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Health Screening of Dog

Health Screening of Dog

An ongoing goal of the Great Dane Health Foundation of America (GDHFA) is to offer a variety of material in order to help owners of pet dogs, as well as breeding dogs, ensure the health and well being of their animals. Our primary commitment is to raise funds that will help support research into the many diseases affecting the Great Dane breed. At the same time, we need to educate and communicate with owners regarding health related issues. In this, our first, issue of the GDHFA Newsletter, we would like to give an overview of the primary health screens that are available.

The first question everyone asks is, "Why are these tests necessary?" A common misconception is that if you are not showing or breeding your dog, you do not need to do health screens. Nothing could be farther from the truth! As a responsible pet owner you should be concerned about the health and longevity of your dog. Health screens are one of the only ways to identify and eliminate certain genetic diseases and defects from a breed. Screening, however, is also a way for pet owners to ensure the health and well being of their dog. Early diagnosis and treatment for certain diseases can improve the quality of life, as well as, the length of life. These screens should not be confused with routine vaccinations, preventatives, or veterinary care. These tests are in addition to your general well care routine.

Certain breeds of dogs are more prone to certain diseases. Technology has led to monumental advances in our ability to diagnose and treat a number of diseases. How do we know what tests are necessary and which are not? How often should we test? Where do we go to get these tests? All are valid questions. Although there is no one right answer for all dogs, there are a few screening areas that are considered more important than others, depending on the breed of dog. The first, and probably one of the most life threatening areas, is CARDIAC. Cardiomyopathy and other heart problems are not uncommon in Great Danes. Any veterinarian can examine your dog by listening to the heart (auscultation), however, many of these diseases can only be diagnosed by a veterinarian who specializes in cardiology. These specialists should be Board Certified. This means that a veterinarian has completed an American Veterinary Medical Association (AVMA) approved residency training program in a specific specialty and passed an examination given by that specialty. Only veterinarians that are board certified may advertise and refer to themselves as veterinary specialists. These Board Certified specialists are also referred to as Diplomats. Only dogs examined by a specialist are eligible for certification by the Orthopedic Foundation for Animals (OFA). OFA is an organization that evaluates, tracks and reports the percentage of cardiac disease, thyroid disease, and hip dysplasia that occurs in numerous dog breeds. The best method for cardiac screening is an echocardiogram, or cardiac ultrasound. The test can be performed on dogs of any age and should be performed every year for breeding dogs, and every one to two years for pet dogs. It is necessary for this type of health screening to be repeated because the condition of the dogs heart can change as it ages.

The next screening area that is very important for Great Danes is HIPS. Canine hip dysplasia (CHD) is the most common heritable (genetic) orthopedic problem seen in dogs. It is found in nearly all breeds of dogs but is especially problematic in large and giant breeds. CHD is a disease whereby hip joint laxity leads to degenerative joint disease (DJD) and progressive osteoarthritis. This laxity can only be diagnosed via radiographs (x-rays). The x-rays can be taken by any veterinarian, however, the evaluation should be done by a specialist. The veterinarian/radiologist can tell you if they see any major problems but they can not "certify" the hips. Certification means that the dog has been found to be free of the genetic defect for which is has been evaluated. In this case, the dog does not have any evidence of CHD or DJD. Organizations such as OFA record and track certified dogs in a registry.

Open registry means that owners can choose to place the evaluation of their dogs hips (eyes, hearts, etc.) where it will be available to other people. When there is data on a sufficiently large number of dogs in a given line, a breeder can evaluate the risk for genetic disease transmission of dogs in that family. The evaluations of every single dog, whether show dog or pet, become an important source of data that will allow breeders to try and selectively eliminate the disease from their lines.

The three most widely used registries are the Orthopedic Foundation for Animals (OFA), PennHIP, and the Institute for Genetic Disease Control (GDC) in Animals.

OFA evaluates the x-rays submitted and rates the condition of the hips as Excellent, Good, Fair, or Dysplastic. They will not certify a dog before the age of 2 years. Follow up evaluations are not necessary unless a specific problem has been identified. Owners have the option of submitting all results to the registry, or just the normal results. The American Kennel Club (AKC) includes OFA certification numbers on their registration slips and certified pedigrees, when dogs are permanently identified via microchip or tattoo.

PennHIP uses a different method for evaluating hip joints and hip laxity. The radiographic procedure involves special positioning of the dog so that the dog’s "passive hip laxity" can be accurately measured (as opposed to OFA’s hip extended method). Passive hip laxity refers to the degree of looseness of the hip ball in the hip socket when the dog’s muscles are completely relaxed. A quantitative measurement is taken called the distraction index (DI), and the dog is then ranked relative to other members of the same breed. Dogs may be evaluated as early as 16 weeks of age. Follow up evaluations are not necessary unless a problem has been identified. All results (normal and abnormal) are included in the registry (database).

The GDC evaluates according to the hip extended method like OFA, but requires a pedigree of the dog to be submitted along with the x-ray. Their ratings are Excellent, Good, Average, or Dysplastic. In addition to the rating, they provide information on the degree of subluxation or laxity, any arthritic changes, as well as the degree of acetabular flattening (if any). GDC is an open registry.

EYES are the next area that need to be examined. These exams need to be performed by a specialist in canine ophthalmology. The examination results are then submitted to the Canine Eye Registration Foundation (CERF). Dogs found to be free of evidence of an inheritable eye disease will receive a certificate and registration number. This information will be entered into the CERF registry. This information is available to help breeders and ophthalmologists identify trends in eye disease and breed susceptibility. There is no minimum age for certification, however, the CERF registration is only good for 12 months from the examination date. Thereafter, the dog must be re-examined by a specialist and re-registered with CERF to maintain an up-to-date CERF number. AKC also incorporates CERF registration numbers on their registration slips and certified pedigrees, when the dogs are permanently identified via microchip or tattoo.

The last area that we will discuss herein, is the THYROID. (This topic is covered in detail on our website. Go to http://www.gdhfa.org/ThyroidLaBrie.htm ). Hypothyroidism (low thyroid) can lead to a multitude of problems. It is the number one endocrine disorder in dogs. Blood can be drawn by any veterinarian, and may be sent out to an approved laboratory, or tested in-house. In-house test results can not be used for certification. OFA is the primary registry for certifying thyroid results. Other genetic registries are also available.

The list below contains a list of the screens mentioned above. This is just a basic overview of what the screen is for, when it should be done, and where you need to go for testing. Cost will vary depending on where you get the testing done. Each topic will be covered in greater detail in future issues. Additional literature will also be added to our library on an ongoing basis.

I. CARDIAC

  • Type of Screens:
    • echocardiography (Doppler) - preferred method for definitive diagnosis
    • Holter monitor - useful in identifying rate/rhythm abnormalities
    • auscultation - primary screening only
    • electrocardiogram (ECG) - only picks up arrhythmias
    • thoracic radiography - used for evaluating dogs with CHD
  • Screens for:
    • Congenital Heart Disease (CHD)
    • malformation of the atrioventricular valves
    • malformation of ventricular outflow leading to obstruction of blood flow
    • defects of the cardiac septa (shunting defects)
    • abnormal development of the great vessels or other vascular structures
    • complex, multiple, or other congenital disorders of the heart, pericardium, or blood vessels
  • Screens done by:
    • all may be done by a board certified veterinary specialist: American College of Veterinary Internal Medicine (cardiology)- submits results to OFA
    • your regular vet can only do auscultation, ECG, and/or thoracic radiography - these are not diagnostic for CHD - can not submit to OFA for certification
  • Registry:
    • OFA
    • Other genetic disease control registries may be available
  • Age:
    • minimum of 1 year
    • certification is good for 12 months from the day of exam
  • Frequency:
    • yearly for breeding dogs
    • at least once for pet dogs, more often if a problem is identified or clinical signs are present

II. HIPS

  • What does the screen consist of:
    • x-rays/radiographic measurements
    • usually requires anesthesia, however, some evaluations may not
    • Screens for:
    • Canine Hip Dysplasia (CHD)
    • Degenerative Joint Disease (DJD)
  • Who takes the x-rays:
    • your veterinarian
    • a board certified veterinary specialist: American College of Veterinary Surgeons (DACVS)
  • Evaluation/Certification:
    • your veterinarian (evaluation)
    • a board certified veterinary specialist: American College of Veterinary Surgeons (DACVS) - evaluation only
    • Orthopedic Foundation For Animals (certification)
    • PennHIP (evaluation/certification)
    • Institute for Genetic Disease Control in Animals
    • Additional genetic disease control registries may be available
    • Foreign countries may have additional registries
  • Age:
    • minimum of 2 years of age for OFA certification
    • as young as 16 weeks for PennHIP evaluation
    • age may vary for a veterinary evaluation (this is just an evaluation - not a certification)
  • Frequency:
    • generally a one time screen unless a problem is identified and then follow up radiographs may be required

III. Eyes

  • Type of Screen:
    • painless eye exam
  • Screens for:
    • genetic eye diseases
  • Screens may be done by:
    • Board certified veterinary specialist: American College of Veterinary Ophthalmologists (ACVO) - submits to CERF
  • Registry:
    • Canine Eye Registration Foundation (CERF)
  • Age:
    • no minimum age
  • Frequency:
    • CERF registrations good for 12 months from the examination date

IV. Thyroid

  • Type of Screen:
    • blood test - (T3, T4, fT3, fT4, TSH, TgAA, T3 autoantibody, T4 autoantibody)
    • full or partial panels
    • may be done by RIA, ELISA, Dialysis
  • Screens for:
    • Canine thyroiditis (hypothyroidism)
  • Screens done by:
    • your veterinarian - sends to testing laboratory (can be certified) or runs the test in-house (for evaluation only)
  • Registry:
    • OFA
    • tests results may be evaluated by your veterinarian - no certification
  • Age:
    • minimum of 1 year
  • Frequency:
    • yearly

Health Screening
By Terasa La Brie & Melissa Dreyer


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