Talpa (poll evil): Description of a case

Abstract

Talpa (poll evil) is a traditional term for an inflammatory illness of horses that manifests itself in a characteristic swelling on the top of the neck and the back of the horse’s head between the ears, which is caused by infection of the bursa (bursitis) in the neck and progresses to a large abscess at the poll. It starts as an inflamed bursa at the anterior end of the neck between vertebrae and the nuchal ligament, and swells until it presents as a characteristic swelling at the poll. The swelling can increase until it ruptures and drains. There are several causes of talpa, such as injury, irritation of the skin, or a puncture wound, but the most common cause is infection by various bacteria, including but not limited to Brucella abortus accompanied with Actinomyces bovis, as well as Bacteroides fragilis, Corynebacterium spp., Escherichia coli, Pasteurella spp., Proteus mirabilis, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus equi, Streptococcus zooepidemicus and even some parasites, such as Onchocerca cervicalis or O. reticulata. Because of the modern efforts to reduce the incidence of brucellosis in livestock, horses are less exposed to Brucella abortus, and hence modern cases of poll evil usually arise from skin trauma due to the horse striking its head against poorly designed or lowclearance structures, or to improper use of equipment, particularly leaving a badly-chosen halter on the horse around the clock. Poll evil is difficult to treat because of the deep-seated nature of the infection. If the bacterial infection of the bursa and nuchal ligament has spread, and purulent discharge is present, antibiotic therapy will be necessary along with hot packs and, possibly, surgery to remove infected and devitalized tissue. The paper presents the aetiopathogenetic background of poll evil and then describes in detail a field case reported in veterinary practice.