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Beating hypothyroidism in pooch pals!

Beating hypothyroidism in pooch pals!Hypothyroidism is due to impaired production and secretion of the thyroid hormones, which results in a decreased metabolic rate. It is the most common endocrinopathy of the dog. The clinical signs are quite variable and almost any organ system may be involved.

Causes of hypothyroidism

The thyroid gland is a small gland that is situated close to the larynx (voice box) in the neck. It is regulated by the small pituitary gland that is located at the base of the brain which produces a hormone called thyroid stimulating hormone (TSH). This hormone stimulates the thyroid gland to produce thyroxine, the thyroid hormone. The pituitary gland responds to the blood level of thyroid hormone by producing more TSH if the thyroid hormone level is low and less TSH if the thyroid hormone level is high. The disorder results as primary, secondary, tertiary and congenital forms and of which, primary hypothyroidism accounts for almost 95 percent of the clinical cases.

Who gets affected?

This condition is commonly noticed in middle-aged dogs between 4 to 10 years of age and affects mid to large size breeds. Golden Retriever, Doberman Pinscher, Irish Setter, Miniature Schnauzer, Dachshund and Cocker Spaniel are the common breeds at risk. There does not appear to be a sex predilection but spayed females appear to develop it more often than intact females.

The symptoms

The clinical signs of hypothyroidism may be vague and insidious in onset, therefore hypothyroidism may be considered in the differential diagnosis of a wide range of medical problems. There is not a specific symptom that is diagnostic for hypothyroidism. The classical dermatological manifestations occur in 60-70 percent of hypothyroid dogs. These may include a dry hair coat, seborrhoea, alopecia, hyperpigmentation and pyoderma. While hair loss occurs in a bilaterally symmetrical pattern, it initially occurs in areas of friction such as the tail, around the neck, lateral trunk and ventral thorax. Lethargy, mental dullness, weight gain, unwillingness to exercise and cold intolerance are the signs that result from decreased metabolic rate. Accumulation of excessive amounts of glycosaminoglycans (mostly hyaluronic acid) in the dermis results in the myxoedematous appearance (tragic facial expression) found in some dogs. Neurological, cardiovascular (bradycardia) and reproductive manifestations have also been recognised. Myxedema coma, a rare syndrome, is the extreme expression of severe hypothyroidism.

Unusual signs include seizures, neuromuscular disorders and peripheral neuropathies. These manifestations are related to the profound hyperlipidemia. Two specific diseases associated with hypothyroidism are megaesophagus and laryngeal paralysis. A loss of smell and taste are also possible. The cornea might undergo fat (lipid) deposits or become ulcerated. Changes with adequate tear production along with internal structures of the eye could occur. Abnormalities in heart strength, rate and rhythm, along with atherosclerosis, could also occur. Inadequate thyroxine makes the immune system less effective at fighting infections, especially the bacterial skin infections (pyoderma) that occur secondarily. Suppression of the immune system might even increase susceptibility to Demodicosis and Malasseziosis. Breeding dogs might have abnormal heat cycles, infertility and high puppy mortality. In addition to low thyroxine, hypothyroidism is implicated in diabetes mellitus and Addison’s Disease and musculo-skeletal disorders.

A study on hypothyroid dogs revealed the following variety and frequency of signs seen with the disease:

Diagnosing hypothyroidism

Hypothyroidism in dogs is probably one of the most over diagnosed diseases in small animal practice. The clinical signs of many diseases mimic those of hypothyroidism. There is no single hamatologic or biochemical test that is conclusive for hypothyroidism and even hormonal tests must be interpreted in light of historical and physical findings. The wide variety of clinical signs and findings associated with hypothyroidism necessitates specific testing of thyroid function to establish a definitive diagnosis. Tests currently available for diagnosing thyroid disease include total thyroxine (TT4), total tri-idothyronine (TT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), TSH response test, TRH response test, T4 and T3 autoantibodies, antithyroglobulin antibodies, nuclear scintigraphy and thyroid gland biopsy. The test chosen will depend on the symptoms and the availability of different tests.

Total T4 Test: This is the most common preliminary test for hypothyroid patients. The TT4 hormone is produced only in the thyroid gland and dogs with a failure of the thyroid gland will have a lowered level of this hormone. However, there are other conditions that can cause a lowering of TT4. So, if this screening test is positive for hypothyroidism, another more specific test is often done to confirm the diagnosis.

Free T4: T4 is present in two forms in the body. The “bound” form is attached to proteins in the blood and is unable to enter the cells. The “free” T4 is not attached to proteins and can readily enter the cells and perform its function. The free T4 is normally present in very small amounts.

TSH Level: In a hypothyroid dog, the TSH level will be elevated because the body is trying to stimulate the thyroid gland to produce more thyroid hormone. If the total T4 and Free T4 are low and the TSH is elevated, a diagnosis of hypothyroidism can be made.

TSH Response Test: The TSH response test has long been recognized as an accurate measure of thyroid function and serves as the “gold standard” measurement in many studies evaluating thyroid function tests. This is because it provides important information about thyroid secretary reserve. Measurement of TT4 before and six hours after intravenous administration of 0.1 U/kg bovine TSH is the recommended protocol. Post-TSH TT4 concentrations above 30 mmol/L are normal, while TT4 less than 20 mmol/L is diagnostic for hypothyroidism.

Thyrotropin Releasing Hormone (TRH) Response Test: The TRH response test is used in humans to differentiate primary from secondary hypothyroidism. In dogs, the test has been used in place of the TSH response test and change in TT4 has usually been measured.

Therapeutic Trial: When diagnostic tests do not provide a clear diagnosis of hypothyroidism, thyroid replacement therapy is suggested as a valid diagnostic step. A positive response to therapy should be interpreted with caution because clinical signs may also improve in euthyroid animals treated with L-thyroxine. A diagnosis of hypothyroidism based on response to therapy should be confirmed by recurrence of clinical signs after withdrawal of supplementation.

Treatment of hypothyroidism

Hypothyroidism in dogs is easily treated. Treatment consists of placing the dog on a daily dose of a synthetic thyroid hormone called levothyroxine. The dose and frequency of administration of this drug varies depending on the severity of the disease and the individual response of the animal to the drug. With few exceptions, replacement therapy is necessary for the remainder of dog’s life. Treatment should be initiated at a dose of 0.02 mg/kg orally every 12 hours and then the dose should be adjusted based on results of therapeutic monitoring. Using twice-daily treatment initially improves the likelihood of response to treatment in all dogs. After clinical signs resolve and TT4 concentrations stabilize within the therapeutic range, the majority of dogs can be maintained on 0.02 mg/kg once daily. The most important indicator of the success of therapy is clinical improvement. Clinical resolution of metabolic signs such as lethargy and mental dullness can be expected within two weeks of starting therapy, while other abnormalities, including dermatologic signs, may take up to three months to resolve.

(Dr K Satish Kumar works at Department of Veterinary Clinical Medicine, College of Veterinary Science, Hyderabad while Dr D Srikala is from College of Veterinary Science, Tirupati.)

Health

Beating hypothyroidism in pooch pals!

Hypothyroidism is due to impaired production and secretion of the thyroid hormones, which results in a decreased metabolic rate. It is the most common endocrinopathy of the dog. The clinical signs are quite variable and almost any organ system may be involved.

Causes of hypothyroidism

The thyroid gland is a small gland that is situated close to the larynx (voice box) in the neck. It is regulated by the small pituitary gland that is located at the base of the brain which produces a hormone called thyroid stimulating hormone (TSH). This hormone stimulates the thyroid gland to produce thyroxine, the thyroid hormone. The pituitary gland responds to the blood level of thyroid hormone by producing more TSH if the thyroid hormone level is low and less TSH if the thyroid hormone level is high. The disorder results as primary, secondary, tertiary and congenital forms and of which, primary hypothyroidism accounts for almost 95 percent of the clinical cases.

Who gets affected?

This condition is commonly noticed in middle-aged dogs between 4 to 10 years of age and affects mid to large size breeds. Golden Retriever, Doberman Pinscher, Irish Setter, Miniature Schnauzer, Dachshund and Cocker Spaniel are the common breeds at risk. There does not appear to be a sex predilection but spayed females appear to develop it more often than intact females.

The symptoms

The clinical signs of hypothyroidism may be vague and insidious in onset, therefore hypothyroidism may be considered in the differential diagnosis of a wide range of medical problems. There is not a specific symptom that is diagnostic for hypothyroidism. The classical dermatological manifestations occur in 60-70 percent of hypothyroid dogs. These may include a dry hair coat, seborrhoea, alopecia, hyperpigmentation and pyoderma. While hair loss occurs in a bilaterally symmetrical pattern, it initially occurs in areas of friction such as the tail, around the neck, lateral trunk and ventral thorax. Lethargy, mental dullness, weight gain, unwillingness to exercise and cold intolerance are the signs that result from decreased metabolic rate. Accumulation of excessive amounts of glycosaminoglycans (mostly hyaluronic acid) in the dermis results in the myxoedematous appearance (tragic facial expression) found in some dogs. Neurological, cardiovascular (bradycardia) and reproductive manifestations have also been recognised. Myxedema coma, a rare syndrome, is the extreme expression of severe hypothyroidism.

Unusual signs include seizures, neuromuscular disorders and peripheral neuropathies. These manifestations are related to the profound hyperlipidemia. Two specific diseases associated with hypothyroidism are megaesophagus and laryngeal paralysis. A loss of smell and taste are also possible. The cornea might undergo fat (lipid) deposits or become ulcerated. Changes with adequate tear production along with internal structures of the eye could occur. Abnormalities in heart strength, rate and rhythm, along with atherosclerosis, could also occur. Inadequate thyroxine makes the immune system less effective at fighting infections, especially the bacterial skin infections (pyoderma) that occur secondarily. Suppression of the immune system might even increase susceptibility to Demodicosis and Malasseziosis. Breeding dogs might have abnormal heat cycles, infertility and high puppy mortality. In addition to low thyroxine, hypothyroidism is implicated in diabetes mellitus and Addison’s Disease and musculo-skeletal disorders.

A study on hypothyroid dogs revealed the following variety and frequency of signs seen with the disease:

Diagnosing hypothyroidism

Hypothyroidism in dogs is probably one of the most over diagnosed diseases in small animal practice. The clinical signs of many diseases mimic those of hypothyroidism. There is no single hamatologic or biochemical test that is conclusive for hypothyroidism and even hormonal tests must be interpreted in light of historical and physical findings. The wide variety of clinical signs and findings associated with hypothyroidism necessitates specific testing of thyroid function to establish a definitive diagnosis. Tests currently available for diagnosing thyroid disease include total thyroxine (TT4), total tri-idothyronine (TT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), TSH response test, TRH response test, T4 and T3 autoantibodies, antithyroglobulin antibodies, nuclear scintigraphy and thyroid gland biopsy. The test chosen will depend on the symptoms and the availability of different tests.

Total T4 Test: This is the most common preliminary test for hypothyroid patients. The TT4 hormone is produced only in the thyroid gland and dogs with a failure of the thyroid gland will have a lowered level of this hormone. However, there are other conditions that can cause a lowering of TT4. So, if this screening test is positive for hypothyroidism, another more specific test is often done to confirm the diagnosis.

Free T4: T4 is present in two forms in the body. The “bound” form is attached to proteins in the blood and is unable to enter the cells. The “free” T4 is not attached to proteins and can readily enter the cells and perform its function. The free T4 is normally present in very small amounts.

TSH Level: In a hypothyroid dog, the TSH level will be elevated because the body is trying to stimulate the thyroid gland to produce more thyroid hormone. If the total T4 and Free T4 are low and the TSH is elevated, a diagnosis of hypothyroidism can be made.

TSH Response Test: The TSH response test has long been recognized as an accurate measure of thyroid function and serves as the “gold standard” measurement in many studies evaluating thyroid function tests. This is because it provides important information about thyroid secretary reserve. Measurement of TT4 before and six hours after intravenous administration of 0.1 U/kg bovine TSH is the recommended protocol. Post-TSH TT4 concentrations above 30 mmol/L are normal, while TT4 less than 20 mmol/L is diagnostic for hypothyroidism.

Thyrotropin Releasing Hormone (TRH) Response Test: The TRH response test is used in humans to differentiate primary from secondary hypothyroidism. In dogs, the test has been used in place of the TSH response test and change in TT4 has usually been measured.

Therapeutic Trial: When diagnostic tests do not provide a clear diagnosis of hypothyroidism, thyroid replacement therapy is suggested as a valid diagnostic step. A positive response to therapy should be interpreted with caution because clinical signs may also improve in euthyroid animals treated with L-thyroxine. A diagnosis of hypothyroidism based on response to therapy should be confirmed by recurrence of clinical signs after withdrawal of supplementation.

Treatment of hypothyroidism

Hypothyroidism in dogs is easily treated. Treatment consists of placing the dog on a daily dose of a synthetic thyroid hormone called levothyroxine. The dose and frequency of administration of this drug varies depending on the severity of the disease and the individual response of the animal to the drug. With few exceptions, replacement therapy is necessary for the remainder of dog’s life. Treatment should be initiated at a dose of 0.02 mg/kg orally every 12 hours and then the dose should be adjusted based on results of therapeutic monitoring. Using twice-daily treatment initially improves the likelihood of response to treatment in all dogs. After clinical signs resolve and TT4 concentrations stabilize within the therapeutic range, the majority of dogs can be maintained on 0.02 mg/kg once daily. The most important indicator of the success of therapy is clinical improvement. Clinical resolution of metabolic signs such as lethargy and mental dullness can be expected within two weeks of starting therapy, while other abnormalities, including dermatologic signs, may take up to three months to resolve.

(Dr K Satish Kumar works at Department of Veterinary Clinical Medicine, College of Veterinary Science, Hyderabad while Dr D Srikala is from College of Veterinary Science, Tirupati.)

Tarot readings for you and your furry pals

Last two issues, we carried write-ups on ‘Dogoscope,’ which informed about the characteristics of your canine angel based on their star signs. As an addendum to it, here are the tarot readings for you and your sweet tail-wagger for the months of May and June 08. Aries
(March 21 to April 20)

Pet parents: The beginning of May indicates a good time for financial investments, expansion in business or thinking about a relationship. The females, especially those at work, will be focused on money or career, will be practical and head strong. It is a good time for buying property, shifting to a new house and settling down. There is an indication of receiving an inheritance for some of you as well. Those connected with spirituality will be inclined towards the same deeply; there is a probability of motherhood as well.

Our furry pals: The cards indicate focus on family duties and time to learn a few tricks. Canines involved in events will be successful and will enjoy themselves. Be careful about their health. Expecting mothers will be blessed with sweet little furry additions to the family.

Taurus
(April 21 to May 20)

Pet parents: The beginning of the month indicates travel, overseas business connections, new assignments and career opportunities. The males can be emotional and at times have mood swings; but they will be very compassionate towards family. There is an indication for some to be disturbed regarding finances or personal issues which may lead to health problems. The elderly male can be slightly authoritative and will be in control of situations, whether personal or professional. However, the young will focus on career and it will be good to be practical, sometimes aggressive and less emotional.

Our furry pals: This is a time for celebration, be it a tour with the family or welcome into new homes. It’s time to master some tricks, receive goodies and bond with new people.

Gemini
(May 21 to June 21)

Pet parents: The beginning indicates a slightly depressing and disturbed week. Take care of your health and please do not be stubborn, instead be less defensive in order to maintain harmony. However, the latter half of the month brings a good emotional beginning, love or a new relationship, a new project or job offer. For those planning a wedding or an engagement, it is a wonderful time to tie the knot. Please do not regret the past as this only brings unpleasantness, so try to be positive and make the most of life.

Our furry pals: It is a very good time for learning and picking up new traits. They will be blessed with emotional happiness, wish fulfi lment and fun. There are good chances for travel and to be surrounded with people in the mid of the month.

Cancer
(June 22 to July 22)

Pet parents: For those who are planning to buy or move into a new house will be successful in doing so. It is also a good time to consider investments. Mid month could bring some criticism or heartbreak or a delay in job offers or starting a new venture. The elderly male or female will be authoritative and certainly have their say in personal or professional matters. People who hope for a new alliance, marriage or commitment, it is a favourable period from May onwards, so be positive and be happy.

Our furry pals: The beginning indicates a blessed time for commitment, which all furry pals are best at, being appreciated for their achievements. Cancerians are moody, and so, it is best suggested to please let them be, as we all need our space.

Leo
(July 23 to August 22)

Pet parents: It is a great time for those in love or planning a marriage or commitment as love is in the air, especially in June. Men who are generally in careers will do very well, especially doctors, lawyers etc.

Our furry pals: The beginning indicates making new friends; especially the females will be bold, courageous and enjoy a sense of importance from their dear ones. There is a good and positive indication or commitment; either planned mating by pet parents or even learning some new tricks.

Virgo
(August 23 to September 22)

Pet parents: The beginning of May indicates a good time for mother-child bonding. The mid month certainly brings positive new beginnings with regards to career and monetary gains. Favourable months to achieve your goals as your stars are bright. Motherhood is on the charts for females while males will focus on career, fi nances, business and stocks.

Our furry pals: The month indicates expectations for new home adoptions. For those planning to enter a contest, victory is defi nitely on the cards.

Libra
(September 23 to October 22)

Pet parents: The beginning indicates criticism or lack of making the correct choices, competitions, quarrels, misunderstandings, and regrets. There will be delay in a travel plan or a project may be blocked and cause some delays in its progress. You all are advised to be cautious while signing any contracts or indulging in money transactions. Some may be inclined towards meditation or even follow a Guru who will be a source of solace. This is clearly a month of ups and downs. You are advised to try to be calm, wise and practical.

Our furry pals: Older furry pals will dominate and bully others in the neighbourhood or at home. Travel forecast for some but a delay around June with regards to being adopted and finding new homes.

Scorpio
(October 23 to November 22)

Pet parents: The beginning indicates for career women a good time, new business opportunity or job offers. It also offers spirituality and an amazing capacity to handle work or home perfectly. There is a wake up call for your consciousness and a blessed time to use your judgment accurately. The month of June is favourable for a celebration, party, rejoicing and making merry. This month also brings positive messages related to love, marriage, commitment and matters of the heart. Those who are in a litigation or matters with legal issues, there will be results.

Our furry pals: A good wish fulfilling beginning and a lot of goodies will be received. The mid month indicates an average time and some will have to be on guard as there may be a bully in the neighbourhood who will try to play Boss.

Sagittarius
(November 23 to December 21)

Pet parents: The beginning is a favourable period for marriage, courtship, commitment and love, also for those who are planning the coming of a baby; this is a good and favourable time to prepare for the new arrival. The men, especially professionals like doctors and lawyers, will be very successful in their respective careers. Those expecting results regarding new ventures will see their wishes fulfi lled by month end. A very vibrant period for the younger generation, who will excel by focusing and being practical. The month of June also indicates some introspection for those who are inclined towards spirituality.

Our furry pals: The beginning indicates some regret and running away from a bully in the neighbourhood. There is a strong indication that appreciation and awards are on the cards.

Capricorn
(December 22 to January 20)

Pet parents: The beginning indicates good time for shopping, indulging in luxuries and motherhood. The month of May is also favourable for making purchases, investments, buying property and fi nancial gains. June is a good time for family togetherness. The time for making donations, helping people or indulging in social work is ideal around the month of June while the end of the month calls for some celebration and party.

Our furry pals: They will be confused, especially those adjusting in a new environment. They may feel depressed but will soon be the centre of attraction and will have loads of fun ‘n’ frolic.

Aquarius
(January 21 to February 19)

Pet parents: This month indicates new beginning of a job via email or an important phone call. It is also a good time for marriage or a commitment. You can be on a spiritual path or think deeply. The month of June indicates good results of your effort. Some of you may be juggling more than one thing at a time – job or relationship. June end is certainly a period of concern, health and work.

Our furry friends: This month calls for extra special care, with regards to health or any decisions pertaining to physical call. A lot of attention is needed for those who may show signs of ill health.

Pisces
(February 20 to March 20)

Pet parents: The beginning of the month indicates confusion, anxiety, emotional regret, etc. There is a need for spiritual help, as you are likely to be over burdened on the home or work front. You may have to make sacrifi ces and probably let go of whatever you are holding on to. The month of June indicates disturbed and diffi cult period, so you are advised to be focused and assess your issues in order to find solutions.

Our furry pals: It is time to make your furry pal comfortable in a new surrounding. There is a possibility of them feeling depressed, confused and scared, but your love will make them feel safe and happy.