ARTHROSCOPIC REMOVAL OF PALMAR PLANTAR OSTEOCHONDRAL FRAGMENTS (POF) IN THE METACARPO-PHALANGEAL AND METATARSO-PHALANGEAL JOINTS OF STANDARD-BRED TROTTERS - OUTCOME AND POSSIBLE GENETIC BACKGROUND TO POF/

A clinical material of 133 Standardbred horses with palmar/plantar ost eochondral fragments (POF) in the meta-carpo- and metatarsophalangeal joints were studied. All horses had their fragments removed with arthr oscopic surgery. 102 of the horses were 3 years old or younger when su rgery was performed. Anatomical localisations of the fragments were in agreement with earlier reports. There was no statistical significant difference in month of birth in the POF-group compared to the total po pulation. Eighty % of the horses that had raced before surgery came ba ck to racing. The racing performance relative to their contemporaries remained the same after the POF operation. 65% of the horses that had not raced before surgery raced after the operation. The breeding index BLUP (Best Linear Unbiased Prediction) was used to evaluate if the PO F-horses differed genetically in racing ability from the total populat ion. The average BLUP value of the POF group was 103.4 (+/- 0.65), whi le the mean BLUP value of the total population was 98.9. This differen ce was highly significant and indicated that these POF horses belonged to a selected group. A homogeneity test of allele frequencies in bloo d type systems was performed to evaluate if any genetic difference was persistent between POF horses compared to the total population. The s tatistical analysis of gene frequencies for alleles in blood type syst ems indicated a genetic discrimination in blood type systems D and Tf.