Laminitis: Recent advances and future directions


Laminitis is common across the world and has a significant impact on equine welfare. While for many years, researchers strove to identify a unifying theory to explain its pathogenesis, in an Editorial in this issue, Professors Belknap and Geor explain that it is more likely that diverse pathways terminate with laminar failure and summarise the current and future directions in laminitis research. This concept has important implications in our understanding of why sepsis, endocrine disease and excessive weightbearing can end in the same sorry situation. It also implies that preventative and therapeutic strategies need to be more sophisticated and targeted at the specific type of laminitis concerned, each of which are discussed in more detail in the Special Focus section of this issue.

Equine Veterinary Journal has a long history of promoting laminitis research. In 2004, EVJ produced a special issue dedicated to laminitis and since that time significant numbers of articles on laminitis have been published every year. In recent years, articles have included fundamental studies examining the morphology of the primary epidermal laminae [1], the lamellar basement membrane changes that occur in the developmental phase [2] and challenging the dogma that metalloproteases have a central role in the pathogenesis of laminitis [3]. Considerable attention has been given to teasing out the specific contributions of inflammatory mediators in sepsis-associated laminitis [4, 5]. There have been considerable steps towards understanding the role of insulin in regulating glucose transport within the hoof [6] and suggesting that while hyperinsulinaemia may be a risk factor for laminitis [7, 8], the widespread basement membrane disintegration that occurs in other forms of laminitis, is not induced by insulin infusions [9]. Furthermore, insulin-glucose proxies, which are used in the clinical setting, were not able to determine llaminitis susceptibility [10]. There is a clear need for further work both to clarify the underlying mechanisms and to provide better clinical tests in endocrinological laminitis. Supporting limb laminitis has received less attention but risk factors for this condition were defined, in a retrospective study, to be greater duration and higher bodyweight in horses treated with casts [11].

With respect to prevention [12], evidence to underpin the use of cryotherapy, a long-established clinical practice, has come from studies using the oligofructose model and it is now clear that its mechanism of action relates to blockade of early inflammatory events [13] rather than any effect whereby inciting mediators were diverted away from the foot due to hypoperfusion, as previously proposed. Effective treatments remain elusive – what we need now are studies to examine the efficacy of cryotherapy applied after the onset of clinical signs. Disappointingly, lidocaine, which was a popular choice in equine hospitals, did not inhibit inflammatory events in either the laminae or skin in horses given black walnut extract [14] but looking to the future, some fascinating work by Carter et al. has shown that epidermal stem cells are lost in chronic laminitis and has thrown up the possibility of a novel approach to therapy [15].

The internet has transformed the general public's ability to find information. Increasingly, horse owners will research ailments suffered by their animals with this powerful tool and laminitis is often targeted in this respect by horse owners desperate to find solutions for their afflicted animals. There is a problem, however, that much of the freely available material lacks rigour and quality. Many scientific journals, including EVJ, are generally not available to nonsubscribers. Currently there is much debate within scientific and political circles, supporting the concept of open access publishing and some are in favour of all scientific papers being made freely available to the readers. To date at least, EVJ has not adopted that model, but we are able to offer individual researchers the opportunity to make their work freely available using Wiley Blackwell's Online Open facility (see for more details). EVJ is also keen to provide free access to information of particular welfare importance and interest to the equine community and to this end, this month, a virtual issue will be launched ( drawing together 15 original research articles with the Editorials and Review Article in this issue.

The virtual issue has been made possible by generous sponsorship from BEVA Trust. I am also grateful to the guest editors of this virtual issue, James Belknap, James Orsini and Andrew van Eps for their enthusiasm, insight and support of this project.