Cat Birth Defects (& What To Do)
Updated on March 26, 2024
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Cat Birth Defects (& What To Do)

Cat birth defects are health conditions that kittens can be born with. These defects can be due to the mother’s health during pregnancy, environment, or genetics.

While it’s relatively common for cats to have birth or congenital defects, owners must be aware of them and how they might affect a kitten’s health. Spotting the signs early helps you take action and give your kitty the right care before abnormal development occurs.

Cat birth defects may include abnormalities of function, structure, or metabolism. Many of these defects resolve on their own. However, in some cases, they require medical attention to correct or are present for the cat’s entire life.

Congenital defects in kittens tend to be rare.1 Some research has shown pedigreed cats are more likely to develop a defect. However, the risk is statistically insignificant. Defects don’t seem to affect one specific breed over another.

Cat Birth Defects (& What To Do) 5

Source: 123rf

Defects can cause physical impairment. In some cases, serious defects are fatal.

Birth defects can vary in terms of how obvious they are. Some are obvious at birth, others are subtle, and some are only apparent when the cat doesn’t develop properly.

Some birth defects are detected when cats show clinical signs of a health problem or are found only with diagnostic testing. Other problems, like a heart defect, could have happened during fetal development or are diagnosed later on.

Learning about the symptoms, causes, diagnosis, and treatments for birth defects can help cat owners be more proactive in keeping their furry friends healthy and increasing their quality of life.

What Are Some of the Genetic Defects Cats Are at Risk for?

Cats may be at risk of certain defects due to abnormal genes passed down through generations. These genetic disorders and hereditary diseases can be evident at birth or manifest later in life.

Cat DNA testing helps identify and manage these defects and congenital abnormalities. Responsible breeding, like testing for simple inherited diseases, has decreased their occurrence.

Blood Type Incompatibility

It’s dangerous for cats with different blood types to breed.

If a blood type B female cat breeds with a blood type A male cat, the litter is at risk of dying shortly after birth. This is due to the incompatibility that destroys the kitten’s red blood cells.

Cleft Palate

A cleft palate occurs when kittens are born with an opening in the roof of their mouths due to the two sides never fusing. Many cat owners wouldn’t think to look inside the top of their cat’s mouth.

Cleft palate is often discovered due to the condition’s corresponding symptoms, which include:

  • Coughing
  • Runny nose
  • Difficulty nursing

A cleft palate is usually inherited. Some breeds are more prone to it than others, including:

  • Siamese
  • Ragdolls
  • Norwegian forest cats
  • Ocicats
  • Persians
  • Savannahs
Cat Birth Defects (& What To Do) 6

Source: 123rf

Other factors that put kittens at risk of cleft palate include:

  • Exposure to certain chemicals
  • Exposure to cortisone
  • Medications
  • Excessive intake of vitamins A and D during pregnancy

Flat Chested Kitten Syndrome (FCK)

Flat-chested kitten Syndrome causes a kitten to develop depression in the rib cage because of a collapsed lung.


This is also known as water in the brain. Hydrocephalus causes cerebrospinal fluid (CSF) to accumulate around the brain or block CSF from flowing outward, leading to pressure around the brain.

Kittens usually develop hydrocephalus because of CSF blockage.

However, other causes of hydrocephalus in cats include:

  • Certain viruses
  • Bacterial and fungal infections
  • Parasitic migration
  • Cysts and tumors

Hypertrophic Cardiomyopathy

Cardiomyopathy is a heart disease in cats that usually leads to heart failure. Hypertrophic cardiomyopathy is the most common among all forms of congenital heart defects.

This condition is characterized by the walls of the heart becoming too thick. Congenital heart disease such as this can sometimes result in death.2

Intestines on the Outside of the Body

Kittens born with their intestines or any other organ exposed should undergo a veterinarian examination immediately. In some cases, surgery can correct the defect.

Cat Birth Defects (& What To Do) 7
Source: 123rf


Some kittens’ eyes do not grow to full size. With microphthalmia, the eyeball appears smaller than normal, and in some cases, it is absent.

Open Fontanelle

The fontanelle is the soft spot on the top of the head that closes soon after birth.

It is present in humans and animals alike. The soft spot allows the skull plates to move so the baby’s head can pass through the birth canal.

It usually seals on its own within a few days or weeks of birth, but if it does not, the brain is exposed to risk.

Pectus Excavatum

Some kittens are born with this unusual chest wall deformity. It’s sometimes called an inverted sternum. It is said to be caused by genetics.

However, pectus excavatum develops spontaneously regardless of the cat’s breed. The condition is often diagnosed several weeks after birth or earlier if it is severe.


This potentially fatal bacterial infection affects kittens two weeks and younger.

If left untreated, septicemia could progress to a severe form, leading to liver failure, respiratory distress, kidney failure, and more.

Swimmer Syndrome

Swimmer syndrome occurs when a kitten cannot crawl or stand normally. The kitten’s hind legs are typically splayed laterally, displaying a frog-like posture.

Umbilical Hernia

This is the most common type of kitten hernia at the belly button.

This occurs because the umbilical ring fails to close fully. The hernia is a protrusion under the cat’s skin, especially when the cat is straining, crying, meowing, or standing.

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What Causes Birth Defects in Cats?

Most of the birth defects in cats have no known cause. Still, experts speculate that two potential causes bring them about:

  • Some congenital cat defects are said to be caused by genetic factors from mutated genes or chromosomal abnormalities
  • Environmental factors like exposure to toxins, viral infections during pregnancy, nutritional deficiencies, and many more may also cause other birth defects
  • Taurine deficiencies are especially problematic for cats

Are Cat Birth Defects Preventable?


Breeders can take steps to reduce the risk of kitten birth defects, and cats can now undergo genetic tests to prevent birth defects.

Cat Birth Defects (& What To Do) 8
Source: Basepaws

Basepaws can test your cats before breeding to determine if any genetic risks are of concern. Preventing birth defects is more difficult when you don’t know a cat’s genetic history.

To reduce the risk of birth defects and let your cat live a normal life, consider the following before allowing your cat to mate:

  • Is your cat’s particular breed makeup prone to birth defects?
  • Was your cat born to a litter with one or more defects, even if it does not have a defect?
  • Has your cat mated before and experienced any issues?
  • Is there anything impeding your ability to provide your cat with a healthy diet and environment once she’s pregnant?
  • Is your cat taking any drugs?
  • Is your cat up-to-date on vaccines, and will any vaccines be needed during pregnancy?

Consider a thorough health examination by a veterinary healthcare professional before breeding your cat, even if you know of no potential risks. An examination should occur before every breeding experience.

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Updated on March 26, 2024
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2 sources cited
Updated on March 26, 2024
  1. 1) “Congenital Defects of Kittens.” Veterinary Information Network.

  2. 2) “The Feline Cardiomyopathies: 2. Hypertrophic cardiomyopathy.” National Library of Medicine.

Angela Natividad
Angela Natividad
Content Contributor
Angela is a full-time digital content manager and editor for Know Your DNA. She also contributes freelance articles to several local and international websites when she has the time. She's always been a voracious believer in finding the truth and ensuring the science is sound.