Category archives: Trixie's Paw Prints

Valid Canine Genetic Testing or "Accuracy" of Canine Genetic Testing

Valid Canine Genetic Testing or "Accuracy" of Canine Genetic Testing

There is a trend in the dog world for people to create a list of health clearances on their dogs as long as their arm. There is certainly nothing wrong with a long list of health clearances if those health clearance are valid for the breed - and that is a big if.

I spoke in a previous blog about the fact that not all diseases that appear to be the same are the same. An extremely involved genetic disorder can appear to be identical in two affected individuals, yet can actually have extremely different causes. More specifically, it can be caused by different gene mutations or even two entirely different genes. In the previous blog we discussed the different types of PRA that have been found in different breeds.

With a slightly different focus I want to discuss specifically how this affects the "accuracy" of genetic testing. We all know genetic testing is "very accurate." But that assumes you are testing for the right thing and that the specific gene test is informative. One example is the melanophilin gene. Two different mutations related to this gene have been identified to be associated with dilute coat color (called blue or the ...

Understanding the Genetics of Disease in Your Dog

Understanding the Genetics of Disease in Your Dog

Many people have misconceptions about genetic terms and what these terms mean related to the inheritance of a health issue in a dog, a family of dogs or a breed. I wanted to take a moment to step back and discuss some of these commonly used terms to help people understand them more clearly.

Most genes (and the genes that will be tested for at Paw Print Genetics ) are located on the chromosomes contained in the nucleus found in most cells. Chromosomes come in 39 pairs (and thus, the genes come in pairs). One through 38 are the numbered pairs (called autosomes) the 39th pair are the sex chromosomes; females have two X chromosomes and males have an X and a Y chromosome. The X is larger and has more genes. Because males have only one copy of the X chromosome (and therefore only one copy of many genes found on the X chromosome), they are at risk of having certain diseases that are unlikely to affect females.
Autosomal conditions are found on one of the numbered chromosomes and X-linked conditions are found on the X chromosome. Each gene has a particular location on the chromosome called a locus. Different ...

Predicting Genetic Disease in Your Dog

Predicting Genetic Disease in Your Dog

Continuing the series on "when genes don't make sense," let’s talk about probabilities. Many people will hear that if a condition is recessive that one in four puppies will be affected or, if it is dominant, that 50% of the puppies will exhibit the trait or be affected with a condition. They will subsequently declare that because the outcome in their litter is different than these exact percentages, it therefore must not be… recessive, dominant or genetic at all.

On the other hand, many people in dogs will say things like "they need to breed a male in order to determine if he produces males or females."

These are different errors in reasoning relating to the same type of probability.

In the first case, people are expecting the actual results to be exactly what is predicted based on possible results or probabilities. In the second case, people are assigning meaning to the random variation that is usually observed (and actually expected) compared to what is predicted based on probability.

To start with the second scenario, millions of sperm are swimming as hard as they can to fertilize the eggs. Roughly 50% of these sperm carry an X chromosome ...

Paw Print Genetics, a Family Endeavor

Paw Print Genetics, a Family Endeavor

Paw Print Genetics is a clinical laboratory dedicated to screening and diagnosis of genetic diseases and carrier states for all dogs. In deciding to start my second company, I engaged the help of my family members. My husband needed to be agreeable to investing (emotionally and financially) in another (yes, another) clinical laboratory. But this time, it would be ours and we could make the decisions, good or bad; we would be responsible for its successes and possible failures. After convincing him that Paw Print Genetics is a great idea, we started doing our homework. It is important to know the market. Our market is dog lovers; not a small market. They include owners, breeders, trainers, veterinarians and all the dogs that they breed, train and sell. Every dog deserves optimal genetic health.

Next came the science. Our staff spent months identifying the known genetic mutations in dogs and developing tests to accurately identify whether a dog is normal, a carrier or affected with these diseases. Some may ask “What does a human geneticist know about canine genetics?” Compared to the human medical literature, I was surprised how little is known about canine genetic diseases. The opportunities to make a ...

How does that work?

How does that work?

Another non-intuitive but common behavior of genes is that one gene can have different but apparently unrelated effects. This is somewhat the opposite of different genes having the same effect (discussed in my previous blog). Making it even more confusing, the same condition could have both at work!

One gene may create a specific appearance but can also cause issues that would not necessarily appear to be related. In scientific terms the word pleiotropy is used to refer to the phenomenon "when one allele or pair of alleles has different effects - particularly when these effects appear unrelated."

Many examples of this phenomenon exist in the dog world. With on-going research, more will no-doubt be identified.

The gene causing Merle color pattern increases the chance for deafness and eye defects. Certain "white" dogs also have increased risk of deafness related to being white. In other breeds, very white appearing dogs (due to other genes) and dogs with albinism have no associated risk for hearing loss. In the case of the Merle and "white piebald" associations the effect begins on cells derived from the neural crest affecting both pigment, auditory and potentially other neural-derived cells, but not all Merles, double merles and ...

So what is it? Dominant, Recessive, not genetic at all?

So what is it?  Dominant, Recessive, not genetic at all?

One of the key issues that people often have in grappling with genetics disease is the fact that genes and disorders that are supposedly genetic don't always make sense (or at least not the sense that people expect them to make.) What they see occur does not pass their intuition or logic of what they think they should see if the condition is really "genetic."

A problem will be identified that has never occurred before and people will say in all honesty---"that has never happened in my line" and yet they are told it is "genetic." This happens in human families as well. A genetic condition is diagnosed in a child and the first thing that both grandmothers say is "that did not come from our side of the family!" In some cases they may be wrong and in others they may be right. Different genes follow different "rules."

Recessive disorders in fact come from both families and are due simply to the fact that both the sire and dam happened to carry the same detrimental recessive gene. These can be passed on for many generations unrecognized and only revealed when two carriers happen to mate AND both ...

Does your Dachshund sleep too much?

Does your Dachshund sleep too much?

Maybe your Doxie has Narcolepsy. Narcolepsy is an inherited condition known to affect Dachshunds. Narcolepsy is a disorder that affects a dog’s ability to stay awake for an extended period of time. Dogs with the inherited form of narcolepsy typically show signs of the disorder between one to six months of age. Affected dogs will fall asleep faster than normal dogs and appear sleepy more frequently. Episodes of narcolepsy tend to occur with positive stimulation like play or food. The affected dog may appear to collapse to the ground with a sudden loss of muscle tone but does not typically lose awareness. Symptoms do not progress over time and do not have other associated health problems.
Genetic testing of the HCRTR2 gene in Dachshunds will reliably determine whether a dog is affected with narcolepsy. Because narcolepsy is inherited in an autosomal recessive manner, the breeding of two carrier dogs has a 25% risk of producing affected pups. Testing is available from Paw Print Genetics to determine the genetic status of your Dachshund. It is recommended that carriers with this mutation are not bred to avoid affected pups.

Why do we do this?

Why do we do this?

Why? For the love of dogs. There is nothing more heartbreaking than when a dog that is loved and has been invested in dies. This is heart breaking when that dog has lived a long full life beyond the expectancy for his size and breed and when that dog has fulfilled many hopes and dreams planned for them. It is far more devastating when that loss is premature due to genetic disease. It is devastating when a much anticipated and planned for litter results in a puppy or puppies that die at a day or weeks old. It is worse still when serious problems occur at a year or two years of age, when that puppy is already a part of their owners' life, plans or family. Whether a beloved companion, part of the family, a beautiful show prospect full of potential, a working dog where hours upon hours have been spent in developing their inborn skills to serve an important purpose, or a performance dog trained to (or not quite to) perfection (as the case may be for many of us) it is tragic when this time, energy, love, hope, money, potential is dashed due to premature death or ...

Does your Brittany have recurring infections?

Does your Brittany have recurring infections?

Complement is a type of protein that plays an important role in the body’s immune system by attacking invading organisms such as bacteria. Complement 3 (C3) deficiency is a disorder of the immune system that affects the Brittany hunting dog. In this disorder, the complement protein is absent. Dogs with C3 deficiency may present with pneumonia and other reoccurring infections, excessive thirst and urination, weight loss, loss of appetite, mouth ulcers and depression. C3 deficient dogs may also develop kidney disease which can lead to kidney failure and death. Genetic testing of the C3 gene PRIOR to breeding in Brittany dogs will reliably determine whether a dog is a carrier of C3 deficiency. Carriers do not have any features of the disease but when bred with another dog that also is a carrier, there is a 25% risk to have affected pups. If the breeding pair has not been screened, prospective buyers should have the puppy screened PRIOR to purchasing to avoid this devastating disease. Paw Print Genetics can help you avoid this disease in your puppies and eliminate this gene from your breeding program.

Genetic mutation may make your Old English Sheepdog sterile

Genetic mutation may make your Old English Sheepdog sterile

Cilia are found on the surface of a large number of cells and beat together in waves to move objects, such as to remove particles and mucus from the windpipe and lungs. In this manner, cilia protect the respiratory system from pathogens that can lead to infection. The structures that make-up the cilia are also found in the flagellum or tails of sperm. Primary ciliary dyskinesia (PCD) is an inherited disorder of the cilia that can be found in the Old English Sheepdog. In PCD, affected dogs have cilia that do not function properly. Fluids cannot be moved in the respiratory tract and can lead to infection. Symptoms include coughing, sneezing, nasal discharge and frequent respiratory infections. Affected dogs may be sterile due to the inability of the sperm to swim properly. Genetic testing of the CCDC39 gene can reliably determine whether a dog is a genetic carrier of primary ciliary dyskinesia (PCD). Carrier dogs do not have features of the disease but when bred with another dog that also is a carrier, there is a 25% risk of having affected pups. Testing should be done PRIOR to breeding so that carriers of this disease are not bred together. Screening ...