Thursday, September 27, 2012

Chronic Laminitis Research: Comparison of Normal vs Chronic Laminitis Horses Shows Difference in Immune, Digestive and Laminar Proteins

"Laminitis is not limited to the foot and chronic laminitis should be considered a multi-system disease" -- Steelman, Chowdhary, 2012

Chronic laminitis treatment usually focuses directly on the feet. The authors define chronic laminitis as the condition of horses who survive acute laminitis but are left with after-effects like coffin bone rotation. They state that 75% of horses with acute laminitis go on to the chronic stage, which they describe as causing permanent lameness. (file photo, courtesy of Vetmoves)

A new paper from the world of laminitis research finds that the anti-inflammatory protein apolipoprotein A-IV (APOA-IV) is raised in chronic laminitis, which suggests that the chronic form of the disease is linked to a more general inflammation, especially of the digestive system, than was previously documented.

Most research into laminitis is conducted on horses suffering from acute laminitis, usually after the ingestion of a large doses of fructans or black walnut in a controlled setting. Chronic laminitis is usually studied because of links to insulin resistance and/or equine metabolic syndrome and Cushing's disease, with minimal testing of systemic findings in horses with lameness in their feet. The focus of most chronic laminitis research is on how the endocrine system's irregular function affects the laminar tissue of the foot.

According to research published this week in the open-access journal BMC Veterinary ResearchDr Samantha Steelman and Professor Bhanu Chowdhary from the College of Veterinary Medicine at Texas A&M University, found 16 proteins that have different levels in the blood of horses with chronic laminitis, but which are not reflected in normal horses. They compared nine foundered horses with 30 healthy control horses collected from horses residing at the private Hoof Diagnostic and Rehabilitation Clinic in Bryan, Texas, where horses are in treatment under the direction of David Hood PhD DVM.

Horses in both groups were in good health, apart from the laminitis. Eleven of the 16 proteins measured are involved in response to wounding, coagulation and inflammation. The remaining proteins included fetuin A and B, both of which are involved in acute immune response, immunoglobin, an indicator of increased antibody levels, and most importantly APOA-IV.

Dr Steelman explained, "APOA-IV is produced by the small intestine. One of its functions is to tell the animal when it is full. It also has antioxidant and anti-inflammatory properties, which might explain the raised levels of APOA-IV."

At 2011's Sixth International Equine Conference on Laminitis and Diseases of the Foot in West Palm Beach, Florida, Dr. Steelman presented a poster titled, "Characterization of laminar, gastrointestinal, and immune system dysregulation in chronic equine laminitis", which was related to the research detailed in today's paper.

In the abstract accompanying her poster, she wrote that it was her team's goal to study the immune system, the gastrointestinal system, and the integumentary system (laminar tissue) using a combination of proteomics, next-generation DNA sequencing, and real time PCR, rather than to focus solely on the foot.

Steelman and Chowdhary's comparative study found interesting variations in all three systems between the laminitic and normal horses. Ultimately, their results support their hypothesis that localized laminar inflammation may be linked to systemic alterations in immune regulation, particularly in the gastrointestinal system.

Research published in BMC Veterinary Research that laminitis is linked to general inflammation, especially of the digestive system, via elevated levels of an anti-inflammatory protein that was not present in horses that do not have laminitis. Proteomics is the study of protein's presence, type and activity level in a condition. (Image courtesy of BMC Veterinary Research)

In other words: Chronic laminitis may show up most in displacement of the coffin bone, prolonged or intermittent lameness and hoof capsule deformity, but the digestive and immune systems are also affected. Most treatment of chronic laminitis currently focuses on making the feet more comfortable.

"From these data we conclude that the pathology of chronic laminitis is not limited to the foot and that chronic laminitis should be considered as a multi-system disease," was Steelman's interesting conclusion in Palm Beach. She recommended that her data be used in developing a more directed therapeutic approach as an alternative to current treatment strategies.

To learn more: Increased Plasma proteomics shows an elevation of the anti-inflammatory protein APOA-IV in chronic equine laminitis by Samantha M Steelman and Bhanu P Chowdhary. (full paper, free download) in the journal BMC Veterinary Research, an open access, peer-reviewed journal.

Dr. Steelman is curator of the Equine Tissue Sharing Program at Texas A&M.

Dr Chowdhary is an expert on equine genetics and also collaborates on research at the Laminitis Institute at PennVet's New Bolton Center, where he collaborates with Drs. Hannah Galantino-Homer and Chris Pollitt.

Dr. David Hood Launches the Hoof Diagnostic and Rehabilitation Clinic in Texas

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