| As summer sets in most horses have shed their | | | | does not occur at all or is greatly reduced. |
| winter coats. But some older horses are still | | | | Other signs include excessive sweating, weight |
| clinging to their winter coat. Some have not shed | | | | loss, poor performance, increased drinking and |
| it at all. | | | | passing increased amounts of urine. Almost all |
| Failure to shed the winter coat is a good indication | | | | affected animals go on to develop laminitis |
| that a horse has Cushing's disease. | | | | eventually. Because the laminitis in these cases is |
| Cushing's disease is being recognised more and | | | | the result of internal problems rather than a |
| more frequently in older horses and ponies. The | | | | momentary dietary indiscretion, it is often more |
| condition is named because of its similarities to the | | | | difficult to treat than laminitis due to dietary |
| human disease of the same name. But there are | | | | causes. |
| significant differences. | | | | Various tests have been used to help to confirm |
| Equine Cushing's disease is associated with | | | | the diagnosis. Unfortunately the tests can |
| excessive cortisol production by the adrenal gland. | | | | sometimes be misleading. In most cases they are |
| In almost all cases, it is caused by increased | | | | not necessary. There is really only one condition |
| activity in the intermediate lobe of the pituitary | | | | that causes older horses not to shed their hair in |
| gland, which sits at the base of the brain. The | | | | summer - and that is Cushing's disease. |
| underlying problem seems to lie with nerves that | | | | So, what can be done for horses with Cushing's |
| should limit the activity of the affected part of | | | | disease? Vets have used a variety of |
| the gland. | | | | medications, originally intended for human use, to |
| In normal horses, ACTH, a hormone from the | | | | treat Cushing's disease in horses. The most |
| pituitary gland, stimulates the release of cortisol | | | | effective seems to be a drug called pergolide. If |
| from the adrenal glands. The blood cortisol level is | | | | the treatment is successful, as well as showing a |
| controlled by a complex "feed back" mechanism. | | | | general improvement in condition, a horse may |
| Basically, an increase in blood cortisol inhibits | | | | start to shed its coat again. |
| further ACTH release, which in turn causes the | | | | Some people have found that herbal mixtures |
| cortisol level to fall. | | | | containing chaste berry extracts have helped, but |
| In horses with Cushing's disease the abnormal | | | | others disagree. |
| pituitary gland produces ACTH, and other related | | | | Clipping the excessive coat will make the horse |
| molecules, some of which increase the "potency" | | | | more comfortable, and may reduce the risk of |
| of ACTH. In addition, the abnormal gland does not | | | | skin infections. Regular corrective trimming of the |
| respond to the normal feedback controls. Most of | | | | feet is likely to be necessary once laminitis |
| the signs seen with Cushing's disease are due to | | | | develops. |
| the increased cortisol activity. | | | | The onset of Cushing's disease need not |
| Often the first sign that a horse is affected with | | | | necessarily mean a horse's days are numbered. |
| Cushing's disease is hirsutism, the development of | | | | But once you spot the telltale signs have a word |
| an excessively long and often curly coat. Shedding | | | | with your vet to discuss the options that are |
| of the coat that normally occurs in summer either | | | | available for managing the condition. |