Genetic parameters for chronic progressive lymphedema in Belgian Draught Horses

Abstract

Genetic parameters for chronic progressive lymphedema (CPL)-associated traits in Belgian Draught Horses were estimated, using a multitrait animal model. Clinical scores of CPL in the four limbs/horse (CPLclin ), skinfold thickness and hair samples (hair diameter) were studied. Due to CPLclin uncertainty in younger horses (progressive CPL character), a restricted data set (D_3+) was formed, excluding records from horses under 3 years from the complete data set (D_full). Age, gender, coat colour and limb hair pigmentation were included as fixed, permanent environment and date of recording as random effects. Higher CPLclin certainty (D_3+) increased heritability coefficients of, and genetic correlations between traits, with CPLclin heritabilities (SE) for the respective data sets: 0.11 (0.06) and 0.26 (0.05). A large proportion of the CPLclin variance was attributed to the permanent environmental effect in D_full, but less in D_3+. Date of recording explained a proportion of variance from 0.09 ± 0.03 to 0.61 ± 0.08. Additive genetic correlations between CPLclin and both skinfold thickness and hair diameter showed the latter two traits cannot be used as a direct diagnostic aid for CPL. Due to the relatively low heritability of CPLclin , selection should focus on estimated breeding values (from repeated clinical examinations) to reduce CPL occurrence in the Belgian Draught Horse.

Chronic progressive lymphoedema in draught horses

“…Lesions occurred significantly more often in horses kept for breeding and the production of meat and/or milk than in riding and work horses (tree pulling and agricultural usage) , although use for breeding and amount of work were not significantly correlated with disease severity by others . Date of clinical examination was shown to be an important random factor, with different results in different age groups , but this finding might be explained by the sampling of distinct groups on specific days, for example, stallion contests vs. foal events.…”

“…Heritability coefficients for the occurrence of CPD‐associated lesions per limb have been estimated in 5 German breeds and in cross‐breeds (US Belgian, Belgian Draught Horse and Swedish Ardenner), and estimates ranged from 0.17 (0.07) to 0.51 (0.32; Table ) . Recently, the heritability coefficient for clinical CPL lesions in Belgian Draught Horses was estimated . Analysis was based on 2 data sets, one comprising horses of all ages with clinical signs of CPL and the second from horses older than 3 years.…”

Prevalence of Chronic Progressive Lymphedema in the Rhenish German Draught Horse

“…The occurrence and severity of CPL-lesions showed interactions between sex and age in previous studies [ 1 , 10 , 12 , 23 , 24 , 25 ]. A study with 37 cases, including mainly German draught horses, three Percherons, one Belgian and one Polish draught horse, and two controls showed a significant correlation between the severity of CPL-lesions and age of the horses [ 12 ].…”

Chronic progressive lymphoedema in Friesian horses: suggestive phenotype of affected horses and genome‐wide association study

“…Overall, affected horses had larger body measurements than control horses, with a significant size difference of gaskin length. These findings are supported by previous observations, whereby males, which tend to be overall larger than mares, tend to display clinical signs at a younger age than females . There was a near significant difference in the length of the forearm.…”

“…Chronic progressive lymphoedema (CPL) is a disorder affecting the lymphatic system with clinical manifestation in the lower legs of many draft horse breeds, including Shires, Belgian draft horses, Clydesdales, gypsy vanners, some German draft breeds as well as Friesian horses . Clinical signs may occur from as early as two years of age .…”