PPID (Pituitary pars intermedia dysfunction) / Cushing's syndrome

PPID (pituitary pars intermedia dysfunction), also known as Cushing's syndrome, is a common endocrinological disorder in middle-aged to old horses. It usually occurs from the age of 15 and there is no gender or breed predisposition. The development is explained by a malfunction in the pituitary gland. Physiologically, this is where the body's own cortisol secretion is coordinated. This is disrupted in the presence of PPID and cortisol is released into the body in an undirected manner. The clinical signs may initially include a general lack of performance, muscle wasting, increased sweating and immunodeficiency. In the advanced course of the disease, delayed shedding or even a lack of shedding, increased drinking and frequent urination can lead to laminitis and insulin dysregulation (ID).

Blood tests are used for diagnosis in order to be able to detect early cases in particular. The first symptoms can be very unspecific and the diagnosis can be made with a simple blood test (ACTH value). If the result is borderline, a TRH stimulation test is recommended for a more detailed diagnosis. To determine the basal ACTH value, the horse may have eaten beforehand (but no concentrated feed) and the blood sample can be taken at any time of day. The value shows diurnal and seasonal fluctuations, so early morning sampling is recommended. For a stimulation test, it is crucial that the sample is taken on an empty stomach in the morning and in the months of January to June. For both tests, stress for the horse should be avoided in advance (pain, acute laminitis, transport...) so as not to influence the result.

If the horse is now diagnosed with PPID, drug therapy with pergolide is recommended. This medication can alleviate the clinical signs and significantly improve the quality of life. Regular check-ups help to find the optimum dose for each horse. In addition, adapting the feed and husbandry helps to optimise the increased requirements according to age.

Equine metabolic syndrome (EMS) / insulin dysregulation (ID) / insulin resistance (IR)

In addition to PPID, EMS is another important metabolic disease in horses. In approximately 30% of PPID affected horses, ID or IR also occurs. This is a derailment of the carbohydrate and fat metabolism. These are risk factors for the development of hormonally induced laminitis.

Horses with EMS suffer from regional or often generalised obesity. The fat pads on the mane crest („cresty neck“), shoulder and croup are a typical sign, along with ravenous appetite, laminitis and colic. Light-fed breeds, such as ponies and robust breeds, are more frequently affected. Years of lack of exercise and an oversupply of feed lead to EMS occurring in middle-aged to older horses.

Diagnostic options include a simple blood test or a dynamic diagnostic test. One of the aims of the test is to assess the horse's insulin regulation. For the blood test, the horse should not have eaten any concentrated feed or grass for 4-6 hours. Hay intake is permitted.

Important therapeutic measures include reducing weight and increasing exercise. If necessary, a feed test and feeding counselling can be arranged in order to provide the optimum amount of nutrients with less feed. Physical exercise is also an important aspect in counteracting laminitis. In therapy-resistant cases, dysregulation can be temporarily counteracted with medication and thus facilitate weight reduction.