The 6 Most Common Genetic Disorders in Dogs
Genetic Disorders in Dogs
By Mindy Cohan, VMD
As a veterinarian, I have naturally contemplated my dogs’ genetic background and pondered about their inherent risk for breed-specific health problems. For example, both of my mixed-breed dogs have had conformations similar to Corgis and Dachshunds. Knowing that these breeds are predisposed to intervertebral disc problems in their spines, I have taken precautions to not allow my dogs to jump off of furniture in order to avoid back troubles.
While there are certain diseases linked to pure bred dogs, there are also various medical problems related to multiple breeds that share similar statures or conformations. When considering the purchase or adoption of a new dog, exercising due diligence about the specific breed as well as the breeder (when applicable) is imperative. Some dog breeds are inherently healthier than others in that they are predisposed to fewer medical problems.
Here, learn more about the most common genetic disorders seen in dogs, which breeds are prone to these conditions and how to treat them:
The mission of the Orthopedic Foundation for Animals (OFA) is, “to improve the health and well being of companion animals through a reduction in the incidence of genetic disease.” The initial motivation of the organization was to specifically minimize the prevalence of canine hip dysplasia. The hip is a ball and socket joint. In order for the joint to function optimally, the ball must conform, or fit snuggly, within the socket. Poor hip conformation will usually result in degeneration of cartilage within the joint, arthritis, and pain.
Signs of hip dysplasia include difficulty rising or laying down, difficulty going up and down stairs, inability to jump onto furniture or into a vehicle and reluctance to run or walk. Depending on the degree of hip dysplasia, medical and sometimes surgical treatments are indicated. Medical therapy includes pain medications, physical therapy, cold laser treatments, glucosamine chondroitin products, and even stem cell therapy. There are several surgical procedures available such as total hip replacement.
Maintaining your dog’s ideal weight is one of the most important ways to reduce the clinical signs of hip dysplasia. The breeds most commonly affected include: German Shepherds, Rottweilers, Bulldogs, Great Danes, Saint Bernards, Neapolitan Mastiffs and Retrievers.
Urinary Bladder Stones
Although bladder stones are sometimes a surprising incidental finding on radiographs, many dogs experience discomfort and exhibit significant clinical problems as a result of stones within their urinary tracts. Symptoms include straining to urinate, urinary accidents, increased frequency of urination and blood in the urine.
While any dog breed or dog of mixed ancestry can develop bladder stones, some pure bred dogs are predisposed to their formation, including Dalmations, Newfoundlands, the Bichon Frise and Miniature Schnauzers.
A long-standing treatment known as a cystotomy involves the surgical removal of stones from the urinary bladder. Other procedures include cystoscopy and laser lithotripsy, in which a scope is passed into the urinary bladder and then a laser is used to break up stones into fragments small enough to pass through the dog’s urethra.
Witnessing your pet having a seizure is very alarming and distressing. During a grand mal seizure, dogs will typically stiffen and fall to the ground, salivate, paddle their legs and some lose control of their bladder and bowels or vocalize. A seizure occurs when the cells in the brain become overly excited and exceed what is called a “seizure threshold.” If no underlying cause can be found, the presumptive diagnosis for recurrent seizures is idiopathic (unknown basis) epilepsy.
While further studies are needed, research has indicated that epilepsy is an inheritable trait in certain dog breeds such as German Shepherds, Beagles, Belgian Tervurens, Keeshonds, Dachshunds, and Golden and Labrador Retrievers. Epilepsy is managed with anticonvulsant medications. Depending on the dog, one drug or a combination of medications is used to control seizures. Since epilepsy cannot be cured, the realistic goal of therapy is to manage seizures by decreasing their frequency and severity.
There are several dog breeds known to have inherited cardiac problems. Cavalier King Charles Spaniels and Dachshunds are at risk for myxomatous valve disease, a condition that causes pressure to develop within the chambers of the heart and eventually lead to signs of heart failure such as coughing, weakness, poor appetite, abdominal distention, difficulty breathing and collapse.
Additionally, breeds such as the Doberman Pinscher, Great Dane and Boxer have a genetic predisposition for dilated cardiomyopathy. Dogs with this condition have abnormal heart musculature which leads to a weakened and dilated heart.
Boxers also have an inherited risk of arrhythmogenic right ventricular cardiomyopathy (ARVC). ARVC, as the name implies, is also a disease of the heart muscle. Boxers and Bulldogs with ARVC develop fatty or fibrous tissue which replaces normal heart cells. This abnormal infiltration results in problems with the heart’s electrical conduction system and arrhythmias (irregular heart beats) occur. Affected dogs experience fainting, heart failure and possible sudden death. Treatment consists of antiarrhythmic drugs and medications for heart failure.
Degenerative myelopathy (DM) is a slowly progressive neurological condition caused by the deterioration of nerve fibers and their myelin sheath within the spinal cord. The failure of nerve signal transmission within the mid-to-lower spinal cord results in symptoms of the hind legs such as weakness, wobbliness, dragging of the hind feet, inability to stand and eventually paralysis. Symptoms do not usually develop until a dog is middle aged or in its senior years of life.
While DM is devastating and there is no cure, affected dogs do not experience pain from the nerve deterioration. The disease, however, takes a psychological toll on both the dog and pet parent. As dogs lose the ability to support their hindquarters, it becomes increasingly difficult for them to posture to urinate and defecate. Dogs with significant hind limb impairment can be greatly aided by the use of a harness or cart.
Although the German Shepherd is most commonly associated with DM, there are many breeds at risk for this inheritable condition, including the American Water Spaniel, Bernese Mountain Dog, Boxer, Borzoi, Cardigan Welsh and Pembroke Welsh Corgi, Chesapeake Bay Retriever, Kerry Blue Terrier, and Pug.
Whether or not you are a fan of brachycephalic dogs, there is no denying that these breeds have become increasingly popular pets. Brachycephalic literally means “short-headed,” but most people refer to these dogs as having a “smushed face.” Examples include the English Bulldog, French Bulldog, Boston terrier, Pug, Pekingese, Shih Tzu and Cavalier King Charles Spaniel.
Pet parents of these breeds become acclimated to their snoring and snorting sounds; some even find this trait endearing. The exaggerated breathing sounds of brachycephalic dogs are due to anatomical abnormalities such as an elongated soft palate, stenotic (narrowed) nostrils, everted laryngeal saccules (tissue in the throat which obstructs airflow), and a narrowed trachea (windpipe). All of these physical characteristics result in respiratory difficulty. Unfortunately, the breeding of these dogs to achieve a flatter nose has hampered their ability to dissipate heat, predisposing them to heat stroke.
In addition to breathing problems, the conformation of brachycephalic dogs also predisposes them to dental issues, skin issues and eye problems. Potential pet parents of these breeds should be aware that these dogs often need extensive maintenance care at home and in the veterinary office, possible corrective surgery for breathing difficulty and extra precautions in hot and humid weather.
Dog breeders have an ethical responsibility to produce healthy pets and to educate their customers about the potential medical issues related to the breed which they propagate. With the advent of many genetic tests (genotypic evaluations), breeders should screen their dogs to determine if they are carriers of established genetic diseases. Potential breeding dogs should also be assessed for behavioral characteristics and physical features, such as hip conformation. Organizations such as the OFA have created databases to help track hereditary diseases in order to prevent unnecessary animal suffering and pet parent’s emotional distress.
Cuious about your dog's breed? Learn more about DNA testing in dogs.