Genetic background of aggressive behaviour in dogs

Abstract

The background of aggression is very complicated and the basis of its occurrence has not been well explained yet. It is thought that tendency to aggressiveness is an effect of both environmental and genetic factors. Aggression is a very undesirable behavioural trait in dogs living with humans. The aim of this study was to determine the relationship between two polymorphisms: DRD4 intron II VNTR and C/T substitution in exon I HTR2B genes and aggressive behaviour in dogs. The VNTR polymorphism in the DRD4 gene was detected by agarose gel electrophoresis following PCR amplification, whereas C/T substitution in the HTR2B gene was analysed using amplification created restriction site-polymerase chain reaction (ACRS-PCR). A total of 121 dogs of several breeds were analyzed. All animals were classified based on a veterinary interview and observation in two groups: aggressive (n = 21) and non-aggressive (n = 100). Significant differences in DRD4 genotype frequencies between aggressive and non-aggressive dogs were observed (P < 0.05). The study provides a clear evidence of an association of VNTR polymorphism within intron II of the DRD4 gene with the occurrence of aggressive behaviour in dogs. Moreover, the findings give good justification for further research aimed at evaluation of the possibility of using this genetic marker in Marker-assisted Selection.