Equine Cushing's Disease (ECD) usually involves mature horses, but can affect horses under the age of ten. Currently there is no cure for this disease, either conventional or herbal, but there are several support therapies available that can help to extend or improve the quality of life for ECD horses.

ECD is normally caused by a benign tumour of the pituitary gland. This gland (located in the horse's skull) is responsible for sending out chemical messengers to other parts of the endocrine system in order to control bodily functions, including temperature regulation, blood sugar levels, fight and flight response, appetite and thirst.

Overproduction of these chemicals leads to a disruption of the endocrine system, stimulating a chain reaction of over- and under-produced hormones, which in turn will wreak overall havoc on the horse's well-being.

Symptoms of an ECD horse include long, often wavy, coat throughout the year; lethargy; increased thirst and urination; sweating; increased appetite; weight loss, particularly decreased muscle mass over the topline; fat deposits, including in the supra-orbital hollows above the eyes; potbellied appearance, caused by a weakening of the stomach muscles; increased risk to infection and laminitis; poor eyesight; and spontaneous lactation.

The overall impression of ECD is that the horse ages at an extremely rapid rate. In addition, neurological symptoms (such as impaired coordination of the hind limbs and hyperventilation) may appear at an advanced stage of the disease, as the enlarged pituitary gland can grow to the point where it causes compression on the brain.

ECD horses need a lot of special care and management, and the precarious state of their health should never be underestimated. Routine management should include clipping in summer and winter; rugging in die winter; keeping stress to an absolute minimum; regular grooming; management of infections; expert hoof care; and, most importantly, extremely strict dietary management.

It's in the diet

An ECD horse's diet should be much the same as horses prone to laminitis, i.e. low sugar/low starch. Excess protein is also a danger, so lucern should be limited or restricted altogether. It is a very common mistake of ill-informed owners to increase concentrate feed to their ECD horses when they notice sudden weight loss, but this will further stimulate the vicious cycle of the disease.

Elevated blood sugar levels over a prolonged period can lead to insulin resistance. So, in effect, ECD horses can suffer the same dietary vulnerability as human diabetics. Ideally, ECD horses should have limited, but constant access to good quality low-sugar grass hays. At the same time, they should never be denied access to forage, as their increased metabolic rate can literally put them at risk of starvation.

ECD and laminitic horses should be ­removed from grazing on "sugar risk days" ­(particularly from high-risk grazing) from around 12 am to 2 pm, depending on the degree of risk. Various other stressors such as overgrazing, drought, flooding and seeding can also cause grass sugar "spikes".

The importance of safe grazing for ECD horses was driven home to me earlier this year: Midnight was an elderly mare, but was still ridden regularly on outrides, when she suddenly developed ECD symptoms, and was confirmed as an ECD case by her vet.

We treated Midnight herbally for the disease for a year-and-a-half, and she had been making steady and noticeable improvement over that period. In spite of this, Midnight went downhill extremely abruptly, exactly after four days of very hot and humid weather, which in turn had followed directly after three days of bitterly cold weather and torrential rain.

Fairly typical of ECD, Midnight spontaneously developed a small weeping sore on the heel bulb, indicative of a breakdown in circulation. The sore temporarily seemed to improve, but four days later breaking down completely and oozing pus, with Midnight rapidly deteriorating into acute discomfort. By this stage she was already past any chance of recovery, so the decision was made to end her suffering.

Herbs for ECD

There are no cures available for ECD, but herbal treatment can provide overall health support, resolve some symptoms and slow down the progress of the disease.

First on the list of recommended herbs for ECD is Chaste Tree Berries (Vitex Agnus castus). This herb is a hormonal normaliser, and has been used in several field trials for ECD horses in the UK with noticeable success. Further trials on the herb are being carried out on ECD horses, as it is not yet understood exactly why it is so effective. At this stage it is theorised that the herb stimulates production of the chemical mediator dopamine, which regulates production of the pituitary gland.

Which brings us to the next recommended herbs for ECD – those which are rich in anti-oxidants. This is because the cells in ECD horses, that in normal horses are responsible for producing dopamine, are for some reason limited in their anti-oxidation capacity and are therefore susceptible to dying. Recommended herbs that are rich in anti-oxidants include Rosehips, Spirulina and Green Tea. Grape Seed and Citrus Bioflavenoid extracts are also rich sources of natural anti-oxidants.

Herbs to support circulation (such as Hawthorn, Nettle and Rosehips) are extremely beneficial, as are the liver and kidney support herbs such as Milk Thistle seed and Dandelion or Golden Rod, as these organs are put under extreme pressure by the disease. Bilberries are also recommended to improve eyesight, as these fruits improve micro-circulation, especially for individuals suffering from metabolic diseases.

Kelp helps to support the endocrine system, and is a rich source of minerals and amino acids, which these horses can become deficient in as a result of increased urination.

ECD horses have an increased risk of infection as a result of elevated blood sugar levels and a suppressed immune system so immune support herbs, such as Garlic, Nettle and Rosehips are recommended. At this stage it's slightly controversial as to whether immune system stimulants should be used for ECD, as it is an auto-immune disease and some feel that stimulating the immune system will hasten the progress of the disease.

Some would rate Echinacea as an immune stimulant, whereas others regard it as an immune system regulator, as it has the remarkable bi-directional ability to either stimulate or reduce white blood cell production as required. There have been successful results reported from using Echinacea as a part of an ECD herbal treatment programme.