How Many Chromosomes Do Dogs Have? Vet Approved Facts & FAQ
By Kit Copson
Updated on
Chromosomes are the building blocks of all the traits your dog inherits from their parents that make them an individual. They are split into pairs, and dogs have a total of 78 chromosomes and 39 pairs. This is identical to the number of chromosomes wild dogs—like dingoes, jackals, coyotes, and, of course, wolves—have.
Read on to find out more.
Chromosomes: The Basics
Chromosomes are coiled structures contained within the nucleus of cells. Chromosomes consist of protein and deoxyribonucleic acid (DNA). The DNA makes up genes—hundreds or even thousands of them within each chromosome.
Contained within each cell are two copies of individual genes, and these are called alleles.
This is the general rule, but there is one exception—reproductive cells (egg cells and sperm cells). These cells contain but one copy of each gene because they inherit just one copy of each chromosome from each parent when they develop.
What Is the Role of Chromosomes?
In brief, the genes contained within chromosomes are responsible for the distinguishing characteristics of each animal. In the case of dogs, they determine things like what color their eyes and coat will be. Gene mutations sometimes occur and cause inherited diseases.
Chromosomes are passed down from parent to offspring during fertilization of the egg by the sperm, and each parent contributes one chromosome to form chromosome pairs.
Alleles (gene copies) come in different forms. Some—like the brown eye allele, for example—are dominant (only a single copy is required for trait expression) while others are recessive (two copies are required for the trait to show). This means that if there is one copy of the dominant allele, this allele will be the one to determine a trait.
How Many Chromosomes Do Dogs Have vs Humans?
The number of chromosomes a living thing has varies greatly. While dogs have 78 chromosomes and 39 pairs—yep, dogs are incredibly genetically diverse—humans have 46 chromosomes and 23 pairs, and cats have 38 chromosomes and 19 pairs.
Genetic Disorders in Dogs
Unfortunately, genetics can sometimes be cruel. In addition to their coat color, eye color, and other physical traits, dogs can inherit a variety of genetic diseases and disorders caused by autosomal dominant disorder, autosomal recessive disorder, or sex-linked disorders (which are linked to the X chromosome).
Autosomal dominant disorder occurs when an abnormal (mutant) allele overcomes a normal allele, resulting in an abnormal trait. Dogs cannot carry this disorder without displaying symptoms, so responsible breeders will not pursue breeding a dog with autosomal dominant disorder.
On the other hand, autosomal recessive disorder occurs when two copies of an abnormal gene are inherited. If this happens, the disorder will be expressed. If the parent dogs both carry the gene, 25% of puppies in the litter will express the disorder, and 50% will be carriers. The remaining 25% won’t inherit the abnormal gene. Carriers don’t come with symptoms, which makes genetic testing necessary to prevent these disorders from potentially being passed down to future generations.
Common Inherited Diseases
According to Mindy A. Cohan, VMD at PetMD, the following genetic disorders are among the most common seen in dogs:
- Heart disease
- Epilepsy
- Degenerative myelopathy (a neurological condition)
- Brachycephalic syndrome (short-snouted dogs like Pugs and Frenchies)
- Some types of bladder stones
- Hip dysplasia
Final Thoughts
So, dogs have a large number of chromosomes—more than humans. That said, a high chromosome count doesn’t mean one organism is more complex than another. Humans do share many genetic similarities with dogs, though, and are susceptible to many of the same inherited diseases, including epilepsy, cancer, allergies, and retinal diseases.
Inherited disorders are something to bear in mind if you’re considering buying a dog from a breeder—be careful who you choose to purchase from. Responsible breeders have their animals tested for potential genetic conditions, only sell to people they trust to care for the dog, and have overall excellent standards of animal welfare.
Featured Image Credit: Zanna Pesnina, Shutterstock
