MINIATURE AUSTRALIAN SHEPHERD ~ GENETIC TESTING

 

 

When I learned of these genetic tests for some of the defects of the Miniature Australian Shepherd, I knew I wanted dogs that have testing and are cleared and normal. I wanted to make sure that I was reproducing animals that are going to be a benefit to the breed in not carrying on these afflictions! It is very important to me that my new puppy owners don't face some of these devistating issues down the road. It can be avoided! Therefore, I wanted to provide information regarding some serious genetic afflictions of Mini Aussies for you to understand. When testing for these, a DNA sample is sent to an accredited lab who then tests the dog’s genes. A dog can be one of three things; Affected, Carrier or Normal.

 

An Affected dog means that it carries the genetic markers to be affected by the mutation. This means that the dog can become sick and show signs of the mutation, therefore affecting their quality of life.

A Carrier is one that, though they may not show signs themselves, or become sick with it themselves, all potential offspring have a 50% chance of having the genetic mutation and being affected even when being bred to a non-carrier (normal.)

Being Normal means that this dog has no genetic markers for the mutation. Meaning they are not affected nor can they possibly pass it on to their offspring if their mate is also normal.

 

Diosa Miniatures is making every effort to be an active force in breeding these genetic mutations out of Mini Aussies. In our breeding program there is no reason to breed a dog that is neither a carrier nor affected. That would feel as though I was  irresponsibley breeding and contributing to the problem. There are special circumstances where a dog can be bred if they have one copy of the gene to another dog that is completely clear. The resulting pups may or may not come out as carriers but would never be affected. If there are outstanding qualities in a specific dog and none of the puppies were going to be sold as breeders, then I could see where a breeder might make an allowance. We, however, do not choose to breed dogs unless they are completely clear.

Your puppy has been fully tested on these mutations and are deemed normal through the testing of their lineage. This assures you that you are getting a puppy that will not only light up your life, be your companion and give you love for years to come, but that this puppy will also be healthy and live a long life as your friend.

 

Diosa Kennels, breeder of quality Miniature Schnauzers and Miniature Australian Shepherds.

 

 

MDR1 Gene Mutation - Multidrug Sensitivity in Herding Breeds:

Multi-Drug Resistance Gene, (MDR) codes for a protein that is responsible for protecting the brain by transporting potentially harmful chemicals away from the brain. In certain breeds, a mutation occurs in the MDR1 gene that causes sensitivity to Ivermectin, Loperamide, and a number of other drugs. Dogs with this mutation have a defect in the P-glycoprotein that is normally responsible for transporting certain drugs out of the brain. The defective protein inhibits the dog's ability to remove certain drugs from the brain, leading to a buildup of these toxins. As a result of the accumulation of toxins, the dog can show neurological symptoms, such as seizures, ataxia, or even death. Dogs with even one copy of this gene can have severe and even fatal reactions to large doses of the drug.

This is often a fatal reaction to certain drugs but most commonly Ivermectin which is found in some dog wormers. For some dogs with the mutation this dosage is fatal. Some dogs with the mutation can handle small doses as prescribed in dog wormers but if they come in contact with a strong dosage as used in horses, it’s fatal. Even eating horse droppings, which all dogs do given the chance, can be fatal.

 

HSF4 Mutation ~ Hereditary Cataracts

Hereditary Cataracts (HC) are a clouding of the lens of the eye caused by a breakdown of tissue in the eye. This condition generally results in an inability to see clearly and can cause total blindness. In canines, cataracts are often familial; this type is known as Hereditary Cataracts. A mutation in the HSF4 gene causes this type of cataracts in several breeds of dogs. In this case, the dog is typically affected bilaterally, in that both eyes are affected by the cataracts. The cataracts associated with HSF4 also occur in the posterior region of the lens. They usually start by being small and grow progressively, though the speed of growth is highly variable. Some cataracts will grow so slowly that the dog's vision remains relatively clear, while others will grow such a way that the dog will quickly go blind. Corrective surgery is possible, though it is costly and is not always effective.

 

A mutation of the HSF4 gene is linked to a form of Hereditary Cataracts in Australian Shepherds. This mutation affects Aussies differently then Boston Terriers, French Bulldogs and Staffordshire Bull Terriers in that the disease is dominant but not completely penetrant. This means that only one copy of the mutation is necessary to predispose a dog to the disease. However, incomplete penetrance means that a dog that has this mutation will not always develop HC. Research suggests that the mutation makes a dog 12 times more likely to develop posterior bilateral cataracts at some point in their lifetime. It is likely that a secondary gene interaction occurs in the small percentage of dogs possessing the HC mutation but does not develop cataracts. This interaction is not yet understood.

 

It should also be noted that not all cataracts are hereditary. Cataracts can also be caused by old age or injury. Also, cataracts that occur in different regions of the lens can also be familial, however, are not attributed to this gene mutation.

 

PRA/Prcd ~ Progressive retinal atrophy / progressive red-cone degeneration

Progressive retinal Atrophy, progressive Rod-cone degeneration (PRA-prcd) is a late onset, inherited eye disease affecting many breeds of dog. PRA-prcd 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. Evidence of retinal disease in affected dogs can first be seen on an Electroretinogram around 1.5 years of age for most breeds, but most affected dogs will not show signs of vision loss until 3 to 5 years of age or later. The rod type cells are affected first and affected dogs will initially have vision deficits in dim light (night blindness) and loss of peripheral vision. Over time affected dogs continue to lose night vision and begin to show visual deficits in bright light. Other signs of progressive retinal atrophy involve changes in reflectivity and appearance of a structure behind the retina called the Tapetum that can be observed on a veterinary eye exam. Although there is individual and breed variation in the age of onset and the rate of disease progression, the disease eventually progresses to complete blindness in most dogs. Other inherited disorders of the eye can appear similar to PRA-prcd. Genetic testing may help clarify if a dog is affected with PRA-prcd or another inherited condition of the eye.

 

Diosa Kennels, breeder of quality Miniature Schnauzers and Miniature Australian Shepherds.