A study into Equine Pastern Dermatitis (EPD), which is more commonly known as mud fever, cracked heels or greasy heel, has revealed that there is “minimal evidence” that the disease is caused by fungal infections.
EPD is a common horse health issue that affects the lower leg. While it is more prevalent in winter, it can occur all year round, particularly in heavily feathered equines with white socks and pale skin.
The name mud fever doesn’t need mud to occur, just wet conditions, and it was previously thought to be caused by a number of bacterial or fungal infections.
However, this research, which has been carried out by 12 CVS Equine practices with the aim of enhancing knowledge about the disease and enabling vets and owners to better treat and manage these cases, has shown that this is not the case.
The evidence
Samples were collected from 76 horses who were diagnosed with EPD in the UK between 2022 and 2024. Their owners were required to complete a questionnaire regarding clinical presentations and management of the disease.
Cells from the samples were analysed, full blood profiles were assessed and bacteria was examined before the data, which included the owner questionnaires and supporting photographs, was evaluated.
The results found that hindlimbs were most affected with lesions most commonly located in the pastern region. Clinical signs included abnormal redness of the skin, scaling, localised swelling and itching.
The samples showed minimal evidence of fungal or parasite infections but a high number of bacteria were found – 186 bacterial colonies were present in the 76 samples.
Penicillin was the antimicrobial agent to which the greatest frequency of resistance was identified, with less than half of cultured organisms demonstrating susceptibility.
‘Becoming more prevalent’
“Equine pastern dermatitis is such a common disease of horses and ponies in the UK and with wetter weather becoming more prevalent, it’s only expected to increase,” said Charlotte Sinclair, CVS Equine development lead.
“We want to be able to offer the best treatment and management advice for horses suffering this condition but research into this condition has been sparse and the evidence-base for the range of treatments offered has been similarly lacking.
“Our analysis of 76 cases over two years has highlighted the multifaceted nature of EPD – both in terms of its clinical presentation and severity and its potential aetiologies.
“Our results show several commonly implicated organisms, however further research is required to determine their clinical significance to EPD.
“We really hope that our work will lead to significant improvements in treatment and preventative healthcare for horses prone to this painful disease.
“The information this study provides on resistance patterns may help to guide antimicrobial use when treating these cases, to help improve antimicrobial stewardship.”
Image © CVS Equine.
