Can dogs have Down syndrome?

We understand how much you love your pup, and that level of care comes with a responsibility to know all you can about their health. That’s why we’re breaking down rare conditions in dogs. 

While Down syndrome, a genetic condition in which one is born with an extra copy of a chromosome, can't affect dogs, other rare conditions do, Dr. Aliya McCullough, Fetch's on-staff veterinarian, tells The Dig.

These rare conditions fall into two categories: inherited conditions, which are passed through genes, and congenital conditions, which arise from abnormal development while a pup is in utero. ‍

What is pituitary dwarfism in dogs? ‍

Pituitary dwarfism, which is caused by genetic mutation, occurs when the pituitary gland fails to produce various hormones, including growth hormones and thyroid-stimulating hormones, Dr. McCullough says. 

Some dog breeds are more susceptible to pituitary dwarfism because of a specific gene. According to Dr. McCullough, it typically affects German Shepherds, spitzes, Weimaraners, Karelian Bear Dogs, Czechoslovakian Vlcaks and Saarloos Wolfdogs. 

Symptoms of pituitary dwarfism include stunted growth, short stature, abnormal coat, hair loss, delayed or absent adult teeth, heart murmurs and skin darkening, thickening and scaling, Dr. McCullough adds. 

If your dog is diagnosed with pituitary dwarfism, the veterinarian will typically recommend growth hormone replacement therapy and thyroid replacement therapy to replace the missing hormones. ‍

What is congenital hypothyroidism in dogs? ‍

Dogs are born with congenital hypothyroidism because of an abnormality while in utero, which means they lack enough thyroid hormones. 

“Thyroid hormones in normal puppies are associated with metabolism, growth and development,” Dr. McCullough explains. “In puppies with congenital hypothyroidism, they are missing the thyroid hormone and therefore have abnormal development.”

Symptoms of congenital hypothyroidism are mental fatigue, constipation or decreased appetite — and the condition alters pups’ physical appearances, too. 

“Dogs with congenital hypothyroidism have large, broad heads with short, thick necks and bowed legs,” she adds. Other physical characteristics include: 

• Narrowed ear canals
• Stunted growth
• Sealed eyelids
• Potbelly
• Delayed tooth development
• Large tongues
• Gait abnormalities
• Poor hair coat 
• Incoordination
  

According to Dr. McCullough, some dog breeds, like French Bulldogs, German Shepherds and Fox Terriers (among others), are more susceptible to congenital hypothyroidism because of their genetic makeup. Ask your veterinarian if your pup is at risk for developing this condition — dogs affected by congenital hypothyroidism usually take pills or tablets to replace the missing thyroid hormones.

What is congenital hydrocephalus in dogs? ‍

If a dog is diagnosed with congenital hydrocephalus, it’s because there was a malformation of their brain while in utero, Dr. McCullough says. This abnormality affects their cerebrospinal fluid (CSF), which protects and delivers nutrients to the brain and spinal cord. The condition causes either increased production, decreased absorption or an obstruction to the flow of CSF.

Your dog is at a higher risk of developing congenital hydrocephalus if they experience viral infections, inherited diseases, a vitamin A deficiency or exposure to chemicals in utero. Talk to your veterinarian if your dog has seizures, behavioral changes, cognitive dysfunction, lethargy, pacing, pressing their head against walls or vision loss as these are symptoms of congenital hydrocephalus. 

According to Dr. McCullough, toy and brachycephalic breeds are the most at risk for developing congenital hydrocephalus because of the way they’re bred. 

Treatment for congenital hydrocephalus seeks to limit the production of CSF. Your vet may recommend steroids or surgery to remove CSF.