There's not much good news on the pastern vasculitis front: Despite intense research, scientists still have not been able to uncover anything reassuring about the condition–no common cause, no successful treatments, no positive prognoses.

“Our study cannot contribute to a more positive prognosis (for the disease),” said Monika M. Welle, DrMedVet, PhD, Dipl. ECVP, of the Institute of Animal Pathology at the University of Bern's Vetsuisse Faculty, Switzerland. “We were hoping to find the causative agent or a treatment option for this disease but did not find any. However, now we at least can say that none of the treatment options used so far is successful, and thus the veterinarian can give a prognosis based on a study.”

Pastern vasculitis—a different problem than pastern dermatitis, or scratches—causes swelling, redness, and raw and/or crusty skin lesions in the pastern area, but lesions can extend to the cannon bone, Welle said. It appears to be an immune-related problem characterized by inflamed blood vessels as seen in hypersensitivity reactions, she said; the damage to the blood vessel walls causes the clinical lesions.

Welle and colleagues investigated biopsies from the affected skin of 20 horses with a confirmed pastern vasculitis diagnosis and compared them to biopsies from 10 healthy horses. They sought to find an underlying cause, make a connection between microscopic findings and outcome, and evaluate treatment efficacy