One of the most interesting facts about dogs is that they have a different number of chromosomes than humans.

Knowing how many chromosomes a dog has can help shed light on the evolutionary development of both species.

So, just how many chromosomes do dogs have?

How Many Chromosomes Do Dogs Have?

The answer is 78. To put this into perspective, humans have 23 pairs of chromosomes for a total of 46, while other animals have varying numbers depending on the species and their evolutionary history.

For example, cats have 38 pairs (76), horses 64 (128), cows 60 (120), mice 20 (40), and chickens 78 (156). This wide range in chromosome numbers reflects the complexities and differences between species.

All mammals have similar chromosomes, but there are still some small differences between them when it comes to size and number.

In the case of dogs, their 78 chromosomes are composed of 39 pairs – 19 autosomal pairs and 2 sex-related pairs. This makes them more closely related to humans than cats or horses in terms of gene expression.

What’s particularly interesting is that while most breeds of dog share the same number of chromosomes, there are some exceptions out there such as Irish Wolfhounds which are believed to possess 79 or 80 chromosomal pairs due to a phenomenon known as polysomy X – an extra copy of one or more X-chromosome genes present in some individuals.

While this doesn’t affect their overall health, it does make them unique compared to other breeds.


It’s amazing how much genetic diversity can be found within different species even when they share common ancestry – as dogs and humans do!

As we learn more about genetics and evolution, we can continue to deepen our understanding of why certain organisms possess certain qualities over others due to their chromosomal makeup.

Ultimately this knowledge can help us better understand our own genetic makeup as well as that of our four-legged friends!