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Open Access Highly Accessed Research article

Characterization of a dopamine transporter polymorphism and behavior in Belgian Malinois

Lisa Lit1*, Janelle M Belanger1, Debby Boehm2, Nathan Lybarger3, Anouck Haverbeke45, Claire Diederich5 and Anita M Oberbauer1

Author affiliations

1 Department of Animal Science, University of California Davis, One Shields Ave, Davis, CA 95616, USA

2 Precision Canine, Phoenix, Arizona, USA

3 Left Coast Canine, Marysville, CA, USA

4 VetEthology, Leemveldstraat 44, Overijse 3090, Belgium

5 Department of Veterinary Medicine, IVRU-NARILIS, University of Namur, 61 rue de Bruxelles, Namur 5000, Belgium

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Citation and License

BMC Genetics 2013, 14:45  doi:10.1186/1471-2156-14-45

Published: 30 May 2013

Abstract

Background

The Belgian Malinois dog breed (MAL) is frequently used in law enforcement and military environments. Owners have reported seizures and unpredictable behavioral changes including dogs’ eyes “glazing over,” dogs’ lack of response to environmental stimuli, and loss of behavioral inhibition including owner-directed biting behavior. Dogs with severe behavioral changes may be euthanized as they can represent a danger to humans and other dogs. In the dog, the dopamine transporter gene (DAT) contains a 38-base pair variable number tandem repeat (DAT-VNTR); alleles have either one or two copies of the 38-base pair sequence. The objective of this study was to assess frequency of DAT-VNTR alleles, and characterize the association between DAT-VNTR alleles and behavior in MAL and other breeds.

Results

In an American sample of 280 dogs comprising 26 breeds, most breeds are predominantly homozygous for the DAT-VNTR two-tandem-repeat allele (2/2). The one-tandem-repeat allele is over-represented in American MAL (AM-MAL) (n = 144), both as heterozygotes (1/2) and homozygotes (1/1). All AM-MAL with reported seizures (n = 5) were 1/1 genotype. For AM-MAL with at least one “1” allele (1/1 or 1/2 genotype, n = 121), owners reported higher levels of attention, increased frequency of episodic aggression, and increased frequency of loss of responsiveness to environmental stimuli. In behavior observations, Belgian Military Working Dogs (MWD) with 1/1 or 1/2 genotypes displayed fewer distracted behaviors and more stress-related behaviors such as lower posture and increased yawning. Handlers’ treatment of MWD varied with DAT-VNTR genotype as did dogs’ responses to handlers’ behavior. For 1/1 or 1/2 genotype MWD, 1) lower posture after the first aversive stimulus given by handlers was associated with poorer obedience performance; 2) increased aversive stimuli during protection exercises were associated with decreased performance; 3) more aversive stimuli during obedience were associated with more aversive stimuli during protection; and 4) handlers used more aversive stimuli in protection compared with obedience exercises.

Conclusions

The single copy allele of DAT-VNTR is associated with owner-reported seizures, loss of responsiveness to environmental stimuli, episodic aggression, and hyper-vigilance in MAL. Behavioral changes are associated with differential treatment by handlers. Findings should be considered preliminary until replicated in a larger sample.

Keywords:
Dog; Belgian Malinois; Dopamine transporter; Behavior; Seizure