Sierra Elite Ranch

(information copied from Paw Print Genetics and Australian Shepherd Health & Genetics Institute)

• Degenerative Myelopathy (DM): Degenerative myelopathy caused by Mutation of the SOD1 gene is an inherited neurologic disorder of dogs. This mutation is found in many breeds of dog, including the Australian shepherd. While it is not clear for some of the other breeds, Australian shepherds are known to develop degenerative myelopathy associated with this mutation. The variable presentation between breeds suggests that there are environmental or other genetic factors responsible for modifying disease expression. The average age of onset for dogs with degenerative myelopathy is approximately nine years of age. The disease affects the White Matter tissue of the spinal cord and is considered the canine equivalent to amyotrophic lateral sclerosis (Lou Gehrig’s disease) found in humans. Affected dogs usually present in adulthood with gradual muscle Atrophy and loss of coordination typically beginning in the hind limbs due to degeneration of the nerves. The condition is not typically painful for the dog, but will progress until the dog is no longer able to walk. The gait of dogs affected with degenerative myelopathy can be difficult to distinguish from the gait of dogs with hip dysplasia, arthritis of other joints of the hind limbs, or intervertebral disc disease. Late in the progression of disease, dogs may lose fecal and urinary continence and the forelimbs may be affected. Affected dogs may fully lose the ability to walk 6 months to 2 years after the onset of symptoms. Affected medium to large breed dogs, such as the Australian shepherd, can be difficult to manage and owners often elect euthanasia when their dog can no longer support weight in the hind limbs.  Takeaway: Normal(clear) and Carrier dogs will not be affected by this disorder. (Reba is our only carrier of DM, she is perfectly healthy and all of her puppies will be healthy) 

• Hereditary Cataracts (HC): Hereditary cataracts (Australian shepherd type) is an inherited eye disease affecting dogs. Cataracts are opacities in the lens of the eye caused by structural changes in lens proteins. A normal lens allows light to pass through it to the Retina in the back of the eye. Light cannot pass through the parts of the lens affected by cataracts and vision becomes blurry. Dogs with Hereditary cataracts (Australian shepherd type) most commonly present between 2 to 7 years of age with small cataracts that are visible on a veterinary eye exam. In dogs that inherit one copy of the Mutation, cataracts develop slowly, sometimes leading to complete blindness. However, it has been speculated that dogs carrying two copies of the mutation are more likely to develop a more rapidly progressing and severe Cataract.  Of note, not all forms of cataracts are inherited and environmental factors such as UV damage can also play a role in the severity of disease. This specific mutation in the HSF4 gene shows Incomplete Penetrance, meaning that not all dogs inheriting two copies of the mutation develop clinical disease. This suggests that other unknown genetic or environmental factors may play a role in modifying disease development and progression. Takeaway: Normal(clear) and Carrier dogs will not be affected by this disease. (All of our dogs are Normal (clear)) 

• Progressive Retinal Atrophy/ Progressive Rod-Cone Degeneration (PRA/PRCD): Progressive retinal Atrophy, cone-Rod dystrophy 4 (PRA-crd4) is an inherited eye disease affecting dogs. PRA-crd4 occurs as a result of degeneration of both rod and cone type Photoreceptor Cells of the Retina, which are important for vision in dim and bright light, respectively. Affected dogs can show symptoms of vision loss or have signs of retinal disease on veterinary ophthalmologic exam by 3 years of age. However, age of onset varies significantly in PRA-crd4 affected dogs, and has been reported from 1 to 15 years of age. Mutations in the RPGRIP1 gene show Incomplete Penetrance, meaning that not all dogs inheriting two copies of the Mutation develop clinical disease. This suggests that other unknown genetic or environmental factors may play a role in modifying disease development and progression. Although progression tends to be relatively slow, most affected dogs (especially those with an early age of onset) will progress to complete blindness. Takeaway: Normal(clear) and Carrier dogs will not be affected by this disease. (Belle and Wrangler are our only carriers of PRA/PRCD, they are perfectly healthy and all of their puppies will be healthy) 

• Multidrug resistance 1 (MDR1): Multidrug resistance 1, also called MDR1, is an inherited condition affecting several breeds of dogs, especially herding dogs such as the Australian Shepherd. The Mutation in the ABCB1 gene associated with MDR1 causes dysfunction of P-glycoprotein, which is responsible for removing certain drugs and toxins from the body. Clinical signs are most commonly associated with distribution of the drug in the central nervous system. If an at-risk dog is treated with one of several common drugs that contain Ivermectin, they are at risk of developing neurologic symptoms that could range from tremors, excess salivation, anorexia and blindness to coma and even death. Because of the defective ability to metabolize specific drugs, these drugs can be lethal even at low doses. The MDR1 mutation does not cause adverse effects in dogs unless the dog is exposed to these drugs. Therefore, veterinarians should be notified when a dog is at risk for multidrug resistance 1 prior to administration of any medications.Though adverse reactions to certain drugs are most commonly seen in dogs having two copies of the mutated gene, carrier dogs can also experience drug sensitivities and dosages need to be adjusted accordingly. Thus, dogs that have one or two mutant copies of the gene are considered at-risk for adverse drug reactions. When carriers of this Mutation are bred with another dog that also is a carrier of the same mutation, there is risk of having affected pups. For each pup that is born to this pairing, there is a 25% chance that the puppy will inherit two copies of the mutation, and a 50% chance that the puppy will inherit one copy of the mutation and, in either case, may be susceptible to having adverse drug reactions, or there is a 25% chance that the puppy will inherit zero copies of the mutation and be normal (clear). This mutation is very common in Australian Shepherd, One in two Aussies has at least one copy of the gene. You may breed dogs carrying the MDR1 mutation, even if they have two copies. MDR1 dogs react to certain drugs.  Before these drugs were introduced into veterinary practice, no one was aware this mutation existed, even though it has been around for at least a century and a half.  The MDR1 listed drugs, while valuable for veterinary care, are not a part of nature and can readily be avoided when you know a dog’s MDR1 status. Australian Shepherd Health and Genetics Institute DOES NOT recommend removing dogs from the breeding pool solely because they carry one or even two copies of the MDR1 mutation. This mutation is only a problem because we administer drugs to dogs to which they can react.  If dogs were wild animals, they wouldn’t receive drugs so this would be no issue at all.  The point is to know your dogs’ status and avoid giving the problematic drugs if they have the mutation.Half of the breed carries at least one copy of this mutation.  Eliminating all these dogs would cause a severe restriction in our breed population which could result in making serious health issues for which we have no tests more common.  Breeders should follow the steps outlined in the question above this one.  Over time—and multiple generations—the frequency of the MDR1 mutation can be reduced without damage to the gene pool. Takeaway: Normal(clear)  dogs will not be affected by this disease. (Sassy and Wrangler are our only carriers of  MDR1, they are perfectly healthy since we avoid Ivermectin with our dogs. All of their puppies should avoid any treatments with Ivermectin and they will be fine, breeding prospects should be tested for MDR1 so that you can identify whether they are normal (clear)[25% chance],  carrier [50% chance], or positive [25% chance] )