Part 3 of our article on French Bulldog health conditions deals with Eye Anomalies and Diseases in French Bulldogs. French Bulldogs are prone to several eye diseases and conditions due to both genetic inheritance and structural predisposition. Diseases include Hereditary Juvenile Cataracts, Distichiasis, Cherry Eye and Progressive Retinal Atrophy (PRA).
Hereditary Juvenile Cataracts (JC or HJC)
Genetic cataracts are also called “juvenile cataracts” in dogs. This terminology refers to the age of presentation with this abnormality which is usually in young dogs. These cataracts may progress to blindness or remain small and not interfere with vision.
DNA screening is now available to breeders to assist in eliminating HJC from their breeding programs. Dogs can receive a test result of Clear (non carrier), Carrier (carries the gene but is not affected by the condition) or Affected. A Carrier dog may be bred, but only to a Clear dog. All resulting puppies must then be tested, and the same process followed for each. Affected dogs should never be bred from or to. Litters produced by breeding clear parent to clear parent do not require DNA testing, although some breeders still choose to do so.
Senile (Late Onset) Cataracts
It’s common to see a sort of ‘milky’ or opaque covering in the eyes of older dogs (and cats). This is usually due to Senile Cataracts (also called Late Onset Cataracts). Senile cataracts generally appear in dogs over six years of age, and some conditions such as diabetes mellitus will increase the likelihood of them developing. Senile cataracts can generally be diagnosed by their simultaneous appearance in both eyes.
There is some debate over whether Senile Cataracts should be operated on. Surgery can be done to remove the cataract from the lens, but this will require a life time of invasive follow up treatment, and blindness or even Lens Induced Uveitis (LIU) can still occur. Non surgical treatment of cataracts includes anti-inflammatory drops several times daily administered to the eye.
Many dogs who develop late onset cataracts have been CERF tested clear for eye anomalies their entire lives until the development of the cataracts. There is no know screening process for Senile (Late Onset) Cataracts at this time.
Often mistaken for Senile Cataracts, Nuclear sclerosis is a normal change that occurs in the lenses of older dogs. Nuclear sclerosis appears as a slight graying of the lens. It usually occurs in both eyes at the same time and occurs in most dogs over six years of age. The loss of transparency occurs because of compression of the linear fibers in the lens. The condition does not significantly affect the vision of the dog and treatment is not recommended.
Progressive Retinal Atrophy
Progressive retinal atrophy, or PRA as it is frequently termed, is a long recognized, hereditary, blinding disorder. It is inherited as a simple autosomal recessive in most breeds.
PRA is a disease of the retina. This tissue, located inside the back of the eye, contains specialized cells called photoreceptors that absorb the light focused on them by the eye’s lens, and converts that light, through a series of chemical reactions into electrical nerve signals. The nerve signals from the retina are passed by the optic nerve to the brain where they are perceived as vision. The retinal photoreceptors are specialized into rods, for vision in dim light (night vision), and cones for vision in bright light (day and color vision). PRA usually affects the rods initially, and then cones in later stages of the disease. In human families, the diseases equivalent to PRA (in dogs) are termed retinitis pigmentosa.
In all canine breeds PRA has certain common features. Early in the disease, affected dogs are nightblind, lacking the ability to adjust their vision to dim light; later their daytime vision also fails. As their vision deteriorates, affected dogs will adapt to their handicap as long as their environment remains constant, and they are not faced with situations requiring excellent vision. At the same time the pupils of their eyes become increasingly dilated, in a vain attempt to gather more light, causing a noticeable “shine” to their eyes; and the lens of their eyes may become cloudy, or opaque, resulting in a cataract.
Diagnosis of PRA is normally made by ophthalmoscopic examination. This is undertaken using an instrument called an indirect ophthalmoscope, and requires dilatation of the dog’s pupil by application of eyedrops. Broadly speaking, all forms of PRA have the same sequence of ophthalmoscopic changes: increased reflectivity (shininess) of the fundus (the inside of the back of the eye, overlain by the retina); reduction in the diameter and branching pattern of the retina’s blood vessels; and shrinking of the optic nerve head (the nerve connecting the retina to the brain). These changes occur in all forms of PRA, but at different times in the different breed-specific forms. Usually by the time the affected dog has these changes there is already significant evidence of loss of vision.
Cherry eye is a common term for prolapse of the third eyelid gland. Many mammals, including dogs, have an “extra” or third eyelid located inside the lower eyelid. This serves as an additional protective layer for the eye. The third eyelid contains a gland that produces a significant portion of the tear film. When this gland prolapses or “pops out”, the condition is known as “cherry eye”.
Traditional treatment for Cherry Eye involves surgical correction of the third eyelid gland. Some veterinarians, however, advise against this, instead counseling a course of daily anti-inflammatory drops and artificial tears, along with a regimen of gently massaging the prolapsed lid back into place. Consult your veterinarian for the most advisable procedure for your dog’s situation.