KnowYourDNA logo

Cat Birth Defects

Writer: Joel
Calendar Icon
Updated on: March 5, 2021
Medical Card  Icon
2 sources cited
Attention Icon
KnowYourDNA is reader-supported. This means we may receive a commission when you buy something from one of the links on this page.

It’s relatively common for cats to be born with birth defects. These defects include abnormalities of function, structure, or metabolism that are present at birth. Many of these defects resolve on their own. But in some cases, they require medical attention to correct or they are present for the cat’s entire life.

Congenital defects in kittens tend to be rare. Some research has shown pedigreed cats have a higher risk of developing a defect. However, the risk is statistically insignificant and defects don’t seem to affect one specific breed over another.

Cat Birth Defects

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

Birth defects might be obvious at birth, subtle and apparent only when the cat doesn’t develop properly, or found only with diagnostic testing.

What are some of the defects cats are at risk for?

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 due to the incompatibility

Cleft Palate

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 and discover cleft palate due to the condition’s corresponding symptoms, which include coughing, runny nose, and difficult nursing.

Cleft palate is usually inherited. Some breeds are more prone to it than others, including Siamese, ragdolls, Norwegian forest cats, Ocicats, Persians, and savannahs. Exposure to certain chemicals in utero also put kittens at risk of cleft palate.

Flat Chested Kitten Syndrome (FCK)

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


Also known as water on the brain, hydrocephalus causes cerebrospinal fluid (CSF) to accumulate around the brain or blocks CSF from flowing outward, which leads to pressure around the brain. Kittens usually develop hydrocephalus because of blockage. However, other causes of hydrocephalus in cats include:

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

Intestines on the Outside of Body

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


Some kittens’ eyes are not grown to full size.

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 plates of the skull 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, it leaves the brain exposed to risk.

Pectus Excavatum

Some kittens are born with this unusual chest wall deformity. It’s sometimes called inverted sternum.


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

Swimmer Syndrome

Swimmer syndrome occurs when a kitten cannot crawl or stand normally.

Umbilical Hernia

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

Want to know the best DNA testing kit for your cat? Read our 2021 Guide.

What Causes Birth Defects in Cats?

Inherited cat birth defects occur due to an inheritance of genes or chromosomal abnormalities. They might also be caused by infections in utero, exposure to drugs, exposure to chemicals or environmental toxins, poor intrauterine environment, hyperthermia, or nutrition deficiencies. Taurine deficiencies are especially problematic for cats. Some birth defects are caused by a combination of two or more of these factors.

Are Cat Birth Defects Preventable?


There are things breeders can do to reduce the risk of kitten birth defects. Basepaws can test your cats before breeding to determine if there are any genetic risks that are of concern.

It’s more difficult to prevent birth defects when you don’t know the genetic history of a cat.

To reduce the risk of birth defects, consider the following before allowing your cat to mate:

  • Is your cat’s particular breed make-up 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 veterinarian professional before breeding your cat, even if you know of no potential risks. An examination should occur before every breeding experience.

The Definitive Guide to Cat DNA testing: What you need to know.

Resources +

Lowell Ackerman DVM, DACVD. “Tufts’ Canine and Feline Breeding and Genetics Conference, 2005.”, 30 Mar. 2015, Accessed 31 Jan. 2021.

CDC. “Learn about Specific Birth Defects.” Centers for Disease Control and Prevention, 5 Aug. 2019,

@ 2021 by Know Your DNA. All right reserved.
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram