Overview
A number of test are available for the Shetland Sheepdog. Two or more of these tests purchased as part of this bundle will be discounted.
- Collie Eye Anomaly associated with the NHEJ1 gene
- Degenerative Myelopathy associated with the SOD1 gene
- Multi-Drug Resistance associated with the ABCB1 gene
- Progressive retinal atrophy (BBS2-type)
- Progressive retinal atrophy (CNGA1-type)
Collie Eye Anomaly
*Optigen Officially Licensed*
Collie Eye Anomaly/Choroidal Hypoplasia (CEA/CH) is a developmental defect of the eye. Specifically, the abnormal development of the choroid – an important layer of tissue under the retina of the eye – in which there is a decrease in the development of the blood vessels. Puppies can be diagnosed by an ophthalmologist as early as 6-8 weeks of age. As the puppies get older the tapetum (the reflective layer at the back of the eye) develops and this can hide the signs of CEA. This phenomenon is called “go normal”, but it does not mean that CEA goes away or gets better. Affected dogs can also develop optic disc coloboma and retinal detachment.
Degenerative Myelopathy
Important: Degenerative Myelopathy is a rare disease that presents most commonly in German Shepherd Dogs and Boxers, sporadically in Pembroke Welsh Corgis, Cardigan Welsh Corgis, Bernese Mountain Dogs, Rhodesian Ridgebacks, Borzoi and Chesapeake Bay Retrievers. It is rarely diagnosed in other breeds or mixed-breed dogs. DM is considered genetically complex and will have more than one contributing genetic variant. The variant targeted by this test is widespread and found in more than 120 breeds. However, association of the variant with the disease has only been shown in very few breeds and should never be used to inform breeding decisions, except where close relatives have been clinically diagnosed.
Canine degenerative myelopathy (previously also known as chronic degenerative radiculomyelopathy) is a progressive disease of the spinal cord in older dogs. Most dogs are at least 8 years old before clinical become apparent. DM usually starts with a muscle weakness, loss of muscle and loss of coordination (ataxia) in the hind limbs. Progression is generally quote slow, but dogs will eventually be crippled within approximately 3 years of the onset of disease.
Multi-Drug Resistance
In certain breeds a mutation on the ABCB1 gene, which encodes the MDR1 protein (which stands for Multi Drug Resistance 1) can cause animals that carry the mutation to be particularly sensitive to certain drugs. The variant was first detected in a subpopulation of dogs that were highly sensitive to Ivermectin-induced neurotoxicity. The variant on the ABCB1 gene results in the brain being unable to efficiently pump some drugs out, causing a toxic build-up of these drugs in the brain. Dogs subsequently experience and range of symptoms from vomiting and diarrhea to lethargy, seizures, or coma.
Progressive retinal atrophy (PRA)
Progressive retinal atrophy (PRA) is the most common form of inherited disease affecting the retina in dogs; the retina detects light and sends images to the brain. Progressive degeneration of the retina at the back of the eye is characteristic of PRA and leads to vision loss and blindness. PRA is not painful to dogs, and the first signs of the disease tend to be bumping in to objects, such as a piece of furniture that has been moved. Mutations in different genes cause genetically different forms of PRA. It affects many different breeds of dog, but each genetically distinct form usually affects one or a small number of breeds. At least two genetically distinct forms of progressive retinal atrophy are found in Golden Retrievers. Research suggests that there may be at least one form that has not yet been identified.
Progressive retinal atrophy (BBS2-type)
A form of PRA in Shetland Sheepdogs is caused by a mutation in a gene called BBS2. In humans, mutations in BBS2 are associated with a condition known as Bardet Biedl syndrome. This novel form of PRA, is unusual as it presents with other characteristics including a wavy, atypical textured coat, upturned nose and dental defects. There is evidence that this syndrome may also cause kidney abnormalities and obesity due to an enhanced motivation for food, but further studies are required to confirm this. The age of onset of this form of PRA is variable.
Progressive retinal atrophy (CNGA1-type)
This specific form of PRA is caused by a mutation in a gene called CNGA1 and is indistinguishable from other forms of PRA in other breeds. The average age of onset of clinical signs is around 5 years, but can be anything between 2 and 11 years
