Eye Disorders
Cataracts: A cataract is defined in the CERF book as "a partial or complete opacity of the lens and/or its capsule. In cases where cataracts are complete and affect both eyes, blindness results." Cataracts are among the most common intraocular lesions and a leading cause of vision loss in the dog. Cataracts may be caused by genetics, trauma, ocular inflammation, diabetes mellitus, genetic retinal atrophy, persistent pupillary membranes, persistent hyaloid remnants, specific nutritional deficiencies, congenital abnormalities and uncommonly by other specific metabolic diseases. The size of cataracts is also highly variable. They may be very small and not affect vision, or complete and cause blindness. If they are incomplete, they may only be present in the cortex or outside layers of the lens, or in the nucleus or center of the lens. Some types of cataracts only affect the capsule, which covers the lens. In every case, however, the cataract is an opaque place in the lens. It doesn't affect vision when it is small because the dog can see around it. Recommendations published in the CERF book include, "breeding is not recommended for any dog demonstrating partial or complete opacity of the lens or its capsule unless the examiner has also checked the space for significance of the above punctate cataract unknown. The prudent approach is to assume cataracts to be hereditary except in unusual cases specifically known to be associated with other causes."
Cataracts can be found in Cavalier King Charles Spaniels, but I have only heard about it in aging Cavaliers which can commonly occur with people also.
Corneal Dystrophy: appears as gray-white, crystalline or metallic opacities in the center of the cornea or close to the periphery. These opacities may affect any layer of the cornea, the epithelium (outer layer), the stroma (the thick, middle layer), or the endothelium (the inner layer). The opacities are usually oval or round and are sometimes doughnut-shaped. The age of onset of the disease varies within and among dog breeds. The opacities usually progress but in some cases they remain static. The mode of inheritance varies among breeds and in many breeds it is unknown.
Corneal dystrophies are usually not painful. In a few breeds, however, a dystrophy can lead to secondary breaks in the epithelial (outer) layer of the cornea. When this occurs a painful corneal ulcer develops requiring intense treatment. In other breeds, a painful ulcer may not develop and the dystrophy itself is not treatable. No medication will "dissolve" the opacity. Surgical removal of the dystrophic area may temporarily decrease the opacity in cases of epithelial dystrophy. Often, however the opacities will reform in the healed cornea.
Corneal Dystrophy can be found in Cavalier King Charles Spaniels, but it is very rare in occurrence.
Distichiasis: a condition in which small eyelashes abnormally grow on the inner
surface or very edge of the eyelids. Both upper and lower lids may be involved. The hairs growing from the lids can irritate the cornea as they rub against it. The affected eye may become red, inflamed, and may develop a discharge. The dog will typically squint or blink often, much like a person with a hair or other foreign matter in the eye. The animal will often rub the eye against objects such as the furniture or the carpet. In severe cases, the cornea may become ulcerated and appear bluish in color from the aberrant hair or from self-mutilation by the pet. Some dogs are not bothered by this disorder at all and in those cases it is best to not do anything. If your dog is bothered and left untreated, severe corneal ulcerations and infections usually develop. The hairs can cause severe irritations and without treatment, the condition usually worsens. As stated, the animal may further irritate the eye through scratching or rubbing against it to the point of self-mutilation. Blindness can also result if infections develop. If your dog is bothered by this condition the abnormal eyelashes are best removed through the use of surgery or electroepilation. With electroepilation, a fine needle is passed into the hair follicle and an electric current destroys the hair and its roots. This procedure may need to be repeated after several months. This is because all of the abnormal hairs may not have developed at the time of the first treatment. When these follicles do start to produce hairs, they will need to be treated. If surgery is performed, the lid is actually split and the areas where the abnormal hairs grow are removed. Both procedures require anesthesia and a full recovery is expected. Antibiotic eye drops may be used following surgery to eliminate infections.
Distichiasis is found in Cavalier King Charles Spaniels. It is a breeder's option and I have known several Cavaliers with this condition who have never been bothered by the condition or needed surgery. I have not heard of any Cavaliers with this condition needing surgery, but I am sure there have been some.
Persistent Pupillary Membranes: Persistent pupillary membranes, or PPMs as they are often called are common
findings on CERF examinations. They may or may not be a problem in a breed
and/or individual dogs. PPMs are remnants of a fetal structure called the
pupillary membrane. This membrane covers the pupil before an animal is born. It
is part of the blood supply to the developing lens (the structure in the eye
that focuses light on the retina). Normally the pupillary membrane completely
absorbs before birth in foals and calves but is partially present and continues
to disappear in neonatal dogs. Absorption may not be complete in puppies when
the eyes first open and small strands or a web-like structure may be seen across
the pupil. These strands normally disappear by four to five weeks of age. In
some dogs these strands do not disappear and become PPMs. PPMs are found in many breeds of dog. In most of these breeds, iris to iris PPMs
are classified by CERF as a "breeder option" problem. This means that most of the PPMs which have been reported in these breeds have been small and are probably sporadically occurring and not hereditary defects. Dogs with these small iris to iris PPMs who have been bred have not been reported to have puppies with vision problems. This does not mean that problems will never occur in these breeds. Owners with dogs diagnosed with PPMs should be aware of the situation and should probably either not breed affected dogs or should breed the affected dogs only to unaffected dogs. PPMs is not found in Cavalier King Charles Spaniels as far as I know.
Progressive Retinal Atrophy (PRA): The first sign of most types of PRA is night blindness. This is because the rods
(the cells which allow vision in reduced light) degenerate before the cones (the
cells which allow vision in the bright light). Often dogs will bump into objects
in a dimly lighted room; a room in which a person can see well enough to avoid
the object. Gradually dogs with PRA will lose their ability to see in lighted
rooms and will go completely blind. They will frequently have dilated pupils.
Sometimes owners will notice increased shininess or hyperreflectivity to the
back of the eye. PRA is found in many pure bred dogs, but Cavalier King Charles Spaniels are not known for this disorder and therefore they are not part of the testing database setup for other breeds where PRA is common.
Retinal Dysplasia and Retinal Folds: Retinal dysplasia occurs when the 2 primitive layers of the retina do not form together properly. Mild dysplasia manifests as folds in the inner retinal layer. These are called "retinal folds". In "geographic" retinal dysplasia there are larger areas of defective retinal development. In the severe form of dysplasia, the 2 retinal layers do not come together at all and retinal detachment occurs. Retinal dysplasia is not progressive. It is a congenital defect and animals are born with as severe a condition as they will ever get. Retinal dysplasia can be detected as early as 6-8 weeks on a CERF examination. However, because the size of the eye is small and young puppies are often wiggling during examination, a 6 month recheck is recommended in order for the ophthalmologist to better see the back of the eye.
Retinal folds rarely cause vision problems for the individual dog. They represent small blind spots which are probably not even noticed by the dog. However, large areas of dysplasia (geographic dysplasia) may lead to large deficits in the visual field and dogs with retinal detachments are completely blind.
There have been many questions about the certifiability of dogs with retinal folds. Retinal folds may be seen in many breeds and still pass a CERF examination and receive a CERF number. This is due to the fact that the condition is thought either not to be hereditary in the particular breed or has never been shown to be connected to serious (blinding) forms of dysplasia. In all breeds, individuals with geographic and retinal detachment forms of retinal dysplasia are NOT certifiable.
Retinal Dysplasia and Retinal Folds have been found in Cavalier King Charles Spaniels, but the occurance is not high. Parents that test clear on CERF can still carry the gene. A parent that is shown to have folds can show up on OFA as a breeder's option. Since this condition is not blinding or progressive and without testing a person would have no idea if a Cavalier had the disorder since it does not affect their ability to function on a daily basis OFA assigns it as a breeder's option. This condition can easily be bred out of line if careful attention is taken in the pairing of Cavaliers for breeding and continued testing is maintained on all offspring through three generations. |
