French Bulldogs are Brachycephalic, which is flat faced appearance of the Frenchie. As a result, one of the most common defects in French Bulldogs is elongated soft palate or cleft palate. Puppies affected with Cleft palate are generally put down at birth, as it is generally considered to be an almost impossible condition to correct. Elongated soft palate can manifest as anything from a mild condition causing labored breathing to severe condition that can cause the affected Frenchie to pass out from moderate exercise.
Frenchies may also have a tendency towards eye issues. Cherry eye, or everted third eyelid, has been known to occur, although it is more common in (English) Bulldogs and Pug Dogs. Glaucoma, retinal fold dsyplasia, corneal ulcers and juvenile cataracts are also conditions which have been known to afflict French Bulldogs.
French Bulldogs can also suffer from a condition called megaesophagus, a term which collectively describes several esophageal disorders and malformations in any combination from single-to-double or multiple. One of the more serious complications in a dog affected with mega esophagus is passive regurgitation, in which the affected dog vomits up food or phlegm after eating or exercise. Passive regurgitation can frequently result in aspiration pneumonia.
Another result of the compacted air way of the French Bulldog is their inability to effectively regulate temperature. While a regular canine may suffer to some degree from the heat, to a Frenchie it may be lethal. It is imperative that they be protected from temperature extremes at all times, and that they always have access to fresh water and shade.
French Bulldogs can also suffer from an assortment of back and spinal diseases, most of which are probably related to the fact that they were selectively chosen from the dwarf examples of the Bulldog Breed. This condition is also referred to as chondrodysplasia.