Can Dogs Have Down Syndrome? What a Pet Owner Needs to Know

The bond between the human and the canine species dates back centuries. Given a dog’s ability to be loyal and to love unconditionally, it comes as no surprise that the two species have been linked for longer than we can imagine. To paraphrase Josh Billings (a.k.a. the humorist and lecturer Henry Wheeler Shaw), “A dog is the only thing on earth that loves you more than he loves himself.” So, if man’s best furry friend can feel similar things to humans, this begs the question of whether pups can suffer from the same medical conditions as humans. This comes as no surprise, as dogs can suffer from behavioral disorders such as depression or anxiety. They can even suffer from certain types of cancer, diabetes, epilepsy, and congestive heart failure—and this is naming just a few examples.

But can the canine species suffer from genetic disorders or chromosomal abnormalities that have so far only been linked to the human species? In particular, can dogs have Down Syndrome? The answer is not so clear. And why is that? Let’s first look at human Down Syndrome.

What is Down Syndrome in humans?

According to the National Down Syndrome Society, Down Syndrome is referred to as a condition when someone has either a complete additional or a partial copy of chromosome 21. So, what is a chromosome, you may wonder? And why does an extra copy or extra chromosome cause problems? Well, it turns out that a lot of things in the human body have to function just the way they are, otherwise problems arise. All of our genetic material is stored in a cell compartment called the nucleus. Every cell has it. Genetic material is stored in genes which carry information that determines all the inherited traits. Genes are organized on rod-like structures or chromosomes. Each nucleus has 23 pairs of chromosomes, one from the mother and one pair from the father. In case of the extra material of chromosome 21, also called a trisomy, Down Syndrome is the consequence.

Down Syndrome Symptoms

Down Syndrome Symptoms

There are several effects that are associated with extra genetic material. The most obvious is a degree of intellectual impairment and this varies between individuals. The US Centers for Disease Control and Prevention (CDC) states that there are some common physical features of Down Syndrome such as a flattened face around the bridge of the nose and small ears, hands and feet. Several medical problems are also common among people with Down Syndrome. These include hearing loss, frequent ear infections, eye diseases, obstructive sleep apnea as well as heart defects that are present at birth.

Can Dogs Have Down Syndrome?

Can they? It all depends on how one looks at the question. Let’s preface this section with the fact that genetic research in dogs is not nearly as advanced as in humans. Along those lines, few individual canine chromosomes or genes have actually been analyzed or sequenced.

According to the CDC, approximately 1 in every 700 babies and children in the United States has Down Syndrome. This cannot be said about dogs with the same certainty. What is known, however, is that if the disorder occurs in dogs, it is much rarer than in humans. While there are several genetic similarities between dogs and humans, it is not known whether what happens in the human chromosome 21 will have the same effect if it were to happen on the canine chromosome 21. The first obvious difference in disfavor of similarities is that humans have 23 sets of chromosomes and dogs have 39, which means that whatever information the human chromosome 21 carries may not be the same as the canine chromosome 21. This would mean that trisomy 21 in dogs would not end up in Down Syndrome in dogs. In fact, information on human chromosome 21 is so unique that it does not appear elsewhere on the chromosomes of other species, including dogs.

Given all this, few vets claim that Down Syndrome does exist in dogs but that the symptoms are vastly different than in humans. The typical scenario is that puppies who seem to have the condition die before they are even born. And, even if born, they do not live for very long. Add to that the trauma of being born that is too much for the puppy to handle and actually ends up in its death. Furthermore, even though human Down Syndrome symptoms appear only after one to two years, canine symptoms such as physical abnormalities and mental retardation are obvious early on. As a result, puppies may not be able to feed themselves which may in and of itself culminate in death. Lastly, the mother also tries to remove any sick puppies from the littler in order to protect her healthy young and this, too, may cause affected puppies to die early on. The overall survival rate of these puppies is about five years compared to ten to 15 years for healthy ones.

What Pet Owners Need to Know

In addition to the aforementioned symptoms, there are several other common Down Syndrome symptoms to look for in your puppy and it is advised that owners look for those symptoms in order to be able to differentiate whether the symptoms are due to Down Syndrome or due to something else like a cognitive dysfunction. Owners are also advised to be cautious to not mix up the above-mentioned symptoms with similar ones that may point to other diseases that are related to growth hormone deficiencies, too much fluid in the brain or liver problems (portosystemic shunt).

So, overall, canine Down Syndrome is a possibility, but not a certainty. While similarities between dogs, cats, and people exist when it comes to this genetic disorder (i.e. a brachycephalic head shape), dog owners should be cautious to get the correct diagnosis from their local vet especially when Down Syndrome-like symptoms may highlight some other serious cognitive dysfunction. Overall, whichever symptoms you notice, consult with your veterinarian as soon as possible as it all may be serious. Better still, it may just be a lot less serious than anticipated.

Laura Day
 

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