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.

Minimum dose of levothyroxine restored the autonomic balance on a Dalmatian female dog with primary hypothyroidism

Background: Hypothyroidism is an endocrine disease that leads to a reduction in the hormones thyroxine (T3) and triiodothyronine (T4), which therapy with levothyroxine restores the clinical signs related to the metabolic rate. Due to the influence of thyroid hormones on the heart, which is under the constant influence of the autonomic nervous system (ANS), dogs with hypothyroidism can develop bradycardia, arrhythmia, and dysautonomia. Heart rate variability (HRV) assesses autonomic modulation by the Holter method, which is scarce in dogs. We aimed to report the cardiac and autonomic effects of the primary hypothyroidism untreated and treated with levothyroxine in a canine case by Holter monitoring. Case: A 7-year-old female Dalmatian, weighing 36 kg, was referred for clinical evaluation due to apathy, weight gain, low hair quality, and lethargy. On physical examination, alopecic lesions on the hind limbs and tail, as well as bradycardia with a heart rate (HR) of 40-50 beats per minute (bpm) were observed, in addition to a 3/6 mitral murmur and 2/6 tricuspid murmur. Given the suspicion of thyroid gland disorder, the blood hormonal measurement revealed an increase in thyroidstimulating hormone (TSH; 0.65 ng/mL) and a decrease in free T4 (0.11 ng/mL) and total T4 (0.44 ng/mL), confirming primary hypothyroidism. Therapy was started with a minimum dose of levothyroxine (0.913 mg, every 12 h), which clinical signs were restored in 5 months of treatment, with weight loss, hair growth, and active behavior. To assess the impact of untreated and treated hypothyroidism on the patient’s ANS, a Holter monitoring exam was performed for 24 h before and after therapy. Before treatment, the average HR was 75 bpm, and the HR2.0s), 1st-degree atrioventricular blocks (AVB), six...

Minimum dose of levothyroxine restored the autonomic balance on a Dalmatian female dog with primary hypothyroidism

Background: Hypothyroidism is an endocrine disease that leads to a reduction in the hormones thyroxine (T3) and triiodothyronine (T4), which therapy with levothyroxine restores the clinical signs related to the metabolic rate. Due to the influence of thyroid hormones on the heart, which is under the constant influence of the autonomic nervous system (ANS), dogs with hypothyroidism can develop bradycardia, arrhythmia, and dysautonomia. Heart rate variability (HRV) assesses autonomic modulation by the Holter method, which is scarce in dogs. We aimed to report the cardiac and autonomic effects of the primary hypothyroidism untreated and treated with levothyroxine in a canine case by Holter monitoring. Case: A 7-year-old female Dalmatian, weighing 36 kg, was referred for clinical evaluation due to apathy, weight gain, low hair quality, and lethargy. On physical examination, alopecic lesions on the hind limbs and tail, as well as bradycardia with a heart rate (HR) of 40-50 beats per minute (bpm) were observed, in addition to a 3/6 mitral murmur and 2/6 tricuspid murmur. Given the suspicion of thyroid gland disorder, the blood hormonal measurement revealed an increase in thyroidstimulating hormone (TSH; 0.65 ng/mL) and a decrease in free T4 (0.11 ng/mL) and total T4 (0.44 ng/mL), confirming primary hypothyroidism. Therapy was started with a minimum dose of levothyroxine (0.913 mg, every 12 h), which clinical signs were restored in 5 months of treatment, with weight loss, hair growth, and active behavior. To assess the impact of untreated and treated hypothyroidism on the patients ANS, a Holter monitoring exam was performed for 24 h before and after therapy. Before treatment, the average HR was 75 bpm, and the HR<50 bpm occurred during 05 h 20 min 36 s. Still, 320 pause events (>2.0s), 1st-degree atrioventricular blocks (AVB), six...(AU)

Complicações de urolitíase por oxalato de cálcio em cão uretrostomisado – Relato de Caso / Complications of calcium oxalate urolithiasis in a urethrosed dog - Case report

The present study aims to report a male canine patient with calcium oxalate urolithiasis,who suffered complications of perineal urethrostomy. Cases of urolithiasis frequentlypresent in dogs, however, their complications are rarely mentioned in the literature,especially when the therapeutic protocol fails.

Complicações de urolitíase por oxalato de cálcio em cão uretrostomisado Relato de Caso / Complications of calcium oxalate urolithiasis in a urethrosed dog - Case report

The present study aims to report a male canine patient with calcium oxalate urolithiasis,who suffered complications of perineal urethrostomy. Cases of urolithiasis frequentlypresent in dogs, however, their complications are rarely mentioned in the literature,especially when the therapeutic protocol fails.(AU)

Diagnóstico de cistite em cães : contribuição dos métodos de avaliação

Os cães podem ser acometidos por diversos tipos de doenças vesicais incluindo cistites, neoplasias e urolitíases, dentre outras. A variedade da etiopatogenia e das formas de apresentação clínica das cistites constitui um fator complicante para o diagnóstico. O presente estudo teve por objetivo evidenciar a importância da inclusão de alguns exames complementares com vistas ao diagnóstico correto das afecções vesicais. Foi realizado um estudo prospectivo para o diagnóstico da condição vesical de 46 animais, machos e fêmeas, selecionados ao acaso dentre os encaminhados para check-up de rotina e os pacientes com algum tipo de sinal ou achado sugestivo de doença vesical. A avaliação consistiu de exame clínico completo e exame específico do trato urinário incluindo urinálise, exame microbiológico da urina por meio de cultura em lâmina e cultura tradicional, e avaliação vesical por meio do exame ultrassonográfico. Os dados foram submetidos à analise estatística descritiva e ao Teste Exato de Fisher para associações. Os resultados evidenciaram que os sinais clínicos e os achados de sedimentoscopia da urina não são específicos, dada a semelhança das manifestações das diversas doenças vesicais. A urocultura e a ultrassonografia vesical foram exames complementares decisivos que possibilitaram o diagnóstico dos casos de cistite bacteriana (n=32) bem como das doenças vesicais coexistentes (n=3) e das doenças vesicais não infecciosas (n=2). Concluiu-se que o exame clínico de rotina, mesmo que a urinálise seja incluída, não é apropriado para diagnosticar doenças vesicais e que a urocultura e o exame ultrassonográfico contribuem de modo decisivo para o diagnóstico correto dos cães com ou sem sinais clínicos de cistite

Dogs can be affected by several types of bladder diseases including cystitis, neoplasia, and urolithiasis, among others. The variety of etiopathology and clinical presentation forms of cystitis is a complicating factor for the diagnosis. The aim of this study was to show the importance of some additional exams inclusion in order to achieve the correct diagnosis for bladder diseases. A prospective study was conducted for bladder condition diagnosis in 46 animals, males and females, taken for random among dogs referred for routine checkup and the patients with some type of signs or finding suggestive of bladder disease. The evaluation included complete clinical exam and specific examination of the urinary tract including urinalysis, urine microbiologic examination by commercially manufactured screening urine culture kit and traditional culture, and ultrasound bladder evaluation. The data were analyzed by descriptive statistic and Fisher?s Exact Text. The results showed that clinical signs and urine sediment findings are nonspecific, given the similarity of the bladder diseases manifestations. The urine culture and bladder ultrasound were decisive additional exams that enable the diagnosis of bacterial cystitis (n=32), as well as of the coexisting bladders diseases (n=3) and non infectious bladder diseases (n=2). It was concluded that the routine clinical examination, even when the urinalysis is included, isn`t appropriated for bladder diseases diagnosis, moreover the urine culture and the ultrasonographyc exam contribute in a decisive way for the correct diagnosis of dogs showing or not clinical signs of cystitis