Fotossensibilização primária em bovinos causada por (Amaranthaceae) Froelichia humboldtiana (Roem. & Schult.) Seub

Abstract

Poisonings by plants are important cause of death of cattle, sheep and goats and direct and indirect losses of flock in Brazil and worldwide. Among the toxic plants that cause economic damage to livestock, there are the photosensitization plants as Froelichia humboldtiana (Roem. & Schult.). This Amaranthacea, popularly known in the semiarid region of Pernambuco and Paraíba as "ervanço", is widely distributed in the areas of scrub from the State of Minas Gerais to Ceará, and can also be found in savannah areas in the State of Goiás. F. humboldtiana is a weed of pastures quite palatable to ruminants and horses and has been often found in degraded areas of the northeastern semiarid. This paper describes three outbreaks of primary photosensitization by F. humboldtiana and experimental reproduction of the disease in a cattle. The epidemiological and clinical data were obtained from the owners and veterinarians responsible for the livestock. After these procedures was recommended the the removal of cattle from invaded pastures. The animals were clinically examined after 30 and 90 days. From these animals samples of blood were collected on the first day of the experiment and on 20th day for determination of serum activities of aspartate aminotransferase, gamma-glutamyltransferase, total, indirect and conjugated bilirubin. Two animals with areas of white fur, crossbred, aged between 8 and 12 months were used as controls.An outbreak of primary photosensitization by F. humboldtiana occurred in Custodia, semiarid region of Pernambuco and another two outbreaks occurred in Agreste of Paraíba. The disease occurred from March to June 2011, affecting 27 bovines out of a total of 70. The main lesions consisted of dermatitis of the white skin, with edema and necrosis. All the bovines recovered after removal from the areas invaded by F. humboldtiana. To produce the disease experimentally, one bovine with white skin was placed for 14 days into an area with F. humboldtiana as the sole forage. This bovine presented photodermatitis on the 3rd day of consumption. The serum concentrations of total, indirect, and conjugated bilirubin and the serum activities of gamma-glutamyl transferase and aspartate-aminotransferase in the spontaneously affected cattle and in the experimental cattle remained within normal ranges. It is concluded that F. humboldtiana causes primary photosensitization in cattle in northeastern Brazil.