Health and Certifications
OFA - Thyroid Registry

• Purpose
• Background on Thyroid Imbalances
• Examination
• Certification
• Preliminary Evaluation
• Thyroid Abnormalities
• Classification
• OFA-Approved Laboratories
• Does OFA have a website?
• How to contact OFA

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 (Hashimoto's Disease); and
• to serve as a database for control of genetic thyroid problems through selective breeding.

Background on Thyroid Imbalances

Autoimmune thyroiditis (Hashimoto's Disease) is the most common cause of primary hypothyroidism in dogs. The disease has variable onset, but tends to clinically manifest itself at 2 to 5 years of age. Hence, dogs may be clinically normal for years, only to become hypothyroid at a later date. 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 4 years of age, annual testing for the first 4 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 Hashimoto's disease.

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 Hashimoto's disease in the offspring.

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.

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.

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.

Thyroid Abnormalities

Two types of thyroid abnormalities will be defined by the registry:

• Autoimmune Thyroiditis (Hashimoto's Disease)
• Idiopathic Hypothyroidism

NOTE: Autoimmune Thyroiditis is known to be heritable.

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 conered to be the "gold standard" for assesment of the thyroid's production and cellular availability of thyroxine.

• 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. TSH 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.

DIAGNOSIS and CERTIFICATION
Normal	FT4D cTSH TgAA	8-30 pmol/L 7-40 mU/L Negative
Positive advanced autoimmune thyroiditis	FT4D cTSH TgAA	< 8 pmol/L > 40 mU/L Positive
Positive compensating autoimmune thyroiditis	FT4D cTSH TgAA	8-30 pmol/L 10-100 mU/L Positive
Positive idiopathic hypothyroidism	FT4D cTSH TgAA	< 8 pmol/L > 40 mU/L Negative

Incorporated in the state of California  April 3, 1974 as a non-profit 501 (c) corporation.   Corporate Number C0706491

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

Animal Health Diagnostic Laboratory
Endocrine Diagnostic Section
P.O. Box 30078
Lansing, MI 48909-7576

OR

Diagnostic Laboratory
New York State College of Veterinary Medicine
Cornell University, Upper Tower Road
Ithaca, NY 14851

NOTE: Other laboratories will be approved by OFA in the near future.

Incorporated in the state of California  April 3, 1974 as a non-profit 501 (c) corporation.   Corporate Number C0706491

You can get more info by visiting OFA's official website.

Contact OFA directly for specific information on the OFA registries:

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

Dr. R.A. Weitkamp ~ President
Greg Keller, DVM, MS ~ Executive Director

email ofa@offa.org

Health and Certifications
OFA ~ Thyroid Registry

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