Potential Genetic Complications of Designer Hybrid Breeds

Designer hybrid breed mixtures can be separated into two camps. 

The first is the designer breed mix that aims to avoid the potential genetic or inherited traits of popular dog breeds. A good example is the Puggle (Pug/Beagle) that aims to subvert the potentially dramatic brachycephalic problems (short-faced) associated with the Pug, hip dysplasia in the Beagle, or other inherited disorders.

The second category is a mixed hybrid breed meant to be a low allergy or low dander dog for humans like the Labradoodle (Labrador/Poodle) also called the Cobber Dog in Australia. Indeed, many breed combinations in this category have emerged like the Schnoodle (Schnauzer/Poodle), Goldendoodle (Golden Retriever/Poodle), Bernoodle (Bernese Mountain Dog/Poodle), Maltese Shih Tzu (also called Mal-Shi, Malti zu, and Malt-Tzu), Cockapoo (Cocker Spaniel/Poodle), etc. The category of low allergy combination dogs has definitely exploded over the past 20 years. 

Companion pet parents who seek out the designer hybrid breeds typically look for a mix of two breeds and then look for the personality type that would best suit their households. We agree, these are important attributes. However, many of the companion pet parents need to be aware of potential health and behavior problems and to do their research.

There is no such thing as a hypoallergenic dog.

We think the term “hypoallergenic dog” is misleading. Yes; breeders can reduce the allergenic factor with mixing shedding and non-shedding dogs, but it is never completely eliminated. In fact, some people find out that their allergic reactions are less with a Wheaten Terrier or another non-shedding breed than a designer mixed breed meant to be low allergy. 

The original designer mixed breed was not created overnight.

The Labradoodle was bred selectively over several generations to be a low dander-producing/allergy dog. Breeders cannot just throw together a Poodle with another breed and call it a low allergy dog. 

The genetic factors that need to be considered.

While designer mixed breeds such as Puggles are sought out for their reduced potential of genetic complications, it appears this factor has not been as carefully considered with mixed breeds breed or purchased for their low allergy factor. 

For example, let’s look at the Aussiedoodle (Australian Shepherd/Poodle) mix.

According to the Washington State University Veterinary Clinical Pharmacology Laboratory, 50% of the Australian Shepherds tested have some form of the multidrug resistance 1 (MDR1) mutation. Breeds such as Collies, Border Collies, Silken Windhounds, Long-Haired Whippets, Miniature Australian Shepherds and others are also susceptible to the mutation. 

What is the MDR1 mutation? The MDR1 mutation can be thought of as an absence of a filter. The mutation allows a higher absorption of drugs and toxic substances to enter the central nervous system which then can breach the blood-brain barrier and create adverse reactions. So, the adverse effects of drugs such as ivermectin (antiparasitic medication indicated for heartworm prevention and other uses) or loperamide (antidiarrheal) can be more immediate and severe for these dogs than the disease or condition they are meant to protect against or treat.

For instance, let’s say a dog inherits mutant MDR1 genes from both parents (written as mutant/mutant). The dog has two copies of the mutant allele and will always pass one to the offspring – no matter the sex of the dog. 

If a dog has normal/mutant alleles, it will tend to have less severe drug reactions. However, it still has a 50% chance of passing the defective gene to the offspring. Again, the sex does not matter. 

So, if an Australian Shepherd has normal/mutant alleles for the MDR1 mutation and is bred with a Poodle, the Aussiedoodle puppy will still have the possibility of having the mutant gene. 

There are many different combinations we could go through here, so we decided to share an example.

Tips on finding a low allergy dog.

If a low allergy mixed breed dog is best for your household, that is fine and understandable. However, you need to research beyond the low allergy and personality to select what’s best for your household. Those are important factors, but there’s more to it.

Checklist

#1. Find out the pedigree and lineage from the breeder.

#2. Find out how the litters are bred to meet suitable low allergy standards for your household.

#3. Find the right personality type and energy level for your household. 

#4. Research on DogWellNet. The website is managed by the International Partnership for Dogs, which has the mission to, “Improve standardization of, and access to, robust genetic testing to support health improvements and a sustainable future for healthy dogs.” It gives a good cross-tabulation of potential genetic mutations across the board. 

#5. Ask the breeder if they have had the mother or the father tested for potential genetic complications. 

#6. You can still introduce a puppy whose parents have genetic mutations. But, before you do, you need to factor in the veterinary and personal costs involved. No matter what, we suggest you have your companion pets tested for the common mutations and health issues of all known breeds in their gene pool. This will help you be the best companion for your pet.

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