Epidermal renewal after treatment of primary canine hypothyroidism using levothyroxine

Background: Primary canine hypothyroidism, an endocrine disorder that causes imbalances in the hypothalamus-pituitarythyroid axis, is a common cause of endocrine dermatoses, which frequently presents with opaque dry brittle hair. Tissue changes are also visible, such as myxedema, hyperkeratosis, epidermal atrophy, alopecia, and others. This paper describes the skin changes caused by primary hypothyroidism in a female dog before and after treatment with levothyroxine. Case: This case study involved a 7-year-old Dalmatian bitch with a history of weight gain and changes such as rough dry brittle hair. For about a year, the dog also had also presented symmetrical erythematous and alopecia skin lesions in the regions of the hind limbs, lower back and tail, progressive lethargy and fatigue after exercise. A hemogram showed mild normocytic and normochromic regenerative anemia, as well as mild leukopenia and neutropenia. Biochemical tests revealed increased levels of creatinine, total cholesterol, and triglycerides. Skin biopsy revealed the presence of comedones in the epidermis and acanthosis and trichilemmal keratinization. Hormonal tests revealed high TSH and low free T4 and total T4 levels. A cervical ultrasound scan showed changes in the thyroid glands, with hypoechoic parenchyma, in addition to increased size of the right lobe, suggesting thyroiditis. Based on these exams, the patient was diagnosed with primary hypothyroidism, and treatment with levothyroxine was instituted. Discussion: Around 90% of dogs with hypothyroidism show a decrease in total T4 and about 65-75% of them show an increase in TSH levels. In endocrinopathy, there is a decrease in the expression of T3 receptors in the keratinocytes and genes responsible for epidermal renewal. Also, molecules that affect epidermal differentiation bind to intracellular receptors belonging to the steroid/thyroid hormone superfamily. In this study, however, the application of the minimum levothyroxine dose restored the normal epidermal pattern for the species and the remaining parameters returned to normal. The hormone T3 acts in the differentiation of keratinocytes, a fact that, although not yet proven, is believed to be indirect and mediated by the epidermal growth factor or by the expression of the genes responsible for the renewal of the epidermis. Besides, some effects on the epidermis caused by deficiency of thyroid hormones may be due to secondary vitamin A deficiency, which is necessary for epithelial differentiation and binding epidermal growth factor (EGF) to the cell. Still, there is a theory that sex hormones also affect the differentiation of the epidermis, as studies show that deficiency causes effects similar to those caused by hypothyroidism. Some studies indicate the investigation of the relationship between secondary vitamin D deficiency and the increased cellularity of the epidermis of the spayed hypothyroid female rats. Additionally, the mechanism of the formation of hyperkeratosis in hypothyroidism is not yet elucidated. T3 is known to regulate keratin gene expression and perhaps also epidermal maturation, epithelial cycle, and normal keratin synthesis. The single treatment with levothyroxine in the female dog was effective in promoting the restoration of gene expression to T3 in keratinocytes.

Picrosirius red and Masson’s Trichrome staining techniques as tools for detection of collagen fibers in the skin of dogs with endocrine dermatopathologies / Picrosirius red e Tricrômico de Masson como ferramentas para detecção de fibras colágenas em pele de cães com dermatopatologias endócrinas

Canine endocrinopathies, such as hypothyroidism and hyperadrenocortism,induce typical dermatological alterations. Collagen fibers are significant for the maintenance of structural integrity,as well as in the determination of tissue function. This study aimed at assessing the coloration caused by Picrosirius Red staining under circular polarization and Masson Trichrome staining, as tools to quantify the total collagen in the skin of dogs exhibiting endocrine dermatopathies. Skin samples taken from dogs with hypothyroidism and hyperadrenocorticism were stained using Hematoxylin and Eosin (HE), Masson’s Trichrome (MT) and Picrosirius Red (PSR). The animals with hyperadrenocorticism revealed a higher percentage of collagen area than did the animals with hypothyroidism PSRp (hypothyroidism = 43.76 ± 0.8255 and hyperadrenocorticism = 47.08 ± 0.8584). The percentage of the collagen area using MT between the groups is given in parenthesis (hypothyroidism = 52.06 ± 0.9371, hyperadrenocorticism = 61 ± 0.7529 and control = 56.88 ± 0.64) (p <0.05). It is therefore, evident that the special stains employed are useful in estimating the percentage of collagen area in the skin, as they revealed that dogs with hypothyroidism had lower collagen deposition whereas those animals with hyperadrenocorticism showed higher quantity of collagen in the dermis.

Endocrinopatias caninas como hipotireoidismo e o hiperadrenocortismo causam alterações dermatológicas características. As fibras de colágeno desempenham um papel vital na manutenção da integridade estrutural e também na determinação da função dos tecidos. O objetivo deste estudo foi avaliar as colorações de picrosirius red sob polarização circular e coloração tricômio de Masson como ferramentas para quantificar o colágeno total da pele de cães com dermatopatias endócrinas. Amostras de pele obtidas de cães com hipotireoidismo e hiperadrenocorticismo foram coradas por Hematoxilina e Eosina (HE), Tricrômio de Masson (MT) e Picrosirius red (PSR). A porcentagem de área de colágeno foi maior nos animais com hiperadrenocorticismo e menor nos animais com hipotireoidismo PSRp (hipotireoidismo = 43,76 ± 0.8255 e hiperadrenocorticismo = 47,08 ± 0.8584). Já a porcentagem de área de colágeno no MT entre os grupos (hipotireoidismo = 52,06 ± 0.9371, hiperadrenocorticismo = 61 ± 0,7529 e controle = 56,88 ± 0.64) (p <0.05). Concluiu-se que as colorações especiais utilizadas são úteis para avaliar a porcentagem de área de colágeno na pele, pois demonstraram que cães com hipotireoidismo demonstraram uma diminuição na deposição de colágeno e os animais com hiperadrenocorticismo apresentaram maior quantidade de colágeno na derme.

Picrosirius red and Massons Trichrome staining techniques as tools for detection of collagen fibers in the skin of dogs with endocrine dermatopathologies / Picrosirius red e Tricrômico de Masson como ferramentas para detecção de fibras colágenas em pele de cães com dermatopatologias endócrinas

Canine endocrinopathies, such as hypothyroidism and hyperadrenocortism,induce typical dermatological alterations. Collagen fibers are significant for the maintenance of structural integrity,as well as in the determination of tissue function. This study aimed at assessing the coloration caused by Picrosirius Red staining under circular polarization and Masson Trichrome staining, as tools to quantify the total collagen in the skin of dogs exhibiting endocrine dermatopathies. Skin samples taken from dogs with hypothyroidism and hyperadrenocorticism were stained using Hematoxylin and Eosin (HE), Massons Trichrome (MT) and Picrosirius Red (PSR). The animals with hyperadrenocorticism revealed a higher percentage of collagen area than did the animals with hypothyroidism PSRp (hypothyroidism = 43.76 ± 0.8255 and hyperadrenocorticism = 47.08 ± 0.8584). The percentage of the collagen area using MT between the groups is given in parenthesis (hypothyroidism = 52.06 ± 0.9371, hyperadrenocorticism = 61 ± 0.7529 and control = 56.88 ± 0.64) (p <0.05). It is therefore, evident that the special stains employed are useful in estimating the percentage of collagen area in the skin, as they revealed that dogs with hypothyroidism had lower collagen deposition whereas those animals with hyperadrenocorticism showed higher quantity of collagen in the dermis.(AU)

Endocrinopatias caninas como hipotireoidismo e o hiperadrenocortismo causam alterações dermatológicas características. As fibras de colágeno desempenham um papel vital na manutenção da integridade estrutural e também na determinação da função dos tecidos. O objetivo deste estudo foi avaliar as colorações de picrosirius red sob polarização circular e coloração tricômio de Masson como ferramentas para quantificar o colágeno total da pele de cães com dermatopatias endócrinas. Amostras de pele obtidas de cães com hipotireoidismo e hiperadrenocorticismo foram coradas por Hematoxilina e Eosina (HE), Tricrômio de Masson (MT) e Picrosirius red (PSR). A porcentagem de área de colágeno foi maior nos animais com hiperadrenocorticismo e menor nos animais com hipotireoidismo PSRp (hipotireoidismo = 43,76 ± 0.8255 e hiperadrenocorticismo = 47,08 ± 0.8584). Já a porcentagem de área de colágeno no MT entre os grupos (hipotireoidismo = 52,06 ± 0.9371, hiperadrenocorticismo = 61 ± 0,7529 e controle = 56,88 ± 0.64) (p <0.05). Concluiu-se que as colorações especiais utilizadas são úteis para avaliar a porcentagem de área de colágeno na pele, pois demonstraram que cães com hipotireoidismo demonstraram uma diminuição na deposição de colágeno e os animais com hiperadrenocorticismo apresentaram maior quantidade de colágeno na derme.(AU)

Calcinose cutânea associada a Hiperglicocorticoidismo em cão: Relato de Caso / Calcinosis cutis associated to Hyperadrenocorticism in a dog: case report

Cutaneous calcinosis is an uncommon condition where it is mostly shown the deposition ofcalcium in the skin layers, generally associated with by endocrinopathies of the adrenalcortex. Here we report a case of a dog with adrenal gland hyperplasia that developedcalcinosis cutis in a middle-aged dog. In this case, the clinical typical presentation,together with histopathological and ultrasonographical findings were extremely importantin the elucidation.

Calcinose cutânea associada a Hiperglicocorticoidismo em cão: Relato de Caso / Calcinosis cutis associated to Hyperadrenocorticism in a dog: case report

Cutaneous calcinosis is an uncommon condition where it is mostly shown the deposition ofcalcium in the skin layers, generally associated with by endocrinopathies of the adrenalcortex. Here we report a case of a dog with adrenal gland hyperplasia that developedcalcinosis cutis in a middle-aged dog. In this case, the clinical typical presentation,together with histopathological and ultrasonographical findings were extremely importantin the elucidation.(AU)

Hipotireoidismo canino - relato de caso / Canine hypothyroidism - case report

Hypothyroidism is an endocrine disease more diagnosed in dogs. The clinical signs most found are lethargy, weight gain, coat coarse and scanty, nonpruritic alopecia and cold intolerance. In this study, we aimed to report a case of canine hypothyroidism in order to clarify important points of this disease, thus contributing to future diagnosis of similar cases. A bitch of 6-year-old was taken to the vet presenting overweight, exercise intolerance, coat coarse, excess of coat loss and hyperpigmentation of skin. Based on exams accomplished as free T4 measurement was diagnosed hypothyroidism and instituted treatment was l-thyroxine indose rate of 11 μg/kg twice daily.

Tríade felina: relato de caso / Feline triaditis: case report

Feline triaditis is the combination of cholangitis, pancreatitis and inflammatory bowel disease (IBD) in cats. The present study was aimed to report the case of feline triaditis highlighting the importance of a proper and effective clinical approach. A queen of 4 years old was taken to the veterinarian presenting lethargy, depression, dehydration and weight loss. It was required a complete blood count, biochemical testing, an abdominal ultrasound and an exploratory laparotomy. Based on exams accomplished was diagnosed feline triad and instituted treatment was fluid therapy and administration of analgesics, nutraceutical and hypoallergenic diet.

Hipotireoidismo canino - relato de caso / Canine hypothyroidism - case report

Hypothyroidism is an endocrine disease more diagnosed in dogs. The clinical signs most found are lethargy, weight gain, coat coarse and scanty, nonpruritic alopecia and cold intolerance. In this study, we aimed to report a case of canine hypothyroidism in order to clarify important points of this disease, thus contributing to future diagnosis of similar cases. A bitch of 6-year-old was taken to the vet presenting overweight, exercise intolerance, coat coarse, excess of coat loss and hyperpigmentation of skin. Based on exams accomplished as free T4 measurement was diagnosed hypothyroidism and instituted treatment was l-thyroxine indose rate of 11 μg/kg twice daily.(AU)

Tríade felina: relato de caso / Feline triaditis: case report

Feline triaditis is the combination of cholangitis, pancreatitis and inflammatory bowel disease (IBD) in cats. The present study was aimed to report the case of feline triaditis highlighting the importance of a proper and effective clinical approach. A queen of 4 years old was taken to the veterinarian presenting lethargy, depression, dehydration and weight loss. It was required a complete blood count, biochemical testing, an abdominal ultrasound and an exploratory laparotomy. Based on exams accomplished was diagnosed feline triad and instituted treatment was fluid therapy and administration of analgesics, nutraceutical and hypoallergenic diet.(AU)