A novel, sustained efficacy, biocide-based treatment for bacterial foot disease in ruminants

Bacterially mediated foot disease is an important and common cause of lameness and debility in cows and sheep. For instance, Digital dermatitis (DD) in cattle results from an erosive and painful dermatitis of heel bulbs and interdigital space, caused by Treponeme bacteria. It occurs predominantly when cows are housed and exposed to an unhygienic underfoot environment contaminated with slurry. The same Treponeme bacteria are also recognised as contributing to non-healing claw horn defects in cattle, namely non-healing white line lesions and toe necrosis which typically require a combination of sustained systemic and topical antimicrobial therapy alongside therapeutic foot trimming in order to affect a cure. In sheep, a range of foot conditions result from bacterial infection, including contagious ovine digital dermatitis (CODD), which predominantly affects the coronary band, underrunning the wall of the hoof and leading to severe lameness. A wide range of topical antibacterial preparations may be used for treatment, most commonly aerosolised chlortetracycline, which are readily washed off into the environment. This limits efficacy and means many animals are treated with systemic antibiotics, posing a risk for development of antimicrobial resistance. A major challenge in developing a non-antibiotic treatments is achieving prolonged topical exposure. Sustained efficacy chlorhexidine (SECHX) preparations have been developed at University of Bristol's School of Oral and Dental Sciences and are currently being developed further by a University spin-out company, Pertinax Pharma Ltd, who will be the industrial partner for this iCASE studentship. CHX is a biocide used widely in veterinary and human medicine, but in current commercial formulations is easily removed from the site of application. Thus far the SECHX has been applied to a wide range of infective conditions in human medicine and has been shown to have excellent medium- and long-term efficacy and a safety profile superior to conventional CHX. In the project described here, the student will develop SECHX as a treatment for ruminant foot infection. Working with clinical researchers in the School of Veterinary Sciences, researchers in the Faculty of Biomedical Sciences and scientists at Pertinax Pharma, the student will develop, characterise and assess formulations for application to livestock animals' feet to treat infection.