In the season of giving thanks, we tend to overfill our plates in celebration. While our horses enjoy a few extra treats -- check out some of the ongoing research into early diagnosis of Equine Metabolic Syndrome and the prevention of founder.
The Anatomy The laminae are interlocking leaflike tissues that hold the hoof onto the coffin bone; thus, swelling or inflammation of the laminae (laminitis) yields instability of the coffin bone within the hoof to some extent, with accompanying severe pain and potentially downward or rotational movement of the coffin bone within the hoof (termed sinking or rotation). Laminitis is called “founder” by some (based on an old maritime term meaning “sinking ship”), and this term is most accurately used to describe a case in which the coffin bone has sunk straight down within the hoof.
Clinical Sign of Disease Laminitis is one of the most common and frustrating clinical presentations in equine practice. While the principles of treatment for laminitis have not changed for several decades, there have been some important paradigm shifts in our understanding of laminitis. Most importantly, it is essential to consider laminitis as a clinical sign of disease and not as a disease in its own right. Once this shift in thinking has occurred, it is logical to then question what disease caused the laminitis.
Managing Equine Metabolic Syndrome More than 90 percent of horses presented with laminitis as their primary clinical sign will have developed it as a consequence of endocrine disease; most commonly equine metabolic syndrome (EMS). Given the fact that many horses will have painful protracted and/or chronic recurrent disease, a good understanding of the predisposing factors and how to diagnose and manage them is crucial. Current evidence suggests that early diagnosis and effective management of EMS should be a key aim for practicing veterinary surgeons to prevent the devastating consequences of laminitis.
Laminitis and EMS Laminitis can be viewed as the vascular dysfunction consequence of metabolic syndrome in the horse (Katz and Bailey 2012). The primary insult to the hoof in EMS is most likely due to alteration in the form and function of the vasculature, rather than inflammation, in contrast with laminitis secondary to systemic inflammatory response syndrome. How this primary insult occurs is unclear, but high insulin concentrations may affect blood vessel tone, resulting in an altered blood supply to the hoof (Venugopal and others 2011, 2014, Keen and others 2012). There is also some evidence to suggest that insulin may have a direct effect on the epidermal cells of the lamellar tissue via insulin-like growth factor signaling pathways (De Laat and others 2013).
Diet Dietary modification is the key to inducing weight loss in the majority of horses with EMS. It is essential to obtain a detailed history from the owner regarding the current feeding regimen and management of the horse, including options for grazing, exercise, and confinement. Tailoring the diet to the individual needs of the horse leads to, very importantly, improved owner compliance and results in a better response to treatment (Morgan and others 2015) The first step is to remove any concentrate feed from the diet, as well as any high sugar treats, such as apples.
The diet should be forage based, with the aim of feeding low- to medium-NSC forage with less than 10 percent NSC content (Frank and others 2010). NSC refers to carbohydrates usually found within the seeds and leaves of plants and includes starches and simple sugars. Horses normally eat approximately 2 to 2.5 percent (NRC 2007) and ponies up to 5 percent (Argo and others 2012) of their body weight as dry matter (DM) in a 24-hour period when given ad lib access to food. It is recommended that to induce weight loss, the horse is fed approximately 1.25 percent of their body weight in DM (approximately 1.5 per cent in fresh weight for hay of 80 to 85 percent DM) per 24-hour period. Diets of less than 1 percent of body weight DM are not recommended because of potential problems with hind gut function, hyperlipaemia, protein restriction and stereotypes (McGregor-Argo 2009).
References and Recommended Reading:References 1 Lameness and Laminitis in U.S. Horses. USDA: APHIS:VS, CEAH, National Animal Health Monitoring System. Fort Collins, CO. #N318.0400. USDA, 2000. www.aphis. usda.gov/animal_health/nahms/equine/downloads/equine98/Equine98_dr_Lameness.pdf 2 West, C. Fall and Winter Bring Forage Risks. Nov. 10, 2004, www.TheHorse.com/1801. 3 New Study: Equine Obesity More Prevalent than Previously Reported. www.TheHorse.com/10038. 4 West, C. Cutting Down on Carbs (for Your Horse). Nov. 17, 2003, www.TheHorse.com/4777. 5 Kane, A, et al. The Occurrence and Causes of Lameness and Laminitis in the U.S. Horse Population. American Association of Equine Practitioners Proceedings, 2000, 277. www.ivis.org/proceedings/aaep/2000/277.pdf.
Further Reading ■ West, C. Feeding Laminitic Horses. The Horse, May 1, 2007. TheHorse.com/9658 ■ Watts, K. Finding and Testing Low-Sugar Forage. May 14, 2007. TheHorse.com/9587. ■ Laminitis information: TheHorse.com/laminitis ■ Metabolic Syndrome information: TheHorse.com/metabolic-syndrome ■ Body Condition Scoring information: TheHorse.com/ body-condition ■ Horse Weight Calculator: TheHorse.com/Tool/WeightCalculator.aspx http://www.thelaminitissite.org/new-researchresearch-by-dat… http://veterinaryrecord.bmj.com/conte…/…/7/173.full.pdf+html