Dalmatian Club of America
Information on Thyroid Disorders
Where is it?
The thyroid gland consists of two lobes located in front of the neck just above the larynx, near the trachea (windpipe).
What does it do?
The thyroid produces THYROID HORMONE. The two most important hormones are Tetraiodothyronine (thyroxin or T4) and Triiodothyronine (T3). It's primary function is the production of thyroxin, a hormone that allows the
dog to maintain an adequate and consistent level of metabolism.
How is the Thyroid Hormone Produced and WHAT does it Do In the Body?
These hormones are essential for life and have many effects on body metabolism, growth and development. The Thyroid gland is influenced by hormones produced by two other organs:
- The Pituitary gland, located at the base of the skull produces thyroid stimulating hormone, (TSH).
- The Hypothalamus, a small part of the brain above the pituitary, produces Thyrotropin releasing hormone (TRH).
In the healthy dog, thyroid hormone is secreted into the blood stream in steady amounts and it regulates the dog's metabolism. A deficiency of thyroid hormone, ( called Hypothyroidism) can lead to a slow metabolism while an over abundance of thyroid hormone (called Hyperthyroidism) can lead to an overactive metabolism. Hyperthyroidism is not common, usually occurs in dogs with tumors of the thyroid gland. The T4 will be above normal and the TSH is below normal in this situation.
What is it?
Hypothyroidism is a relatively common endocrine disease in dogs, it is a condition in which the dog has a deficiency of the thyroid hormone in the blood stream. Thyroid hormone regulates metabolism, and therefore,
affects almost every system in the body. Hypothyroidism caused the thyroid gland ceasing to function properly, the most common cause of canine thyroid dysfunction is autoimmune thyroiditis (estimated 90% of cases), and tends to clinically manifest at 2 to 5 years of age. Decreased production of thyroid hormone is associated with destruction or degeneration of the thyroid gland.
Thyroid Panels and antibody tests should be used for genetics screening of apparently healthy animals to evaluate their fitness for breeding. Common tests that evaluate thyroid gland function by measuring thyroid hormone
concentration in the blood are Total T4, TotalT3, Free T4 and TSH.
What is T3, T4, TSH, TgAA?
These are tests that evaluate the thyroid gland function by measuring the thyroid hormone concentration in the blood.
- T3 and T4 levels are used as an indicator of thyroid functions.
- cTSH (canine Thyroid Stimulating Hormone) Test, is the current "gold standard" test for measuring thyroid gland function. In this test, T4 concentration in the blood are measured BEFORE and 6 hours AFTER the administration of TSH.
- TgAA (Thyroglobulin Autoantibodies) This test is an indication of the presence of the autoimmune process in the dog's thyroid.
What causes Hypothyroidism?
The causes of Hypothyroidism are classified as Primary, Secondary or Tertiary.
Primary causes are the most common and are associated only with the thyroid gland.
Secondary causes are associated with the pituitary gland, such as a deficiency of TSH.
Tertiary causes, such as a deficiency of TRH, are associated with the Hypothalamus.
A high percentage of dogs with hypothyroidism are due to the thyroid gland being attacked by the dog's own immune system. At least 50% of hypothyroidism cases are caused by lymphocytic thyroiditis. The result is gradual destruction of the functional thyroid cells that produce, store, and secrete thyroxin.
Autoimmune thyroiditis is the most common cause of primary hypothyroidism in dogs. 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.
Exposure to drugs, many medications can adversely affect thyroid function.
Less than 5% of the cases of hypothyroidism are related to disease within the pituitary gland. In addition, hypothyroidism can be induced by prolonged administration of glucocorticoids (steroids).
Toxin and Chemical preservatives.
Nutritional imbalance or deficiencies.
Bacterial Infection caused by Strep, Staph or Pneumococcus.
Hypothyroidism is blamed for a wide range of common and uncommon symptoms. It is not known whether an inadequate level of circulatin thyroxin is the culprit behind all of them. Other blood tests may be performed to
evaluate other body systems since concurrent diseases such as Cushing's disease (characterized by an abnormal production of steroids) or Diabetes can cause low levels of circulating thyroid hormone. However, controlling
these disease processes usually eliminates the need for hypothyroidism treatment. Other systemic illnesses such as kidney and liver insufficiency, heart failure, or immune system disorders can falsely lower thyroid levels
and this phenomena is known as euthyroid sick syndrome.
What are the symptoms?
Dry coat, hair loss often on the tail ("rat tail"), hind quarters or flank that is not a result from scratching, hair thinning over the body, excessive shedding, seborrhea, bacterial skin infection, (skin abnormalities are the most common clinical signs) excessive skin pigmentation, lethargy (dog just want to lay around), excessive sleeping, seeking warm places to curl up, weight gain despite limited food intake, muscle or nerve weakness, abnormal heat cycles,absence of heat cycle, short or prolonged heat cycles, silent heat, false pregnancy, infertility, chronic ear infection, seizures, facial puffiness "sad facial expression", sudden changes in temperament.
Clinical signs are slow to develop and are only evident when 75% of the thyroid gland is not functioning.
How is Hypothyroidism Diagnosed?
Hypothyroidism is diagnosed by a blood test to measure the level of thyroid hormone, many thyroid panels are available.
The T4 and TSH and the FT4D assay are the best for diagnosing hypothyroidism, but do not identify the cause. The TgAA ( Thyroglobulin Autoantibody) assay is a test used that is highly specific for lymphocytic thyroiditis. Information from this three-part testing panel is used in the OFA thyroid registry database as the best possible means of diagnosing thyroid disease.
The first two tests tell us if the dog is hypothyroid and the third reveals if the dog has inherited thyroid disease.
If your pet is not treated, s/he will continue to exhibit the signs of hypothyroidism. Spontaneous remission does NOT occur; however, with the proper veterinary treatment your dog can resume a normal life with normal life expectancy.
A dog is to be examined by the attending veterinarian and have a serum sample sent to an OFA approved Laboratory for testing. The approved laboratory must be contacted for the appropriate submission forms.
Thyroid Testing In Dogs
OFA Thyroid Registry
The OFA established a registry for Hypothyroidism with the help of Dr.Ray Nachreiner. The purpose of the registry are to assist breeders in selecting sound dogs for breeding purposes and to develop and maintain a database for the study of hypothyroidism dogs.
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 mating are most appropriate for reducing the incidence of Autoimmune thyroiditis in the offspring.
To submit a dog to the registry, it is taken to the owner's regular veterinarian, who draws blood for submission to a certified laboratory. The sample is handled and shipped following guidelines described by the laboratory. The laboratory performs the tests (FT4D,cTSH and the TgAA) and reports to the owner, veterinarian and the OFA. At the time of submission the owner has the option of placing results in an open or closed registry.
A certificate and breed registry number will be issued to all dogs found to be normal at 12 months of age. It is recommended that re-examination occur at ages 2,3,4,6, and 8 years.
A Reference for Dog Breeders and Owners
For more information visit the following URLs
||"Thyroid testing in dogs"by Dr:Karen J. Wolfsheimer DVM, Ph.D.
Diplomat,American College of Veterinary Internal Medicine Associate Professor,Louisiana
||"OFA Canine Thyroid Registry", by Dr Ray Nachreiner, DVM, Ph.D.The purpose of this Registry is to identify those dogs that are phenotypically normal for breeding programs.Each dog is to be examined by the attending
veterinarian and have a serum sample sent to an OFA approved laboratory for testing. A certificate and breed registry number will be issued to all dogs found normal.
||"Soloxine", learn more about the thyroid replacement drug.
|International Symposium on Canine Hypothyroidism University of California at Davis.
||The Symposium was held at the University Of California at Davis in August 1966.To obtain the very valuable notes on this symposium write to the following address and ask for the WHITE PAPERS on Canine Hypothyroidism
and send $5.00 US funds to: Cindy Foust, AKC/CHF, 251 W Garfield Rd, Suite 160, AURORA, OH, 44202
||Thyroid By Jan Cooper
||Good source of Information on Thyroid disorders by CELESTE M. GONZALES CVT. This article is found at the DCA page which is the Official home page of the Dachshund Club of
America ,click on to "ENTER HERE", then scroll down and click on DCA Health and Welfare (of Dachshunds), then scroll down till you get to THYROID/HORMONAL DISORDERS.
||By Dr.Jan Cooper. To find this article follow the Red instruction above.
The approved laboratory must be contacted for the appropriate submission forms, sample handling procedure and laboratory service fee before collecting the sample.
More information is available at the OFA web site at http://www.offa.org
These laboratories can be contacted for information on fees and instructions
for sample preparation and shipping.
Currently, samples may be submitted to:
Animal Health Diagnostic Laboratory, Endocrine Diagnostic Section
B629 W.Fee Hall-B, Michigan State University
Lansing, MI 48824-1315
Diagnostic Laboratory, New York State College of Veterinary
Cornell University, Upper Tower Rd
Ithaca, NY 14851
Veterinary Diagnostic Laboratory, Attn. Sample Handling
College of Veterinary Medicine, University of Minnesota
1333 Gortner Ave.
St.Paul, MN 55108
Animal Health Laboratory, University of Guelph, Bldg. 49, McIntosh
Guelph, Ont Canada N1G 2W1
University of California, Veterinary Medical Teaching Hospital
Clinical Pathology, Chemistry, Room 1017, 1 Garrod Drive
Davis, CA 95616
Texas Veterinary Medical Diagnostic Laboratory
1 Sippel Rd.
College Station, TX 77843
This is what OFA Thyroid Certificate looks like
Treatment involves supplementing with a synthetic form of thyroid hormone, drug of choice is SALOXINE. Activity usually improves after 7 to 10 days of treatment; however, improvement of skin conditions may take up to 6-8weeks.
The first few months of treatment require repeated blood tests to assure the proper dosage of medication is being given. After the correct dosage is achieved, yearly blood tests are used for monitoring the condition.
|How is Hypothyroidism Treated?
- When the blood results are returned and the diagnosis of hypothyroidism is confirmed, your veterinarian will prescribe a trial dose of thyroid hormone supplement. The product of choice is usually levothyroxine sodium tablets (Soloxine). This medication must be administered, according to your veterinarian's instructions. Activity usually improves after 7 to 10 days of treatment; however, improvement of skin conditions may take up to 6-8weeks. The first few months of treatment require repeated blood tests to assure the proper dosage of medication is being given. After the correct dosage is achieved, yearly blood tests are used for monitoring the condition.
- Avoid Unnecessary drugs.
- Avoid Toxins and Chemical preservatives.
- Good nutrition is an essential component of maintaining a healthy immune system. Dr.Jean Dodds DVM,in one of her lectures, suggests fresh, home-cooked vegetables with herbs and meats such as lamb, chicken and turkey
can be added as supplements.
It should be checked every six months because the amount of thyroid hormone produced by the body (the amount of supplement needed) will vary with time, season, other diseases, exercise, age, etc. and periodically there will be the need to change the thyroid hormone dosage to avoid either over-supplementing or under-supplementing.
|Why should the Thyroid Level be checked once every six months during treatment?
Overdose of thyroid hormone can result in panting, nervousness, increased thirst and urination, increased appetite and weight loss. If you should notice any of these symptoms, please contact your veterinarian so the dose of your pet's medication can be adjusted.
Levothyroxine Sodium (L-thyroxin). Soloxine is a synthetic hormone, comes in tablet from, it acts to stimulate metabolism, growth, development. Soloxine is absorbed rapidly from the gastrointestinal tract after oral administration.
Indications: Provides thyroid replacement therapy in all conditions of inadequate production of thyroid hormones.
Administration: Soloxine tablets maybe administered orally or placed in the food.
It is advisable NOT to substitute Soloxine with the GENERIC type hormone replacement
Above Research information was Obtained from :
On-Line Hypothyroid Symposium
OFA , Canine Thyroid Registry at http:// www.offa.org
Endocrinology (Small Animal Clinical Journal)
The above information was submitted by Nilda