Body Size 2

Body size in dogs is an adaptive trait that can be inherited and has been associated with variants present in several genes, such as IGF1R.

Definition

The body size of dogs is influenced by a complex interaction of factors, encompassing both genetic and environmental aspects. These factors include diet, care provided, environmental conditions, age and general health of the dog. Although all of these elements play a significant role, the genetic factor stands out as the primary determinant of dog size. An example of a gene related to body size in dogs is IGF1R.

Genetic basis

The presence of two copies of the variant significantly increases the likelihood that the dog will exhibit a small or diminutive body size (less than 25 centimeters). On the other hand, the absence of either copy increases the chances that the dog will develop a large body size. When there is a single copy of the variant, there is a greater likelihood that the dog will exhibit a small body size. It is important to note that body size in dogs may be influenced by other variants that have not been identified or examined in our test; therefore, the presence or absence of this variant does not guarantee that the dog will necessarily be smaller or larger.

Other relevant information

Studies of body size in dogs have linked this trait to a variant in the IGF1R gene, which encodes the insulin-like growth factor 1 receptor, underscoring the crucial importance of the IGF1 pathway in regulating size diversity in dogs. Whereas another size-associated variant from the IGF1 gene is present in most small breeds and absent in almost all larger breeds, the IGF1R mutation presented here appears to have a more modest impact: it contributes to very small size, although some dogs can be tiny without carrying the variant.

Bibliography

Hoopes B.C., Rimbault M., et al. The insulin-like growth factor 1 receptor (IGF1R) contributes to reduced size in dogs. Mamm Genome. 2012 Dec; 23(11-12): 780-790.

Rimbault M, Beale HC, Schoenebeck JJ, et al. Derived variants at six genes explain nearly half of size reduction in dog breeds. Genome Res. 2013 Dec;23(12):1985-95.