UNDERSTANDING LAMINITIS IN HORSES

Laminitis is one of the most feared equine diseases due to its painful nature and the severe impact it can have on a horse’s health and longevity. This article provides a comprehensive overview of laminitis, its causes, symptoms, treatment, and prevention strategies.

What is laminitis?

Laminitis is a complex, multifactorial disease involving inflammation of the laminae. These laminae suspend the pedal bone within the hoof and are crucial for the foot’s stability and function. When these laminae become inflamed, they fail to adequately support the pedal bone in the hoof, which can result in the pedal bone rotating or sinking within the hoof. This condition is extremely painful and, in severe cases, may render a horse permanently lame or even necessitate euthanasia.

Causes of laminitis

Laminitis can be triggered by various factors, often related to metabolic issues, mechanical stress, or specific diseases. Key triggers include:

– Metabolic issues: Conditions like Equine Metabolic Syndrome (EMS) and Cushing’s disease (PPID) can predispose horses to laminitis.

– Dietary factors: Overconsumption of carbohydrates, particularly lush, sugary grasses or excessive grain intake, can lead to laminitis.

– Mechanical stress: Excessive weight-bearing on one leg due to injury on the opposite leg or prolonged use on hard surfaces can induce laminitis.

– Systemic infections: Diseases that cause systemic inflammation, such as severe colic or a retained placenta in broodmares, can trigger laminitis.

– Toxins: Exposure to certain toxins, either through contaminated feed or bedding materials, can cause laminitis.

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Common causes of toxin-induced laminitis

Toxin-induced laminitis typically occurs when horses ingest feed or forage contaminated with specific toxins. Common culprits include:

– Mycotoxins: These toxins are produced by fungi that contaminate feed, especially grains and hay. Conditions that promote mould growth, such as dampness and poor storage, increase the risk of mycotoxin production.

– Endotoxins: These are released during bacterial infections, particularly gastrointestinal illnesses. Conditions such as severe colic or enteritis can lead to the release of endotoxins into the bloodstream, triggering systemic inflammation and laminitis.

– Plant toxins: Certain plants, like black walnut, contain substances that are highly toxic to horses. Even brief exposure, such as using black walnut shavings as bedding, can induce laminitis.

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Symptoms of laminitis

Recognising the signs of laminitis early is crucial for effective management and recovery. Common symptoms include:

• Lameness: This is one of the first signs; it is often more pronounced when walking or on hard surfaces.
• Increased digital pulse: A bounding pulse in the foot is often noticeable.
• Heat in the hooves: The hooves may feel noticeably warmer than usual.
• Painful reaction to hoof pressure: Horses with laminitis often react painfully to even light pressure on the hooves.
• Altered stance: Affected horses might adopt a ‘leaning back’/’sawhorse’ stance to relieve pressure on the front hooves or lie down frequently to avoid standing.

Diagnosis and treatment

Prompt diagnosis and treatment are critical in managing laminitis effectively. Diagnosis typically involves a thorough veterinary examination, possibly supplemented by X-Rays, to assess any changes in the hoof structure.

Treatment strategies include:

• Pain management: Administration of anti-inflammatory drugs to reduce pain and inflammation.
• Cryotherapy: Icing the hooves or the legs can help to reduce inflammation in the tissues.
• Rest: Minimising movement and providing soft bedding, such as wet sand, will likely be necessary for some time until the condition has stabilised.
• Hoof support and care: Specialised shoeing, such as reverse shoes, clogs, or hoof boots, supports the hoof and alleviates pressure.
• Dietary management: Adjusting the diet to low carbohydrate and sugar content, especially during recovery.
• Correcting underlying issues: Treating any primary causes, such as metabolic diseases or infections, is essential for long-term management.

A note on acute vs chronic laminitis

The terms ‘acute’ and ‘chronic’ in laminitis refer to different stages of the disease in horses, each presenting unique challenges and requiring specific management strategies.

Acute laminitis

Acute laminitis describes the initial phase of the condition and involves the sudden onset of symptoms. This phase typically occurs within 24 to 72 hours after exposure to a trigger, such as excessive intake of carbohydrates, severe colic, extended standing on hard surfaces, or other stressors that disrupt the blood flow to the lamellar tissues. During this stage:

• Symptomsinclude severe lameness, heat in the hooves, increased digital pulse, and pain in the hoof area, especially when pressure is applied.
• Treatmentis critical at this stage and focuses on alleviating pain, treating the underlying cause (if identifiable), and preventing further damage to the lamellar tissues. Strategies might include anti-inflammatory medications, cryotherapy (icing), and mechanical support to the hooves.
• Durationof this phase can vary but typically involves the first days following the onset of symptoms and is crucial for the prognosis of the horse.

Chronic laminitis

Chronic laminitis refers to the long-term consequences of the disease, which can occur if the acute phase is not effectively managed or when the horse repeatedly experiences episodes of laminitis. Chronic laminitis involves:

• Persistent symptomssuch as ongoing lameness, changes in hoof shape (like the development of ‘founder rings’ or a dropped sole), and, in severe cases, a visible rotation or sinking of the coffin bone within the hoof.
• Managementincludes long-term changes to lifestyle and care, such as dietary modifications to prevent further episodes, regular and specialised hoof care, and possibly custom shoeing to support the altered hoof structure.
• Prognosisin chronic laminitis can vary widely. Some horses may maintain a reasonable quality of life with proper management, while others might suffer from persistent pain and lameness that could eventually necessitate euthanasia.

Key differences between acute and chronic laminitis

• Timeframe and severity:Acute laminitis is immediate and severe, focusing on early intervention to prevent permanent damage, whereas chronic laminitis deals with the long-term consequences and management of a condition that has led to structural changes in the hoof.
• Treatment goals:In acute laminitis, the goal is to stabilise the condition and prevent it from progressing. In chronic laminitis, the focus shifts to managing pain, maintaining mobility, and preventing further episodes or complications.
• Outcome and prognosis: The prognosis for acute laminitis can be good if treated promptly and effectively, preventing progression to chronic changes. Chronic laminitis often indicates permanent changes in the hoof, requiring ongoing management and potentially leading to a reduced quality of life.

Understanding these differences is crucial for horse owners and caretakers to recognise the signs early, initiate appropriate interventions, and implement long-term management strategies to help affected horses lead as normal a life as possible.

Prevention of laminitis

Preventive measures can significantly reduce the risk of laminitis. Key strategies include:

• Diet control: Reducing and closely monitoring the intake of lush grass and grains, and monitoring the quality of hay to avoid mycotoxin exposure.
• Regular exercise: Maintaining a regular exercise regime can help manage weight and improve metabolic health. NOTE: This should only be undertaken when a horse fully recovers from an episode of laminitis.
• Routine hoof care: Regular farrier visits to ensure that hooves are properly trimmed and balanced.
• Early intervention for at-risk horses: Implement proactive management strategies for horses with known risk factors for laminitis.

Final thoughts

Laminitis remains a critical concern in equine health due to its potential to cause severe pain, disability and even death. Understanding the causes and symptoms is essential for early intervention and effective management. Through diligent care, proper diet, and routine medical oversight, the risks associated with laminitis can be minimised, leading to healthier, happier horses.