Surtos de fotossensibilização e dermatite alérgica em ruminantes e equídeos no Nordeste do Brasil / Outbreaks of photosensitization and allergic dermatitis in ruminants and equidae in northeastern Brazil

O presente estudo foi conduzido com o objetivo de determinar as causas de fotossensibilização em ruminantes e equídeos no Nordeste do Brasil, através da revisão dos laudos de exames arquivados no Laboratório de Patologia Veterinária da Universidade Federal da Paraíba. Durante os quatro anos do estudo foram diagnosticados 22 surtos de fotossensibilização, incluindo 11 surtos de fotossensibilização primária e oito surtos de fotossensibilização hepatógena. A intoxicação por Froelichia humboldtiana foi a principal causa de fotossensibilização e a única causa de fotossensibilização primária. As espécies mais gravemente afetadas por fotossensibilização primária foram os asininos, caprinos, bovinos e ovinos, mas os equinos e mulas também são afetados. A intoxicação por Brachiaria decumbens foi a principal causa de fotossensibilização hepatógena e afetou apenas os ovinos e bovinos. Outras plantas associadas com fotossensibilização hepatógena incluíram Enterolobium contortisiliquum e Lantana camara. Dermatite alérgica foi diagnosticada em dois rebanhos ovinos e em um cavalo. Os animais tinham lesões crônicas, caracterizadas por alopecia, crostas e hiperpigmentação no topo da cabeça, ao redor dos olhos (ovinos) e nos membros (equino). O prurido foi o principal sinal clínico observado nos casos de fotossensibilização primária e hipersensibilidade à picada de insetos.(AU)

The study was conducted to determine the causes of photosensitization in ruminants and equidae in northeastern Brazil through a review of the files at the Laboratório de Patologia Veterinária of Universidade Federal da Paraíba. During four years of the study 22 outbreaks of photosensitization were diagnosed, including 11 outbreaks of primary photosensitization and eight outbreaks of hepatogenous photosensitization. Poisoning by Froelichia humboldtiana was the main cause of photosensitization, and the only cause of primary photosensitization. The most severely affected animals by primary photosensitization are donkeys, goats, cattle and sheep, but horses and mules may also be affected. Poisoning by Brachiaria decumbens was the main cause of hepatogenous photosensitization, and affected only sheep and cattle. Other plants associated with hepatogenous photosensitization in cattle include Enterolobium contortisiliquum and Lantana camara. Allergic dermatitis was diagnosed in two flocks of sheep and in a horse. The animals had chronic lesions characterized by areas of alopecia, crusts and hyperpigmentation on the head, around the eyes (sheep) and at the legs (horse). Itching was the main clinical sign in cases of primary photosensitization and insect hypersensitivity.(AU)

Primary photosensitization caused by ingestion of Froelichia humboldtiana by dairy goats.

This study aimed to describe the first report of an outbreak of primary photosensitization in dairy goats caused by Froelichia humboldtiana. The disease occurred from March to May 2014, in a mixed flock of 15 Saanen, Alpine, and crossbred lactating goats. The entire flock was affected; however, the Saanen and cross-bred goats developed more severe lesions, and their milk production decreased by as much as 75%. Lesions were progressive and consisted of skin hyperemia, edema, and necrosis, especially in depigmented areas. An experimental study with two goats resulted in photodermatitis, similar to that observed in the natural cases, 10-14 days after the beginning of plant ingestion. Serum activities of aspartate aminotransferase (AST) and -glutamyltransferase (GGT) and, direct, indirect, and total bilirubin serum concentrations were within the normal ranges. In conclusion, F. humboldtiana causes primary photosensitization in goats with a negative impact on milk production.