PHYSICAL AND SEROLOGIC EXAMINATIONS OF FOALS AT 30 AND 45 DAYS OF AGEFOR EARLY DIAGNOSIS OF RHODOCOCCUS-EQUI INFECTION ON ENDEMICALLY INFECTED FARMS

Objective-To evaluate results of physical and serologic examinations o f foals at 30 and 45 days of age on 3 types of farms with various prev alences of clinical disease (endemic, sporadic, none) caused by Rhodoc occus equi and to determine whether evaluations were helpful in early diagnosis and control of the disease. Design-Prospective cohort study. Animals-144 foals at 30 and 45 days of age. Procedure-During a 2-year period, 36 foals on farms at which R equi infection was endemic, 71 f oals on farms at which the disease was sporadically detected, and 37 f oals on farms without the disease were examined by means of auscultati on of lungs, serum biochemical and hematologic analyses, and determina tion of antibody titers against R equi, using ELISA. Transtracheal asp irates were obtained from 14 of 32 foals that had clinical signs of di sease and 7 of 41 seropositive feats that did not have clinical signs of disease. Results-Prevalences of respiratory tract disease and serop ositive conversion rates for 45-day-old foals on endemically and spora dically infected farms were significantly higher than on farms without the disease. Rhodococcus equi was isolated from trachael aspirates of seropositive foals, even when clinical signs were not evident. Clinic al Implications-Physical and serologic examinations of foals at 30 and 45 days of age were useful for early diagnosis of R equi infection, e specially for foals on farms at which the disease was endemic.