. Utilise high energy fibres such as copra meal or beet pulp to meet your horse’s energy requirements.
- Use cereal grains sparingly and only where necessary. When feeding grains, feed only processed grains as this will minimize the risk of starch being delivered undigested to the hindgut.
- Never feed grain or grain-based products to an overweight horse, a horse with Equine Cushing’s Syndrome or IR or horses which have suffered previous bouts of laminitis.
- Anti-oxidants such as Vitamin E may be of benefit to horses suffering from tissue damage and stress. Ranvet’s Ration Balancer supplies a supplementary source of Vitamin E, along with other key vitamins and minerals.
- Avoid treats such as sugar cubes, molasses and apples as these are high in sugar.
- Utilise energy dense feedstuffs such as oils and fat based feeds for energy provision. Omega 3 fatty acid supplementation such as Grand Prix Oil is also beneficial due to anti-inflammatory activity.
What about pasture and forage?
You need to be aware of the type of pasture and roughage being fed. Many forages can have high levels of NSC’s, such as fructan and simple sugars like glucose and sucrose. If you are concerned about the level of NSC’s in your roughages, it is possible to have them analysed to determine the NSC content however as a general rule, pasture should be restricted and horses allowed to graze at short intervals preferably in the early hours of the morning when NSC levels are at their lowest due to minimal photosynthesis.
*Lucerne hay is typically a low NSC containing hay. Furthermore, soaking hay in cold water for 1 hour prior to feeding will help eliminate any sugars.