by Jette Eva Madsen.

After the article on defects on Norwegian Forest Cats there has been some reactions about the nature of some of the defects.

Luckily only very few breeders have experienced litters where these defects were found. Even fewer have had the chance to get to know all the defect.

One of the defects that I know is quite wide spread but very poorly understood is the defect called flatchestedness.

The problem

The problem is well know throughout the world of pedigree cats. Personally I came over it first time in a Swedish magazine for Burmese cats but through the years I have seen NFC-kittens throughout Europe with this defect. More interesting is the fact that the breeder had often not noticed the defect.

The development of the defect

When the kitten is born it look perfectly normal. The kitten behave and drink normal until the age of app. 4 days. Then suddenly the chest start to grow in a deform way so that the kittens chest develop a pronounced flatness in the horizontal plane. You can feel it when you hold the kitten in your hands and also these kittens always lies on their belly since the flat form prevent them from lying on their side.

In a lot of cases the kitten goes on drinking and gaining weight just at a slower pace than the litter mates. In the severe cases the kitten get so flat that it has not enough power to drink its mothers milk any more since the volume in which the lungs has to work become very limited. Also I believe that the chest can get so deform that there is not enough room for other internal organs apart from the lungs.

The development of flatness proceeds until the kitten is around 10-14 days old where the development suddenly stops.

If the kitten manages to survive the first 3 weeks of age it has an extremely good chance of developing into a totally normal looking kitten. At 3 months of age most flatchested kittens will have nearly the same size as their litter mates. At this time the form of the chest is near normal just a bit more square at the sides and with a slight indentation between the shoulder blades.


It is still not totally know what causes the flatchestedness to appear but it is certain that it is a combination of two different things:

  • The content of certain minerals / vitamins in the mothers milk.
  • The ability of the kitten to take up the minerals / vitamins from the milk.
  • This far a low level of taurine in the mothers milk is thought to be the main cause for the defect. You will experience that some kittens in the litter has a better take up of the taurine from the milk since only very rarely the whole litter is effected.

What can I do?

When you discover that one or more of your kittens in a litter is effected you can help by feeding all kittens some KMR-milk. If you suspect that your litter of kittens could be in danger of developing the defect you can try to prevent it by feeding your female a vitamin/mineral paste containing taurine (Pfitzer has one).

Which queens are more likely to have flatchested kittens?

  • Queens who have had flatchested kittens before.
  • Queens who are for some reason in poor condition at time of birth.
  • Old queens.

The genetic behind the defect

The genetic of this defect is still unknown, but it is possibly first of all a matter of the condition of the queen and the content of her milk.

I do however think that flatchested kittens should not be used as breeders as well as I would stop using queens who repeatedly have flatchested kittens in their litters.