Laminitis is a disease of the attachment between the hoof wall and the bone within the capsule. The bone is attached through a series of leaflets which support the entire weight of the horse. When this attachment becomes severely inflamed it can break down resulting in a loss of the foot's structural integrity. In severe cases the bone displaces relative to the hoof capsule in the form of rotation or sinking.
The horse pictured above developed laminitis secondary to endocrine disease. He developed septic pedal osteitis secondary to the disease process. Dr. Lordan managed him in glue on shoes with a treatment plate to access the compromised area. The abscess pocket was treated with medical grade maggots. The horse recovered well.
Causes of laminitis include endocrine diseases, sepsis or severe illness, support limb laminitis and mechanical. Endocrine disease is one of the most common causes we see in the field. Horses that are overweight are prone to Equine Metabolic Syndrome which can lead to insulin resistance. Older horses with Cushings (Pituitary Pars Intermedia Dysfunction) can develop laminitis by a similar mechanism. These horses are very sensitive to sugars in grasses or in their feed and their diets must be managed very carefully.
Laminitis caused by severe illness such as pleuropneumonia, retained placenta or endotoxemia follows a slightly different chemical pathway. This form of laminitis can progress very rapidly .
Support limb laminitis is the result of prolonged weight bearing . For example, a horse with a fracture may refuse to stand on the injured limb during the healing process and this compromises the structures in the supporting limb. The supporting limb then develops laminitis and begins to deteriorate.
Horses with laminitis are often diagnosed by clinical examination but radiographs are necessary to determine the severity of disease and follow its progression. An adjunctive diagnostic tool is the venogram.
The horse's foot is enveloped in a vast network of blood vessels and when the bone shifts or moves within the hoof capsule it compromises the blood supply. This in turn contributes to the breakdown of the foot and prevents normal growth. The venogram allows us to identify those areas of compromise and make more specific treatment recommendations.
In extreme cases of rotation or displacement a deep digital flexor tenotomy may be indicated. This is considered a salvage procedure as very few horses can ever be ridden again.
The deep digital flexor tendon acts as an antagonist to the lamellar attachments and when the lamellae break down, the tendon contributes to rotation. By cutting the tendon we remove that antagonistic force and pressure on damaged vasculature. This results in rapid growth of the foot.
While many horses can be treated with conservative management, medication and shoeing, laminitis is a severe disease with sometimes fatal consequences.