Genetic parameters for CPL in Belgian Draught Horses
Chronic progressive lymphedema (CPL) occurs in several draught horse breeds, like the Belgian Draught Horse. In the lower limbs slight to severe swelling occurs with progressively deteriorating skin lesions and deformation.
Heritability estimates of previous studies in six German draught horse breeds showed an average heritability of 0.22. One of these horse breeds, the Rhenish German Draught Horse, was founded on Belgian Draught horses. This supports the assumption of genetic CPL susceptibility in the Belgian Draught Horse. In this study the genetic parameters for CPL associated traits in Belgian Draught horses were estimated to look at the possibility of selecting against CPL susceptibility in breeding programmes.
A multitrait animal model was used in this study that included clinical scores of CPL in the four limbs, skinfold thickness and hair samples. Next to that, age, gender, coat colour and limb hair pigmentation were taken as fixed effect and date of recording as random effect. A restricted dataset was formed that excluded horses under three years of age, because CPL is often uncertain in younger horses.
The results show that skinfold thickness and hair diameter cannot be used as a direct diagnostic for CPL, since they were highly correlated. The heritability of CPL is relatively low. Advised is to select on estimated breeding values based on repeated clinical examinations to reduce CPL occurrence in the Belgian Draught Horse.
Expert opinion by Anouk van Breukelen
In this study permanent environmental effects, like the date of measuring, were shown to be highly important, which was not shown in earlier study. For future data collection, continued measurement is advised.
> From: Keyser et al., J. Anim. Breed. Genet. 131 (2014) 522-528. All rights reserved to Blackwell Verlag GmbH. Click here for the online summary.