Flat chested kitten syndrome (FCKS) and pectus excavatum (PE)

Uncommonly, kittens will be born with, or develop in the first few weeks of life, deformities of the wall of the chest (thorax). The result of the deformity can be to reduce the space for the lungs and affect the blood circulation. The severity of the deformity is very variable so its effects can range from nothing to severe difficulties breathing and oxygenating the blood. Severely affected kittens may not survive. 

Pectus excavatum, also known as funnel chest or cobbler’s chest, is caused by a dipping of the end of the sternum (breastbone) toward the vertebral column (back bone) creating a funnel-like depression midway along the kitten’s body. 

Flat chested kitten syndrome is an angular deformity affecting the whole length of the chest resulting in the chest shape being narrower from sternum to vertebral column than it should be. FCKS can also be associated with deformities of the vertebral column itself. 

Where the chest deformity is having a significant impact on a kitten then a number of things may alert you to the issue:

• The kitten is failing to gain weight at the same rate as others in the litter 
• The kitten is not feeding well 
• The kitten’s breathing is faster and/or more labored than its littermates 
• You feel a difference in the kitten’s chest shape when handling it. 

If the chest deformity is having little impact on a kitten's ability to breathe you may only appreciate it when you handle the kitten and notice a difference in chest shape or see when the kitten is walking that it ‘looks different’. 

We don't know the precise cause of either FCKS or PE.  

It is likely that there is a genetic element as FCKS is seen more commonly in some breeds and some lines of kittens than others but this is not the whole story. It is also likely that events during the queen’s pregnancy have an impact on how the disease shows itself. FCKS is a syndrome rather than a single disease meaning that the cause may be different between individuals or between breeds. 

PE tends to be a relatively random event and although there may be a genetic background, it seems to be primarily associated with the way that a particular kitten develops in the uterus of the queen. 

We don't know of any specific way that FCKS or PE can be prevented. 

Keeping a queen healthy during pregnancy is important which means that she is fit, active, is appropriately wormed and vaccinated, has a good quality balanced diet in appropriate amounts and stress is kept to a minimum. 

There is some suggestion that the use of radiator beds or similar where the queen becomes very hot during her pregnancy may be undesirable. 

For queens that have had more than one litter with flat chests the advice is to avoid the same mating and, in more severe cases, stop breeding from the queen. 

If a tom cat has had flat chested kittens in litters born to different queens then consideration should be given to no longer using him as a stud cat. 

Your veterinary team will assess the severity of your kitten’s clinical signs and will advise on treatment options: 

• Short-term supplementary oxygen may be necessary, rarely antibacterial treatments if there is evidence of secondary pneumonia 
• Assisted nutrition to ensure sufficient calorie intake for growth 
• External splints or surgical intervention may be advised 
• In FCKS the value of taurine and potassium supplementation is unknown and controversial. 

With FCKS one of the keys seems to be assisted nutrition to keep the kitten growing as in many kittens the chest deformity will appear to resolve by 3-4 weeks of age. 

Whether a kitten survives or not will depend on the severity of the clinical signs they are showing and the response to treatment. Sadly, the more seriously affected kittens often will not survive. 

Early intervention is key to success so it is important that:

• Kittens are assessed regularly and weighed daily. 
• Seek advice if any kitten is failing to gain or losing weight. 
• Any interventions are undertaken sooner rather than later. 
• Good levels of nutrition are maintained – this may require tube feeding with appropriate guidance.