Clara Mason, DVM

44 Cloverleaf Street
Winfield, WV 25213

(304)340-1401

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Recent Advances in LAMINITIS in Horses

Laminitis is classified in 4 categories:

1.  Endocrinopathic

2.  Sepsis-induced or inflammatory response syndrome (SIRS)

3.  Traumatic

4. Support or contralateral-limb laminitis

ENDOCRINOPATHIC Laminitis

-In endocrinopathic laminitis, horses may suffer from Hyperinsulinemia and elevated ACTH concentrations such as in Cushing's disease and these are the main factors contributing to this type of laminitis in horses. Risk factors include obese horses, horses with pituitary pars intermedia dysfunction and those with equine metabolic syndrome (EMS).

ENDOTOXEMIA Laminitis

-Sepsis in the horse is the cause of endotoxemia laminitis. During the inflammatory cascade, inflammatory processes involving cytokines and tissue necrosis factors (TNF) in addition to matrix metalloproteinases cause the breakdown of the basement membrane and separation of the epidermal and dermal lamellar tissue within the hoof.

SUPPORT LIMB Laminitis

-This may be a result of altered blood flow in the foot because of a decrease of loading and unloading.  Glucose metabolism may also be affected during overloading of the support limb, which can contribute to lamellar damage.  For instance, when there is injury to a foot and the horse is not loading proper weight on the "off" foot, additional body weight and improper loading to the opposite foot may contribute to laminitis in the "healthy" foot.

TRAUMATIC Laminitis

-Any serious injury to a foot that triggers the inflammatory cascade can lead to laminitis in the affected foot.

LAMINITIS DISEASE PROGRESSION

There are 4 PHASES to laminitis disease progression

1. Developmental

2. Acute

3. Subacute

4. Chronic

DEVELOPMENTAL

-This is the phase between the initial incident or exposure to the causative agent up to the onset of clinical signs (which may include lameness, increase in digital pulses with or without fever).  It generally lasts 24-60 hours.

ACUTE

-This phase is defined by the onset of clinical signs, including bounding digital pulses, lameness, heat and possible positive response to hoof testing. If the horse doesn't experience mechanical failure of the foot, the acute pause is over within 72 hours of the onset of clinical signs and is followed by the subacute or chronic phase.

SUBACUTE

-This pause occurs if there is minimal damage to the lamellae and no radiographic evidence of rotation or sinking of the third phalanx (P3 or coffin bone). This is an important time to prevent disease recurrence and to heal the foot.  Clinical signs that were seen in the acute phase will resolve in the subacute phase, and the horse will become sound with healing. This phase can last up to several months.

CHRONIC

-This phase is intimated if lamellar damage i not controlled and rotation or distal displacement (sinking of P3/Coffin bone) occurs. Chronic laminitis can cause coffin bone remodeling and decreased sole concavity (dropped sole). Development of a lamellar wedge (scar horn) can result. This will cause an improper interdigitation of the lamellae between the coffin bone and hoof capsule. There can also be damage to the solar dermis, preventing growth.

PREVENTION AND TREATMENT OF LAMINITIS

1. CRYOTHERAPY

-This treatment works best in horses with sepsis or SIRS laminitis. Cold therapy should be initiated and continued for 48-72 hours during the entire developmental phase and for another 24 hours beyond the end of clinical signs of the primary disease. It is important to soak the foot, pastern, fetlock and distal cannon region. The suggested temperature of the cold-therapy should be 41-50 F. Crushed ice is preferred to ice cubes because there is better contact with the crushed ice to the treatment area of the horse.  ice wraps are not suitable because of the trapped air between the wrap and the leg. Cryotherapy is beneficial during the Early Acute Phase.

2. PAIN MANAGEMENT

-Pain management is imperative in treatment of laminitis. Though Bute and Banamine are both still used to manage pain and inflammation in laminitic horses, Equioxx is preferred especially in chronic cases due to lack of irritation of this drug to the stomach lining.

3. MECHANICAL SUPPORT

-Mechanical supports are designed to relieve forces on the laminar tissue, load the sole corium (especially at the toe) and move the break-over back to improve com for t and stimulate sole growth. These include  roller shoes, synthetic shock-absorbing shoes that reduce vibration and glue-on shoes. pit-in pad products oriental impression material can also providee sole support. Soft-Ride boots are another option.  Drastically, a deep digital flexor tendon (DDFT) tenotomy combined with derivational shoeing can help min many cases. By cutting the DDFT, you move the loading of the foot backward removing the additional weight on the toe. Additional weight loading on the toe can prevent the corium from growing.

4. BISPHOSPHONATES

-Tildren and Osphos may be beneficial by stopping bone pain, damage and loss.

5. STEM CELL THERAPY

-Stem cells can help in the repair phase after rotation. During the lamellar wedge formation (thick rubbery and unstable mass of tissue that prevents proper attachment of the coffin bone to the hoof capsule) which occurs approximately 60 days after rotation, Stem Cell therapy does not seems to have any benefit.  Therefore, use of stem cells needs to occur prior to the 60-day mark.

***excerpts are from an article written by Sallie Hyman, DVM in DVM360  Feb 2015 pg: E5-E8.