HYPOTHYROIDISM

CT3, T4, Free T4 and Free T3onversion of T4 to T3    autoimmune thyroiditis

You may have noticed your dog is putting on a few pounds lately although you havenít changed its diet. Your Pei has a skin condition, lack of energy! After taking your pet to your vet, it has been discovered that your pet has an under active thyroid gland.
Thyroid tests should include T3, T4, Free T4 and Free T3 and antibodies for both T4 and T3 must be done on the sharpei
Your Sharpei has been lethargic lately?  Gone is the waggish attitude and the passion for chewing those Nylabones? She/He sleeps most of the time and seems to seek out sunny areas or lie near your heating vents. Her/His coat has been dry, his skin flaky and that pesky ear infection keeps re-occurring.  Could your Sharpei be hypothyroid?  It certainly is something to consider, especially since the Pei, like other dogs, have a predisposition for the disease. But such a diagnosis must be made with care. Although, hypothyroidism is a common endocrine disease of  dogs, the condition is frequently misdiagnosed. So take a deliberate step in protecting your dogís health and become familiar with the disease...
Hypothroidism is Becoming More Common in the Sharpeiy
What is Hypothyroidism?  (Thyroid tests should include T3, T4, Free T4 and Free T3 and antibodies for both T4 and T3)

Hypothyroidism is a disorder in which the thyroid gland (two small lobes located in the neck ) secretes insufficient thyroid hormone. Hypothyroidism isnít life threatening if treated properly, but it does diminish quality of life. Once diagnosed, however, the disorder is relatively easy to treat.

The thyroid gland produces the thyroid hormones that are critical to maintaining your dogís normal metabolic rate. This is the speed at which the body converts nutrient energy into energy fuelling the body. If the thyroid gland degenerates or becomes inflamed, it can no longer produce sufficient quantities of hormones. As a result, cells donít convert the nutritional energy it needs into biologically usable fuel as fast as usual.

This decreased cell function causes a number of physical changes in a hypothyroid dog. Nearly half of such dogs gain weight (with no change in diet). Over a third become lethargic and mentally dull, and just under a third show hair or skin abnormalities. Hair-producing cells slow down, so there is less hair growth and more hair loss. Skin-producing cells slow down, so there is more wrinkling and hyperpigmentation, skin thickening, poor quality hair coat, excess scurf and scale, seborrhoea and secondary pyoderma. hypothyroid pets may suffer an increased propensity to joint disease, especially ligament damage...

Some vets also suspect a link between behaviour problems and hypothyroidism. Increased aggression is the most commonly suspected behaviour change, but some vets speculate that a few hypothyroid dogs may develop anxiety- related or compulsive behaviours. If your pet develops a sudden behavioural change, have your dogs thyroid status examined.

Since the physical signs of hypothyroidism develop gradually and vary from dog to dog, the disorder often goes undiagnosed. But vets have found that hypothyroidism typically develops after 2 years of age and is more common in certain breeds such as Golden Retrievers, Sharpei, Doberman Pinschers, While all owners should be on the lookout for changes in their dogís appearance or behaviour that suggest hypothyroidism, owners of middle-aged dogs or genetically predisposed dogs should be especially watchful. If you notice any signs, consult your vet. By simply taking a sample of your dogís blood, it can be determined if the dog has hypothyroidism... Thyroid tests should include T3, T4, Free T4 and Free T3 and antibodies for both T4 and T3.

There are two forms of thyroid hormone secreted by the thyroid gland; T3 (triiodothyronine) and T4 (thyroxine). T3 is usable thyroid hormone while T4 must first pass through the liver and other tissues before it can become T3, the usable thyroid. It is important that your Vet does All the T test listed above...

Here is where it begins to get a little complicated, but I'll do the best I can to help simplify it. The thyroid gland itself is regulated by two different hormones, TRH and TSH. Now, if T4 gets too low, (remember it's not usable yet when it starts travelling around the body) the brain tells the TRH, "Hey, wake up, go get TSH and tell him to get to work!" Now TRH knows that TSH 'hangs out' at the nearby Pituitary gland, and so heads straight there to find him. Well, as soon as TSH hears about the thyroid shortage he races to the thyroid gland and stimulates it to get busy and produce more thyroid hormone. Hence , being the first one to be released into active duty, TRH is the THYROID RELEASING HORMONE. while  TSH stands for THYROID STIMULATING HORMONE ...

As a consequence of all of this, Hypothyroidism (the shortage of usable thyroid in the body) is usually the condition seen when a thyroid imbalance is suspected. Hypothyroidism is becoming all too common in our breed and it would be desirable if all of our breeding dogs were tested...

Why do skin problems seem to go hand in hand with thyroid imbalance? In order for our dogs to have healthy skin and coats, the cells that make up the body must be healthy and multiply. It is not fully understood, but thyroid hormone is essential in regulating the metabolism of each individual cell. Whenever the cells cannot function efficiently, one of the visible results is the skin will loose it's elasticity, and can ultimately result in dry, crusty, scaly skin. The end result can be a dog with a very sparse coat and a dull, almost hardened gray skin that will have a obnoxious odour. A dog left untreated will be miserable with uncontrollable itching all over and will further damage itself by chewing to the point of producing raw and oozing sores, a condition ideal for bacterial infections to flourish...

It is found to be a fact that hypothyroidism is definitely associated with reduced resistance and a greater susceptibility to bacterial infections. So if your dog develops any type of skin ailment or a wound that does not seem to respond readily to treatment, you might want to check for a thyroid deficiency...


Hypothroidism is Becoming More Common in the Sharpeiy

 The thyroid is regulated by two different hormones, (TSH) the Stimulating Hormone and (TRH) The Releasing Hormone .  Because of the amount of thyroid hormone a dog needs, hypothyroidism is the disease usually seen whenever there is a thyroid imbalance or malfunction.

There is a lot of confusion about whether a dog has thyroid disease or not. Most people seem to think that they can tell if there is a problem and therefore only then they should take their dog to be tested. When it comes to the thyroid, nothing can be further from the truth.

As thyroid disease develops, it usually starts out as autoimmune thyroiditis.  The best way to explain it is that there are antithyroid antibodies in the blood. In people, this is sometimes referred to as Hashimoto's disease or lymphocytic thyroiditis. The worst part of this is that in very many of the cases.....it is genetic! Without testing your breeding stock you won't know about it until later, when clinical symptoms begin to appear. Tragically this may be after the dog/bitch has been bred and then the predisposition for the disease is passed on to the next generation....and so on....and so on. An improved test for TgAA, made by Oxford BioMedical is now commercially available, and although not as yet a definitive diagnostic test, it is the best available marker for autoimmune thyroiditis at this time.
Thyroid tests should include T3, T4, Free T4 and Free T3 and antibodies for both T4 and T3.
Since you may now have a basic understanding of T3 and T4. Remember, T3 (triiodothyronine) is the usable thyroid hormone and T4 (thyroxine) has to be converted into T3.. The level of these two hormones is not always inter-related, in other words, the dog may show adequate T4 and yet not be producing enough T3, or visa versa. That is oversimplified, but hopefully you get the idea!.

Most Vets request only the T4 hormone level that is found in the blood to be measured by their lab. But since there is a tiny amount of T4 hormone that is not in the blood, or free T4, that is also converted and aids intracellular health, this too should be measured. The only way to know if your dog has thyroiditis and later is a candidate for hypothyroidism is to be sure you ask for a measurement of the total T3 and T4 along with a measurement of the free T3 and T4. Since studies have shown a definite link between the Cholestrol level and T4 in dogs, your vet should also request a cholestrol level from the SAME blood samples. The results of the testing for cholestrol in relationship to T4 is called the ³K² values. With the addition of this test, you may detect early thyroid disease before any clinical symptoms are apparent. Once clinical symptoms appear, the ³K² value can aid in identifying whether the dog has low, normal or high thyroid function...The skin is not itchy, unless secondary infection or other problems are involved.
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Clinical signs of  Hypothyroidism

  • lethargy
  • mental dullness
  • exercise intolerance
  • neurologic signs (polyneuropathy, seizures)
  • weight gain
  • cold intolerance
  • mood swings
  • hyperexcitability
  • stunted growth
  • chronic infections

 

Dermatologic Diseases

  • dry, scaly skin and dandruff
  • coarse, dull coat
  • bilaterally symmetrical hair loss
  • "rat tail" or "puppy coat"
  • hyperpigmentation, black skin
  • seborrhea or greasy skin
  • pyoderma or skin infections
  • myxedema
  • chronic offensive skin odor

 

Hematologic Disorders

  • bleeding
  • bone marrow failure
  • low red blood cell count (anemia)
  • low white blood cell count
  • low platelaet

 

Cardiac Abnormalities

  • slow heart rate (bradycardia)
  • cardiac arrhythmias
  • cardiomyopathy

 

Occular Diseases

  • corneal lipid deposits
  • corneal ulceration
  • uveitis
  • keraconjunctivitis sicca (dry eye)
  • infections of eyelid gland (meibomian gland)

 

Gastrointestinal Disorders

  • constipation
  • diarrhea
  • vomiting,  bile

 

Neuromuscular Problems

  • weakness
  • stiffness
  • laryngeal paralysis
  • facial paralysis
  • "tragic expression"
  • knuckling or dragging feet
  • muscle wasting
  • megaesophagus
  • head tilt
  • drooping eyelids

 

Reproductive Disorders

  • infertility or either sex
  • lack of libido
  • testicular atrophy
  • hypospermia
  • aspermia
  • prolonged interestrus interval
  • absence of heat cycles
  • silent heat
  • pseudopregnancy
  • weak, dying or still born pups

 

Other Associated Disorders

  • IgA deficiency

  • glycosuria

  • loss of taste

  • loss of smell (dysosmia)

  • chronic, active hepatitis

  • adrenal indocrinopathies

  • pancreatic indocrinopathies

  • parathyroid indocrinopathies

Diagnosing hypothyroidism would seem to be as simple as measuring thyroid-hormone levels in the blood. However, this simple technique can give an inaccurate diagnosis because some illness such as Cushing's disease- overactive adrenal glands-- and medications, such as cortisone suppress the level of circulating thyroid hormones.
The most accurate test is the - thyroid stimulating hormone -
TSH- response test. In this test, the vet measures thyroid-hormone levels in the dogís blood, administers TSH (a chemical that stimulates thyroid-hormone secretion), then re-measures hormone levels to determine whether the thyroid gland responded by producing additional thyroid hormones. While the TSH response test is reasonably accurate, it is expensive to administer. Also, this hormone is now difficult to find because of decreased production by the manufacturers.

Newer tests are available, that are as accurate (although not 100 percent) and less expensive than the TSH response test. With these tests the a combination of the levels of thyroid hormone -T4- and a specific thyroid hormone-Free T4 - as well as the level of TSH in a dogís blood are measured. Hypothyroid dogs have both a high TSH level and a low free-T4 level.

Vets treat hypothyroidism by prescribing supplemental thyroid hormone, which the owner must administer to the dog orally once or twice a day. These medications are initially prescribed according to your petís weight. Your vet will closely monitor your dog in the initial stage of treatment by retesting the thyroid level- T4- to make sure the animal is getting the appropriate dosage. Too little hormone wonít alleviate the signs, while too much can cause a dog to develop hyperthyroidism (excessive thyroid hormone causing agitated and overactive behaviour, weight loss, excessive drinking, and excessive urination).

Once thyroid- hormone levels have stabilized within a normal range, your vet will likely check the levels every six months to every year. The dose levels of medication used to treat this disease in dogs is much higher than the rate use to treat hypothyroidism in people.

Once treatment begins, most hypothyroid dogs are increasingly active and show fewer behaviour problems within a week. Hair growth typically accelerates in about a week, too, although bare spots may take months to fully grow in. Most dogs begin to lose excess weight within 2 to 4 weeks of starting treatment.

If you suspect hypothyroidism, consult your vet. The treatment for hypothyroidism is straightforward, and the medication is relatively inexpensive...

Thyroid tests should include T3, T4, Free T4 and Free T3 and antibodies for both T4 and T3  for sharpei dogs
If youíve read this far, youíve learned quite a bit about this disease. But whatís the good news about this condition? After all, no one wants to care for a dog with a life long illness. The good news is the prescribed, thyroid medication has few side effects and is of a reasonable cost. Even better news is once the diagnosis is made and the dog supported with replacement hormones, a dramatic improvement in the animalís condition will result and most, if not all, disease signs will reverse. The treatment is relatively simple, relatively inexpensive, easy to deliver, and effective. In short, hypothyroidism is quite manageable and that, my friend, is the very best news of all. Why? Because it gives us a chance for a lifetime of togetherness with our wonderful Sharpei companions...
 

GENETIC OR CAUSED

Because of the amazing number of breeds that have developed this "hereditary" problem, many scientists are beginning to look for a man-made cause to this problem. Evidence is pointing towards the possibility of common environmental toxins, vaccine overload, and the diet being fed to today's dogs being the causative agent of hypothyroidism. All of these theories need further investigation, but are interesting possibilities. Let's look at a few of them...

Many of today's pesticides mimic the structure of mammalian hormones. Further, chicken, and beef are often laced with steroids and antibiotics on purpose to increase mass for market. Some dogs have a genetic susceptibility to diseases that attack their own immune system. Researchers suspect that these immune-mediated diseases may be triggered by environmental chemicals, viruses, repeated inoculation with multi-valent modified live vaccines, and other immune system challengers. It is reasonable to hypothesize that some canine endocrine problems may be caused by these additives...Affected Dog's should not be boosterd.
Hereditary.  Affected Dog's should not be Bred From!...

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