Blog Archives for the year 2018

There aren’t many things sweeter in life than a cavalier King Charles spaniel (CKCS). From their friendly, outgoing demeanor to their adorable, pouty eyes, they have definitely become one of my favorite breeds over the years. It appears that others understand my enthusiasm for the breed as well. In the fifteen years from 2002 to 2017, CKCS have moved up from 40th place to 19th place on the AKC’s registration statistics and are one of the most popular breeds in the United Kingdom. Unfortunately, like other popular dog breeds, cavaliers have their share of inherited diseases that can potentially reduce their quality and quantity of life. At Paw Print Genetics, we strive to control these diseases for our canine companions.

One interesting yet, debilitating disease unique to the CKCS is an inherited neurological condition first reported in 1983¹, known as episodic falling syndrome (EFS). Affected dogs begin showing signs of spastic muscle contractions of the limbs and trunk between 14 weeks and 4 years of age particularly during exertion, excitement, or frustration. As an episode starts, affected dogs most commonly develop rigid hind limb extension, a convex bending of the spine (“roach backed”), and hold their head near the floor ...

At Paw Print Genetics, we are often asked this question: “Why do I need to send in a sample on the dam if I just want to know the father of my pups?”. The simple answer is because we need to compare the DNA of the pup to both parents in order to confidently confirm or exclude a potential sire.  Here is an example that helps explain why we need both parents for parentage testing. Keep in mind that a pup receives half of its DNA from its mom and half of its DNA from its dad, so for every marker that we examine, the pup has one allele (gene copy) from mom and one allele (gene copy) from dad.

For parentage (paternity) testing, we use a set of 99 informative markers to confirm or exclude a potential sire. For each marker, we get two results because the pup has two sets of DNA, one from the mom and one from the dad. The two alleles are each assigned a number based on their DNA sequence.  For example, for marker “A”, the pup might be 1,3; one allele has sequence 1 and the other allele has ...

The breeding of dogs identified as genetic carriers of recessive disease is a hotly debated topic in the canine breeding world with many breeders firmly entrenched in their own personal approach to the issue. With increasing regularity, dog breeders and their clients are bringing genetic questions (including those about breeding carriers) to their veterinarians under the assumption that most veterinarians would be up to speed on the current information and genetic testing available. Unfortunately, at Paw Print Genetics we occasionally speak to breeders whose veterinarians have given them advice about breeding carriers that may not be in the best interest of the kennel or the breed. Given the large number of variables and differences between the way kennels are operated and the recessive disease risks of individual breeds, there is not necessarily a breeding approach that would be appropriate in 100% of cases. However, understanding some guiding principles and the potential ramifications of doing so, can help a veterinarian advise their dog breeding clients in a way that will help them meet their goals without increasing the incidence of recessive diseases in a kennel or in the breed.

What is a “Carrier” of a Recessive disease?

As a quick refresher ...

Paw Print Genetics was approached by the Australian Shepherd Health & Genetics Institute (ASHGI) to conduct a pilot project on blue-eyed, tricolored (BET) Australian shepherds (Aussies) to understand whether these dogs have the SINE insertion in the PMEL gene that can cause a variety of coat color and pattern variations known as merle.  Identifying whether these dogs do or do not have the merle mutation can help inform how to conduct a larger research study.  The merle mutation seemed a logical place to start, as dogs with classic merle coat color patterns can have blue eyes [Clark et al., 2006].

With the help of ASHGI and several breeder volunteers, we collected 38 BET dogs that have blue eyes but no coat variations associated with carrying a copy of the merle mutation. These dogs were not randomly selected from the whole Aussie population, but rather, were sent to us from the breeder volunteers. Thus, many of the dogs collected may have been related.

Paw Print Genetics recently launched a high-resolution test for merle that allows for identifying variation within the SINE insertion and allows for discrimination of the various possible merle alleles. Using this DNA sequence-based, high-resolution test, we ...

The genetics of coat color inheritance for an individual dog can be confusing, and for some breeds, determining the potential colors of your pups can be even more difficult. For those breeders that are concerned or simply curious about potential coat colors of their future litters, genetic testing of prospective parents can save a lot of time, money and heartache when it comes to predicting colors. 

This color chart attempts to show how the various, known genes interact to produce certain colors. Some genes are dominant over other genes, while some alleles (specific copies of a gene) are dominant over other combinations of alleles at the same gene (or locus) or dominant over other genes in this pathway. By understanding how these genes interact, you will be able to better predict the outcomes in your breeding program.

So how can two light colored parents produce an all black litter? In some breeds, such as the Labrador retriever, it is not possible for two yellow parents to produce black or chocolate pups because the gene that controls whether a dog is yellow or black is the E locus. Yellow Labs are ee and black Labs are either Ee or EE ...

Coat color genetics can be very confusing. There are many different genes that can contribute to the overall coat color in a dog and for each gene, there can be different mutations that can contribute to color variations.  The B locus (or gene) is responsible for many of the brown coat colors seen in dogs (also referred to as chocolate or red, depending on the breed).  When performing genetic testing of the B locus, the test result is determined by examining three specific locations within the B gene of a dog, known as the b^c, b^d, and b^s. The overall B locus genotype for a dog is determined by the combination of genotypes (variations) present at the b^c, b^d, and b^s loci (locations within the B gene). 

For most genes in the dog, there are two copies of that gene, one inherited from the mom and one inherited from the dad.  The B locus is no exception in that although both parents have two copies of the B locus, the mom contributes only one copy of the B locus to each of her pups, randomly selected from her two B alleles that she carries ...

The often-debated biological argument of “nature versus nurture” is at the center of the challenging considerations dog breeders must make in their effort to produce the healthiest, happiest, and most beautiful dogs they can. Breeders routinely contact the veterinarians or geneticists at Paw Print Genetics (PPG) looking for genetic testing to identify dogs that may be at risk of producing puppies with certain diseases. Given the emotional, temporal, and monetary damages associated with being forced to remove a dog from a breeding program, it is important for breeders to understand whether the disease in question appears to be inherited or whether there might be a more likely environmental explanation for what they see in their blood line. However, when no genetic testing is available for a particular condition, the answer to the question of nature versus nurture may not be quite as straight forward as it may seem at first glance. Keeping your mind open to environmental factors associated with disease might prevent your clients from having to remove their prized breeding dog from their gene pool.

An All-Male Litter?

As a veterinarian, one of the great joys of helping improve the genetic health of dog kennels are the many ...