Incidence and Heritability of Osteosarcoma in the Irish Wolfhound

Abstract

Study Aim Osteosarcoma is the primary bone tumor that occurs most frequently in dogs. It is the tumor type in about 85% of all primary bone tumors and affects mainly giant breed dogs of middle age. The Irish Wolfhound as a giant breed falls perfectly into the category at risk for developing osteosarcoma, and has been shown to have an increased risk in previous studies. Incidence and the heritability of this trait in the Irish Wolfhound had not yet been calculated. The aim of this study is to collect information on a group of Irish Wolfhounds to determine the incidence and estimate heritability in order to evaluate whether a follow-up association study would prove useful.

Materials and Methods A test group was formed of 532 dogs whose blood samples were collected. The owners or breeders of these dogs were contacted by telephone and information was collected on osteosarcoma status and other relevant facts (age of occurrence, location of the tumor, diagnostic imaging performed). Radiographic imaging was set as the diagnostic method minimally required to assign a dog with a positive bone cancer status. This data was used to calculate the incidence and estimate heritability using linear and logistic models in ASReml.

Results With the data collected an incidence of 6.34% (17 out of 268 deceased dogs) was calculated using the cases in which the diagnostic requirements had been met. The estimated heritability was 0.15 (± 0.09) on the liability scale (logistic model), and 0.33 (± 0.12) on the observed scale (linear model). The linear model showed a result that different significantly from zero. There appeared to be a sex predisposition, with female dogs at a 2.33 higher risk of developing bone cancer than males.

Conclusion These results indicate that an associations study using DNA markers might be fruitful.