The Canine 39: An encyclopedia of your dog’s genome

An average-sized dog may have 10 trillion cells in its body. If you stretched all the DNA in these cells end to end, how far would it reach?

Just like humans, dogs have a genome that consists of genetic information called DNA. The genome can be thought of as a large encyclopedia that contains all the instructions necessary for making a dog–and a copy of it can be found in every cell in a dog’s body. 

A dog’s genome is made up of 39 pairs of chromosomes. One chromosome of each pair is inherited from the dog’s mother, and the other is inherited from the dog’s father. Each chromosome is like a volume in the encyclopedia.

Zooming in a bit further, each chromosome is comprised of genes. Genes are like entries in each volume of the encyclopedia. They contain the instructions for making individual proteins, each of which has a specific function. For example, a protein could impact how vulnerable a dog is to a certain disease. Or it could affect the shape of a dog’s muzzle, or coat color, or any other of the multitude of differences between breeds.

Zooming in even further still, each gene is made up of individual DNA molecules. These molecules form the genetic code and are read as the letters A, T, C and G. The process of DNA sequencing allows us to read this code. We use DNA sequencing to determine the ancestry of your dog, to conduct genetic testing to calculate risk factors for different genetic diseases, and to measure how DNA methylation patterns change with age.

A closer look into the components that make up a canine cell

Canine genome by the numbers

  • Number of chromosomes: 39
  • Total number of genes: ~20,000
  • Total length of the genome: 2.3 billion DNA letters

To me, it’s quite remarkable that the entire 2.3 billion letter genome can fit inside each microscopic cell in a dog’s body. As it turns out, that’s only possible because chromosomes are very tightly packed with genetic information. If you stretched out the DNA in one dog cell, it would reach over 4 feet long. 

An average-sized dog may have 10 trillion cells in its body. If you stretched all the DNA in these cells end to end, it would reach over 7 billion miles, or over 80 times the distance between the earth and the sun. That’s quite a set of encyclopedias!