Dogs used for breeding should be issued with an ACES (Australian Canine Eye Scheme) certificate issued by a registered specialist in veterinary ophthalmology. These certificates are required to be renewed annually.
Any opacity of the eye lens is called a cataract. There are many causes of cataracts and some are inherited. If cataracts are in both eyes and they mature the dog may become blind. Surgery is available in the cases where the cataract grows and causes vision loss. The posterior, polar, sub capsular cataract (PPS) is better known as the star cataract. It is usually in both eyes and generally becomes apparent between 6 to 18 months of age. Some dogs develop this problem as late as 6 to 7 years of age or in some cases as early as 6 to 8 weeks. This cataract may be slowly progressive but it rarely interferes with vision. The condition is inherited, probably as a dominant trait with incomplete penetrance. It is advised not to breed from affected animals as matings with affected dogs have produced litters of blind pups.
Entropion is an inherited condition of the eyelid where the border of the eyelid turns in and hair normally on the outside of the lid rubs on the surface of the eye, causing irritation and in severe cases ulceration of the cornea. Surgery is required to alleviate the dog’s discomfort and prevent damage to the eye. There are a number of genes are involved in the inheritance of entropion. Factors such as head conformation, eye socket shape and depth are involved. Affected animals should not be used in a breeding program.
Extra Eyelashes (Distichia)
Extra eyelashes are found right on the eyelid edge, and they grow from glands there. They are called distichia as they form a double row of eyelashes. Extra eyelashes may or may not cause irritation to the eye. Most Golden Retrievers that are affected do not have clinical signs or evidence of corneal irritation. Surgery is only required if the extra eyelashes are actually causing disease. The condition is believed to be inherited in a dominant manner.
Progressive Retinal Atrophy (PRA)
Progressive Retinal Atrophy (PRA) is a group of inherited genetic diseases that cause vision loss. PRA is inherited as an autosomal recessive trait which means that the condition is passed on from both parents. The retina is the light sensitive layer of tissue at the back of the eye and is responsible for registering visual stimuli and transmitting them via the optic nerve to the brain. Retinal atrophy causes this layer of tissue to gradually degenerate. Affected dogs initially show signs of night blindness, but in time the day vision degenerates resulting in the total loss of vision. Most dogs with PRA also end up developing cataracts. The degeneration of the retina releases factors that cause cataracts to form. DNA tests are available for two PRA genes, prcd-PRA and GR_PRA1. This condition is rare in the Golden Retriever in Australia.
Persistent Pupillary Membranes (PPMs)
Persistent Pupillary Membranes (PPMs) are strands of tissue that fill the front, fluid-filled chamber of the eye. These tissues should have dissolved away as the eye developed. Instead they persist and can affect vision in the more severe cases. Most cases of PPMs are mild but may result in small focal cloudy spots in the front of the eye.
Horner's syndrome is a neurological condition where the sympathetic nerve to the eye is not functioning normally. It is not painful. Symptoms may include a small pupil, droopy upper and lower eyelids, a visible third eyelid or a sunken eye. Most of the time no cause is found (idiopathic) and the symptoms resolve over a period of six to eight weeks. Golden Retrievers seem to be prone to developing idiopathic Horner’s syndrome.
The normal pressure within the dog’s eye is 10 to 25 mm Hg. Glaucoma is diagnosed when the pressure increases to greater than 30 mm Hg. This increased pressure can rapidly cause blindness and pain. Once the eye becomes enlarged, the eye is blind. In some dogs, including the Golden Retriever, the outflow of fluid from the eye is blocked by an abnormal drainage angle. Secondary glaucoma can develop due to inflammation of the eye (uveitis), lens luxation, blood in the eye, or growths inside the eye. Surgery is usually required to control glaucoma although in some cases eye drops can be used. Gonioscopy examines the drainage angle with a special contact lens to check if the eye is predisposed to glaucoma. If the drainage angle is malformed there is a greater risk of glaucoma developing in the eye. If an eye is predisposed to glaucoma, then lifetime treatment with eye drops is required. However, it is still possible for the eye to develop glaucoma. Prompt recognition and treatment are essential to save vision. Early signs are redness of the white of the eye, a blue, hazy eye or a fixed dilated pupil.