Could oil extracted from a shrub which is native to Australia's east coast be the next weapon in the fight against pastern dermatitis?
Kunzea oil proved an effective treatment in a study of the condition, also known as scratches, mud fever, mud rash, or greasy heel, researchers reveal.
Many factors have been implicated in pastern dermatitis, which may explain the poor response to treatment that is often achieved.
But now, researchers at the University of Tasmania's School of Pharmacy have had promising results using ointment containing kunzea oil to treat the condition.
Kunzea oil is obtained from the white kunzea or "tick bush" (Kunzea ambigua) - a shrub native to the sandstone soils along the eastern Australian coast.
The plant has been used in traditional folk medicine for the treatment of diarrhoea, inflammation and wounds. The oil, produced commercially in north-eastern Tasmania, contains various active constituents such as pinene, 1-8-cineole (eucalyptol), and sesquiterpene alcohols.
Twenty-one horses with pastern dermatitis completed the study.
One group was treated with the test ointment containing 20 per cent kunzea oil. A second (control) group was treated with an ointment that was similar, except that instead of kunzea oil it contained 2 per cent ketoconazole, an antifungal agent.
Initially the affected areas were cleaned (no antiseptic preparations were used) to remove the crusts, and then dried. Some horses had to be sedated to allow this to be done. The ointment was then applied and repeated twice daily.
The researchers gauged the response by measuring the change in size and severity of the lesions before treatment and seven days later.
After one week's treatment with kunzea oil ointment, all cases had improved, and more than half were completely cured. In contrast, two horses treated with the control ointment were cured, two had improved, and the remaining six were no better.
Staphylococcus aureus was isolated from many of the cases. Previous work by the same research team has shown that kunzea oil kills Staphylococcus aureus and various other Gram positive organisms, and is also active against yeasts and dermatophytes.
Kunzea oil's action against Staphylococcus aureus is probably behind its success in treating mud fever.
The researchers suggest that the kunzea oil's action against Staphylococcus aureus probably explains its success at treating the pastern dermatitis in these horses.
In a report published in the Veterinary Record, they state: "The treatment of 11 horses with pastern dermatitis with an ointment containing kunzea oil, a potent antibacterial essential oil, cured most cases within seven days and was more effective than the control formulation containing ketoconazole.
"The ointment was a safe, fast-acting and effective treatment for pastern dermatitis in this group."
No heavy horses were included in the study. They are usually more severely affected and further work needs to be done to demonstrate that kunzea oil is as effective in draft horses.
The study was also limited in that only horses in a restricted geographical area were treated. Similar success may not be seen in other areas with different environmental conditions.
Even so, the results were encouraging and, if they were repeated in other areas, kunzea oil could find a place in the treatment of this frustrating condition.