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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

Respiratory impairment (increase respiratory rates and effort)

Reduced activity

Failure to thrive


This often can be detected just by feeling the rib cage around 10 days of age, but can develop as early as 3 days. It can appear just overnight so checking often can be required. An x-ray may also be performed to see the extent of the dysfunction.

FCKS is often misdiagnosed by veterinarians as Pectus excavatum (PE) but there is little connection between the two other than the fact that FCKS kittens can also present with PE. The primary difference is PE affects the sternum and cartilage attached to the ribs allowing their connection and the rib cages flexibility. FCKS on the other hand affects the whole rib cage. DURATION:

Some kittens/cats will always suffer from this condition others can resolve on their own.


It's important first to understand that kittens are born immature. We all know they are blind and deaf but their lungs are immature as well. Over a few days, the lungs will fully inflate which doesn’t occur until about three days after delivery. If something goes wrong, the lungs cannot inflate properly and thus the rib cage is not supported properly and goes flat. Atelectasis or collapsing of the lungs occurs when respiration fails in a newborn kitten but it can also occur when there is an obstruction in the airways or a deficiency in a substance called Surfactant. The substances basically coats the lungs so its surfaces don’t get stuck together.

A deficiency of surfactant can cause Atelectasis as well as pressure coming from outside the lungs via fluid or air. Other causes can include obstructions in the airways, infections and lung disease. Genetics

While a genetic component is very possible, it actually is fairly rare and most likely influenced by additional factors such as environmental factors. The main indication that it would be genetic would be if whole litters or large portions of litters are affected versus just one kitten. This also explains why recessive inheritance (genes that are carried in the genetic code of the parents that are not outwardly expressed but can be produced if paired with another parent that carries) is fairly unlikely as well. Furthermore with the rate at which changes of the chest occur and how flexible the skeletal system is deformities or connective tissue abnormalities are more common.

Nutrition Mothers that may produce large amounts of milk may produce kittens that expression colic more readily which may have a hereditary component. Others suggest a lack of taurine and or Arachidonic acid could be an influence as well.

Other causes may include problems associated with:

  • Kittens that are premature

  • From large litters and thus may be small and less developed

  • Herpes virus

  • Lung infection

  • Abnormality of the epiglottis resulting in colic

  • Inhaling a foreign objects

  • Tumors

  • Diaphragmatic hernia

  • Diaphragmatic spasm

  • Respiratory tract infection or pneumonia (if FCKS develops later on

  • Environmental (if cases are more isolated)

  • Breeding two barrel-chested cats

In the past, FCKS has been thought to be caused by a muscle spasm but that is no longer the case.


Treatment is difficult to define given the number of different causes and the wealth of anecdotal information that should still be considered as much is valid.

Conventional Steroids (typically Dexamethasone) in conjunction with antibiotics like amoxicillin. The steroids will increase growth while the antibiotics will take care of underlying infections. Synthetic surfactants which can be nebulized. If nebulized keep in mind this must be done within 3-4 days of birth to be effective. Surgical correction

Natural Animal derived surfactants

Depending on the severity treatment may not be necessary in which some cases can be left to resolve on their own.


Encouraging the kitten to lay on its side while sleeping and nursing Creating a correction vest



If these situations do not apply there are a few methods of vests. One involves creating a ridge on the stomach side of the vest which will make your kitten lay on its side while alss hoping to change the shape of the rib cage. There are many designs but most feature a toilet paper tube or part of a plastic bottle and vet wrap.


Several breeders recommend 1000 mg of taurine be given to the mother until the kitten has recovered

**keep in mine most taurine supplements are artificial supplements. Natural options are heart glandular and whole raw food options such as heart, thigh and shoulder meat, tongue and whole prey Supplement the kitten with extra meals to prevent weight loss or nutrient deficiency Pinching the Phrenic nerve

Oxygen While in human cases with chest abnormalities oxygen or CPAP machines are used this is not often a safe treatment method for kittens.

PROGNOSIS: There are many factors that will influence prognosis Survival is greatly INCREASED if:

If the kitten continues to gain weight If flatness does not change in a negative direction If the kitten makes it passed two milestones: 10 days and 3 weeks even if the kitten is still flat Survival is greatly DECREASED if:

If the chest continues to flatten If breathing becomes heavily labored

If the kitten continues to lose weight If the kitten is compromised by another respiratory-related illness/disease (chlamydia, mycoplasma, calicivirus, pneumonia).


Without knowing the exact cause prevention can be difficult however diet is one good place to start. Surfactant, for example, is derived partially from arachidonic acid which is found in meat and eggs which are a huge component of a species appropriate raw diet.

Some have suggested avoiding the use of any medications during pregnancy including conventional and natural remedies unless it has been proven to be safe or its completely necessary.

Finally making sure kittens meow/scream in the days following the birth can also prevent lung collapse or at least catch it quickly.

BREEDING CONSIDERATIONS: Breeders especially those breeding Burmese and Bengals should be aware of FCKS when considering or already breeding. It is advisable not to breed cats that have FCKS however there is mix information out there regarding if a recovered FCKS cat should be used for breeding. A breeding cat however that has produced FCKS will not always produce FCKS kittens in the future.

In addition, other factors may be affecting the prevalence such as Streptococcal G in the cattery if there are isolated cases. If breeding cats are consistently producing whole litters of FCKS with all options exhausted and treated then it is best to remove them from your program.

Line breeding lines that have produced FCKS is unadvisable as well. One more specific theory is breeding two barreled chested cats can produce FCKS kittens. This concept was first explored in the Burmese breed but has been found consistent in domestic cats as well as Bengal.

USEFUL PAPERS AND STUDIES There are not many resources or scientific articles on the topic of FCKS unfortunately most information is from breeders and their experience with the condition and what they have discovered via trial and error. THORACIC WALL DEFORMITIES IN KITTENS Kit Sturgess, MA,VetMB, PhD, CertVR, DSAM, CertVC, MRCVS RCVS Recognised Specialist in Small Animal Medicine

Sturgess C. Flat chested kittens - does taurine have a role to play? Burmese Cat Club News (U.K.), vol 12, no 8, 1995

Sturgess CP, Waters L, Gruffydd-Jones TJ et al. Investigation of the association between whole blood and tissue taurine levels and the development of thoracic deformities in neonatal Burmese kittens. Vet Rec 141:566-570, 1997

Thoracic malformations in Bengal cats Results from a questionnaire to breeders BS Holst1,2, C. Ley3 , MH Gustavsson2, CJ Ley1, G Andersson4 and S Mikko4 1Department of Clinical Sciences, 2Centre for Reproductive Biology in Uppsala (CRU) 3Department of Biomedical Sciences and Veterinary Public Health, 4Department of Animal Breeding an Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden Charlesworth, Timothy M and Christopher P Sturgess. “Increased incidence of thoracic wall deformities in related Bengal kittens.” Journal of feline medicine and surgery 14 6 (2012): 365-8 . Edinburgh FAB resident, Royal Dick Veterinary Hospital: Report in FAB Journal (1993), vol. 31 (1) 71-72VETERINARIANS

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