Eye diseases in Siberian Huskies
by Jennie Lamond
What follows is a brief explanation about each of the disorders that has been known to affect Siberian Huskies, their genetic inheritance (put in simple terms), and the suggested strategy for breeding. This article has been put together with information from Dr Robert Stanley from Animal Eye Care, Malvern Victoria, along with several web pages which are stated at the end of the article.
Crystalline corneal dystrophy
Appearance: Round or oval areas of the cornea appear opaque (milky or metallic), usually beginning within the first two years.
Possible Problems: These deposits are not likely to cause blindness.
Treatment: Removal of the fatty deposits which cause the opacity do not appear to assist, as the opacity will re-occur.
Genetic Inheritance: In this form (as for the Siberian Husky particularly), the disorder is a recessive trait, which varies in degree of expression. Therefore, only those dogs who carry two genes for the defect will express it, though the severity may vary.
Breeding Protocol: As it is considered more of a 'blemish' than a disorder which impacts on the life of the dog, it is considered to be at the breeder's discretion that an affected dog be used. To better the breed, it is suggested not to breed affected dogs. If an affected dog is bred to another dog, there is a chance that this dog, who does not express the problem, may be a carrier. If this is the case, each pup has a 50% chance of expressing the problem, and the pups who do not express it will be carriers. If the unaffected dog used for breeding is not a carrier, each puppy will be a carrier. Having large numbers of carriers in the population would make it difficult to breed away from this defect.
Entropion - inward rolling of the eyelids
Appearance: Usually occurring within the first two years, the lower eyelid rolls inward onto the eye. Eyeballs may be small in comparison to socket size.
Possible Problems: Scarring of the cornea can occur. Generally the condition is very painful.
Treatment: Surgery is required in most cases, with severe cases requiring more complex treatment.
Genetic Inheritance: Suggestions of a dominant gene and multiple genes have been made. It is also felt that some facial characteristics (associated with proportions of eyeballs and sockets) contribute.. The condition can be caused by injury or surgical scarring, but is mostly inherited.
Breeding Protocol: Due to the severity of effect and the unknown nature of genetic inheritance, it is suggested that affected dogs are not bred from. This is a rare problem in Siberian Huskies, thus breeding affected dogs would bring increased problems into the breed, which is an easily avoidable situation.
Appearance: By definition it is opacity of the lens. Therefore, any colouration, or partial colouration of the lens could possibly be a cataract. One eye or both eyes may be affected.
Possible Problems: Can cause altered vision or blindness, though the most common type experienced by Huskies is slow to progress, and rarely causes vision problems.
Treatment: When blindness has occurred, or rapid formation of cataracts is affecting both eyes, complex surgery can be an option to retain the dog's vision.
Genetic Inheritance: Generally thought to be autosomal recessive (a dog needs two copies of the bad gene to have the problem), research is being undertaken to produce a DNA test, assisting in identification of carriers.
Breeding Protocol: Affected dogs are not recommended for breeding, as those dogs who express the disorder would produce 100% carriers in the puppies, and 50% possible affected dogs if they are bred with an unidentified carrier. The future availability will assist breeders to recognise potential carriers, preventing the breeding of puppies with this defect.
Distitchiasis - extra eyelashes
Appearance: Not easily visible with the naked eye, Distitchiasis is the condition of eyelashes coming out of an abnormal position such as the glands that are located along the eyelid edge.
Possible Problems: Can cause scarring on the retina, discomfort, excessive tearing, or corneal ulcers. Thick, hard eyelashes, and those more central to the eyeball can cause this pathology, though Siberian Huskies have soft eyelashes and generally do not experience any pathology. Not to be confused with Ectopic cilia (hairs which grow towards the eyeball from the inside of the eyelid), which usually cause pain and pathology.
Treatment: One or two complex surgeries would permanently remove the offending eyelashes.
Genetic Inheritance: Although it has been established that this is an inherited trait in many breeds, it is rare in Siberian Huskies and has yet to be defined.
Breeding Protocol: It is difficult to predict what would occur when breeding an affected dog. Severe cases and those which have been problematic, may be more likely to reproduce in that form. Breeder discretion is advised.
Appearance: Small white spots at the edge of the cornea.
Possible Problems: Rarely interferes with vision.
Treatment: None available.
Genetic Inheritance: Believed to be inherited.
Breeding Protocol: None specified.
Appearance: Small white streaks may be seen by an opthalmologist, which indicate folds in the retina of young, growing puppies.
Possible Problems: There is no material to suggest that this disorder affects Siberian Huskies. The only information, contained in notes submitted by Dr. Robin Stanley, specifies that most dogs grow out of the problem.
Breeding Protocol: This is a serious problem in some breeds, such as Samoyeds, where affected individuals are recommended to be removed from breeding programs.
Progressive Retinal Atrophy (PRA)
Appearance: It is not visible without opthalmology until the very late stages, where cataracts may occur. The noticeable signs begin with the dog being apprehensive about going outside or getting around in the dark (night blindness), which progresses into the same types of problems in unfamiliar surroundings during the day. This can occur at any age, but is most common between five months and three years.
Possible Problems: Mild blindness progresses into total blindness.
Treatment: No medical treatment is available, however lifestyle changes and training prior to the dog becoming blind can assist the quality of later life once blindness occurs.
Genetic Inheritance: In the Siberian Husky, inheritance is sex-linked. This means two things. Most evidently, more males suffer from the disorder than females. At the level of genetics, the disorder is carried on the X chromosome, of which there are two in females, and one in males. When a female inherits one X chromosome containing the disorder, the corresponding gene can compensate, making the female not a sufferer, just a carrier. When a male inherits an X chromosome with the disorder, the Y chromosome is unable to compensate, making him a sufferer. A female sufferer has two X chromosomes with the disorder, and a carrier has only one defective X chromosome. When puppies are produced, each male inherits one X chromosome from the mother, and a Y chromosome from the father, and females receive an X chromosome from each parent. An affected male matched with a female will not produce male offspring with the disorder unless the female he is bred with is a carrier. He will however produce females who are all carriers if the female he is bred to is not a carrier, and if she is a carrier, he will likely produce affected females.
Breeding Protocol: Affected dogs and bitches should not be bred from. The recent establishment of a DNA test will make avoiding PRA much easier in the future. It is therefore recommended that females are tested for carrier status prior to breeding.
Appearance: The eye could be red, the eyeballs blue, and the pupils permanently larger than usual.
Possible Problems: Permanent blindness results if treatment is not sought early.
Treatment: Surgery and eye drops can halt the blinding, and medications can reduce pain when the condition is severe. EARLY TREATMENT is the only way to prevent permanent blindness.
Genetic Inheritance: It is noted as being hereditary, but no specific pattern of inheritance has been identified.
Breeding Protocol: Affected dogs should NOT be bred. Very small or abstracted drainage angles represent high glaucoma risk.