Diagnosis of congenital and adult-onset hypothyroidism in cats

Whereas hyperthyroidism is the most common endocrine disorder in the cat, hypothyroidism is the least common feline endocrine disorder. This is a the result of several factors including low index of suspicion, rarity of the naturally occurring hypothyroidism in cats, and a lack of species specific tests for endogenous TSH and antithyroglobulin antibodies. Nonetheless, hypothyroidism does occur in cats, especially in kittens and after radioactive treatment for hyperthyroidism. The clinician should become familiar with the common presentations of congenital and adult-onset hypothyroidism in cats. In addition, some of the tests specific to dogs (such as endogenous canine TSH) may be utilized to diagnose subclinical hypothyroidism in cats. Fortunately, the treatment of feline hypothyroidism with synthetic levothyroxine is both straightforward and effective.     

铅对骨骼毒性的作用机制研究进展

铅（plumbum,Pb）在自然界中广泛分布,铅及其多数化合物是一种不可降解的环境污染物,可通过废水、废气、废渣大量流入环境,产生环境污染及健康危害。随着都市化、现代化进程的加快,铅已经成为生活中最常见的化学污染物。近年来,铅与骨骼方面的疾病越来越受到人们的关注,铅对骨骼损伤机理的相关研究也不断深入。资料表明,铅对骨骼的毒性可能是通过损伤内分泌器官而间接影响激素合成干扰钙磷代谢和影响骨矿物代谢,阻碍骨骼发育或通过毒化细胞和影响钙信使系统活性部位中的钙而直接干扰骨细胞的功能。文章就铅对钙磷代谢、碱性磷酸酶和骨钙素及成骨细胞凋亡相关基因表达的影响进行了综述,为生产实践和研究提供参考资料。     

哺乳动物妊娠期钙代谢的研究进展

哺乳动物体内的钙代谢通常包括钙平衡和钙稳态。钙平衡是指体内总钙含量保持相对恒定的状态,钙稳态则指细胞内外的钙离子浓度保持稳定。肾脏、肠道、骨骼及雌性动物乳腺是动物体钙代谢的主要器官,其中存在着许多精细而复杂的调控网络。妊娠期钙代谢紊乱会严重影响母畜及胎儿的营养健康,维持体内钙代谢稳态对围产期哺乳动物尤为重要。本文综合近年来国内外妊娠期哺乳动物钙代谢相关研究,从不同组织器官钙代谢情况及钙代谢过程中重要的调节因子的调控作用进行综述,旨在为妊娠期哺乳动物钙代谢调控相关研究提供思路。     

The diagnostic value of alkaline phosphatase in canine medicine: a review

This paper describes the structure, functions, distribution and normal values of alkaline phosphatase (AP) and its isoenzymes in canine tissues and serum. The diagnostic value of the enzyme is discussed in liver and bone disease, neoplasia, and endocrine disorders including hyperadrenocor-ticalism, diabetes mellitus, hypothyroidism and hyperparathyroidism. The effects of therapy with glucocorticoids, anticonvulsants and tolbutamide on serum AP are described. At present, AP is of the greatest diagnostic value in liver, bone and endocrine disease in the dog but its use in neoplastic conditions and in intestinal and renal disease has yet to be fully investigated.     

Equine thyroid dysfunction.

Hypothyroidism is the most common type of thyroid gland dysfunction reported in horses. Primary, secondary, and tertiary causes of hypothyroidism are discussed. Equine hypothyroidism remains a controversial endocrine disorder because extrathyroidal factors, including the administration of drugs and systemic diseases, affect serum triiodothyronine (T3) and thyroxine (T3) concentrations in horses. Accurate diagnosis of hypothyroidism therefore requires assessment of the hypothalamic-pituitary-thyroid axis. Diagnostic procedures for evaluating thyroid gland function are outlined and results of studies utilizing experimental models are discussed.     

Calcium metabolism in birds.

Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.     

成纤维细胞生长因子23在骨矿物质代谢中的作用及其调控机理

骨源性激素成纤维细胞生长因子23(FGF23)介导由甲状旁腺、肾脏、骨骼和维生素D组成的负反馈回路,建立"骨骼-肾脏-甲状旁腺"内分泌轴,参与骨矿物质代谢并发挥重要作用。钙、磷、铁、维生素D、甲状旁腺素(PTH)、成纤维细胞生长因子受体(FGFR)/FGF以及蛋白质翻译后修饰调控FGF23的分泌、活性和胞内过程。随着深入的研究,探索出了一些以FGF23为靶点治疗骨矿物质代谢障碍疾病的新疗法。本文综述了FGF23在骨矿物质代谢中的作用及其调控机理的研究进展,以期为相关研究提供参考依据。     

Diagnosis and treatment of gastric motility disorders.

A disorder of gastric motility should be suspected in patients with chronic vomiting. Imaging studies are used to confirm delayed gastric emptying, the most common form of a gastric motility disorder. Other causes of chronic vomiting, for example, metabolic or endocrine disorders, other abdominal disorders, mechanical causes of gastric obstruction, and lower gastrointestinal tract disease, are then ruled out. If no underlying cause is determined, a functional disorder of gastric emptying is presumptively diagnosed. Treatment consists of dietary management and gastric prokinetic agents. Cisapride is the drug of choice for treating delayed gastric emptying followed by erythromycin and ranitidine or nizatidine.     

Canine hypothyroidism: a review of aetiology and diagnosis

Hypothyroidism is recognised as an important endocrine disorder of dogs, and a frequent differential for numerous presenting complaints. Its diagnosis has never been straight forward as results suggestive of hypothyroidism can occur for a variety of reasons in dogs with normal thyroid function (euthyroid). As a consequence, the accurate investigation of hypothyroidism has been hindered by the potential inclusion of a number of cases not truly hypothyroid. In recent years, the development of newer diagnostic tests, e.g. free thyroxine, canine thyroid stimulating hormone, thyroglobulin autoantibodies, has significantly improved our ability to reliably differentiate hypothyroidism from other clinically similar disorders. This has led to a marked increase in our knowledge of the phenotypic, genotypic and aetiological aspects of this disorder in dogs.     

Metabolic and toxic causes of canine seizure disorders: A retrospective study of 96 cases

A wide variety of intoxications and abnormal metabolic conditions can lead to reactive seizures in dogs. Patient records of dogs suffering from seizure disorders (n = 877) were reviewed, and 96 cases were associated with an underlying metabolic or toxic aetiology. These included intoxications by various agents, hypoglycaemia, electrolyte disorders, hepatic encephalopathy, hypothyroidism, uraemic encephalopathy, hypoxia and hyperglycaemia. The incidence of the underlying diseases was determined.The most common causes of reactive seizures were intoxications (39%, 37 dogs) and hypoglycaemia (32%, 31 dogs). Hypocalcaemia was the most frequent electrolyte disorder causing reactive seizures (5%) and all five of these dogs had ionised calcium concentrations ?0.69 mmol/L. Eleven per cent of dogs with seizures had metabolic or toxic disorders and this relatively high frequency emphasises the importance of a careful clinical work-up of cases presented with seizures in order to reach a correct diagnosis and select appropriate treatment options.     

Conditions associated with canine hypothyroidism.

Careful review of the literature regarding clinical signs caused by hypothyroidism in dogs has shown that some assumptions regarding the relation of hypothyroidism to other conditions are based on anecdotal evidence. Cutaneous manifestations are present in most hypothyroid dogs, but the specific abnormalities and breed variations remain to be clearly defined. Decreased metabolic rate manifested by obesity and lethargy is also common. Neurologic manifestations, although uncommon, clearly occur in hypothyroid dogs. Cardiac abnormalities seem to be common, but their clinical significance is questionable. The only consistent hematologic abnormality that occurs in hypothyroid dogs is anemia; evidence for acquired von Willebrand's disease or other bleeding disorders is negligible. Reproductive dysfunction secondary to hypothyroidism is unlikely to occur in male dogs, and there is no evidence to support abnormalities in female dogs. The relation of megaesophagus, laryngeal paralysis, ocular abnormalities, and gastrointestinal disorders with hypothyroidism remains to be established. Future research into canine hypothyroidism may serve to convert dogma into a more clear understanding of the manifestations and pathophysiologic findings of this common endocrinopathy.     

Lipid metabolism and hyperlipidemia in dogs

Lipid metabolism in dogs can be divided into exogenous and endogenous pathways and exhibits some unique characteristics compared to other species. Hyperlipidemia is common in dogs, and can be either primary or secondary to other diseases. Secondary hyperlipidemia is the most common form and can be a result of endocrine disorders, pancreatitis, cholestasis, protein-losing nephropathy, obesity, and high fat diets. Primary hyperlipidemia is less common and usually associated with certain breeds. Hypertriglyceridemia of Miniature Schnauzers is the most common type of primary hyperlipidemia in dogs in the United States, and appears to have a genetic basis although its etiology remains unknown. Possible complications of canine hyperlipidemia include pancreatitis, liver disease, atherosclerosis, ocular disease, and seizures. Management is achieved by administration of low fat diets with or without the administration of lipid-lowering agents such as omega-3 fatty acids, gemfibrozil, and niacin.     

Congenital hypothyroidism of dogs and cats: a review

Congenital hypothyroidism is a rare and underdiagnosed congenital endocrine disorder in dogs and cats and the true incidence is unknown. The disorder may cause a range of clinical signs depending on the primary defect, which affect production of thyroid hormones; some cases present when adult. Hallmark clinical signs of congenital hypothyroidism are mental impairment and skeletal developmental abnormalities, resulting in disproportionate dwarfism; goitre may or may not be present. Documented causes of congenital hypothyroidism in dogs include deficiency of, or unresponsiveness to, thyrotropin-releasing hormone (TRH) or thyroid-stimulating hormone (TSH), thyroid dysgenesis, dyshormonogenesis and iodine deficiency. In cats, TSH unresponsiveness, thyroid dysgenesis, dyshormonogenesis and iodine deficiency have been confirmed. Adequate replacement therapy results in a successful outcome in the majority of cases, especially when started early in life, as permanent developmental abnormalities can be prevented. This review describes reported cases in dogs and cats, diagnostic investigation, and recommendations for treatment.     

Clinical signs and concurrent diseases of hypothyroidism in dogs and cats.

Canine hypothyroidism may present with a wide range of clinical signs. The most common clinical signs are those of a decreased metabolic rate and dermatologic manifestations; however, many other clinical signs have been associated with hypothyroidism. There is strong evidence for a causal relation between hypothyroidism and a variety of neurologic abnormalities; however, the association between hypothyroidism and other manifestations, such as reproductive dysfunction, clinical heart disease, and behavioral abnormalities, is less compelling. Further studies are necessary to determine the full spectrum of disorders caused by hypothyroidism.     

Autoantibodies to pancreatic islet cells in canine diabetes mellitus

Indirect immunofluorescence on normal canine pancreatic tissue fixed in Bouin's solution was used to detect islet cell antibodies in dogs with diabetes mellitus, other endocrine diseases, and pancreatitis. 18 of 25 dogs with diabetes mellitus alone, 2 of 8 dogs with diabetes mellitus and concurrent pancreatitis, and 2 of 2 dogs with diabetes mellitus and concurrent pancreatic exocrine insufficiency were positive for autoantibody. 2 of 12 dogs with hypoadrenocorticism, 3 of 6 dogs with hyperadrenocorticism, 6 of 28 dogs with hypothyroidism and one of 19 dogs with pancreatitis alone were also antibody positive. None of 20 healthy dogs or 20 dogs with disorders other than those of the pancreas or endocrine organs were antibody positive. Islet cell antibodies were demonstrated in dogs with diabetes mellitus and other endocrine disorders. The possibility of autoimmune involvement in the development of diabetes mellitus in the dog should be considered.     

钙缺乏对蛋鸭血清骨代谢指标的影响

为了观察钙缺乏对蛋鸭骨代谢的影响,探讨钙缺乏性骨病发生的机理,将120只600日龄产蛋山麻鸭随机分为正常日粮组、1/2石粉组和1/4石粉组,连续饲养12周。结果发现钙缺乏可导致蛋鸭血清骨钙素水平下降,骨碱性磷酸酶(BALP)水平升高,Ⅰ型羧基端末肽(CTX-Ⅰ)水平升高。认为钙缺乏通过影响相关骨代谢因子分泌,使骨形态结构发生异常改变,最终导致骨骼矿化障碍。     

钙磷代谢对动物骨骼健康影响的研究进展

骨骼构成机体结构的基本框架,骨形成和骨吸收的动态平衡关系到骨骼健康。钙和磷是动物体骨骼生长发育过程中重要的矿物质元素,机体对其吸收与调控直接影响骨代谢过程。血钙和血磷水平的变化,改变了机体相关调节激素的分泌,而这些激素可影响骨骼发育,因此,钙、磷代谢与骨骼健康紧密相关。综合国内外钙、磷代谢和骨代谢等方面的研究,从钙、磷的吸收和代谢,含量和比例以及钙磷代谢相关调节激素对骨骼发育的调控机制等方面进行综述,旨在为后续动物钙、磷代谢和骨骼之间调控的研究提供参考。     

PRE- AND POST-TREATMENT ULTRASONOGRAPHY IN HYPOTHYROID DOGS

Primary hypothyroidism is a frequent endocrine disorder in the adult dog. However, false-positive diagnoses are common because of the relatively low accuracy of most commonly used biochemical tests. The purpose of this study was to describe the ultrasonographic features of the thyroid gland in hypothyroid dogs, to calculate the diagnostic sensitivity of gray-scale ultrasound using a combination of clinical symptoms and biochemical thyroid tests as gold standard, and to investigate the evolution of the ultrasonographic features after treatment of hypothyroidism. Eighteen dogs were studied prospectively. All dogs underwent an ultrasound examination at first presentation and 13 underwent one or two additional ultrasound examinations over time. At first presentation, a sensitivity of 76.5% (95% CI [50.0-93.0% 1) for decreased echogenicity, 64.7% (95% CI [38.385.8% 1) for inhomogeneity, 70.6% (95% CI 144.0-89.7%]) for irregular capsule delineation, 64.7% (95% CI [38.3-85.8%]) for abnormal lobe shape and 47.1% (95% CI 123.0-72.2%]) for decreased relative thyroid volume was obtained. Combining these five parameters together resulted in an overall sensitivity of 94.1% (95% CI [71.3-99.9%]) for gray-scale ultrasound in the detection of acquired hypothyroidism at first presentation. A continuous decrease of thyroid volume was seen over time after treatment, while the other investigated parameters did not change significantly during the follow-up period. None of the thyroid glands were considered normal at the last presentation. Grayscale ultrasound is a sensitive and quick test for the diagnosis of primary hypothyroidism in dogs.     

Long-term effects of dietary anion-cation balance on acid-base status and bone morphology in reproducing ewes

The beneficial effects of anionic salts on calcium metabolism have been shown by supplementing rations with such salts during the last 3 weeks of pre-partum. However, there are few reports on the effects of anionic salts supplementation for periods of 4 weeks or longer on acid-base status, mineral metabolism and bone morphology. This study was conducted to evaluate the effects of the long-term dietary supplementation of anionic salts on the acid-base status, plasma minerals concentrations and bone morphology in sheep. Twenty-seven twin-bearing sheep were assigned to two experimental groups and a control group, depending on dietary cation-anion difference (DCAD) (+272.6, -88.9 and + 164.5 mEq/kg DM, respectively). Sheep assigned to each dietary treatment received their respective rations beginning 6 weeks prepartum and continuing until 12 days post-partum. Diets containing anionic salts induced a mild metabolic hyperchloraemic acidosis from 1 week pre-partum to 2 days post-partum that was completely compensated by non-respiratory mechanisms. These changes on acid-base status were accompanied by an increase of plasma ionized calcium levels. Plasma total calcium, phosphorus and magnesium concentrations were not affected by dietary treatment. Parathyroid hormone concentrations were related to the concentration of ionized calcium of plasma and were higher in sheep fed the cationic diet. Plasma osteocalcin levels were increased in sheep fed the anionic diet and cortical bone remodelling occurred in all the animals during late pregnancy in light and electron microscopy observation, but was particularly evident in the sheep fed the anionic diet. Bone turnover might be stimulated because of the role of the bone in buffering systemic acidosis. The data suggest that anionic salts ameliorated calcium metabolism around parturition by increasing bone resorption and the concentration of ionised calcium in plasma, possibly mediated by a mild hyperchloraemic metabolic acidosis induced by the salts.     

Hormonal regulation and calcium metabolism in the rabbit.

Calcium is an important mineral in homeostasis in all vertebrate animals. It is the most abundant mineral in the body, and is the major component of bones and teeth. In addition, calcium is involved in various vital physiologic processes, including blood coagulation, muscle contraction, membrane permeability, nerve conduction, enzyme activity, and hormone release. Calcium metabolism in the rabbit differs in several respects from that of most mammals. This article discusses calcium metabolism and its hormonal regulation in the rabbit, as compared with normal calcium metabolism in other mammalian species. Medical disorders associated with this unique metabolism are introduced briefly.