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.     

The effects of thyroid hormones on the skin of beagle dogs

The effects of hypothyroidism on canine skin were determined by comparing morphologic, morphometric, and hair cycle differences in skin biopsy samples from 3 groups of age- and gender-matched Beagle dogs: (1) euthyroid dogs; (2) dogs made hypothyroid by administration of 131I; and (3) dogs made hypothyroid and maintained in a euthyroid state by treatment with synthetic thyroxine. After 10 months of observation, there was slower regrowth of hair 2 months after clipping in the untreated-hypothyroid dogs. Untreated-hypothyroid dogs had a greater number of follicles in telogen and fewer hair shafts (ie, a greater number of hairless telogen follicles) than did the control group. The control dogs had a greater number of telogen follicles but the same number of hair shafts as the treated-hypothyroid group. Treated-hypothyroid dogs had the greatest number of follicles in the growing stage of the hair cycle (anagen). This study suggests that, at least in Beagles, induced hypothyroidism does not affect the pelage as dramatically as has been described in naturally occurring disease. This is because normal Beagles retain hair shafts in follicles for long periods, and the alopecia of hypothyroidism appears to evolve slowly because of the prolongation of this haired telogen stage. The evaluation of thyroxine-treated hypothyroid dogs demonstrates that thyroid hormone supplementation of Beagle dogs with induced hypothyroidism stimulates hair growth.     

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 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.     

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.     

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.     

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.     

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.     

Seasonal Moulting in Adult Male Raccoon Dog (Nyctereutes procyonoides)

Abstract

Seasonal moulting was studied by quantitative histology and external observations in adult male raccoon dogs. Moulting of the underfur hairs is characterized by a heavy loss of old winter hair in spring and an intensive growth of new winter hair in autumn. Only few mature and growing underfur hairs were found in the hair cover in summer. The new intermediate and large guard hairs started to develop in April and May. All the new guard hairs had developed by the end of June. About 7 and 3.5 months were needed for the growth of new winter guard and underfur hairs respectively. At the end of November the winter fur was mature. The bundles with an intermediate guard hair contained more underfur hairs than the bundles with a large guard hair in the mature winter fur. The thickness of dermis and the grade of skin colour peaked in the autumn moult, indicating a close relation to the activity of hair follicles.     

An analysis of canine hair re-growth after clipping for a surgical procedure

Hair growth and replacement have been studied extensively in humans, sheep and laboratory rodents, but in dogs and other mammalian species few studies have been published. The objectives of this study were: (1) to determine the time required for the hair to re-grow in dogs after clipping for a surgical procedure; (2) to define whether the season of the year influenced the period of time required for re-growth and; (3) to determine if season might influence the telogen: anagen ratio. Eleven Labrador retrievers were recruited during spring, 10 during summer, six during autumn and 10 during winter. Hairs re-grew to their preclipped length in 14.6 weeks, 14.5 weeks, 13.6 weeks and 15.4 weeks when shaved in the spring, summer, autumn and winter, respectively. The differences in these values were not significant suggesting that season has no effect on the rate of hair re-growth in Labrador retrievers housed indoors (P = 0.12). The mean values for the telogen: anagen ratio in each season were: 5.2 (spring), 6.1 (summer), 9.5 (autumn), and 5.3 (winter). The differences in these values also were not significant (P = 0.89). The percentage of hairs in telogen was over 80% in all four seasons.     

Bilateral third eyelid ectopic cilia in an adult horse

A 15‐year‐old Cob mare presented with a 4‐month history of chronic epiphora and intermittent blepharospasm in the right eye. On ophthalmic examination, two translucent aberrant hairs were identified at the third eyelid margin corresponding to an area of corneal fibrosis and neovascularization. Partial excision of the third eyelid was performed, and histopathology confirmed ectopic hair follicles. Two weeks later, clinical signs recurred in the same eye. Examination revealed another pair of aberrant hairs on the bulbar surface of the third eyelid near its leading edge. This portion of the third eyelid was also excised, and histopathology confirmed two additional ectopic hair follicles. Eight months later, the horse developed similar clinical signs in the left eye. Ophthalmic examination showed a single aberrant translucent hair at the third eyelid margin associated with focal fibrosis and neovascularization of the ventromedial cornea. Partial excision of the third eyelid was performed, and histopathology confirmed an ectopic hair follicle within the third eyelid conjunctiva. Excision was curative at 4 years postoperatively with no further recurrence in either eye.     

Hair Dye Effects on the Hair Coat and the Skin of the Dog: A Scanning Electron Microscopic Study

Eight healthy dogs of mixed breeds with short hair coats were used in this study. The skin and the hair of a small area on the left side of the saddle region were dyed 80 times once every day with a permanent hair dye, Clairol Hair Dye Flaxen Blonde. The dyed regions were red and dry toward the last two weeks of the experiment. None of the dogs had abnormal hair shedding. Four of the dogs were restless, and their epidermis were parakeratotic and hyperkeratotic.
The cuticular cells of the hair shafts of two dogs upon examination showed deep fractures at the lower part of the hair shaft. The fractures extended through the whole thickness of the cuticular cells leading to splitting of the hair shaft. Secondary hairs showed excessive peeling of their cuticle cells causing distortion and deterioration of the cortex of the hair. Cuticular cells of large numbers of hairs lost their apical parts and some of them were deformed due to partial dissolution attributed to the intensive use of the hair dye. The intensive usage of the hair dye on the compound type of hair coat of the dog caused damage to the hair shafts and to the skin in the form of irritation, dryness and parakeratosis of the epidermis. Also, some of the dogs became restless and hyperactive during the later part of the experiment.     

辽宁绒山羊皮肤毛囊细胞凋亡特点的研究

采用TUNEL法在一个生物年的周期内每隔两月对绒山羊体侧部的皮肤毛囊进行检测,观察毛囊细胞凋亡的周期性变化特点。结果表明,控制毛囊生长变化的凋亡细胞是成簇分布的,毛乳头的成纤维细胞很少有凋亡现象,细胞凋亡与毛囊周期性生长具有相关性,兴盛期毛囊凋亡细胞减少,退行期凋亡细胞显著增多。常年长绒型与季节长绒型品系在一年内的凋亡细胞变化情况基本一致,只是常年长绒型品系在兴盛前期的细胞凋亡明显低于季节长绒型品系。     

Wnt10b参与外源褪黑激素促进绒山羊绒毛生长的研究

本实验旨在研究Wnt10b在内蒙古成年绒山羊皮肤中的表达变化规律和褪黑激素(MT)对其表达量的影响。每隔1个月按照2 mg/kg BW的剂量在受试内蒙古成年绒山羊耳后皮下埋植MT。连续采集12个月(从2009年8月到2010年7月)的肩胛部皮肤样品,应用实时荧光定量PCR技术检测Wnt10b的表达量。结果表明:Wnt10b在内蒙古成年绒山羊皮肤组织中毛囊生长中期和休止前期高表达;埋植MT提高了Wnt10b在内蒙古成年绒山羊皮肤组织中毛囊休止期和退行期的表达量。结果提示,Wnt10b参与内蒙古绒山羊毛囊生长的信号传递过程,并在退行期和休止期转变过程中发挥作用;Wnt10b参与了外源MT促绒毛生长的毛囊周期性变化过程。     

The effect of topical minoxidil treatment on hair follicular growth of neonatal hairless descendants of Mexican hairless dogs

The effect of daily topical minoxidil treatment on hair growth was investigated in eight neonatal hairless pups. After 21 days of minoxidil treatment, hair growth occurred in the minoxidil-treated areas of each neonatal hairless pup. The numbers of hairs in the treated areas increased as compared with that in the areas treated with vehicle only. Histological findings revealed that the skin treated with minoxidil contained many hair follicles derived from epidermal ingrowths (hair germs) projecting into the dermis. These hair follicles showed various stages of neofolliculogenesis. After 31 days of treatment, terminal hair growth was observed. In the minoxidil-untreated areas, epidermal ingrowths remained undifferentiated. These results revealed that hairless dogs developed hair growth reactions following minoxidil-treatment when such treatment is applied in the early neonatal period. Neonatal hairless pups are a useful model for evaluating the effectiveness of hair growth stimulators.     

Comparison of hair follicle histology between horses with pituitary pars intermedia dysfunction and excessive hair growth and normal aged horses

Background –  Pituitary pars intermedia dysfunction (PPID) in older equids is commonly recognized by a long hair coat that fails to shed. Objective –  The aim of this study was to compare hair follicle stages in PPID‐affected horses with excessively long hair coats with the stages of normal aged horses (controls) and to compare hair follicle stages in PPID‐affected horses after 6 months of treatment with pergolide mesylate with those of control horses. Animals –  Eight PPID‐affected horses and four normal, age‐matched, control horses. Methods –  Skin biopsies were collected from the neck and rump of PPID‐affected and control horses. A diagnosis of PPID was established based on hair coat changes and supportive overnight dexamethasone suppression test results. Skin biopsies were repeated after 6 months of treatment with pergolide. The number of hair follicles in anagen (A) or telogen (T) was counted for each skin biopsy using transverse sections. Results –  Pretreatment biopsies had a greater percentage of A follicles (neck 96%, rump 95%) and a lower percentage of T follicles (neck 4%, rump 5%) in PPID‐affected horses than in control horses (A, neck 15%, rump 25%; and T, neck 85%, rump 75%). After treatment with pergolide, all PPID‐affected horses had improved shedding, and the percentages of A follicles (neck 69%, rump 70%) and T follicles (neck 31%, rump 30%) were not different from untreated control horses (A, neck 68%, rump 82%; and T, neck 32%, rump 18%). Conclusions –  These findings document that excessive hair growth (hypertrichosis) in PPID‐affected horses is due to persistence of hair follicles in A. Furthermore, treatment with pergolide improved shedding and reduced the percentage of A follicles in PPID‐affected horses.     

Oestrogen receptor antagonist and hair regrowth in dogs with hair cycle arrest (alopecia X)

An oestrogen receptor pathway that regulates the telogen-anagen hair follicle transition in mice has been described. The purpose of this study was to investigate whether fulvestrant, a pure oestrogen receptor antagonist, would cause hair regrowth in Pomeranian dogs with hair cycle arrest (alopecia X). Eleven Pomeranian dogs with hair cycle arrest were randomly assigned to receive two intramuscular injections of either 10 mg kg(-1) fulvestrant (n = 6) or an equal volume of saline (n = 5) 1 month apart. Complete blood count, chemistry panel, and urinalysis were monitored prior to the first injection and monthly for 2 months. Dogs were evaluated each month for degree of hair growth, percentage of body affected, and quality of new hair growth. Three control dogs received fulvestrant after the completion of the study. In addition, one control dog and one treatment dog received two subcutaneous injections of 20 mg kg(-1) fulvestrant 1 month apart. No dogs that received 10 mg kg(-1) fulvestrant had any evidence of hair regrowth. The control dog that received 20 mg kg(-1) fulvestrant had substantial hair regrowth 1 month after the first injection. No adverse effects from the treatment were noted. Fulvestrant does not appear to be a feasible treatment for dogs with hair cycle arrest (alopecia X) when administered intramuscularly at 10 mg kg(-1). A higher dose of fulvestrant requires more investigation but may be cost-prohibitive.