Archives for March 2013

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 ...

At least 33,000 years ago, humans began the process of domesticating certain members of the gray wolf species. Since that process began, humans have genetically manipulated canines to fill various roles – beginning with tasks that increased means of survival and later to simply serve as companions. Those evolutionary changes have been a benefit to humans, but have caused health issues within many dogs – because as we’ve bred for desired physical traits, detrimental genetic mutations have also been passed along within many breeds.

The consistent selective breeding of canines has led to hundreds of breeds with standard and predictable attributes, or traits.

For example, the short-legged, long-bodied dachshunds allowed them to easily enter underground tunnels and burrows of badgers and other small animals; long-eared, keen-smelling bloodhounds were bred to trail deer, wild boar and later humans; some of the oldest breeds, the sight hounds, which include greyhounds, whippets and saluki, were selectively bred for long legs, strong aerobic endurance, sharp eyesight and the desire to chase feathered and furred game.

These consistent traits were brought about by mixing several different canines that possessed desired attributes (i.e., flat-coated retrievers were likely a combination of St. John’s Water Dogs ...

Throughout the evolution of the modern canine, one of the most important symbiotic relationships with humans has been as the role of protector by the dog.

Those wolves that stuck close to humans in hopes of scavenging leftovers, and which slowly evolved into modern canines, provided early man with advanced warning systems and protection when other wild creatures in nature provided a much greater threat than they do today.

However, not much has changed in tens of thousands of years. Today’s dogs are used by the military, businesses and in homes throughout the country (and world), for protection and guard duty.

In fact, the right dog in a home can be a greater deterrent for criminals than the presence of a firearm. In a study that involved 589 convicted property offenders, the question was asked: “How effective is each of the following likely to be in preventing burglary, breaking and entering and grand theft?”

The results were:

0: not effective; 1: somewhat effective; 2: very effective

Monitored burglar alarms: 1.51
Electronic sensors in windows: 1.35
Closed circuit TV cameras in stores: 1.31
Private security patrols: 1.14
DOG IN HOUSE: 1.11
Weapons in home: 1 ...

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 ...

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 ...

A phenomenon in canine competition circles known as popular sire syndrome can produce strong, competitive and intelligent puppies that go on to become, and produce, champions. The occurrence can also produce puppies that fill the breeding pool with genetic maladies.

When a male dog wins a prestigious championship, he obviously has what it takes to win at the highest levels. The effect is that his value as a stud dog skyrockets as breeders with females hope to produce puppies that can replicate their father’s accomplishments.

Often that trendy stud dog is bred with many female dogs throughout the country. When this happens, you can see that male dog show up in pedigrees from previously unrelated lines. In a large breeding pool, say with Labradors, the effects aren’t as profound as in a smaller population, but they’re still present and can cause issues for future generations regardless of population size. If that popular stud dog has any genetic disorders in his DNA, his puppies will likely harbor those mutations – at best becoming carriers and at worst being affected with the related disorder – and can continue to contaminate the breeding pool.

Even in a large breeding population, the bottleneck ...

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 ...

There’s a saying in dog breeding: "like produces like." A good breeder knows this and will attempt to pair dogs similar in conformation, drive, disposition and trainability together so the puppies will be of consistent and known quality.

When it comes to selecting a puppy that is to be used for a very specific task, such as hunting, the show ring, herding or guide and detection dogs, future successes and ease of training for those tasks are heavily dependent genetics. Finding the best line of dogs with proven genetics, as well as the disposition and conformation you want is most greatly influenced by the dog’s sire and dam.

Too often today it seems that an inordinate amount of emphasis is placed on the sire’s accomplishments and lineage. While selecting a sire with a pedigree decorated with titles, or one with comprehensive experience, from the venue you’re wanting to participate in is important, the dam’s genetics, disposition and pedigree are just as important, if not more so.

There’s a theory out there, one that I like to keep in mind when looking at pedigrees, which says the bottom line of a dam’s pedigree is ...

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? 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 ...