Equine Lung worm: A Systematic Review

Abstract

Lungworms are parasitic nematode worms of the order Strongylidae that infest the lungs of vertebrates. Dictyocaulus arnfieldi is the true lungworm affecting donkeys, horses, mules and zebras and is found throughout the world. Dictyocaulus arnfeildi can cause severe coughing in horses and because patency is unusual in horse (but not in donkeys) differential diagnosis in disease due to other respiratory disease can be difficult. Adult Dictyocaulus worms are slender, medium sized roundworms, up to 8 centimeter long. Females are about one third longer than males. They have a whitish to grayish color. Dictyocaulus worms have a direct lifecycle, i.e. there are no intermediate hosts involved. The pathogenic effects of lungworm depends on their location within the respiratory tract, the number of infective larvae ingested, the animal immune status, on the nutritional status and age of the host. Despite the prevalence of patent D. arnifieldi infection in donkeys, overt clinical signs are rarely seen; however, on close examination slight hyperpnoea and harsh lung sounds may be detected. Diagnosis is based on clinical signs, epidemiology, presence of first-stage larvae in feces, and necropsy of animals in the same herd or flock. Bronchoscopy and radiography may be helpful. Larvae are not found in the faeces of animals in the prepatent or postpatent phases and usually not in the reinfection phenomenon. ELISA tests are available in some laboratories. Bronchial lavage can reveal Dictyocaulus arnifieldi infections in horses. The concern of lungworm in Ethiopia is increasing and is now to be a major problem of equines. Routine deworming of horses and donkeys may help prevent cross infection when kept together. Reducing pasture contamination with infective larvae is a key preventative measure that can be achieved to a large extent with adequate management measures. Rotational grazing with a change interval of 4 days and keeping the paddocks empty for at least 40 days significantly r