Acute laminitis refers to the first few days of a laminitis episode during which clinical signs are observed. Laminitis is a painful condition that causes damage to the hoof laminae, which anchor the coffin bone to the hoof wall.

During the acute phase, horses typically display signs of pain including a “rocked back” stance, a stiff gait, or a reluctance to move. The hooves may feel hot with a stronger digital pulse.

Left untreated, acute laminitis can cause life-threatening debilitation or lead to euthanasia. However, with prompt and aggressive treatment, most horses recover from the condition and return to soundness within two months. [1]

There are multiple and interrelated factors involved in the development of acute laminitis. Factors currently being investigated include inflammation, enzyme activation, insulin resistance, vascular endothelial dysfunction, and excessive weight-bearing on the hoof due to a severe lameness in the opposite limb.

Treatment for laminitis focuses on nutritional and medical management. Types of treatments include cryotherapy, anti-inflammatory therapy, pain management, and biomechanical interventions. The single most important part of treatment is to identify and remove the cause.

What is Acute Laminitis?

Laminitis affects the epidermal (insensitive) and dermal (sensitive) laminae of the equine hooves. It can occur in one or more hooves but is most common in the front hooves.

Laminitis can affect adult horses and ponies of any breed or age. However, horses with systemic illness or underlying endocrine diseases, including pituitary pars intermedia dysfunction (PPID) and equine metabolic syndrome (EMS), have an increased risk of this condition. [2]

The acute phase of laminitis involves the onset of clinical signs including pain, heat, and increased digital pulse. This phase can progress to the point that the coffin bone becomes displaced within the hoof capsule, known as founder.

Laminitis can become a chronic condition for some horses. Once a horse has had a bout of acute laminitis, they have an increased risk of future recurrence. [24]


Healthy vs. Laminitic Horse Hoof | Mad Barn CanadaIllustration:


Phases of Laminitis

There are five phases of laminitis recognized by veterinarians. These phases include the developmental phase, acute phase, subacute phase, chronic phase and refractory phase.

Developmental phase: The horse is exposed to one or more predisposing factors that trigger laminar separation in the hoof but with no outwardly visible signs of pain. This phase can last for anywhere from 8 to 60 hours depending on the triggering factor. [20]

Acute phase: The horse displays clinical signs of pain or lameness, along with a bounding digital pulse and heat in the hooves. This phase lasts between 24 to 72 hours and may conclude with the coffin bone rotating and sinking in the hoof, known as digital collapse. [20]

Subacute phase: If there is no evidence of coffin bone rotation or digital collapse after 72 hours of the acute phase, the horse is considered to progress to the subacute phase of laminitis. During this phase, the horse experiences less severe clinical signs and the hoof begins to recover. [20]

Chronic phase: When the coffin bone rotates and sinks (displacement of the distal phalanx), the horse progresses to the chronic phase of laminitis. This phase can last for a few months or it can last for the remainder of the horse’s life. Clinical symptoms may resolve during this period, or the horse may remain lame and continue to experience ongoing pain. [20]

Refractory phase: In some cases, the horse does not respond to conventional laminitis treatment within 7-10 days after the onset of the acute phase. These horses may have extensive damage to the laminae and severe pain. They may require surgical treatment and may never return to soundness. [20][21]

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