Why are Shibas different from other dogs?
A gene-analytical tracing.  

It has always been an established fact in genetics that not only the physical appearance of a creature is congenital but also its immaterial traits. Not only hair colour, size, conformation etc. are inherited but also behaviour, temperament and character.[1]

This applies for dogs as well as for humans. Everyone knows that the individual breeds strongly vary in look and character. Thus for example Dalmatians are said to be agile and obedient, Great Danes are considered to be good natured and sensitive, Retrievers dutiful and companionable. And the Shiba? In literature and reports by breeders and owners, as well as having many amiable traits, the Shiba is constantly referred to as being "strong-willed", "independent", "stubborn", "aloof with strangers" – saying in short that the Shiba is different from other breeds and requires "very firm handling".

In the end-1990s, a group of Japanese scientists studied breed differences using the behavioural profiles 19 dog breeds including six Japanese dog breeds.[2] Profiles were obtained from the scores judged by small animal veterinarians, veterinary nurses and dog trainers. Highly significant breed differences were observed for all traits. High scores for aggressiveness, such as territorial defence, hostility toward other dogs and dominance over owners were clearly observed in the six Japanese breeds, whereas those same breeds scored low estimates in friendly scores such as demand for affection, alacrity in obedience training, playfulness, and adaptability to new owners, in contrast to friendly breeds such as Labrador and Golden Retriever.

From modern molecular biology it is well known that so-called neurotransmitters (messengers) control behaviour in men and animals. Neurotransmitters are biochemical substances relaying information from one nerve cell to the other. These substances are provided by enzymes which are located in specific genes. For example there is a gene for the so-called tyrosine hydroxylase (TH) that is an enzyme involved in the conversion of tyrosine to dopamine which is an important neurotransmitter. Another gene contains the so-called dopamine betahydroxylase (DBH), this being an enzyme that accelerates the conversion of dopamine to noradrenaline.

Scientists from the university in Tokyo have recently examined those two behaviour-relevant genes TH and DBH in five diverse breeds to find out to which extent the gene structure at these loci are different.[3] Gene variations (alleles) in Golden Retrievers, Labrador Retrievers, Maltese, Miniature Schnauzers and Shibas were analyzed. In fact significant genetic differences were detected in these five breeds, which is not really surprising. What was remarkable was that in the Shibas two so-called SNPs by the name of C97T (TH) and A1819G (DBH) were found which do not exist in the other breeds at all. As SNP (Single Nucleotide Polymorphism, pronounced "snip"), variations of single base pairs within a gene are referred to.

The researchers in Tokyo explain the existence of the specific SNPs in the Shiba by the fact that the Shiba belongs to the less domesticated breeds and therefore has a bigger genetic variety. They consider their result as confirmation of another study according to which the Shiba is one of the rare breeds that are genetically related closely to the grey wolf, i.e. the progenitor of all current domestic dogs. Hence it follows that two more breeds also closely related to the wolf genetically – the Basenji and the Chow Chow – are as well as the Shiba mostly characterised as "strong-willed".

How exactly the genetic disposition is related to typical behaviour and character is not known yet. The research in this point is just beginning.[4] So let's wait if more special "Shiba genes" will be detected.

References


[1]  John Paul Scott & John L. Fuller: Genetics and the social behavior of the dog, The University of Chicago Press 1971.

[2]  Tanabe, Y., Ogata, M., et al.: Breed difference in behavioral profiles of dogs: Quantitative analyses by veterinarians in Japan, Japanese Journal of Human Animal Relations 3 (1999), pp. 92-98 [Japanese, English summary].

[3]  Takeuchi Y., Hashizume C., Chon E. M., Momozawa Y., Masuda K., Kikusui T., Mori Y.: Canine tyrosine hydroxylase (TH) gene and dopamine -hydroxylase (DBH) gene: their sequences, genetic polymorphisms, and diversities among five different dog breeds, Journal of Veterinary Medical Science 67 (2005), pp. 861-867.

[4]  Ogata N., Hashizume C., Momozawa Y., Masuda K., Kikusui T., Takeuchi Y., Mori Y.: Polymorphisms in the canine glutamate transporter-1 gene: identification and variation among five dog breeds, Journal of Veterinary Medical Science 68 (2006), pp. 157-159.
Hashizume C., Masuda K., Momozawa Y., Kikusui T., Takeuchi Y., Mori Y.: Identification of an cysteine-to-arginine substitution caused by a single nucleotide polymorphism in the canine monoamine oxidase B gene, Journal of Veterinary Medical Science 67 (2005), pp. 199-201.

© Holger Funk 2008

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