Pectus Excavatum: The ‘Flat-Chested’ Kitten Syndrome#

You pick up a newborn Maine Coon kitten, and instead of a round, full belly, his chest feels flat. Like a turtle shell. When he tries to crawl, his legs splay out to the sides.

This is Pectus Excavatum (Funnel Chest) or the related Flat Chested Kitten Syndrome (FCKS). [cite_start]According to Feline Husbandry, this is a developmental anomaly where the sternum (breastbone) collapses inward, compressing the heart and lungs. [cite: 866]

In a giant breed like the Maine Coon, which grows rapidly, this compression can be fatal if not caught in the first 10 days.

Identifying the “Swimmer”#

Affected kittens are often called “Swimmers” because of how they move.

• The Paddle: Because the chest is flat, the legs cannot pull underneath the body. The kitten paddles with legs splayed wide.
• The Pant: If you listen closely, the kitten breathes fast and shallow. The lungs have no room to expand.
• Weight Loss: They often cannot compete for a nipple and fade away.

The Cause: Genetics or Environment?#

The debate rages.

• Genetics: Robinson’s Genetics suggests a hereditary component, possibly recessive. [cite_start]It is often seen in inbred lines. [cite: 866]
• Environment: Some studies suggest lung infections (pneumonia) or simple gravity (lying on a flat surface too long) can exacerbate it.

The Cure: The “Corset” Splint#

If caught early (before the bones calcify at 3-4 weeks), Pectus can be corrected with a homemade splint.

1. The Mold: A vet creates a rounded cast (using a toilet paper roll or plastic) that fits around the kitten’s chest.
2. The Suture: The vet places sutures around the sternum and ties them to the external cast, literally pulling the chest wall outward.
3. Time: The kitten wears this “corset” for 2-3 weeks. As he grows, the bones harden in the correct, rounded shape.

Conclusion#

A flat-chested kitten is an emergency. Do not “wait to see if he grows out of it.” He won’t. With immediate splinting, these kittens can live normal lives. Without it, they often die of heart failure by 12 weeks.

References#

1. Pedersen, N.C. Feline Husbandry. “Developmental Anomalies: Pectus Excavatum,” p. [cite_start]114. [cite: 866]
2. Vella, C. et al. (1999). Robinson’s Genetics. “Flat-chested kitten syndrome,” p. [cite_start]192. [cite: 1916]
3. Journal of Feline Medicine and Surgery. Surgical correction of Pectus Excavatum.
4. Walsh, L.G. The Maine Coon Cat. “Maine Coon Health Watch,” p. [cite_start]88. [cite: 3086]