Age-dependent expression and heritability of owner-reported dermatological symptoms in Labrador retrievers:...

In decentralised breeding programmes, consistent health monitoring can be challenging, yet accurate phenotyping is essential for informed selection. This study evaluated whether a concise owner-based online survey could capture clinically relevant dermatologic signs in a Belgian assistance-dog breeding population, and whether the resulting phenotypes could support breeding decisions.

Survey data were collected between June 2024 and October 2025 from 223 Labrador retrievers (median age 2.1 years, range 11 months to 8 years). Owners reported the frequency of otitis externa, general itch, paw biting, skin redness and bald spots, recoded into ordinal symptom scores and summed into a total symptom score. Analyses were performed for the full population and by age group (younger vs. older than 3 years).

Overall, 38% of dogs had a non-zero total symptom score. Confirmed canine atopic dermatitis was associated with markedly higher scores (rate ratio = 9.3, 95% CI = 7.2 to 11.9). Each one-point increase in combined parental score corresponded to approximately 9% higher expected offspring score (rate ratio = 1.09, 95% CI = 1.06 to 1.12). Overall heritability was 0.52 (95% highest posterior density 0.24 to 0.75), with substantial age-related variation: h² = 0.05 in dogs under 3 years and h² = 0.81 in dogs aged 3 years or older.

A brief owner-based survey can generate semi-quantitative dermatological phenotypes associated with confirmed disease and familial risk. Symptom expression in younger dogs showed low heritability, which may reflect incomplete phenotype expression at this age but could also result from environmental influences, whereas phenotypes in older dogs seem to more strongly reflect genetic predisposition, suggesting later-life records may better support selection decisions in decentralised breeding programmes.