Cushings Disease has a new name. Pituitary Pars Intermedia Dysfunction (PPID), also known as Equine Cushing’s Disease, is an endocrine disease. An endocrine disease affects the production of the hormones that regulate your horse’s body. Hormones interact with each other and have many effects on the body so disruption to normal hormone production and activity can have many effects. Some of these become more and more noticeable with time.
In the past, some middle-aged horses (15–20 years) were not diagnosed as having PPID because it was assumed the symptoms were simply a consequence of ageing. Knowledge among owners is now increasing, and more and more horses are being properly diagnosed, treated and are returning to good health. These horses can then have a richer, more productive, and interactive middle age.
PPID IN DETAIL
The hypothalamus and pituitary glands, located at the base of your horse’s brain, are the command and control centre for the production of its hormones. These chemical messengers are distributed around your horse’s body to all
other tissues via the bloodstream. In a normal horse, these hormones exist in a fine balance, and play an important role in maintaining and controlling bodily functions.
In some older horses and ponies, neurons (nerves) in the hypothalamus undergo progressive degeneration, and produce insufficient quantities of a nerve transmitter substance (neurotransmitter) called dopamine. Dopamine is important in controlling the secretions of a part of the pituitary gland called the pars intermedia, which in turn is responsible for controlling the secretion of hormones including the important ACTH hormone. When the pars intermedia does not receive enough dopamine from the hypothalamus, the ultimate outcome is the production of abnormally high levels of these hormones, resulting in disease symptoms.
The three most obvious symptoms are:
This is a common, painful and potentially devastating condition affecting the hooves of horses and ponies. Growth rings are often visible (as shown here), indicating repeated episodes of laminitis.
In the foot of the normal horse or pony, the hoof wall and the pedal bone (the lowest bone in the foot) are joined together by finely structured tissues called the laminae. Despite the large weights being borne by the laminae, they are relatively delicate, and easily damaged. In laminitis, the laminae become inflamed and extremely painful, making weight-bearing very difficult for affected horses.
Horses and ponies with laminitis will find it difficult to put their feet down, and will often adopt a ‘rocked back’ stance to take weight away from the painful tissues. If the condition goes on for some time, or there are repeated occurrences in a horse, the damage can become irreversible, leading to rotation of the pedal bone and permanent foot pain. In many cases of this severity, euthanasia becomes the only option.
Laminitis is a key warning sign, especially if it is recurrent, chronic, or of insidious onset; up to 70% of mature horses seen for laminitis have been found to have PPID. In fact, all laminitic horses should be tested for PPID.
2. CHANGES IN HAIRCOAT (HIRSUTISM)
This ranges from mild changes in coat shedding, right through to a full, long, curly, overgrown coat (‘hirsutism’). The presence of hirsutism is thought by some experts to be the most reliable single indicator of underlying PPID,
although not all horses with PPID develop this symptom, especially in the early stages of PPID.
3. CHANGES IN BODY CONFORMATION
– Fatty deposits above the eyes.
– Muscle wasting leading to ‘pot belly’ appearance.
– Muscle wasting and persistent sinusitis.
OTHER ‘CLASSIC’ INDICATORS OF PPID INCLUDE:
• Lethargy, poor performance.
• Recurring infections (e.g. sinusitis) and impaired immune system.
• Excessive sweating.
• Changes in appetite.
• Increased drinking and urination.
HOW CAN YOU TREAT PPID?
PRASCEND® can help your horse look and feel healthy and happy again. Effectiveness studies showed improvement of signs within 3 months. And results were even better at 6 months of treatment. The treatment acts directly on the dopamine-producing neurons in the hypothalamus, helping to bring cortisol concentrations in the bloodstream back to normal levels. The medication is given once daily, and can be mixed with a small volume of molasses or food to ease administration; alternatively it can be dissolved in a small volume of water and administered directly into the mouth. Tablets should not be crushed.
Usually there is a short lag between the beginning of treatment, and seeing your horse return to normal in terms of clinical signs. Those will improve generally within 6–12 weeks after initiation of the treatment. However, it can take up to a year to see the full benefit of treatment.