Preliminary Observations of the Breed Composition of Mixed Breed Dogs in the USA
ACVIM 2008
P.G. Jones; A.J. Martin; R.J. Stark; S.M.D. Davison; P.J. Markwell
Waltham Centre for Pet Nutrition
Melton Mowbray, Nottingham, UK

Mixed breed dogs comprise approximately 50% of the dog population in the USA. A SNP based test designed to determine the breed composition of mixed breed dogs has recently been made available commercially.a The aim of this study was to collect preliminary data on the breed composition of mixed breed dogs in the USA.

Blood samples were collected in veterinary hospitals from 891 dogs. DNA was extracted and typed at more than 300 different SNPs across the genome using selective hybridization and PCR amplification, followed by a discriminatory single base-pair primer extension reaction. The SNP variants were detected by mass spectrometry. A Bayesian generative model was then used to infer the family tree of a dog from comparison of detected genotypes with 134 breed signatures developed previously from more than 8000 pure bred dogs. Inference was performed on eleven different family tree models, and the best-fit model selected using the deviance information criterion.

The number of breeds detected per dog averaged 3.3, with German Shepherd Dog the most commonly detected breed (Table). Twenty-seven of the dogs were considered to be pure bred.


Percentage of
total breeds detected


Percentage of
total breeds detected

German Shepherd Dog


Golden Retriever


Labrador Retriever


Cocker Spaniel


Chow Chow






Siberian Husky




Poodle (miniature)


This study provides a first assessment of the mixed breed dog population of the USA. The data suggest that this test could be of value in both veterinary practice and research to determine the breeds present within mixed breed dogs.

a. WISDOM PanelTM MX, Mars Veterinary, Rockville, MD

Speaker Information
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Peter Markwell

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