Laminitis can occur in horses of any breed and age, and can be a serious and painful condition. As Equine Vetrehabbers or Vet Rehab Therapists, we can play a role in managing and treating pain in subacute or mild cases, and encourage correct biomechanics in the horse during their recovery, as a part of the multidisciplinary team.
Severe, acute laminitis is considered a veterinary emergency, and can be life threatening. Continuous ice therapy for 48-72 hrs is commonly used in the acute phase of laminitis to reduce the temperature of the hoof and slow the progression of the condition. During the recovery phase of the condition, veterinary rehabilitation therapists can play a role in reducing pain, supporting posture and weight distribution, and reducing compensatory dysfunction, together with the veterinarian and farrier.
Below we discuss the causes, effects and management of horses facing this condition.
The Causes of Laminitis
There are three main reasons a horse might develop laminitis:
- Diseases associated with sepsis or endotoxemia
Conditions linked to sepsis or endotoxemia include grain overload or excessive ingestion of carbohydrates, retained fetal membranes, colic and enterocolitis.
- Endocrinopathic origins
This most commonly occurs in overweight ponies and can be triggered by grazing lush pastures. It is a common aspect of equine metabolic syndrome and pituitary adenoma.
- Supporting limb laminitis
Supporting limb laminitis can occur any time a horse places excessive load on one limb for an extended period of time. It is usually secondary to an acute lameness, post-operative procedures, radial nerve paralysis, joint sepsis or tendon injury.
A diagnosis of the cause of laminitis is essential to the effective treatment of the condition.
The Effect of Laminitis
Laminitis occurs when the laminae supporting the coffin bone within the hoof capsule become inflamed and damaged. In severe cases, the laminae fail, leading to rotation and sinking of the pedal bone within the hoof wall. This process is extremely painful, and can be very difficult to manage, especially if rotation of the pedal bone occurs. In severe cases, horses may need to be euthanized.
The pedal bone or phalanx can rotate in three different ways:
- Sinking, or symmetrical distal displacement of the entire phalanx;
- Rotation, or palmer rotation of the distal margin of the distal phalanx, which probably occurs when the laminae in the quarters and heel maintain some integrity, while the deep digital flexor tendon exerts force on the structure;
- Very rarely, a unilateral distal displacement occurs, usually to the medial side in the forelimb.
Forelimb laminitis is most common, but laminitis can occur in the hindlimbs in severe cases or in a supporting limb laminitis.
Clinically, horses become depressed, lose their appetite, spend time in recumbent positions, have an abnormal stance, and are markedly reluctant to exercise. You will be able to palpate heat around the hoof wall and coronary band, with a palpable or visible and exaggerated digital pulse. Pressure on the sole of the hoof, especially the toe region, may be painful.
The management of laminitis is usually divided into mechanical and pharmacological – we can add a complementary protocol in certain cases.
Mechanical management or support aims to support the hoof while reducing the lever arm within the hoof, by shortening the toe and bringing the point of breakover further back. At the same time, you want to reduce pressure on the hoof wall, and distribute weight across the sole and frog of the hoof. Clogs are one way in which this might be achieved.
Sand surfaces are incredibly valuable to horses with laminitis, as sand conforms to the sole and frog and allows the hoof to easily pivot over a breakover point, without adding torsional forces on the wall of the hoof. Sand can be added to the horse’s stable as bedding, even if it is only in a small portion of the stable.
In acute cases, the pain horses experience is linked to inflammation in the lamellae, while pain in chronic cases is very much multifactorial and involves an element of neuropathic pain as a result of peripheral and central sensitisation.
Effective pain control is essential, as is having objective outcome measures to monitor the horse’s response to pain medication and their progression.
Pharmacological management may include the use of NSAIDs, gabapentin, acetaminophen, epidurals and peripheral nerve blocks, depending on the severity and progression of the case and the treating veterinarian.
There are many modalities that Veterinary Rehabilitation Therapists can utilise to support horses with laminitis, to reduce inflammation and pain.
The first, and most commonly used modality, is ice.
Ice has been validated and studied, specifically in the treatment of laminitis, with regard to methods of icing, duration, and the effectiveness of cooling the laminae.
In acute cases, the continuous application of cryotherapy for 48 to 72 hours is recommended. The goal is to maintain the hoof wall surface at temperatures of between 5 and –7 °C, which has been shown to
- prevent lameness;
- improve epidermal laminar histological scores;
- reduce expression of messenger RNA for matrix metalloproteinase 2; and
- reduce lamellar inflammatory signaling in horses with carbohydrate overload-induced laminitis.
Kullman et al evaluated the use of ice for 48 hours as a means of preventing laminitis in horses with colitis, and found them to be ten times less likely to develop laminitis than horses not similarly treated.
There are, however, significant drawbacks to this management. To maintain an ice slurry, ice needs to be replaced every one to two hours and the horse needs to be monitored continuously. Their movement is also completely restricted during this time.
The most effective cooling method according to the research, includes ice boots containing ice and water or a circulating refrigerated bath or spa. Both of these methods restrict movement and require constant monitoring of the patient. In addition, the hoof and lower limb remain wet for the duration of the treatment, which has significant drawbacks and may contribute to softening of the hoof capsule.
Novel dry cryotherapy application methods have been investigated, showing only moderate success at maintaining the hoof wall at a temperature below 10 °C.
The Soft Ride Ice Spa Boots have been developed to allow some mobility in the horse, while maintaining treatment with a slurry of ice and water.
Ice socks are commonly used in practice as an inexpensive and effective method of applying ice to the limb for extended durations of time, without limiting motion of the horse or requiring the hoof to remain in an ice slurry. There is an increased element of management however, as ice will need to be replaced often to maintain the hoof at a temperature below 10 °C. There are not any studies that I have been able to identify, that evaluate the effectiveness of ice socks.
Ice should be used both in horses who have developed acute laminitis and in horses at risk of developing secondary arthritis, as a preventative measure.
Reducing inflammation through the use of PEMF and laser
Both PEMF and laser therapy can be used to reduce inflammation and pain in a variety of conditions. There are not yet any studies evaluating the use of these modalities for laminitis, and their inclusion in a treatment protocol should be discussed with the veterinarian.
Supporting postural adaptations and loading patterns with kinesiotape
In horses at risk of developing laminitis as a result of secondary overloading, kinesiotape can be used to support the limb. In laminitic limbs, an inhibitory application can be applied to the deep digital flexor tendon and muscle to reduce the pull of this tendon on the distal phalanx, while supporting the superficial digital flexor tendon.
Additional areas of the body can and should be supported with kinesiotape as the horse adopts a pronounced postural change, including to the hamstrings and tendons of the hindlimbs, and the thoracolumbar fascia. We may also want to support the muscles of the thoracic sling.
In horses recovering from laminitis, the thoracic sling, abdominals, back and hamstrings may all be painful as a result of the change in posture and offloading of the forelimbs. These areas should be treated accordingly through the recovery and rehabilitation of the horse.
In patients that are prone to developing laminitis, we can play an impotant role in supporting and educating the owner, as well as supporting the horse. By becoming familiar with the different methods of applying ice, or purchasing ice boots that you can rent out to owners in these situations, you can play a role in the acute management of laminitis together with the veterinary team managing the patient. While ice is the most important treatment intervention to start with, kinesiotape, PEMF, TENS and laser can all play a role in reducing inflammation and pain in the patient through the recovery phases of the condition.
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