HYPOTHYROIDISM
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Introduction
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Clinical Signs
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Diagnosis
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Treatment
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Living with HypoT4
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What is hypothyroidism?
The thyroid glands located in your pet’s neck produce hormones, including T3 (liothyronine) and T4 (levothyroxine), which are required for normal metabolism. Dogs with thyroid disease usually produce too little thyroid hormone (hypothyroidism), while cats with thyroid disease usually produce too much thyroid hormone (hyperthyroidism).
Hypothyroidism is a clinical condition resulting from a lowered production and release of thyroid hormones from the thyroid glands. This deficiency is caused by immune-mediated destruction of the thyroid gland, by natural shrinking (atrophy) of the gland, by dietary iodine deficiency, or as a congenital problem. In dogs, immune-mediated destruction accounts for almost all cases.
The disease is more common in medium- to large-breed dogs with some breeds more likely to be affected: Doberman Pinschers, Irish Setters, Golden Retrievers, Great Danes, Old English Sheepdogs, Dachshunds, Miniature Schnauzers, Boxers, Poodles, and Cocker Spaniels. It is also more commonly diagnosed in middle-aged dogs between the ages of 4 and 10 years.
The thyroid glands located in your pet’s neck produce hormones, including T3 (liothyronine) and T4 (levothyroxine), which are required for normal metabolism. Dogs with thyroid disease usually produce too little thyroid hormone (hypothyroidism), while cats with thyroid disease usually produce too much thyroid hormone (hyperthyroidism).
Hypothyroidism is a clinical condition resulting from a lowered production and release of thyroid hormones from the thyroid glands. This deficiency is caused by immune-mediated destruction of the thyroid gland, by natural shrinking (atrophy) of the gland, by dietary iodine deficiency, or as a congenital problem. In dogs, immune-mediated destruction accounts for almost all cases.
The disease is more common in medium- to large-breed dogs with some breeds more likely to be affected: Doberman Pinschers, Irish Setters, Golden Retrievers, Great Danes, Old English Sheepdogs, Dachshunds, Miniature Schnauzers, Boxers, Poodles, and Cocker Spaniels. It is also more commonly diagnosed in middle-aged dogs between the ages of 4 and 10 years.
The most common signs of hypothyroidism in dogs include loss or thinning of the fur, dull hair coat, excess shedding or scaling, weight gain, reduced activity and reduced ability to tolerate the cold. The hair loss occurs primarily over the body, sparing the head and legs, and is usually not accompanied by itching or redness of the skin. Some dogs will have thickening of the skin and increased skin pigment, especially in areas of friction, such as the armpit (axilla). Hypothyroid
dogs frequently have concurrent ear infections.
Hypothyroid dogs may also develop secondary skin infections that may be itchy and result in sores on the body. The disease can cause an accumulation of substances called mucopolysaccharides that can cause the muscles of the face
to droop, giving your pet a facial expression that is sometimes described as “tragic.”
Less commonly recognized signs that may be seen in a small number of dogs with hypothyroidism include dilation of the esophagus (megaesophagus), causing regurgitation and abnormal function of nerves or muscles. This leads to weakness or decreased ability to walk.
dogs frequently have concurrent ear infections.
Hypothyroid dogs may also develop secondary skin infections that may be itchy and result in sores on the body. The disease can cause an accumulation of substances called mucopolysaccharides that can cause the muscles of the face
to droop, giving your pet a facial expression that is sometimes described as “tragic.”
Less commonly recognized signs that may be seen in a small number of dogs with hypothyroidism include dilation of the esophagus (megaesophagus), causing regurgitation and abnormal function of nerves or muscles. This leads to weakness or decreased ability to walk.
Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms. You will need to provide your veterinarian with a thorough history of your dog's health leading up to the onset of symptoms.
Routine laboratory testing includes a complete blood count, biochemistry profile, total T4, and urinalysis. Your doctor may be able to make an initial diagnosis based on the results of these tests, but additional testing is frequently required to confirm the diagnosis. Additional tests include T3, Free T4, and TSH.
Routine laboratory testing includes a complete blood count, biochemistry profile, total T4, and urinalysis. Your doctor may be able to make an initial diagnosis based on the results of these tests, but additional testing is frequently required to confirm the diagnosis. Additional tests include T3, Free T4, and TSH.
Good treatment options are available for treating dogs with hypothyroidism. The treatment is usually life-long, with carefully administered oral medication given in conjunction with dietary restrictions at home. The deficient hormones are given in synthetic form, with the dosage adjusted occasionally based on your dog's individual physical condition and progress. Most clinical symptoms will resolve after a few months, but only your veterinarian can determine whether your dog's medicine dosage should be adjusted or changed.
Conscientious compliance with the prescribed drugs and diet is required for successful therapy. Your veterinarian will adjust the dosage of the synthetic hormones as necessary for your dog and will also monitor the usefulness of any other medications that have been prescribed. The levels of thyroid hormones in your dog’s blood will need to be monitored periodically to ensure your pet is continuing to receive the correct amount of medication.
Do not change the type or dosage of the drug yourself, and never give anything new to your dog without first consulting with your veterinarian. This caution includes the use of herbal remedies. Diet modifications, including a reduction in fat, are recommended during the initial phase of therapy. Most dogs respond well to therapy, with activity levels and mental alertness increasing significantly after only a relatively short period of time.
Do not change the type or dosage of the drug yourself, and never give anything new to your dog without first consulting with your veterinarian. This caution includes the use of herbal remedies. Diet modifications, including a reduction in fat, are recommended during the initial phase of therapy. Most dogs respond well to therapy, with activity levels and mental alertness increasing significantly after only a relatively short period of time.