Archives for November 2014

While the history of the beagle’s early breed development has been lost due to lack of record keeping, the mid to late 1800’s saw the arrival of the modern beagle on the shores of North America. From its English homeland where it was developed to hunt rabbits and other small game, the beagle has become one of the most popular breeds in the United States, ranking 4^th overall in the 2013 American Kennel Club’s registration statistics. Behind their charming, deep throated vocalization known as baying, lies a social, even tempered and jovial dog breed suited for modern family life. Unfortunately, like other purebred dogs, the beagle is known to inherit some genetic diseases that can dampen the spirits of this normally energetic and fun-loving breed. One such inherited disease of beagles is known as Musladin-Lueke syndrome (MLS), a multi-systemic disease of connective tissue.

Named after beagle breeders Tony and Judy Musladin and Ada Lueke, MLS was first reported in the 1970’s and has now been identified in multiple countries including England, Australia, America and Japan. In 2010, a genetic mutation in the ADAMTSL2 gene was found to be responsible for the unique clinical signs of this disease. Though not ...

Subvalvular aortic stenosis (SAS), one of the most common inherited cardiac diseases in dogs, is a major concern for many owners of large breed dogs including the Newfoundland, golden retriever, American Staffordshire terrier and Rottweiler. SAS is caused by an abnormal ring or ridge of tissue in the left ventricle of the heart resulting in a partial obstruction of the left ventricular outflow tract; the pathway that allows blood to flow from the left ventricle, through the aortic valve and into the aorta which carries oxygenated blood to the body. In mild cases, dogs live a normal life, free of clinical signs related to the vessel narrowing. However, in moderate to severe cases of SAS, the increased strain placed upon the heart to pump blood through the partially obstructed aortic valve can result in structural changes of the heart muscle, congestive heart failure, arrhythmias and sudden death. SAS also predisposes dogs to development of potentially lethal bacterial infections of the aortic valve. Unfortunately, it is not possible to predict the severity of disease in puppies by examining the hearts of affected parents. Mildly affected parents can have severely affected puppies and vice versa. On average, SAS-affected dogs only live to ...

From their ancient Egyptian roots depicted in carvings of their predecessors, the speed and agility of the greyhound has long fascinated humans who found great potential in the breed as hunting companions, and much later, as fantastic family dogs. Like other members of the large grouping of dog breeds known as sighthounds, it was obvious to their ancient human handlers that the greyhound’s exceptional athletic skill, lean muscular body, and keen vision could be invaluable for hunting both large and small game. While it is no longer as common for greyhounds to be used for hunting, their docile temperament outside of the hunt contributed to an easy transition to the more domestic lifestyle most greyhounds now live. Though able to run 40 miles per hour when properly conditioned, with regular exercise the greyhound is just as content taking it easy with their human family members. Despite their majestic appearance and impressive athletic attributes, like other purebred dogs, greyhounds are known to inherit some genetic diseases that may keep this talented runner at the starting block. One such disease, known as greyhound polyneuropathy (GP), is caused by a mutation in the NDRG1 gene.

GP is a severe, progressive neurological disease similar ...

Since the first exhibitions of the modern basset hound in the late 19^th century, their mellow and charming personality has made them a popular family dog. Though according to the Basset Hound Club of America, it is not unusual for a basset hound to be a little stubborn or to have “selective hearing” (especially if following a scent trail), this minor annoyance is easily tempered by their affectionate and sensitive disposition. Originally bred for hunting with a person on foot, the basset hound’s short legs kept them from outrunning their handler while following their exceptional nose. Unfortunately, like other purebred dogs, the basset hound has also been unable to outrun susceptibility to certain inherited diseases. One such condition is a disease of blood platelets known as thrombopathia that occurs due to a mutation in the RASGRP1 gene.

Dogs affected with thrombopathia produce a dysfunctional form of a protein important in the aggregation of platelets during blood clotting. The resulting inability to produce functional blood clots leads to easy bruising and frequent episodes of spontaneous bleeding from the gums, nose, and the gastrointestinal tract. Affected dogs may also show signs of lameness due to spontaneous bleeding in joints. Loss of ...

The intelligent, prey-driven English springer spaniel (ESS) has forged its path as a popular, hardworking companion for bird hunters while maintaining a loyal and affectionate personality suitable to family life. Until the early 1900’s, springer spaniels were produced in the same litters as cocker spaniels; springers were chosen from the largest puppies of the litter and were trained for flushing or “springing” game while the smaller littermates were labeled cocker spaniels and were trained for hunting the elusive woodcock. Since then, springer spaniels have been further split into the generally leaner, shorter haired field (hunting) variety and the denser boned, densely haired show (“bench”) line. Unfortunately, like other purebred dogs, English springer spaniels are known to inherit genetic diseases that can keep some individuals from reaching the great potentials for which the breed is capable. One such inherited condition is an eye disease known as progressive retinal atrophy, cone-rod dystrophy 4 (PRA-crd4) caused by a mutation in the RPGRIP1 gene.

Progressive retinal atrophy (PRA) is not a single disease, but rather a group of inherited diseases each caused by different genetic mutations in different genes. The various forms of PRA affect over 100 different dog breeds. Though there are variations ...

Paw Print Genetics is often asked if the same mutation always causes genetic disease, especially when the mutation is identified in a breed different from that originally investigated.  The answer is not simple.  For many of these types of genetic questions, I go back to my ‘human’ roots as a human geneticist.  Because more than 4,500 diseases and their genetic causes are known, human genetics can shed considerable light on problems just beginning to be investigated in dogs.

Currently, there are about 185 known mutations in dogs, with about 150 that cause disease and another 30 or so that cause traits such as coat color or coat length.  In dogs, these disease-causing mutations have been narrowly defined to certain breeds or certain clinical features (phenotypes), but is this always the case?

In human genetics, anything imaginable has been described. Certainly, there are diseases that are caused by single mutations; in this case, one mutation causes one disease.  But there are many examples of multiple mutations in one gene causing one disease and examples of multiple mutations in multiple genes causing one phenotype (one disease).  Likewise, there are many examples of the same exact mutation ...

We train our dogs to do certain things, like sit, stay, lay down, retrieve or even run through an agility course. Training a dog takes patience and persistence. It means providing consistent clues that your dog will eventually come to understand if done in the same manner. But I’ve recently come to wonder, have I trained my dog, or has she trained me?

Every time we sit down to eat dinner, our dog Daisy runs to the front door, whips around and stares at us. Invariably, one of us says, “Daisy needs to go out” and my daughter groans, gets up and lets her out.   Most of the time, Daisy does her business, but sometimes, she runs out to the middle of the yard, expecting my daughter to follow her and hopefully play.  This has led us to believe that Daisy’s behavior of running to the door and then staring us down, has trained us to respond in a particular way, and has us wondering if she brags to the other dogs that she has trained her human to stand up and open the door on command.

Likewise, Trixie the Wiener Dog has my husband trained to take ...