Hereditary Cataract - Eye Disease in Malamutes (HC)

BVA, KC and ISDS run Eye Scheme to ensure that there is no evidence of hereditary eye disease in dogs used for breeding. Malamutes can display condition in two categories: congenial (present from birth) and non-congenial (acquired later in life). This screening can be done for congenial condition in dogs as young as six weeks old (and up to 12 weeks) but it is more likely that vet will suggest screening in neonatal stage when eyes are more mature. Basic classification divides into two:

Congenital inherited conditions:
• Goniodysgenesis/primary glaucoma
• Persistent hyperplastic primary vitreous
• Retinal dysplasia
• Collie eye anomaly
• Congenital hereditary cataract

Non-congenital inherited conditions:
• Hereditary cataract
• Primary lens luxation
• Generalised progressive retinal atrophy
• Retinal pigment epithelial dystrophy (central progressive retinal atrophy)

For some congenital inherited problems litters of puppies are screened to establish the status of the whole litter. For dogs of any age, individual certificate are issued every 12 months depending on known eye disease for each breed. Below are breed that can be affected in each classification:

Congenital inherited conditions:
• Miniature Schnauzer

Non-congenital inherited conditions:
• Alaskan Malamute
• Australian Shepherd
• Belgian Shepherd Dog
• Boston Terrier
• Cavalier King Charles Spaniel
• German Shepherd Dog
• Giant Schnauzer
• Irish Red and White Setter
• Large Munsterlander
• Leonberger
• Miniature Schanuzer
• Norwegian Buhund
• Old English Sheep Dog
• Poodle (standard)
• Retriever (Chesapeake Bay)
• Retriever (Golden)
• Retriever (Labrador)
• Siberian Husky
• Spaniel (American Cocker)
• Spaniel (Welsh Springer)
• Staffordshire Bull Terier

The canine lens is an asymmetrical, transparent, biconvex sphere, with more convex aspect positioned posteriorly. A cataract is defined as any opacity of the lens or its capsule. Cataract formation can be:

• Congenital – due to in utero insult
• Traumatic – as a result of blunt or penetrating injury to the eye
• Metabolic – as a consequence of, for example, diabetes mellitus
• Toxic – caused by some drugs
• Nutritional – produced by inappropriate diets
• A complication of other primary ocular diseases – such as uveitis or neoplasia

A specialist vet can easily distinguish inherited cataracts and those by other causes. Dogs with cataracts should not be bred as this will cause undesirable abnormalities within breeding line. Unfortunately inherited cataracts progress to visual impairment and blindness. They can be surgically removed but like any major surgery it is not a pleasant one for the dog and new onsets can occur. Dogs screened by a vet can be only diagnosed if they are affected; however dog who is a carrier of single gene mutation can’t be visually diagnosed. BVA offers DNA testing for inherited eye disease where buccal swab is used to determine one of the three possible genetic compositions:

• Normal – two normal copies of the gene
• Carrier – one normal copy of the gene and one recessive, mutant copy
• Affected – two copies of recessive mutation

Carrier’s genotype is treated clinically as normal due to normal gene effectively silencing recessive gene. If the dog is affected, parents of this puppy are by definition carriers of this recessive gene (they do not have to be classified as affected).

BVA Eye Scheme offers the tools for breeders to avoid spreading of hereditary diseases for a variety of dog breeds. Health screening is a part of responsible breeding. Well done for you if you choose to be part of it, either by visual yearly checks or DNA tests. But if you choose not to test your dogs, and are actively breeding, please reconsider. It can make a world of difference for those little puppies you are bringing to the world.