Can dogs suffer from Down syndrome?

06-06-2020
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Down syndrome is exclusive to humans and is caused by a trisomy of chromosome 21.

Down syndrome is a set of physical and mental symptoms caused by a genetic disorder. And, although it is common to find cases in humans, it is not the same in other species. If you’ve ever wondered, the answer is no, dogs can’t have Down syndrome.

Although some dogs may have similar symptoms, there is another explanation for their cause. Humans and canines share many genetic disorders, but Down syndrome is not one of them.

What is Down syndrome?

When we speak of any syndrome, we are referring to a set of symptoms characteristic of one or more diseases. Down syndrome is known for the following symptoms:

  • Recognizable facial features: flattened face, especially at the nasal bridge, small almond-shaped eyes, a small neck and small ears
  • Different degrees of cognitive impairment
  • Weak muscle tone or loose ligaments
  • Hearing loss and tendency to ear infections
  • Eye conditions such as cataracts or myopia
  • Sleep apnea
  • Heart malformations
  • Other frequent problems: intestinal obstructions, anemia, thyroid problems, leukemia, Hirshsprung disease …
A dog sitting next to a child with Down syndrome

Moreover, the origin of the syndrome is in the chromosomes. Human beings have 46 chromosomes. Of these 46 chromosomes, half is supplied by sperm at the time of fertilization. The other half comes from the ovum.

The cells of people with Down syndrome have an extra chromosome in their nucleus. 47 chromosomes instead of 46. More concretely, it is an additional chromosome 21. Hence the alteration known as trisomy 21.

On the other hand, each species, whether animal or not, has a specific number of chromosomes . This is how DNA condenses inside cells.

The breakdown of chromosomes occurs in the same way in other animals,  such as dogs. It is therefore possible that they have trisomy on a pair of chromosomes, but not Down syndrome.

Can dogs suffer from Down syndrome?

A similar syndrome has only been discovered in non-human primates with whom we share 98% of genetic information. However, this is not the case in other species such as dogs or cats. Nevertheless, they may suffer from other genetic abnormalities that share some of their symptoms.

You have certainly seen on the Internet rumors about Down syndrome in cats, tigers, dogs … accompanied by photos whose characteristics remind us of those of the syndrome. The origin of these physical traits can be a malformation, a disease or a genetic alteration, but in no case Down syndrome.

Cat with facial deformity but no Down syndrome

The most similar characteristics were observed in animals using a laboratory mouse strain , the Down’s syndrome mouse. The researchers created it to study Down syndrome on an animal model.

Using the chromosome 16 of the mouse, they succeeded in creating a trisomy with the genes of chromosome 21 in humans. The objective was to study the expression of these copies of genes as well as their similarity with Down syndrome, the interaction between genes and the possible future gene therapy to be developed.

Genetic diseases in dogs

Animals may also suffer from cognitive impairment. However, this is equal to Down’s syndrome which can occur due to several factors. For example, the  cognitive dysfunction syndrome that occurs in older dogs. It can occur in cats, but it is much less obvious. This is therefore due to old age.

Finally, we share with dogs many genetic diseases. Some result from mutations in specific chromosomes, such as night blindness, cataracts, and even narcolepsy. Therefore, some breeds are excellent models for studying diseases in humans.

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