Flat Chested Kitten Syndrome (FCKS)

Updated: Apr 2, 2020

Kittens develop an abnormal rib cage which often is flat/squished There are varying severities of this condition from a kitten that looks like they were stepped on, to a kitten with a dip in the back. 30% of cases also are afflicted by Pectus Excavatum.

PREVALENCE: There are not as many scientific papers out there directly on the topic and most information is shared and collected from the breeding community however some statistical information we can share from what is available includes:

Some studies report a biased towards male kittens

In a study performed in the UK 3-4% of Burmese kittens were affected

In a study performed in 2017 in Sweden, there is a higher prevalence in Bengal kittens (6%) than Domestic Short Hairs (DSH) with 44% of breeders experiencing a malformation in 1-3 litters with 36% passing away by 4 weeks of age In 50-60% of cases, this condition resulted in mortality


The most obvious is the chest or rib cage is flat or abnormally shaped

In mild case, there will be a ridge along the side of the rib cage

Other deformities such as

  • Pectus Excavatum (caving in of the chest that can also result in impaired cardiac and lung impairment)

  • Kyphosis (a forward rounding of the spine)

  • Lordosis (dip in the spine behind the shoulder blades)

Weight loss

Impairing ability to eat