FEED ADVICE – HEALTH

Optimal Cushing’s Management: Essential Tips

Cushing’s disease, also known as pituitary pars intermedia dysfunction (PPID) is the most common hormonal disorder in horses. While all horse breeds can be affected, native breeds may be more prone, as well as older horses.

The condition involves an overgrowth in the pituitary gland’s pars intermedia at the base of the brain. This region of the pituitary gland produces hormones that play a crucial role in regulating various bodily functions. This growth leads to an overproduction of adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal gland to produce excessive amounts of cortisol. Symptoms include abnormal hair growth, chronic infections, laminitis, excessive sweating, increased drinking and urination, weight loss, lethargy, and muscle loss. Other signs may include abnormal fat deposits, reproductive issues in mares, abnormal mammary gland development, and ligament degeneration.

Key Highlights

Cushing’s disease, also known as pituitary pars intermedia dysfunction (PPID), is a common endocrine disorder.

It primarily effects older horses over the age of 15, and is most commonly seen in native breeds such as Welsh and Dartmoor ponies.

Clinical signs include delayed sheeding, abnormal fat deposits and muscle loss.

Treatment options include medications and dietaty management.

Understanding Cushing’s

Cushing’s disease, or PPID (Pituitary Pars Intermedia Dysfunction), occurs when part of the brain’s pituitary gland – the pars intermedia – stops working properly. This gland normally helps regulate hormones that control many of the body’s vital functions.

In horses with Cushing’s, the pars intermedia becomes overactive, usually due to a benign tumour or age-related degeneration. This causes the gland to release too much of a hormone called ACTH (adrenocorticotropic hormone). ACTH then overstimulates the adrenal glands, leading them to produce excessive cortisol – the hormone often referred to as the body’s natural “stress hormone”.

Chronically high cortisol levels can affect nearly every system in the horse’s body. Common signs include a long, curly coat that doesn’t shed properly, weight and muscle loss, increased drinking and urination, laminitis, lowered immunity, and recurring infections. Left unmanaged, these clinical signs can have a serious impact on the horse’s well-being.

Clinical Signs

Identifying the early warning signs and symptoms of Cushing’s disease is crucial for early detection and management of the condition. While the clinical signs can vary, there are several key indicators that horse owners should be aware of.

Physical Changes Seen with Cushing’s

Horses affected by PPID exhibit several distinct clinical features. Abnormal hair growth, known as hirsutism, is commonly seen along the crest of the neck, shoulders, and tail head. In advanced stages, Cushing’s can cause progressive muscle wastage and a loss of musculature along the topline, resulting in a pot-bellied appearance and reduced exercise tolerance. Laminitis, characterised by foot tenderness, lameness, and a characteristic stance, is a recurring issue in horses with PPID, complicating their management. Additionally, PPID compromises the immune system, making affected horses more susceptible to infections, delayed wound healing, and heightened vulnerability to parasitic infestations.

Behavioural Changes seen with Cushing’s

In addition to physical changes, horses with Cushing’s disease often show behavioural alterations that can significantly affect their quality of life and performance. These changes can be subtle but are important to recognise:

Horses may exhibit changes in temperament, becoming more irritable, lethargic, or showing mood swings. This can impact their interaction with handlers and overall behaviour.

Additionally, Cushing’s disease can lead to a decline in energy levels and athletic performance, affecting the horse’s ability to perform tasks or participate in activities as they normally would.

Polyuria (excessive urination) and polydipsia (excessive drinking) are frequent signs, indicating disruptions in fluid and electrolyte balance due to hormonal imbalances.

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Illustration of a horse's brain showing the pituitary gland and effects of increased ACTH levels caused by benign tumors, including symptoms like increased thirst, delayed shedding, infections, and behavior changes.

Diagnosis of Cushing’s

Accurate diagnosis of Cushing’s disease in horses involves a combination of diagnostic approaches. These approaches help assess the horse’s hormone levels and detect any abnormalities associated with the condition.

Diagnostic testing for Cushing’s disease typically includes:

Blood sample analysis:

A blood sample is taken to measure hormone levels, including adrenocorticotropic hormone (ACTH) and cortisol.

Dexamethasone suppression testing:

This test involves administering a synthetic steroid called dexamethasone and measuring the horse’s hormone response.

ACTH levels:

An elevated ACTH level is a common indicator of Cushing’s disease.

These diagnostic approaches provide valuable information for accurately diagnosing Cushing’s disease in horses and determining the most appropriate treatment strategies.

In addition to blood tests, imaging techniques can be used to confirm the diagnosis of Cushing’s disease in horses. These techniques help visualise the pituitary gland and detect any abnormalities associated with the condition.

One imaging technique commonly used is magnetic resonance imaging (MRI). MRI provides detailed images of the pituitary gland, allowing veterinarians to identify any growth or abnormality in the region of the pituitary gland affected by Cushing’s disease.

Imaging techniques, combined with blood tests and other diagnostic approaches, provide a comprehensive evaluation of the horse’s condition. They help confirm the diagnosis of Cushing’s disease and guide veterinarians in developing an appropriate treatment plan.

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Treating a Horse with Cushing’s

Treatment for Cushing’s disease in horses primarily involves medication aimed at regulating hormone levels.

One of the most prescribed medications is pergolide. Pergolide works by suppressing the production of adrenocorticotropic hormone (ACTH) and cortisol. Typically administered orally in tablet form of varying strengths, pergolide requires careful monitoring of hormone levels and clinical signs to gauge its effectiveness. Vets often recommend periodic retesting of ACTH levels after initiating treatment and at regular intervals thereafter to assess the horse’s response and adjust the treatment plan as needed. This monitoring ensures optimal management of the condition and supports the horse’s ongoing health.

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Dietary Managment for Cushings Disease

Dietary management and environmental adjustments play a crucial role in managing Cushing’s disease in horses. These strategies help support the horse’s overall health and well-being and minimise the impact of the condition.

A low-starch, high-fibre diet is essential, as it helps prevent glucose spikes and reduces the likelihood of insulin dysregulation and laminitis. High-quality forage forms the cornerstone of their nutrition, providing vital nutrients while promoting gastrointestinal health and supporting optimal metabolic function. Supplementing with essential vitamins and minerals such as vitamin E, selenium, and magnesium addresses common deficiencies in PPID-affected horses, supporting overall health and immune function. Hydration management is also vital, ensuring PPID horses, especially those prone to polyuria and dehydration, have continuous access to clean, fresh water. These dietary and management practices are integral to maintaining the well-being and quality of life of horses with PPID.

Did you know the majority of the Pure Feed range is suitable for horses with Cushings? We specialise in low sugar and starch, high fibre feeds, fortified with vitamins and minerals to help address the common deficiencies.

Consider limiting field access during periods of high sugar content. These sugars are naturally present in grasses and can vary depending on factors such as species, time of day, weather conditions, and growth stage.

During certain periods like spring, grass tends to accumulate higher levels of sugar due to factors such as cooler temperatures and increased sunlight. This rapid growth phase, often seen in lush, young grass shoots, can lead to higher concentrations of sugars. In some cases, particularly in certain grass species or under specific environmental conditions, the accumulation of sugars can exceed what is normal for horses to efficiently process. Ideally during this period, horses should have restricted grazing time, or wear a muzzle to limit grass intake.

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Conclusion

In conclusion, Cushing’s disease presents a significant challenge in health management. This hormonal disorder impacts horses of various breeds, particularly older individuals, and manifests through a range of clinical signs. Early detection, regular vet checkups, medication and correct diet can help horses with Cushing’s disease live a normal life. Due to the prevalence of Cushing’s, there is continual research and advancement in treatment options offer a more optimistic outlook for horses.