HOOF HORN ABNORMALITIES IN LIPIZZANER HORSES AND THE EFFECT OF DIETARY BIOTIN ON MACROSCOPIC ASPECTS OF HOOF HORN QUALITY

This study involved a macroscopic evaluation of hoof quality in 152 Li pizzaner horses (130 from Austria and 22 from other countries) and a c ontrolled double blind trial of the effects of biotin on hoof horn gro wth and quality over 19 months in 42 stallions from the Spanish Riding School (SRS) in Vienna. Using a grading system that incorporated eval uation of horn wall, white line, sole and frog, the macroscopic study revealed the following: 90% of the Austrian Lipizzaners had soft white lines and crumbling, fissured horn at the bearing border of the walls ; 39% of the stallions of the SRS, >4-years-old, had medium to severe hoof horn changes. Daily administration of 20 mg biotin to a test grou p of horses (n=26) and a placebo to a control group (n=16) showed that after 9 months the test group had significantly improved compared to the beginning of the trial and the placebo group (P<0.01). In the test group, further improvement was observed during the following 5 months and, subsequently, the same good level of hoof condition was maintain ed over 3 further years of observation, Growth rate of the horn wall w as equal in the biotin and placebo group, being 7 mm/28 days, giving a wall renewal period of 11 months. Mean plasma biotin level of untreat ed horses was 350 ng/l; plasma levels of biotin supplemented horses we re >1000 ng/l. It was concluded that continuous dietary supplementatio n with biotin at a daily dose of 20 mg is indicated to improve and mai ntain hoof horn quality in horses with less than optimum quality hoof.