Can dogs have dwarfism? The short answer is yes. Dogs diagnosed with dwarfism can often be identified by their bulging eyes and shorter legs. This is usually due to a lack of growth hormones. That said, different forms of dwarfism — achondroplasia and pituitary dwarfism, for instance — can affect dogs differently.

Let's take a closer look at what causes dwarfism, how dogs with dwarfism are affected and the breeds that are most likely to have this condition.

Types and Causes of Dwarfism in Dogs

While there are several different types of dwarfism that can cause a genetic change to a dog's normal growth, size, quality of life and lifespan, dogs diagnosed with dwarfism usually have one of the following types:

Achondroplasia

The most common version of dwarfism in dogs is achondroplasia — a condition also observed in humans. Achondroplasia in humans is caused by the genes that encode for growth factor receptors in a cell type known as a fibroblast. Although we don't know the exact genetic location in dogs, a similar inherited mutation results in the disproportionately short limbs we observe in certain dog breeds, such as dachshunds and corgis.

Dogs with achondroplasia are also referred to as having chondrodysplasia or osteochondrodysplasia. This nomenclature is based on the fact that the affected genes impact a dog's bones and cartilage (the root "chondro" refers to cartilage while "osteo" refers to bones).

Pituitary Dwarfism

Also referred to as juvenile-onset panhypopituitarism, this disorder can often be more serious, on average, than achondroplasia. Pituitary dwarfism occurs either when part of the pituitary gland fails to develop normally during fetal development or as the result of a benign brain tumor affecting this area. The result is a depletion or complete lack of growth hormone, which is often accompanied by other hormone deficiencies. Dwarfism is the inevitable result in all cases.

Dwarfism's Effect on Dogs

With achondroplasia, dogs tend to have the following:

• Larger than normal head
• Undershot jaw
• Shorter nose
• Crooked teeth
• Enlarged joints
• Corkscrew tails
• Bowed limbs

Some dogs diagnosed with dwarfism may have more severe problems associated with the disease, including spinal problems such as spina bifida, spinal deviations, hemivertebrae, brachycephalic syndrome, angular/rotational limb deformities and intervertebral disc disease, among others. In some breeds, these diseases are inherited by design, while in others, the mutation occurs more sporadically. In this latter group, the additional problems associated with achondroplasia are often more severe.

In the case of pituitary dwarfism in dogs, affected dogs will fail to grow normally starting at about two months of age. Their bones don't achieve skeletal maturity until they're about four years old, and the deficiency of related hormones typically leads to a loss of hair and a lack of adult dentition, among other issues depending on what hormonal deficiencies they're experiencing. Sadly, these dogs tend to have a shortened lifespan.

Breeds Prone to Dwarfism

As mentioned above, some dogs are expressly bred for dwarfism. By design, dogs like dachshunds, many bulldog breeds, corgis, basset hounds, pugs and Pekingese (among others) are genetically selected for this form of dwarfism.

In the case of pituitary dwarfism in dogs, German shepherds are overrepresented among affected breeds. This lends affected dogs a coyote-like appearance, which is the textbook visual representation of this condition. Pituitary dwarfism in dogs is also accompanied by a characteristically shrill bark. Other breeds, including the Finnish Spitz, Miniature Pinscher and Karelian bear dogs, have also been reported to inherit this autosomal recessive trait.