Noisy breathing and breathing difficulties in cats with relatively broad, short skulls

This is a short discussion on the connection between noisy breathing and difficulties in breathing due to the skull shape of domestic cats. This has been discussed quite a lot on the Internet, normally in reference to Persian and Exotic Shorthair cats, because it is these cats which have been selectively bred to have a relatively broad, short skull. These are called brachycephalic skulls. You see dogs with these skulls as well (e.g. French bulldogs). They create a popular appearance in both dogs and cats because potential purchasers of a purebred cat or dog are attracted to the baby-like appearance of these companion animals.

I have heard a lot about breathing problems and the authors frequently refer to this health condition in cats with this skull shape (shortened muzzle essentially). I’m pleased to say that I’ve bumped into a nice scientific study which pinpoints more precisely the reasons behind this health issue.

I’m going to keep this article away from scientific terminology as best I can because I know that people don’t like to read scientific stuff. And it isn’t just the Persians and Exotics which have these skull shapes. Although they are the number one culprits if that is the right word.

In this study, a comprehensive questionnaire was sent out to about a thousand people in China and the UK. The participants were asked to photograph their cats and 373 valid photographs were obtained with allowed them to take measurements.

The participants were asked whether their cat had breathing difficulties or suffered from noisy breathing. They were asked observe the fluency of breathing when their cat was asleep when they were awake. They were asked to score the degree of noise and the degree of difficulties in breathing that their cats had on a scale of 1-4 in respect of snoring, snorting and wheezing when sleeping. And they were asked to provide a score of 1-6 in respect of breathing difficulties following activities. The higher the score the worse the breathing. This score is referred to as RS (respiratory score).

They obtained information about noisy breathing and breathing difficulties in 373 cats. And the cats weren’t all Persians and Exotics (see list above). The scientists wanted to have a wide range of cat breeds to see whether they could drill down and isolate breathing problems with Persians and Exotics.

In order to assess the skull shape accurately they produced two ratios. Firstly, they measured the position of the nose in relation to the face in general. They call this the “nose position ratio (NP%). They also calculated the muzzle length in relation to the skull (M%). See these measurements in the images above.

To calculate the ‘proportional muzzle length’ ratio (M%) as they call it, they compared the distances between the tip of the nose and the area just behind the head on the upper neck and the distance between the tip of the nose and the nasal stop as shown in the picture.

As to the ‘nose position ratio’ (NP%), the scientists compared the distance between the top of the head and the tip of the chin, and the distance between the end of the nose (at the top of the nose leather) and the nose stop or nasal stop. The photo illustrates these dimensions.

The study found a direct correlation between breathing difficulties and the cat’s nose position as quantified by NP%. A smaller NP% predicted a higher risk of breathing difficulties; this relationship can be explained by abnormalities of the upper respiratory system such as increased soft tissue within the nose, laryngeal pathology and/or soft palate dysgenesis, all of which can be associated with the brachycephalic head confirmation.

I’m going to leave it there because it becomes highly technical but essentially the study confirms that the foreshortened muzzles of brachycephalic cats resulted in noisy breathing and breathing difficulties. You can read the full study by clicking on this link if you wish.

P.S. If you’d like me to write more on this please ask in a comment.

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