Cat With Down Syndrome: Can Cats Have Down Syndrome?

Can cats have Down syndrome? There are a lot of questions about this condition, and if it affects felines. We get into the details, and answer the question: Can cats have down syndrome?

Danielle DeGroot

Last Updated: September 21, 2023 | 6 min read

Sad cat looking out the window while person holds them

Feline owners often ask questions about their pet’s mental state and development. One area that gets significant interest is if cats can have Down syndrome. There is a lot of internet buzz and attention, but can cats really have the condition? Owners often ask this question after seeing behavior or physical traits in their pets.

People often ask about cats and Down syndrome if their pet has uncommon facial features. Unusual physical features have led many to claim their pets have the condition, but that claim is more complex than it may seem.

We get into the details, answer your questions about if cats can have Down syndrome, and clear up some misconceptions people may have.

What Is Down Syndrome?

DS in humans is when someone has an extra copy of Chromosome 21. Medically, the occurrence is referred to as Trisomy 21. Chromosomes are structures within the nucleus of cells that carry genetic information called genes. Plants and animals both have chromosomes in their cells. DNA, as this genetic material is called, gets passed from parents to their offspring and contains that individual’s specific and unique genetic makeup. While humans and felines do not have the same DNA, there are similarities.

People with Trisomy 21 have 47 chromosomes rather than the normal 46. DS can affect physical appearance, including smaller bodies, large eyes, small necks, and a flattened face. People with Trisomy 21 often have tongues that poke out of their mouths. They have varied degrees of intellectual disabilities. The name Down syndrome is after the doctor John Langdon Down, a British doctor who was the first to describe the condition. Originally it was called Mongolism.

Can Cats Have Down Syndrome?

No, cats cannot have Down syndrome. Felines do not share the same number of chromosomes as humans, so they cannot have DS. Their genetic makeup is not structured in the exact same way, so although they can develop other genetic mutations, felines cannot have DS. If you suspect our cat or kitten has it, they do not. They may, however, have different genetic mutations and neurological disorders.

Technically there is an exceedingly rare circumstance in which felines can inherit three copies of a chromosome. The occurrence is called XXY trisomy and creates a sterile male calico cat. Many are sickly and cannot survive long.

Symptoms Of Down Syndrome In Cats

Owners may see symptoms in their feline friends that appear similar to Down’s syndrome. While that is not what they have, some conditions cause unusual symptoms or developmental delays. Chromosomal anomalies may not always cause physical traits. They can also cause behavioral ones. Most genetic mutations affect kittens so much they cannot survive long after birth. Others will impact how a cat looks or behaves.

Conditions In Cats Similar To DS

Sad cat on a side of a sofa

Sometimes people believe a cat has a condition like DS due to features like low muscle tone, small or odd-shaped ears, a broad nose, large, upturned eyes, vision issues, hearing loss, difficulty walking, or using the litter box. These are valid reasons to seek medical care and advice for your pet but are not indicators of DS. Felines cannot have Trisomy 21. Therefore, any symptoms they have are related to something else.

Cerebellar Hypoplasia

A condition that can mimic symptoms of DS is cerebellar hypoplasia. It happens when the cerebellum in the brain does not develop fully. In some cases, it is caused by the feline distemper virus that mother kitties may contract during pregnancy. Cerebellar hypoplasia can cause kittens to have incoordination, clumsiness, tremors, and other loss of physical control. Felines can perform some functions normally but will always seem off-balance and uncoordinated. Most kitties with cerebellar hypoplasia can live very happy lives but will require special care. They do not grow out of the affliction, but it is not degenerative and does not tend to worsen as they age.

Eyelid Agenesis

Eyelid agenesis causes felines to be born missing part or a complete eyelid. It makes their eyes look large and round but also causes them to be susceptible to infections, inflammation, and damage. Eyelid agenesis is also called eyelid coloboma and is a congenital defect. The condition is rare but is the most common congenital eyelid defect in felines. It can affect one or both eyes. Eyelid agenesis occurs more in certain breeds, including Burmese and Persian.

Feline Dysautonomia

Feline dysautonomia is a rare, widespread degeneration of the autonomic nervous system. It leads to loss of mental function, nerve degeneration, unresponsive pupils, irregular heart rate, digestive upset, muscle loss or weakness, and emotional distress, among other symptoms. There is no cure or definitive treatment for feline dysautonomia, but it is manageable. Some owners and holistic veterinarians use CBD oil or treats, along with medications, antibiotics, and other as-needed treatments. When detected early and managed properly, kitties can live long, fulfilling lives with dysautonomia.

Haws Syndrome

Haws syndrome is a condition that affects the third eyelid of felines and is relatively common. The third eyelid will either protrude or prolapse, and it can happen for a variety of reasons. While it does not affect a feline’s vision, it may be hard to see due to the blockage from the third eyelid. Haws often comes on suddenly and has been associated with gastrointestinal inflammatory issues. Felines often develop watery diarrhea shortly before eyelid protrusion. Though it looks uncomfortable, felines are not in pain. The good news is that the condition generally resolves on its own, though some kitties may require treatment for diarrhea.

Hepatic Encephalopathy

Hepatic encephalopathy allopathy is a liver malfunction, rendering it unable to remove toxins from the blood. The condition occurs because of a congenital defect. The toxins circulate through the blood system, including to the brain, and can cause some very severe system malfunctions. Most often, it appears as symptoms of liver failure due to the buildup of toxins in the brain. Symptoms include vomiting, diarrhea, trouble urinating, dehydration, constipation, balance problems, weakness, aggression, seizures, visual impairment, collapse, jaundice, and even coma. Kittens with hepatic encephalopathy will require treatment, a hospital stay, and often surgery to repair the malfunction in the liver.


Hydrocephalus is a condition that occurs when too much fluid builds up in the brain. Often called water in the brain, cerebral spinal fluid (CSF) gathers in excess amounts due to a draining issue, which can build up and put extreme pressure on the brain. Hydrocephalus can cause a domed head, often with a soft spot at the top. A kitten’s eyes may be cast downward and may have vision issues, mental dullness, difficulty litter box training, and seem physically disoriented. Symptoms of hydrocephalus generally become clear between 8 and 12 weeks.

Spina Bifida

Spina bifida is also called Manx syndrome. It is a congenital defect that occurs due to improper fusion of the vertebrae during embryonic development. The defect causes an opening in the spinal column leading to spinal cord exposure. Spina bifida can cause problems controlling the back legs and controlling the bowel, and urine. It is more common in tailless or stumpy breeds like the Manx. Kittens born with spina bifida will seem normal at birth, but it will become more noticeable when they start to walk. They may have a clumsy gait, weakness in the back limbs, incontinence, seizures, partial or complete paralysis, limping, as well as malformation or swelling of the spine.


Strabismus is a condition that causes cats to appear cross-eyed. The eyes are out of alignment and move in abnormal directions. Though kitties can still see, the condition often affects their ability to focus and depth perception abilities. Some kittens are born with it; others may develop it later in life. Strabismus is more common among certain breeds, including Siamese, Himalayan, and some Persians. Symptoms include rapid eye movement, bulging eyes, head tilting, seizures, walking to one side, and disinterest in food. If these symptoms develop suddenly, seeking treatment as soon as possible is best.

Toxins & Poisons

Felines are highly inquisitive creatures and often get into things they should not. Potentially dangerous elements include food, plants, and household chemicals. Cats who have ingested a toxic plant or flower like a lily, tulip, or poinsettia, or foods like chocolate, onion, or artificial sweetener like xylitol may start to exhibit sudden, severe symptoms. A buildup of toxins in the body for any reason may lead to odd behavior. It is not a sign of DS but rather an indication that your pet should be seen at the vet very soon.

Frequently Asked Questions

Do Cross-Eyed Cats Have Down Syndrome?

No, cross-eyed cats do not have DS. Felines cannot have Trisomy 21. Other things can cause discomfort or improper eye function. Possibilities include infection or health issues like strabismus.

Can Cats Be Born With Down Syndrome?

No, felines do not develop DS. They can be born with a variety of other congenital and chromosomal defects.

Do Cats Get Depressed?

Yes, felines can experience depression and anxiety. They often experience depression after a change in the home, like a new kitten, moving houses, or a major household change like new furniture or the loss of another pet. There are even antidepressants felines can take to help.

Can Cats Have Autism?

No, as far as research shows, felines cannot have autism. They can develop behavior that resembles that of humans on the autism spectrum, but it does not mean they have the disorder.

Final Thoughts

Cats cannot be born with or develop Down syndrome because they do not have the same number of chromosomes as humans. Though they can be born with hereditary and congenital conditions and develop certain ailments as they age, felines simply do not have the correct genetic makeup for it ever to occur. We often tend to give our pets human characteristics and attributes. The process is called anthropomorphizing. It means that we look at our pet’s behaviors as we would a human’s. Though their behavior and symptoms may mimic human conditions, we are not the same species. In some cases, humans and kitties can develop some of the same medical concerns. However, DS is not one.

Videos and social media sites portraying kitties with DS or poking fun at the issue are disrespectful of people with DS, as well as the animals. Though these may be entertaining, there are far more wholesome sites and options for cat content.

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