Alkaline phosphatase reaction in hair follicles of male beagle dogs during hair cycle stages.

The literature reviewed has revealed differences of opinion concerning the location of alkaline phosphates and its relationship to the hair cycle stages. This project was undertaken to determine alkaline phosphatase activity in the hair follicle stages: anagen, catagen, and telogen. Skin biopsy samples were collected over a period of 1 year from 9 purebred male Beagle dogs. At the beginning of the experiment 3 dogs were 2 weeks of age, 3 dogs were 12 months of age and 3 dogs were 21 months of age. The skin biopsies were taken monthly from alternate sides of each animal near the thoracolumbar region. Samples were fixed in 80% chilled alcohol and the alkaline phosphatase activity was determined by Gomori's calcium cobalt method. A total of 250 slides with seven sections per slide was examined. Each slide contained between 14–60 hair follicles. During anagen stage, the reaction of the dermal papilla for the presence of alkaline phosphatase was variable. A weak or negative reaction was observed in this study which was an unexpected finding. The reaction of the dermal papilla to alkaline phosphatase was positive in catagen stage. The cells of the dermal papillae in telogen stage were strongly alkaline phosphatase positive. The reaction was not confined to the blood vessels but occurred in all parts of the dermal papilla in both early and late stages.     

Histology of the hair cycle in male beagle dogs

A detailed histologic study of the hair follicles of male Beagle dogs was made to determine changes in microscopic structure associated with the three stages in the hair cycle. Observed changes are that the bulbs of hair follicles in anagen are more closely associated with adipose tissue than they are in telogen. This is due to the deeper penetration of the follicles into the subcutaneous tissue during anagen. The hair germ cells of telogen were presumed to arise from the stratum basale of the matrix cells rather than from the outer root sheath cells. During telogen, the dermal papilla is separated from the club hair, but remains in close proximity to it. There is no connecting stalk as is reported for other animals.     

Exercise-induced hyperkalemia in hypothyroid dogs

We investigated the effect of hypothyroidism in dogs on (1) the Na+-, K+ -ATPase concentration in skeletal muscle, and (2) potassium (K+) homeostasis at rest and during exercise. Prior to and 1 year after induction of hypothyroidism by surgery and subsequent radiothyroidectomy, the Na+-, K+ -ATPase concentrations were quantified in biopsies of sternothyroid muscles of seven Beagle dogs by measuring [3H]ouabain binding capacity. In addition, plasma K+ concentrations were measured at rest and after treadmill exercise in six hypothyroid and seven euthyroid Beagle dogs. During hypothyroidism, the mean Na+ -, K+ -ATPase concentration in muscle biopsies was 41% lower than during euthyroidism. The mean resting plasma K+ value of the hypothyroid dogs was significantly (14%) higher than that of the euthyroid dogs. In the hypothyroid dogs, plasma K+ concentration increased significantly during exercise, whereas there was no rise in the euthyroid dogs. The rise in plasma K+ concentration could not be ascribed to muscle damage, as plasma creatine kinase concentrations remained within reference range. Also renal K+ retention was an unlikely explanation, as plasma aldosterone concentration and plasma renin activity rather increased than decreased during exercise. In conclusion, hypothyroid dogs tend to develop hyperkalemia during exercise, which for a large part can be explained by the severe reduction of the Na+ -, K+ -ATPase capacity in the skeletal muscle pool.     

The phase of hair growth in hypothyroidism in the dog

The stage of hair growth which predominated in dogs not affected with hypothyroidism appeared to be breed-dependent. For example, in boxers, Labradors and collies, the resting stage (telogen) predominated, whereas in West Highland White terriers and cairn terriers the active stage (anagen) predominated. However, even in pet dogs kept mainly indoors, the proportion of hairs in anagen tended to increase during the winter months.In dogs affected with hypothyroidism, the proportion of hairs in anagen or telogen in members of a particular breed was the same as in the normal dogs of the breed. From this, it appeared that breed was more influential than hypothyroidism in determining the predominant phase of hair growth.     

The canine hair cycle - a guide for the assessment of morphological and immunohistochemical criteria

The hair follicle has a lifelong capacity to cycle through recurrent phases of controlled growth (anagen), regression (catagen) and quiescence (telogen), each associated with specific morphological changes. A comprehensive classification scheme is available for mice to distinguish the cycle stages anagen I-VI, catagen I-VIII and telogen. For dogs, such a classification system does not exist, although alopecia associated with hair cycle arrest is common. We applied analogous morphological criteria and various staining techniques to subdivide the canine hair cycle stages to the same extent as has been done in mice. Of all the staining techniques applied, haematoxylin and eosin stain, Sacpic, Masson Fontana and immunohistochemistry for vimentin and laminin proved to be most useful. To evaluate the applicability of our criteria, we investigated skin biopsies from healthy beagle dogs (n=20; biopsies from shoulder and thigh) kept in controlled conditions. From each biopsy, at least 50 hair follicles were assessed. Statistical analysis revealed that 30% of the follicles were in anagen (12% early and 18% late), 8% in catagen (2% early, 5% late and 1% not determinable) and 27% in telogen. Thirty-five per cent of hair follicles could not be assigned to a specific cycle stage because not all follicles within one biopsy were oriented perfectly. In conclusion, this guide will not only be helpful for the investigation of alopecic disorders and possibly their pathogenesis, but may also serve as a basis for research projects in which the comparison of hair cycle stages is essential, e.g. comparative analysis of gene expression patterns.     

Serum thyroid hormone concentrations and thyrotropin responsiveness in dogs with generalized dermatologic disease.

Fifty-eight dogs with generalized dermatologic disease that had not been given glucocorticoids systemically or topically within 6 weeks of entering the study were evaluated for thyroid function by use of the thyrotropin-response test. Dogs were classified as euthyroid or hypothyroid on the basis of test results and response to thyroid hormone replacement therapy. Baseline serum thyroxine (T4), free T4 (fT4), and triiodothyronine (T3) concentrations were evaluated in the 58 dogs. Serum T4, fT4, and T3 concentrations were evaluated in 200 healthy dogs to establish normal values. Hormone concentrations were considered low if they were less than the mean -2 SD of the values for control dogs. Specificity of T4 and fT4 concentrations was 100% in predicting hypothyroidism; none of the euthyroid dogs with generalized skin disease had baseline serum T4 or fT4 concentration in the low range. Sensitivity was better for fT4 (89%) than for T4 (44%) concentration. Significant difference was not observed in serum T4 and fT4 concentrations between euthyroid dogs with generalized skin disease and healthy control dogs without skin disease. Serum T3 concentration was not accurate in predicting thyroid function; most of the euthyroid and hypothyroid dogs with skin disease had serum T3 concentration within the normal range.     

Influence of inflammation and coat type on oestrogen receptor immunohistochemistry

The purpose of this study was to evaluate oestrogen receptor alpha staining in a variety of breeds and skin conditions. The influence of inflammation and coat type on the presence and intensity of oestrogen receptor alpha staining was evaluated. Approximately 1700 haematoxylin and eosin (H&E)-stained slides of skin biopsies were screened for presence of small hair bulbs. Slides from 94 cases were submitted for oestrogen receptor alpha immunohistochemistry. H&E-stained skin biopsy tissues were examined for inflammation and hair follicle stages. Oestrogen receptor alpha staining characteristics of telogen follicles, flame follicles, large anagen bulbs, small hair bulbs and early anagen hairs (capped bulbs) were recorded. To assess the influence of inflammation and coat type on oestrogen receptor staining of hair follicle types, chi-square tests, Fisher's exact tests and logistic regression models were performed. Slides were classified as inflammatory (65) and noninflammatory (29). There were no statistically significant differences in oestrogen receptor staining when comparing inflammatory to noninflammatory skin biopsies or skin biopsies from dogs with different coat types. A subset of 13 noninflammatory biopsies from alopecic skin was identified. There was a statistically significant increase in the number of flame follicles in this subset as compared to all others. Comparison of oestrogen receptor staining of hair follicle types from these biopsies and all other biopsies revealed a statistically significant increase in the number of mature telogen hair follicles stained in this subset. No statistical difference in staining of early follicle stages was noted. Therefore, the oestrogen receptor is unlikely to be the controlling factor for the transition from telogen to anagen in the dog.     

Thyroid sonography as an effective tool to discriminate between euthyroid sick and hypothyroid dogs

The diagnosis of canine hypothyroidism and its differentiation from euthyroid sick syndrome still is a major diagnostic challenge. In this study, ultrasonography was shown to be an effective tool for the investigation of thyroid gland diseases. Healthy control dogs (n = 87), dogs with euthyroid sick syndrome (n = 26), thyroglobulin autoantibody-positive (TgAA-positive, n = 30) hypothyroid dogs, and TgAA-negative (n = 23) hypothyroid dogs were examined by thyroid ultrasonography. Maximal cross sectional area (MCSA), thyroid volume, and echogenicity were measured. Statistical analysis identified highly significant (P < .001) differences between euthyroid and hypothyroid dogs both in thyroid volume and in MCSA, whereas no significant differences in thyroid size were detected between healthy euthyroid dogs and dogs with euthyroid sick syndrome. In euthyroid and euthyroid sick dogs, parenchymal echotexture was homogeneous and hyperechoic, whereas relative thyroid echogenicity of both TgAA-positive and TgAA-negative hypothyroid dogs was significantly lower (P < .001). When using arbitrarily chosen cutoff values for relative thyroid volume, MCSA, and echogenicity, thyroid volume especially was found to have highly specific predictive value for canine hypothyroidism. In summary, the data reveal that thyroid sonography is an effective ancillary diagnostic tool to differentiate between canine hypothyroidism and euthyroid sick syndrome.     

Thyroid-Stimulating Hormone Stimulation Tests in Cardiomyopathic Doberman Pinschers: A Retrospective Study

Thyroid-stimulating hormone (TSH) response tests were performed in 152 Doberman Pinschers. Seventy-nine dogs had cardiomyopathy (46 were in congestive heart failure [CHF] and 33 were not in CHF). Seventy-three dogs were presented for noncardiac problems (15 with skin disease, 21 with neurologic disease, 20 with internal medicine disorders, and 17 with other problems), although some may have had cardiomyopathy. The TSH response test results in the cardiomyopathic group were interpreted as normal or euthyroid-sick in 45 (57%) dogs, abnormal in 23 (29%) dogs, and equivocal in 11 (14%) dogs. The prevalence of hypothyroidism in the CHF and non-CHF cardiomyopathy groups was not different. Among the dogs presented for noncardiac problems, 27 (37%) were assessed as normal or euthyroid-sick, 29 (40%) as hypothyroid, and 17 (23%) as equivocal. No significant differences were found in the prevalence of hypothyroid test results among the subgroups of these dogs. The prevalence of hypothyroidism was not higher in the cardiomyopathic group compared to the other group, and 63 and 49% of cardiomyopathic dogs with or without CHF, respectively, tested as either euthyroid or euthyroid-sick.     

辽宁绒山羊2品系皮肤毛囊周期性变化的比较研究

皮肤切片采用HE染色方法,对辽宁绒山羊常年长绒型品系和季节长绒型品系皮肤表皮厚、真皮厚、次级毛囊和初级毛囊深度、密度,次级毛囊和初级毛囊毛球宽度,S／P值等作了详细统计观察,从形态学方面研究了辽宁绒山羊皮肤毛囊在1年内的变化规律。结果表明：两品系辽宁绒山羊毛囊的兴盛期为4～10月,退行期为11～12月,休止期为1～3月,持续时间分别为7、2、3个月。兴盛期经历时间最长,退行期最短。但在毛囊的退行期,因为大多数毛囊的活性还很高,因此在退行期绒毛仍在生长,特别是在退行前期（10、11月份）还是绒毛的快速生长期。     

Oestrogen receptor evaluation in Pomeranian dogs with hair cycle arrest (alopecia X) on melatonin supplementation

The role of oestrogen receptors in dogs with hair cycle arrest (alopecia X) was investigated by immunohistochemistry. The purpose of this study was to determine if hair regrowth in dogs with hair cycle arrest treated with melatonin was associated with a decrease in follicular oestrogen receptors. Fifteen Pomeranians (excluding intact females) with hair cycle arrest were enrolled. Two biopsies were obtained from alopecic areas of the trunk before and after 3 months on melatonin. Haematoxylin and eosin-stained tissues were examined and oestrogen receptor-alpha was demonstrated immunohistochemically. Common histopathological findings included hyperkeratosis, follicular keratosis, excessive tricholemmal keratinization (flame follicles), thin epidermis, few small anagen bulbs, epidermal pigmentation and melanin aggregates within follicular keratin. Melanin aggregates within basal cells and hair were an occasional finding. After 3 months, 40% (six) dogs had mild to moderate hair regrowth. Biopsies from six dogs showed histological evidence of an increase in anagen hairs and eight dogs had a decrease in epidermal pigmentation. Moderate to marked staining intensity of oestrogen receptor-alpha was noted in all sebaceous gland basal cells, all small hair bulbs and follicular epithelium of telogen hairs. There was no oestrogen receptor-alpha staining of nuclei within the epidermis, apocrine glands or dermal fibroblasts. Large anagen hair bulbs had minimal to no oestrogen receptor staining. Hair regrowth was not associated with a change in oestrogen receptor-alpha staining.     

Endogenous TSH in the diagnosis of hypothyroidism in dogs

To determine whether measurement of canine thyrotropin (cTSH) would aid in the diagnosis of hypothyroidism, serum samples of 65 dogs with clinical signs suggestive of hypothyroidism were evaluated. Diagnosis was confirmed in 26 dogs and excluded in 39 dogs based on TSH-stimulation testing. Total thyroxine (T4) was significantly lower and cTSH significantly higher in hypothyroid dogs compared to euthyroid dogs. Canine TSH was above (> 0.6 ng/ml) in 15 (57.7%) and below the upper limit of the reference range in 11 (42.3%) of the hypothyroid dogs. All of the euthyroid dogs had a cTSH < 0.6 ng/ml. In all dogs with a cTSH above the upper limit of the reference range hypothyroidism could be confirmed. Therefore, our results show that measurement of cTSH has an excellent specificity (100%) and is a valuable tool in confirming canine hypothyroidism. However, due to the low sensitivity of cTSH assays (60%), it can not be recommended to exclude the disease.     

The effect of body region on the canine hair cycle as defined by unit area trichogram

The impact of anatomic location on trichogram analysis of the hair cycle phases was evaluated in 15 clinically normal dogs. The purposes of this study were to determine if the number of hairs in anagen and telogen vary among anatomic sites within a dog and to see whether there is an optimal region to sample hairs for canine trichogram evaluation of the hair cycle phases. In each dog eight sites were sampled. Four (26.7%) of the 15 dogs had no significant differences in the number of hairs in anagen and telogen among the eight body sites examined. Nine (81.8%) of the remaining 11 dogs had only one site that revealed significant differences in the number of hairs in anagen or telogen. In seven (77.8%) of these dogs only the anagen differed significantly, and in two (22.2%) dogs both phases differed significantly. Two (18.2%) dogs revealed two sites with significant differences in the number of hairs in anagen. The number of hairs in anagen and telogen in the shoulder area did not vary significantly in any of the dogs. This observation, coupled with the ease of sampling at this site, indicates that the shoulder is the site of choice when studying variations in ratios of hair cycle phases using unit area trichogram. Our results also suggest that numbers of telogen and anagen hairs from body regions with different hair shaft lengths do not vary significantly, and the occasional inconsistent results noted at some body sites might be due to sample collection technique.     

Plasma von Willebrand factor concentration and thyroid function in dogs

Plasma von Willebrand factor antigen concentration was determined in 15 dogs with suspected hypothyroidism, in 1 dog with hyperthyroidism, and in 14 euthyroid dogs. The mean +/- SEM von Willebrand factor:antigen concentration in hypothyroid dogs (47.1% +/- 12.6%) was significantly decreased (P less than 0.0005), compared with that in euthyroid dogs (94.7 +/- 5.6%). Four hypothyroid dogs were given thyroxine for 1 month and all 4 had an increase in von Willebrand factor:antigen concentration. The plasma von Willebrand factor:antigen concentration was 200% in the hyperthyroid dog. Seemingly, reduced concentrations of plasma von Willebrand factor:antigen can be found in dogs in association with congenital von Willebrand disease or with von Willebrand disease acquired through hypothyroidism.     

Effect of 131I-induced hypothyroidism on indices of reproductive function in adult male dogs

Hypothyroidism has been cited as a cause of infertility, abnormal semen quality, and poor libido in people and animals. The purpose of this study was to evaluate the effect of hypothyroidism on variables indicative of reproductive function in adult male dogs. Nine normal dogs were randomly assigned to 2 groups. Hypothyroidism was induced with 131I in 6 dogs. Three dogs remained untreated, normal, and euthyroid. Thyroid hormone concentrations, body weight, clinical signs, and reproductive function were determined for each dog every 3 months for 2 years. Reproductive function was assessed by determining daily sperm output, total scrotal width, spermatozoal motility and morphology, libido, and serum testosterone and luteinizing hormone concentration responses to exogenous gonadotropin-releasing hormone. The 131I-treated dogs developed clinical and laboratory signs of hypothyroidism. In the hypothyroid dogs, serum concentrations of thyroid hormones were consistently below the reference range and were significantly lower than that in the euthyroid dogs. There was no difference in reproductive function between the hypothyroid and euthyroid dogs. The results of this study show that 131I-induced hypothyroidism does not affect indices of reproductive function in adult male dogs.     

Thyroid-stimulating hormone and total thyroxine concentrations in euthyroid, sick euthyroid and hypothyroid dogs

Canine thyroid-stimulating hormone (cTSH) was measured in a variety of clinical cases (n= 72). The cases were classified as euthyroid, sick euthyroid, hypothyroid or hypothyroid on non-thyroidal therapy on the basis of their history, clinical signs, laboratory results (including total thyroxine concentrations and, where indicated, thyroid-releasing hormone [TRH] stimulation tests) and response to appropriate therapy. Additional samples were taken during some of the TRH stimulation tests to measure the response of cTSH concentrations following TRH administration. A reference range (0 to 0–41 ng/ml) was calculated from the basal concentrations of cTSH in a group of 41 euthyroid dogs. Six of nine cases of confirmed hypothyroidism had basal cTSH concentrations above the reference range, whereas the remainder were within the normal range. One of these three remaining cases was a pituitary dwarf and did not show a rise in cTSH concentration following TRH stimulation. In contrast, only one of a group of six hypothyroid dogs that had been on non-thyroidal treatment within the previous four weeks had increased concentrations of basal cTSH. This study also found that five of a group of 16 dogs with sick euthyroid syndrome had increased cTSH concentrations. It was concluded that cTSH measurements are a useful additional diagnostic test in cases of suspected hypothyroidism in dogs but that dynamic testing is still required to confirm the diagnosis of hypothyroidism.     

Hoxc13在哺乳动物毛囊发育调控中的研究进展

同源盒C13(Hoxc13)基因与毛囊发育和毛发性状的形成密切相关.在哺乳动物毛囊的周期性发育过程中,Hoxc13通过调控角蛋白关联蛋白(KAP)基因等来控制毛囊在生长期、退行期和休止期之间转换,进而直接控制毛发性状的形成和改变,对皮毛动物产业发展具有重要的经济意义.本文围绕Hoxc13的结构特点、生物学功能以及作用机...     

Hair cycle in dogs with different hair types in a tropical region of Brazil

Hair cycle activity has been extensively studied in humans, sheep and laboratory animals, but there is a lack of information in dogs. Besides varying according to species, breed, sex and general health, hair growth is mainly affected by climatic variations. The aim of the study was to evaluate the follicle activity in three breeds of dogs with different hair types, in the city of Viçosa, Minas Gerais (latitude 20°45′S), Brazil. Twenty‐one male dogs of boxer, labrador and schnauzer breeds were trichographically analysed monthly over 12 consecutive months. Hair percentage of telogen and anagen hairs at the different stages of the hair cycle in boxers and labradors was not significantly different, but both differed from the schnauzers. A significant correlation between hair follicle cycle and environmental temperature and photoperiod was noted in the boxers and labradors. In these breeds, a larger number of telogen hairs were observed during the hottest months of the year, and an increase in anagen hairs during the coldest months. The mean percentage of telogen hairs was 93, 90 and 55.3% for boxer, labrador and schnauzer, respectively.