Pneumonia causada por Rhodococcus equi em um potro da raça Crioula / Pneumonia by Rhodococcus equi in a Criollo Foal

ABSTRACT

Background: Rhodococcus equi is a facultative intracellular bacteria, gram positive and telluric. The airway is the main form of transmission. Clinical manifestations include enteritis, lymphadenitis and pneumonia in foals. Foals with pneumonia are infected during the first days of life, although clinical symptoms manifest mainly between 1 and 6 months of age. Susceptibility to infection is related to amount of microorganism inhaled or ingested; decline of humoral immunity; immune system immaturity and failure in cellular response. The objective of this study is to report the case of a Criollo foal with pneumonia by Rhodococcus equi, with the description of diagnosis and therapeutic methods. Case In the Hospital of Veterinary Clinics of UFPel, it was attended a Criollo foal, 3 months old, with tachycardia, dyspnea, hyperthermia, mild bilateral nasal mucopurulent secretion and bilateral pulmonary rattling sounds. In CBC it was found hyperfibrinogenemia, leukocytosis with neutrophilia and normocytic normochromic anemia. In the thorax radiographic examination it was evidenced areas with increased radiopacity and irregular edges in dorsal and caudal lung field. In the transtracheal fluid it was isolated Rhodococcus equi bacteria and submitted to antibiogram test. Treatment was based on azithromycin (10 mg/kg), rifampicin (2.5 mg/kg) orally (PO) for 60 days, flunixin meglumine (1.1 mg/kg) intravenously (IV), omeprazole (4 mg/kg) PO for 45 days and fluid was administered from daily clinical evaluation. The foal accompanied by his mother was transferred to a field with improved native pasture, shaded, with water ad libitum and feed 3x a day. After 30 days of hospitalization, the animal presented anorexia, lethargy, fever associated with leukocytosis. At this time it was added to treatment metronidazole (30 mg/kg) PO every 12 h for 10 days. After 35 days, the foal presented severe diarrhea, which ceased in 5 days, and in the first 3 days it was administered activated charcoal PO. The CBC results indicated a reduction in the number of leukocytes and fibrinogen during the hospitalization period. In the same period, the ultrasound evidenced a reduction in lesions diameter observed previously in pulmonary area. After 75 days the foal showed an improvement in overall clinical frame and he was discharged. Discussion: Early diagnosis of R. equi infection allied with the results of laboratory tests, allowed specific and immediate treatment improving the foal prognosis of living. The description of the occurrence of pneumonia R. equi in Criollo foals is unusual. In this case, the animal developed infection during the breeding season (February), when it was housed in a reproduction centre. In this centre, the foal remained part of the day in a sand hose, high ambient temperature, overcrowded paddocks and large turnover of equines from various age groups. These factors predispose to installation and permanence of the disease. Due to Criollo breed appreciation and increased use of assisted reproductive in this breed, the raisin system implies in gathering of factors risk that predispose the occurrence of R. equi in foals. The clinical evaluation associated with laboratory tests was imperative in order to obtain definitive diagnosis of R. equi infection and foals monitoration. The treatment based on the antibiotics azithromycin and rifampin associated with supportive therapy was effective in resolving a clinical case of Rhodococcus equi pneumonia in a Criollo foal 3 months old.