Demographic characteristics, site and phylogenetic distribution of dogs with appendicular osteosarcoma: 744 dogs (2000-2015)

Objective: To report demographic characteristics of a contemporary
population of dogs with appendicular osteosarcoma and assess the
relationship between demographic characteristics, site distribution, and
phylogenetic breed clusters. Design: Retrospective case series. Methods: A
search of the Veterinary Medical Database was performed for dogs with
appendicular osteosarcoma as a new diagnosis. Entries were reviewed for
the sex, neuter status, age at diagnosis, breed, affected limb, and tumor
location. The reported breed for purebred dogs was used to categorize each
dog into one of five phylogenetic groups based on microsatellite analysis.
Results: 744 client-owned dogs were included in the study. Study dogs were
represented by a male-to-female ratio of 0.95:1.0, the majority of which
(80.9%) were neutered. Most dogs were diagnosed between 7-10 years of age.
The majority (77.8%) of dogs were large or giant-breed dogs. Purebred dogs
comprised 80.4% of the population. The most common purebred breed affected
by OS was the Rottweiler (17.1%). The most common phylogenetic group
represented was Mastiff-Terrier (M-T, 26.3%). OS was more commonly located
in the forelimb (64.2%) versus the hindlimb (35.8%), and the humerus was
the most common site (20.9%). The distribution of age groups and tumor
locations were significantly different between phylogenetic clusters. The
distribution of age groups and neuter status were significantly different
between size groups. Conclusions and Significance: The demographic data of
canine appendicular OS are similar to previous reports. The data on
phylogenetic associations can guide future studies aimed at evaluating the
genomic mutations that contribute to OS development and its biological
behavior.