v  DNA testing and DNA profiling

v    Degenerative Myelopathy (DM)

First I would like to show my extreme gratitude to the three people who were instrumental  and indispensable in creating this article:

A HUGE thank you to Diane Migas of Blue Steel Great Pyrenees, and GPCA health committee, for endless discussions on these important issues.

An equally BIG thank you to Catherine de la Cruz of Poste de Pompier Working Pyrenees (GPCA LGD Chair), for sharing her knowledge on the subject and giving me permission to quote parts of her studies!

A TREMENDOUS thank you to Pat Long (BMDCA Health Committee member, Berner-Garde Trustee, Berner 1, Co Owner Berner-L) for her editing assistance. The many additions she has made to this article are indispensable!

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This article explains hopefully in layman's terms, most of the common medical tests and the certification of such, that Responsible breeders test their "potential" breeding stock for...... BEFORE they breed any one dog.

Now, of course different breeds have some different medical issues...In some breeds certain tests are imperative. In others where the incidence of a certain disease is rare, most likely some tests will not be as necessary. One should consult with their National breed club, as to which diseases are prevalent in their breed... and should be screened for.

For example, there are very few eye problems in Great Pyrenees. Some eye diseases having no incidences "reported" at all. Yet even so, some breeders want to be sure they are not perpetuating a certain potentially inherited defect, so they have their stock tested anyway.

But for the purpose of this article, I have decided to explain the most commonly used tests for large breed dogs.

I hope to convey the message that the health testing of breeding stock is an extremely important practice. Not only for the total well-being and future of purebred dogs, but for the protection of potential puppy owners and their future with their beloved pet.

Unfortunately, according to a study by Catherine de la Cruz (GPCA LGD Chair) in 1998/99 of the AKC Studbook for Pyr breedings; 

She found by comparing those dogs name by name against the OFA/GDC lists of dogs certified as clear of hip dysplasia… that fewer than 10% of Great Pyrenees being bred were being tested and certified clear of hip dysplasia. 

(NOTE: dogs are listed in the studbook only the first time they are ever bred)

The term "Vet checked" does not mean that the sire and dam of a litter has been thoroughly screened for genetic inherited diseases.

When looking for a pup, ask the breeder what genetic health screening has been done on their breeding stock. Don't accept the blanket statement "All my dogs are tested." Ask to see a copy of their certification and any history of genetic defects or temperament issues in the pup's pedigree. 

I hope this article helps you understand these tests and their purpose.

There are quite differing opinions on the use of health testing, their importance and accuracy. I will not get into discussing the points of that debate here.... I will just say that in the end, breeders have to decide for themselves what is important in their breeding program, and Potential Puppy owners have to decide for themselves if they can accept and live with each breeder's decisions. 

But to quote one responsible breeders statement on the importance of health testing....."Like I said before, all we can do is stack the odds in our favour and I think that is the very least we can do." Quite profound in my view.

To those breeders who say..."I don't need to x-ray, I have never had a dog with HD!"  All I respectfully ask..."How do you know, if you have never x-rayed?"

Some tests should be done after the age of 2 years because the diseases may not be apparent until later in life. Other tests can be done soon after the puppy is born, such as blood or DNA testing

Unfortunately there is not a test for all genetic health issues that can occur, but I will list the ones that can be tested for, starting with the oldest and most commonly known and used... Hip x-rays.

This testing should be done on an animal that is at least 24 months of age, and should be done at the very least for each dog used for breeding before it is ever bred. Ideally, a breeder will want to know the status of each dog in that family in order to better predict the potential breeding results.

Breeders can do preliminary testing at 12 months with OFA and as early as 6 months with PennHIP. Preliminary testing can be really useful to breeders evaluating their stock...but the OFA will not certify a normal hip/elbow until the dog is 2 years of age.  

Bone Structure - OFA (Orthopedic Foundation for Animals) or PennHIP (University of Pennsylvania Hip Improvement Program) Certification  

Hips:

The purpose of x-raying the hips is to see if a breeders stock is affected with inherited Canine Hip Dysplasia (HD). If so, to find out the degree or severity of HD. This disease is progressive; that is, it gets worse with time.

It is advised that dogs should be put under to get an accurate reading.   A dog that is not sedated will tense up - therefore, can pull the hips into sockets (through tense muscles) and not give an accurate reading.   Also, bitches should not be x-rayed 60 days prior to and after their season. There is too much laxity during these hormonal times.

The dog's x-rays should be submitted to the OFA for evaluation by three randomly selected, board-certified veterinary radiologists.

A dog will be rated as one of the following:

1.      Excellent

2.     Good

3.     Fair

4.     Borderline

5.     Mild

6.     Moderate

7.     Severe

Quote from the OFA website: "The hip grades of excellent, good and fair are within normal limits and are given OFA numbers. This information is accepted by AKC on dogs with permanent identification and is in the public domain. The OFA radiologist reviews radiographs of borderline, mild, moderate and severely dysplastic hip grades and a radiographic report is generated documenting the abnormal radiographic findings. Unless the owner has chosen the open database, dysplastic hip grades are closed to public information. "

These registries are important as they evaluate and record incidences of inherited diseases of bones and joints in certain lines of a particular breed. This valuable information can then be used by breeders, so that they can choose dogs whose lines are as free as possible from these illnesses, for their breeding program.

The database is also useful to puppy buyers to look into the health history of the pup they are considering.

The OFA also maintains registries on other conditions, which are known to be genetic in certain breeds of purebred dogs.

For more information see: www.offa.org.  

Hip laxity has been shown to be an excellent predictor of hip dysplasia. PennHIP is a method performed by specially trained vets to measure that joint laxity. The result is a measurement called the Distraction Index (DI). A low DI indicates a tight hip socket and a lower chance of hip dysplasia. The PennHIP database is a closed database, so a copy of the report would be needed in order to verify any claims made.

For more information see: http://www.vet.upenn.edu/ResearchCenters/pennhip//

Elbows

The OFA also evaluates and certifies x-rays of elbows.

Abnormal elbows are reported as:

·        Grade I—minimal bone change along anconeal process of ulna (less than 3mm).

·        Grade II—additional bone proliferation along anconeal process (3-5 mm) and subchondral bone changes (trochlear notch sclerosis).

·        Grade III—well developed degenerative joint disease with bone proliferation along anconeal process being greater than 5 mm.

Like the hip certification, the OFA will not certify a normal elbow until the dog is 2 years of age.

Patellar Luxation:

The patella, or kneecap, is located in the stifle joint in the 2 hind legs of dogs.

In patellar luxation, the kneecap luxates, or pops out of place. Even in mild cases, as a result of patellar luxation, your dog may develop other degenerative joint changes, such as osteoarthritis as it ages.

There are two categories of Patellar Luxation in large breeds, which are according to the OFA "either known to be heritable or strongly suspected."

They are:

 q      Medial Luxation: Is the most commonly seen luxatation. It is not associated with trauma and occurs early in life.

q       Lateral Luxation in Large and Giant Breeds: The most common is a knock-knee stance. The dog has more functional disability with lateral luxation than with medial luxation.

The examination is completed while the dog is awake.

The dog is examined by your veterinarian who then completes the application form according to the guidelines from the OFA, indicating the results of the dog's patella evaluation.

A certificate and breed database number will be issued to all dogs found to be normal at 12 months of age or older.

For information on how Patellar Luxation is graded see: http://www.offa.org/plgrade.html

Congenital Heart Defects

A Board Certified Cardiologist should do the testing and evaluation.

Diagnostic procedures include one or more of the following: Physical exam, X-rays, electrocardiogram, Echocardiography (with Doppler) or Cardiac catheterization with angiocardiography.

When testing the heart they are ruling out:

Ø     Murmurs

Ø     Cardiomyopathy- refers to disease of the heart muscle (the myocardium) without malformation of the heart or its valves. The heart works harder to compensate for the loss of contractility, eventually leading to congestive heart failure. The abnormalities in the heart muscle cells give rise to irregular heart rhythms, which may cause sudden death. There is a breed predisposition to dilated cardiomyopathy in many giant breeds. 

Ø     Aortic disorders such as: Sub-Aortic stenosis, Atrioventricular Valve Dysplasia, Pulmonic Stenosis

      Note - SAS can be determined as early as 12 weeks

Ø     Size in relation to dog

The arterial and venous pulses, mucous membranes, and precordium should be evaluated. Heart rate should be obtained.

According to the OFA: "While there are exceptions, virtually all common congenital heart defects are associated with the presence of a cardiac murmur."

For further in-depth explanation of the tests and what their results tell you, see these links:  

OFA- http://www.offa.org/cardgrad.html

Canine Inherited Disorders Database - http://www.upei.ca/~cidd/intro.htm

Cardiology Northwest- http://www.heartvet.com/showpracfaq.cfm?FAQID=2378&Private=1  

EYES (should be done annually for an accurate picture or just once if DNA marker testing is available, see below)

§        Retinal deformities or degeneration in the retina such as: retinal dysplasia (right), hereditary cataract, goniodysgenesis/primary glaucoma, primary lens luxation, etc.

§        Entropion- is a condition of the eyelids wherein they "roll in" on the eyeball itself, causing irritation and secondary infections. Sometimes causing ulcerations of the cornea itself.  

§        Ectropion- is the opposite of entropion, and this describes the condition where the eyelid tissue is everted, or "rolled out", leading to increased exposure of the eyeball.  

§        Progressive Retinal Atrophy (PRA)- a disease where the retina slowly deteriorates. PRA is an inherited condition known to occur in many breeds of dogs. Dogs with PRA gradually lose eyesight due to degeneration of the retina. There is no treatment for PRA. This disease is sometime referred to as "night blindness." Most PRA affected dogs eventually become entirely blind.

§        Floaters- Spots (often called floaters) are small, semi-transparent or cloudy specks or particles within the vitreous, (the clear, jelly-like fluid that fills the inside of the eyes). Floaters are often caused by small flecks of protein or other matter trapped during the formation of the eyes before birth. They can also result from deterioration of the vitreous fluid, due to aging; or from certain eye diseases or injuries.

THYROID

Autoimmune thyroiditis is the most common cause of primary hypothyroidism in dog, and is known to be heritable in some breeds. Dogs should be tested every year or two in order to be certain they have not developed the condition. Dogs may be clinically normal for years, only to become hypothyroid at a later date.

The entire thyroid panel should be done. Your veterinarian will take a blood sample and send it to a laboratory for testing. Such as the Animal Health Laboratory at the University of Guelph in Ontario Canada, or the Animal Health Diagnostic Laboratories at Michigan State University in the US.

BLOODWORK:

Pyr's as well as many larger breed dogs are susceptible to inherited blood disorders.

Blood work should be done annually and should be the Super Chem (in addition to your heartworm, tick borne diseases).

The Super Chem gives a good picture of what's going on. If something is abnormal, further testing should be done.  It also could provide one with early detection of other non inherited problems, so that it may be dealt with swiftly, and possibly save the dog's life.

Specialized blood tests look for:

v    Coagulation disorders: Factor XI deficiency: a rare clotting disorder of several dog breeds. Protracted bleeding from surgical procedures is a feature. Affects both sexes.

v    Von Willebrands disease is considered to be a mild to moderate bleeding disorder. Many dogs with this disease do not ever experience a severe bleeding episode. But they can and there are reports of fatalities associated with this condition and surgical procedures. . (DNA testing is available for this in many breeds, see below.)

¨     Diabetes

¨     Alkaline Phosphatase levels

¨     Cancer

¨     Cushing's

¨     Pancreatitis

¨     Ehrlichia

¨     Lymph Problems

¨     Immune mediated hemolytic anemia

¨     Thrombocytopenia and platelet problems

Other general problems they look for in the blood are:

¨     Elevated creatine values in bloodwork

¨     Low amylase and low albumin

¨     Increased ALT levels

¨     Rise in white cell count

¨     High BUN on pre surgery bloodwork panel

¨     High levels of calcuim - Hypercalcemia

¨     Hematocrit (HCT)

¨     High globulin count (hyperglobulinemia),seizures, lethergy in Westie

¨     Increased platelet count

¨     Continued elevated lipase levels following pancreatitis

¨     Elevated Amylase levels, pancreatitis and bladder problems

¨     High Potassium levels with diarrhea

¨     High cholesterol levels

DNA testing and associated DNA profiling:

DNA Testing is currently used for two purposes:

1)     To detect genetic diseases

2)     To determine parentage or pedigree.

Scientists have been able to develop DNA tests for specific diseases and certain breeds; by studying genes linked to certain inherited diseases. This information can then be used by a breeder to ensure that affected pups are never produced!

DNA tests are currently available for the following diseases and breeds (as of November 2002):

**Please note that the DNA diagnostic services are only available for the breeds listed below at this time, as different breeds have different genetic markers.***  

See: www.vetgen.com

Or: www.optigen.com

Ø     Copper Toxicosis: Bedlington Terrier: A genetic disorder that affects several breeds and causes copper accumulation in the body which leads to liver disease. It is estimated that 25% of Bedlington Terriers are affected by the disease and 50% are carriers at this time.

Ø     von Willebrand's Disease: Scottish Terrier, Doberman Pinscher, Shetland Sheepdog, Manchester Terrier, Poodle (all), Pembroke Welsh Corgi, Kerry Blue Terrier, Papillon, Bernese Mountain Dog: An inherited disease that leaves dogs susceptible to abnormal bleeding following injuries or surgical procedures.  

Ø     Phosphofructokinase Deficiency: English Springer Spaniel, Cocker Spaniel: A genetic deficiency which causes mild to moderate anemia with severe episodes of bleeding.

Ø     Progressive Retinal Atrophy: Irish Setter, Australian Cattle Dog, Bullmastiff, Cardigan Welsh Corgi, Chesapeake Bay Retriever, English Cocker Spaniel, Labrador Retriever, Mastiff, Poodle (miniature and toy), Miniature Schnauzer, Nova Scotia Duck Tolling Retriever, Portuguese Water Dog, Samoyed, Siberian Husky, Sloughi: An inherited degenerative eye disorder that leads to blindness.