Clinical Updates I—Laminitis

Managing laminitis entails a multifaceted approach and includes nutritional management in all cases. Using advanced imaging techniques, as part of the diagnostic workup, provides guidance in the treatment options and includes computed tomography, computer modeling, digital radiography and venography. The therapeutic procedures are trimming, shoeing, deep flexor tenotomy and hoof wall resection as possible considerations and is dependent on the clinical findings. When applicable, preventive measures such as cryotherapy and techniques to prevent support limb laminitis can be implemented.     

Laminitis: Recognition of At-Risk Individuals,and Methods of Prevention

Even with the many advances made in the understanding of the pathophysiology, new treatments and preventative measures, laminitis continues to plague the equine population. Identification of risk factor and at-risk individuals remains the best approach with this disease.     

Laminitis in Horses: Through the Lens of Systems Theory

Systems theory is a way of describing complex and dynamic relationships. We applied systems theory to the structure and function of the equine foot in an effort to better understand laminitis and, in so doing, reconcile the various theories of its etiopathogenesis and find more universally effective preventive and therapeutic strategies. The foot is described as an open system, and its inherent vulnerabilities are explored. Cascade failure is discussed as a potentially unifying theory of laminitis. The fundamental failure in laminitis is failure of the lamellar dermal−epidermal bond, but that endpoint can be reached via vascular, enzymatic, inflammatory, or mechanical mechanisms, or any combination thereof. Inflammation is discussed as a common denominator, making anti-inflammatory therapy of greater importance than just pain management. Multimodal anti-inflammatory therapy is discussed, including selective COX-2 inhibitors, heparin, nutraceuticals, and inhibitors of matrix metalloproteinases (MMPs). Multimodal analgesic therapy also is important and may include nonsteroidal anti-inflammatory drugs (NSAIDs), opiates, epidural analgesics, physical therapy, relief of weight bearing, diligent nursing care, deep digital flexor tenotomy, and case-appropriate trimming and shoeing. Preventing laminitis still comes down to risk management: knowing the risk factors applicable to an individual horse and adjusting the management accordingly. Examples include weight management and control of carbohydrate intake in overweight horses and ponies, the use of pergolide in patients with pituitary pars intermedia dysfunction (PPID), and distal limb cryotherapy in high-risk patients. It is anticipated that application of molecular biologic techniques will further advance treatment and prevention of laminitis.     

The Role of Insulin in Endocrinopathic Laminitis

Laminitis is a devastating disease of horses that usually arises as a consequence of major systemic disease or endocrine disturbances. Research has been confounded by apparently disparate results and theories on pathogenesis. Models of laminitis have greatly advanced our understanding of the disease, yet have mostly involved perturbations of the gastrointestinal tract or inflammatory models. A major trend in research on laminitis in the past few years has been the increasing interest in endocrine dysfunction resulting in laminitis. A new model of laminitis associated with hyperinsulinemia has recently been discovered and the central role of high insulin in triggering endocrinopathic laminitis highlighted. This review discusses the pathophysiology of insulin resistance and hyperinsulinemia in horses and possible mechanisms of insulin-induced laminitis.     

A Fresh Look at the Process of Arriving at a Clinical Prognosis Part 1: Laminitis

Laminitis is a disease that represents a loss of the normal homeostatic mechanisms that control the day-to-day function of the distal phalanx. The degree or severity to which homeostasis is affected is directly related to the severity and the final outcome for the equine patient. A systematic approach including the physical examination, digital radiography, venography, and newer techniques such as computer tomography and magnetic resonance imaging can assist the clinician in developing a prognosis for the acute and chronic laminitis case. How quickly we are able to return the foot back to a normal state of homeostasis or the response to treatment is important as a predictive value for outcome.     

Update on Metabolic Diseases Associated With Laminitis in Horses and Ponies

Several recent scientific publications describe some important findings that may further improve our ability to diagnose and manage both equine Cushing's disease (ECD) and equine metabolic disease (EMD). This abstract provides a brief summary of recent findings in ECD and EMD that have immediate application for clinical practice.     

A Farrier Making Every Contact Count: A Microlevel Analysis of Farrier-Client Interaction for Partnership Working in Managing a Horse With Laminitis

There is an evidence base in human and small animal veterinary health care contexts which understands how practitioners engage in partnership working with patients and owners to support adherence to treatment/care plans. However, as yet, it is believed there is no similar evidence base for how practitioners in equine health care contexts work with equine owners. It is argued that this is essential for understanding complex equine practitioner-owner interaction involving the prevention and management of laminitis. The aim of this study was to explore farrier-client interaction where risk management for an equine recovering from laminitis was being undertaken. A case report method involved a microlevel analysis of a farrier-client consultation. The consultation was video-recorded and analyzed using a conversation analysis approach to identify the linguistic and paralinguistic features of the interaction. These were compared with conversation analyses in other health care contexts to identify the actions being accomplished within the consultation. The analysis identified a number of joint actions, including managing epistemic stance (or knowledge rights) and deploying the animal’s presence to navigate problem sequences which supported progression of the consultation through a three-stage model involving “team-”, “option-”, and “decision-” talk, known to be associated with partnership working in human health care contexts. The study highlights the importance of developing an empirical evidence base in equine practice for how practitioners engage with owners based on a microlevel analysis of real-world interactions. It is argued this evidence base is necessary in supporting effective practitioner training in partnership working with clients to promote their adherence to treatment/care plans.     

Venograms for Use in Laminitis Treatment

Venography is a very valuable tool that can be used in the diagnosis and treatment of laminitis. It can be used to assess vascular damage in the hoof before changes in radiographic detail occur. When used at onset, the venogram proves to be most valuable. They can not only give baseline measurements but can also show the level of damage that has already occurred. Initial venograms allow farriers and veterinarians to evaluate what degree of corrective treatment is necessary for the best outcome. In addition, a series of venograms can show the process of pathology as well as recovery. From here, treatment can be altered to accommodate the case.     

A Novel Approach to the Treatment and Prevention of Laminitis: Botulinum Toxin Type A for the Treatment of Laminitis

Laminitis is an inflammation of the lamina of hoofed animals. According to the United States Department of Agriculture (USDA), laminitis impacts approximately 2% of the horse population each year. Because of the severity of the inflammation and chronic pain, it is frequently necessary to euthanize these horses. Surviving horses may be left useless, with resultant economic and social impact on the industry. Current interventions for laminitis are based on supportive care and alteration of biomechanical forces on the digit. The transition from laminitis to laminar failure (founder) is believed to be caused by the “weight of the horse and the forces of locomotion driving the bone down into the hoof capsule.” We hypothesize that an important factor is the torsional forces placed on the distal phalanx (coffin bone) by the deep digital flexor muscle and tendon. The paralyzing effect of botulinum toxin will result in a decrease of these torsional forces and therefore will aid in the prevention or treatment of the sequelae of laminitis. Seven horses with varying degrees of laminitis were evaluated. Each underwent pretreatment and posttreatment radiographs as well as pretreatment and posttreatment Obel grading. Each horse received botulinum toxin type A injected into the belly of the deep digital flexor muscle. In all cases there was radiographic stabilization of pedal displacement from the dorsal hoof wall. Obel scores showed improvement of 1 to 2 grades during the time monitored.