Summer sores secondary to hoof crack in an Andalusian Stallion

INTRODUCTION. Horse cutaneous habronemosis caused by larvae of the spirurid nematodes Habronema microstoma and Habronema muscae is also known as “summer sores’’. These lesions are often severe and disfiguring (Scott and Miller, 2003 Equine Dermatology, pp. 357-360). Although Habronema-caused lesions at the distal hind coronary grooves have been described (Schuster et al., 2010 Vet Parasitol. 174:170-174), cases of hoof cracks with secondary summer sores have never been reported. The present report describes clinic-pathological and surgical features of a quarter crack case complicated by cutaneous habronemosis at the dermal layers. MATERIALS AND METHODS. A 15-years-old, Andalusian stallion was referred to the Veterinary Teaching Hospital (VTH) of the University of Teramo for a neoformation of the hoof and severe lameness. The clinical examination revealed a total thickness vertical quarter crack and a protruding and exuberant granulomatous mass. The mass was surgically removed and subjected to histopathological, microbiological, and parasitological examinations. In particular, a conventional copromicroscopical analysis was performed, and faecal and skin samples were subjected to a duplex semi-nested PCR able to differentiate H. muscae and H. microstoma. RESULTS AND CONCLUSION. The molecular positivity of faecal (H. muscae) and skin (H. muscae and H. microstoma) samples indicates the primary role of Habronema in causing the hoof granulomatous mass and confirms previous data which showed the correlation between animals with summer sores and the concomitant occurrence of gastric infections (Vasey, 1981 Compend Cont Educ Pract Vet. 3:290-298). A septic pododermatitis with granulation tissue reaction was confirmed by histology. The secondary intention healing, the persistent bacterial infection and the parasitic infection have fostered the exuberant granulation tissue reaction, which occurs very rarely in the healing of foot wounds (Parks, 1997 Equine Vet Educ. 9:317-327). This is the first description of a hoof wall crack complicated by summer sores in the simultaneous presence of gastric habronemosis. A prompt diagnosis during fly activity especially in horses with a history of "summer sores" and / or which live in endemic areas, is imperative for timely treatment and efficacious prevention of disfiguring cutaneous habronemosis.