If you have done any research at all on aussies I am certain you have seen this abbreviation. This is by far the most common issue found in aussies as it has a breed prevalence of 50%! That means that for every two dogs you look at, one of them will have at least one MDR1 gene. So what is it? 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. Now don't panic! It's not nearly as bad as it sounds. 1. MDR1 mutant dogs must receive the mutant gene from BOTH PARENTS to be affected. Carriers, dogs with only one mutant gene, are not affected in the same way, although sensitivity can occur in really high doses.
2. Whether your dog is N/N ("Negative" or "Clear") or M/M ("Positive" or "Mutant") for MDR1, the breed as a whole is more sensitive than other breeds to the ivermectin based drugs and should avoid them whenever possible. Please be aware that a general veterinarian may not relate that your dog is an aussie and may have this gene. It is up to YOU to advocate for your dog and bring this up with your vet. Even then, not all Vets are familiar with this list or the MDR1 Mutation.
Drugs to AVOID: Ivermectin (antiparasitic agent) "Heartguard" Loperamide (Imodium: over-the-counter antidiarrheal agent) Doxorubicin (anti-cancer agent) Vincristine (anti-cancer agent) Vinblastine (anti-cancer agent) Cyctosporin (immunosuppressive agent) Digoxin (heart drug) Acepromazine (tranquilizer) Butorphanol (pain control)
Note, Heartguard is on the list because it can cause seizures in sensitive Aussies. Use Interceptor or Sentinel instead. Interceptor® is a non-Ivermectin based heartworm treatment safer for most mini Aussies. For those that can no longer find Interceptor, Sentinel proves to be a good replacement. As always, please seek your own vet’s advice. Sentinel® combines Interceptor® and Program® into one pill.
**All Renegade Dogs are tested for MDR1 or known by parentage. Almost all of our dogs are CLEAR, but we do have a couple of carriers.**
This is a terrible disease that never has to happen. Dogs that receive two copies of this gene *will* go blind. Maybe at two years, maybe at four weeks old, but no amount of medical intervention will save their sight. This whole disease can be avoided by pairing dogs together in such a way that will not produce an affected puppy.
**ALL RENEGADE DOGS ARE N/N AND 100% CLEAR FOR PRA-PRCD. This means we will NEVER produce a dog with this disorder!!**
Progressive Retinal Atrophy (PRA) is common in many breeds of dogs and has been identified in Australian Shepherds. It affects the entire retina and is the canine equivalent of retinitis pigmentosa. Typically, the clinical disease is recognized first in early adolescence or early adulthood. Puppies may be blind by six to eight months. An ophthalmologic examination by an ACVO-certified vet should be able to identify cases of PRA.
All dogs affected with PRA eventually go blind. Carriers show no clinical symptoms. Symptoms are subtle, starting with night blindness, some eye dilation, progressing to complete blindness. It is quite common not to notice anything wrong until the dog is nearly completely blind.There is a genetic test to identify normal/clear, carrier, and affected dogs. This disease is thought to be a simple autosomal recessive gene, thus two recessive genes are needed for a dog to be affected and an affected dog’s parents are either carriers or also affected.
HSF4 or HC
A number of breeds are known to suffer from HC and there are almost certainly different genetic causes for a number of these. Mutations in one gene called HSF4, has been shown to cause HC in a number of different breeds (Australian Shepherd, Boston Terrier, French Bulldog and Staffordshire Bull Terrier). the same gene has been identified as a risk factor for bilateral posterior polar subcapsular cataracts in the Australian Shepherd. This form of cataract has quite a variable age of onset and in this breed, the HSF4 mutation appears to behave as an autosomal dominant condition. This means that a dog must inherit only one copy of an abnormal gene (one from its mother or one from its father) before its health may be affected. Research suggests that the mutation makes a dog 12 times more likely to develop posterior bilateral cataracts at some point in their lifetime.
A cataract is an “opacity”, or loss of transparency of the lens of the eye. The opacity may be confined to a small area of the lens, or it may affect the whole structure. A complete cataract affecting both eyes will result in blindness, whereas small non-progressive cataracts will not interfere with vision. Primary cataracts occur in some breeds; in other breeds the cataract may develop secondarily to another inherited disorder such as progressive retinal atrophy or glaucoma.
**ALL RENEGADE DOGS ARE N/N AND 100% CLEAR FOR HSF4. This means we will NEVER produce a dog with the genetic form of this disorder!!**
This disease is one of those that will immediately rule a dog out of my program. I really try to look at the dog as a whole and "not throw the baby out with the bathwater" so to speak. However, this gene is powerful enough to cause serious health problems (reoccurring cataracts that must be surgically removed and WILL continue to come back) with only one copy of the gene. It is not worth even having a carrier in my program knowing that half of their puppies will be inflicted with the same disorder as the parent.
Although this is not a "genetic disease" per sey, it is very much a preventable condition cause by genetics and I felt it worth mentioning for the sake of education.
Double Merle is the common term for homozygous merles (dogs with 2 copies of the merle gene). These dogs are also sometimes (inaccurately) referred to aslethal whites (this is considered by many to be a derogatory term). Merle is a dominant gene. A dog with one copy of the gene will have partial lightening (a normal merled coat). With two copies, the effect is doubled, resulting in some to most of the coat turning white. Double Merle pups are born when both of the parents are merle. It doesn't matter what color merle, how much merle the parents have, how little (or how much) white trim, what breed they are, or even that the parents are the same breed. Statistically, 25% of the pups from two merle parents will be Double Merles.
The range of health problems that occur in double merle dogs is vast. They can have vision problems, various eye problems, multiple of those various eye problems, one or both eyes too big or too small, missing eyes, or even no eyes at all. That in conjunction with hearing problems, hearing loss, or total deafness truly classify them as "special needs" from birth, and really at no benefit to the breeder.
Everyone knows that the popular demand is for merle puppies, specifically blue merles. When breeding tri color/bi color/ or self (solid color) to a merle dog you have the probability of 50% merle and 50% tri/bi/self. Unknowledgeable breeders attempt to increase their odds of producing more merle puppies than tri/bi/self puppies by breeding two merles togther. In this case, your probability ratios are 25% tri/bi/self, 50% normal merle (SAME AS THE PREVIOUS WAY), and 25% Double Merle. So let's recap.. Merle to merle breeding produces 50% normal merle and 50% double merle or tri/bi/self. SO WHY?? I started to post them here, but I'd rather not fill my site with sadness, but just google "double merle" and see what photos come up. When you stop crying (or being grossed out) you will understand why we do not breed merle parents together, no matter how beautiful.
As I said before, there are many other genetic tests and certifications we could perform on our dogs. There is always "more" out there. Some of these we will start in the next year or so and others we are choosing not to do. If you have any specific questions about a particular health issue and where our dogs stand, please feel free to contact us! I believe in full honesty about my dogs, life, etc and will happily give you any information I have.
The list below are just a few places you can find more information on those health concerns listed above and overall aussie health! Enjoy!
Aussies are generally a healthy breed, but just like most other breeds they have their vexes. Fortunately for us, most of the nasties can be prevented by selective breeding based on the results of genetic testing. We could go into great depth on each possible disorder known to have ever occurred in the breed but I think that would be counter productive, giving too much scary irrelevant info vs the relevant facts on common issues.
I'm sure you've seen all the letters in blue next to our dogs and wondered what in the world they meant. Those are the results of the genetic testing we have had done on our dogs. We made them public on our site so you can feel confident about the genetic health of your new furbaby!