OFA Thyroid Registry

OFA-Approved Laboratories
The laboratory certification process will include quality control, quality assurance and reagent certification.

Laboratories may apply and if successful, will be approved to perform analyses for OFA thyroid certification. A site visit by a qualified veterinary endocrinologist chosen by OFA will be required and continued quality assurance and quality control will be necessary to maintain certification. Fully certified status can be obtained by passing the site visit and passing the results of the first OFA quality assurance assay result test.

The approved laboratory must be contacted for the appropriate submission forms, sample handling procedures, and laboratory service fee before collecting the sample.

The OFA thyroid application and check to OFA must accompany the serum sample to the laboratory of choice. Upon completion of test, the laboratory then forwards all appropriate paperwork to OFA.

Currently, samples may be submitted to one of the following OFA-approved laboratories:

Endocrine Diagnostic Section Diagnostic Center for Population & Animal Health 4125 Beaumont Road, Room 122 Lansing, MI 48910-8104 517-353-0621	Laboratory Services Division University of Guelph Door P2 Bldg. 49, McIntosh Lane Guelph, Ontario Canada N1G 2Wl 519-824-4120 ext. 54501
Diagnostic Laboratory New York State College of Veterinary Medicine Cornell University Upper Tower Rd. Ithaca, NY 14851 607-253-3673	Antech Diagnostics* 1111 Marcus Ave. Suite M28 Lake Success , NY 11042 800-872-1001 *only the Lake Success, NY location of Antech has been certified to process OFA thyroid panels
Veterinary Diagnostic Laboratory Attn: Sample Handling College of Veterinary Medicine University of Minnesota 1333 Gortner Ave. St. Paul, MN 55108 612-624-0761	Texas Veterinary Medical Diagnostic Laboratory 1 Sippel Rd. College Station, TX 77843 979-845-3414
University of California Veterinary Medical Teaching Hospital Clinical Pathology, Chemistry, Room 1017 1 Garrod Drive Davis, CA 95616 530-752-7380	Vita-Tech 1345 Denison St. Markham, Ont, L3R 5V2 CANADA 1-800-667-3411

Orthopedic Foundation For Animals
2300 E. Nifong Blvd.
Columbia, MO 65201-3856
phone (573) 442-0418
fax (573) 875-5073

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	Hypothyroidism Article	AKC/CHF Hypothyroidism White Paper


Purpose Background on Thyroid Imbalances Examination Certification Preliminary Evaluation Thyroid Abnormalities Classification Diagnosis and Certification Samoyed Thyroid Statistics OFA-Approved Laboratories Samoyed Thyroid Stats OFA fees OFA's website Contact OFA Acknowledgment References
Purpose The purposes of the OFA thyroid registry are:
to identify those dogs that are phenotypically normal for breeding programs and to gather data on the genetic disease ~ autoimmune thyroiditis [TOP]
Background on Thyroid Imbalances Autoimmune thyroiditis is the most common cause of primary hypothyroidism in dogs, causing over 50% of the cases. It is the inherited form of hypothyroidism and is thought to be polygenetic. Primary refers to those cases of hypothyroidism associated with only the thryoid gland, not the pituitary or hypothalamus. (see Table 1.)The disease has variable onset, but tends to clinically manifest itself by 2 to 5 years of age. Hence, dogs may be clinically normal for years, only to become hypothyroid at a later date. Symptoms will not appear until about 75% of the thyroid gland is already destroyed. The incidence of hypothyroidism in Samoyeds is approximately 6%. Symptoms are wide ranging, and may be confused with a lot of other disease entities. Table 2. lists symptoms which can be attributed to an inadequate level of circulating thyroxin (T4). The markers for autoimmune thyroiditis, autoantibody formation (autoantibodies to thyroglobulin, T4 or T3), occur prior to the occurrence of clinical signs. The majority of dogs that develop autoantibodies have them by 3 to 4 years of age. Development of autoantibodies at any time in the dog's life is an indication that the dog, most likely, has the genetic form of the disease. As a result of the variable onset of the presence of autoantibodies, periodic testing will be necessary. Dogs that are negative at 1 year of age may become positive at 6 years of age. Hence, dogs should be tested every year or two in order to be certain that they have not developed the condition. Since the majority of affected dogs will have autoantibodies by 5 years of age, annual testing for the first 5 years is recommended. After that, testing every other year should suffice. Unfortunately, a negative at any one time will not guarantee that the dog does not have autoimmune thyroiditis. The registry data can be used by breeders in determining which dogs are best for their breeding program. Knowing the status of the dog and the status of the dog's lineage, breeders and genetic counselors can decide which matings are most appropriate for reducing the incidence of automimmune thyroiditis in the offspring. [TOP] Examination Each dog is to be examined by an attending veterinarian and have a serum sample sent to an OFA-approved laboratory for testing according to OFA procedures. The laboratory fee will be determined by the approved laboratory. Check with the referral laboratory for special sample handling and tests for registry purposes. [TOP] Certification A certificate and breed registry number will be issued to all dogs found to be normal at 12 months of age. Ages will be used in the certification process since the classification can change as the dog ages and the autoimmune disease progresses. The OFA fee is $15 and no charge will be made for recertification at a later age. It is recommended that re-examination occur at ages 2, 3, 4, 6, and 8 years. All data, whether normal or abnormal, is to be submitted for purposes of completeness. There is no OFA fee for entering an abnormal evaluation of the thyroid into the data bank. Information on dogs determined to be abnormal (positive or equivocal) will not be made public without the explicit permission of the owner or agent. Those dogs with laboratory results that are questionable and therefore not definitive, will be considered as equivocal. It is recommended that the test be repeated in 3 to 6 months. [TOP] Preliminary Evaluation Evaluation of dogs under 12 months of age can be performed for private use of the owner since a few dogs are already positive at that age. However, certification will not be possible at that age. [TOP] Thyroid Abnormalities Two types of thyroid abnormalities will be defined by the registry:
Autoimmune Thyroiditis NOTE: Autoimmune Thyroiditis is known to be heritable. Idiopathic Hypothyroidism [TOP]
Classification The method for classifying the thyroid status will be accomplished using state of the art assay methodology. Indices of thyroiditis:
Free T4 by dialysis (FT4D) This procedure is considered to be the "gold standard" for assessment of the thyroid's production and cellular availability of thyroxine. FT4D concentration is expected to be decreased in dogs with thyroid dysfunction due to autoimmune thyroiditis. Canine Thyroid Stimulating Hormone (cTSH) This procedure helps determine the site of the lesion in cases of hypothyroidism. In autoimmune thyroiditis, the lesion is at the level of the thyroid, and the pituitary gland functions normally. The cTSH concentration is expected to be abnormally elevated in dogs with thyroid atrophy from autoimmune thyroiditis. Thyroglobulin Autoantibodies (TgAA) This procedure is an indication of the presence of the autoimmune process in the dog's thyroid. [TOP]

Table 1. Diagnosis and Certification
Normal	FT4D = 9-40pmol/L
	cTSH = 0-30 mU/L
a	TgAA = negative
Positive autoimmune thyroiditis	FT4D < 9 pmol/L
a	cTSH > 30 mU/L
a	TgAA = positive
Positive compensative autoimmune thyroiditis	FT4D = 9-40 pmol/L
a	cTSH = or > normal range
a	TgAA = Positive
Idiopathically reduced thyroid function	FT4D < 9 pmol/L
a	cTSH > 30 mU/L
a	TgAA = Negative
All other results are considered equivocal.

Table 1. Causes of Hypothyroidism
Primary	Those associated with the thyroid gland, i.e., a deficiency of Thyroxin-T4.
Secondary	Those associated with the pituitary gland, i.e., a deficiency of Thyroid Stimulating Hormone-TSH.
Tertiary	Those associated with the hypothalamus, i.e., a deficiency of Thyrotrophin-TRH.

Table 2. Symptoms of Thyroxin (T4) Deficiency
Common	Uncommon	Unknown
Skin changes Lethargy Weight gain Mental dullness Exercise intolernance	Female infertility Neuromuscular signs Ocular changes Cretinism Myxedema	Male infertility Clotting disorders cardiovascular changes Behavioral changes Gastrointestinal signs