LAMENESS IN 3-YEAR-OLD STANDARD-BRED TROTTERS INFLUENCE OF PARAMETERSDETERMINED DURING THE FIRST YEAR OF LIFE

The aim of the study was to use parameters determined during the first year of life in order to predict risk of lameness at three years of a ge. A total of 265 Standardbred trotters with previously recorded radi ographic changes of the tarsocrural, metacarpo- and metatarsophalangea l joints were randomly examined as three-year-olds for an epidemiologi c study of lameness. Eighty horses were classified as sound and 185 ho rses as lame with moderate and severe symptoms in 138 and 47 horses, r espectively. The variables included in the study were gender, radiogra phic groups, period of birth, feeding rations in the first winter and sire index calculated as the frequency of lame horses in each progeny group. A significant difference in sire index and period of birth was found in the initial statistical analysis between sound, moderately an d severely lame horses. All the variables were entered in a multivaria te logistic regression model. A stepwise procedure was performed and r esulted in contribution of the sire index (p<0.01) and group 2 (p=0.05 ) (presence of radiographic changes other than palmar/plantar bony fra gments in the metacarpo- and metatarsophalangeal joints). The risk of lameness increased with approximately a factor of 2.0 for every 10% in crease in sire index for the presence of the actual radiographic chang e. At a given value of sire index, the risk of lameness increased with a factor of 5.3 if radiographic changes other than palmar/plantar bon y fragments in the metacarpo- and metatarsophalangeal joints were pres ent. Normal findings or other radiographic changes, gender, feeding ra tions and period of birth did not influence the risk of lameness.