Heritability of distichiasis in Havanese dogs in Norway

Abstract

Background Distichiasis is a presumed inherited eyelid disease, characterized by misplaced eyelashes. The effect on eye health and animal welfare varies between individuals; most mild cases show no clinical signs, but some affected animals develop painful corneal disease. In this study, we investigated the prevalence and heritability of distichiasis in the Norwegian population of Havanese dogs. Results A total of 1156 Havanese were included in the study. Out of these, 168 were affected with distichiasis, making the prevalence in our sample 14.5% (95% CI 12.5–16.6%). There was no sex predisposition. Most affected individuals were graded “mildly affected”. The estimates generally showed high heritabilities, which varied between 0.276 (linear model) and 0.720 (Bayesian threshold model). The linear estimates, after conversion to the underlying scale (h2l = 0.664–0.674), corresponds well to the results of the Bayesian models. Conclusions The estimated heritability of distichiasis in Havanese is high and the prevalence is moderate. The high heritability indicate that a significant selection response could be obtained by simple mass selection. To secure good animal welfare, it’s important to control the number of affected individuals and especially the severely affected.

Heritability estimates of distichiasis in Staffordshire bull terriers using pedigrees and genome-wide SNP data

“…The estimated heritability of h 2 pedO = ~ 0.22 and h 2 pedT ~ 0.48 on the underlying scale agrees with other studies of dogs [ 8 , 10 ], even if there is some variation between breeds. While Ketteritzsch estimated a lower heritability in Tibetan terriers [ 9 ], our estimated pedigree-based heritability is slightly lower than in the study of Bellamy et al [ 16 ].…”

“…Due to the low prevalence and limited predictive value in the youngest age groups, the pedigree-based heritability estimates were based on dogs examined after 52 weeks. We based our estimates on a linear model, as Bellamy et al showed a good agreement between heritability estimates from the Bayesian threshold model and heritability from linear models converted to the underlying scale [ 16 ]. The estimated heritability of h 2 pedO = ~ 0.22 and h 2 pedT ~ 0.48 on the underlying scale agrees with other studies of dogs [ 8 , 10 ], even if there is some variation between breeds.…”

“…The affected dogs are graded as mildly or severely affected; earlier, the grade moderately affected was also included. We have treated the phenotype as a binary trait (affected/unaffected) due to missing categorisation in about 16% of the affected dogs, low numbers of the more severely affected dogs and previous practice in heritability estimates of distichiasis [ 8 , 9 , 16 ].…”

“…Heritabilities ( h 2 ) for distichiasis have been reported for: the Tibetan terrier ( h 2 = 0.043, 849 dogs) [ 9 ], Elo ( h 2 = 0.238 ± 0.122, 234 dogs) [ 10 ], English cocker spaniels ( h 2 = 0.22 and 0.51, 799 dogs) [ 8 ], and Havanaise ( h 2 = 0.276 linear model and h 2 = 0.720 Bayesian threshold model, 1156 dogs) [ 16 ].…”

Epidemiology and clinical significance of canine distichiasis: A retrospective study of 291 cases

“…4 It is considered an inherited condition, but the mode of inheritance remains unknown. [4][5][6][7][8][9] These aberrant hairs may cause ocular discomfort and ocular surface alterations, such as ulcerative or non-ulcerative keratitis. 2,3 To date, there have been no reports on the prevalence of the clinical signs associated with distichiasis in dogs.…”