Bacteria and yeast on the surface and within non-inflamed hair follicles of skin biopsies from cats with non-neoplastic dermatoses.

Coccoid bacteria and/or yeasts were found in the surface keratin or exudate or, rarely, the pilar canal of non-inflamed hair follicles upon light microscopic examination of skin biopsies from 57 of 338 cats (16.9%) with non-neoplastic skin disorders. The presence of these microorganisms did not appear to suggest a specific dermatosis, nor the existence of a clinically relevant infection in the majority of cases.     

Bacteria and fungi on the surface and within noninflamed hair follicles of skin biopsy specimens from horses with healthy skin or inflammatory dermatoses

A retrospective study using light microscopy was performed to assess the prevalence of surface and follicular bacteria and fungi in skin biopsy specimens from 247 horses with inflammatory dermatoses and from 27 horses with healthy skin. Cocci were found on the surface of specimens from 23% (95% confidence interval 18%, 29%) and 7% (95% confidence interval, 0%, 19%), respectively, of horses with skin disease and horses with healthy skin. Of the nine dermatoses with at least 10 cases in our series of horses, bacterial folliculitis had a higher prevalence of surface bacteria (57%; 95% confidence interval 34%, 81%) than the other eight (which all had a prevalence < 30%). There was a significant association between the prevalence of surface cocci and the extent of epidermal hyperkeratosis. Cocci were found in the keratin of noninflamed hair follicles in only 2% of the horses with skin disease, and in none of the horses with healthy skin. Fungal poroconidia were found on the surface of 4% of the horses with skin disease, and on none of the horses with healthy skin. Yeasts were not found.     

Lymphoid nodules in skin biopsies from dogs, cats, and horses with nonneoplastic dermatoses

In a retrospective histopathologic study of nonneoplastic dermatoses, lymphoid nodules were found in 0.3% of 3,408 canine, 5.1% of 469 feline, and 4.5% of 325 equine skin biopsies. In all 3 species, the majority of cases wherein lymphoid nodules were found were diseases of presumed immune-mediated nature. In cats and horses, the majority of cases were also diseases characterized by tissue eosinophilia.     

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.     

Occurrence of Staphylococcus intermedius on the hair and skin of normal dogs.

Aerobic bacterial populations were studied on the distal hair coat and at the skin surface of the shoulder, rump and abdomen of 10 healthy dogs. Coagulase negative staphylococci (CNS) were more frequently isolated from the hair than the skin at the shoulder and rump. There was no difference in the isolation rate of coagulase positive staphylococci (CPS) (Staphylococcus intermedius) between the hair and skin. Total skin counts were greatest on the abdomen whereas CNS counts from the hair were least at this site. There were no differences between CPS counts at the three sites on either hair or skin. The populations on the relatively unfavourable microenvironment of the distal hair may represent contamination rather than colonisation. The low populations of CPS at the skin surface also indicate contamination or transient colonisation rather than true resident status.     

Cell proliferation kinetics in the hair root matrix of dogs with healthy skin and dogs with idiopathic seborrhea

Cell proliferation kinetic values were established for the hair root matrix of primary anagen follicles of 14 Beagles and 4 Cocker Spaniels with healthy skin and 9 Cocker Spaniels with primary idiopathic seborrhea. Indices were established by intradermal pulse labeling with tritiated thymidine, followed by cutaneous biopsy and autoradiography. The hair root matrix cell labeling index was 23.4 +/- 3.5% for Beagles, 24.4 +/- 4.0% for healthy Cocker Spaniels, and 24.9 +/- 4.3% for seborrheic Cocker Spaniels. These values indicate a rapidly proliferating cell population. Differences among these cell kinetic data for the 3 groups of dogs were not statistically significant. Although significant cell kinetic differences have been reported for other epidermal structures (interfollicular epithelium, upper hair follicle external root sheath, sebaceous glands) in seborrheic Cocker Spaniels, proliferation of hair root matrix cells apparently remains unaffected.     

The reaction of hair follicles in the vicinity of full-thickness excised skin wounds in the dog

The changes which take place in hair follicles close to full-thickness excised skin wounds in the thoracic and metatarsal regions of the dog are described. The follicles make a significant contribution to the bulk of epithelial cells which are capable of migrating to form the new epidermis, and their behaviour explains why the migrating epithelium is first seen to grow on to the surface of the wound in the sector which lies in the direction of hair flow, and why a zone of alopecia surrounds the excised wound.     

Cell proliferation of epidermis, hair follicles, and sebaceous glands of beagles and cocker spaniels with healthy skin

Cell proliferation kinetic values were established for the epidermis, hair follicle epithelium, and sebaceous glands of 10 Beagles and 4 Cocker Spaniels with healthy skin and coats. Values were established by intradermal pulse-labeling injections of [3H]thymidine, examination of cutaneous biopsied tissues, and autoradiography. The epidermal basal cell-labeling index was 1.41 +/- 0.46% for Beagles and 1.71 +/- 0.56% for Cocker Spaniels. The hair follicle basal cell-labeling index was 1.46 +/- 0.78 and 1.07 +/- 0.42%, respectively. Calculated epidermal cell-renewal time for viable layers of the epidermis was 23.38 +/- 5.93 days for Beagles and 20.97 +/- 4.92 days for Cocker Spaniels. Differences between cell kinetic data for the 2 breeds were not significant (P greater than 0.05). The basal cell-labeling index for the sebaceous gland was significantly (P = 0.009) lower for Cocker Spaniels (0.40 +/- 0.18%) than for Beagles (1.81 +/- 1.08%). Seemingly, epidermal and follicular cell proliferation kinetics in healthy dogs was similar between the 2 breeds, whereas sebaceous gland basal cells were less proliferative in healthy Cocker Spaniels than in healthy Beagles.     

Skin surface lipids and skin and hair coat condition in dogs fed increased total fat diets containing polyunsaturated fatty acids

It is generally believed that diets containing increased amounts of polyunsaturated fatty acids (PUFA) result in improved canine skin and hair coat (SHC). However, the extent to which dietary fat amount and type play a role remains to be systematically investigated. The objective of this study was to investigate the role of both increased dietary fat amount and type on SHC assessments of dogs. Improvements of SHC conditions were investigated after feeding three diets containing increased total dietary fat (i.e. 13% total fat) for 12 weeks in relation to a lower fat acclimation diet (i.e. 9% total fat). The higher fat diets varied in polyunsaturated and saturated fat types and amounts but total fat was kept constant. Skin and hair coat assessments were performed at selected intervals by a trained group of veterinarians and graduate students. In addition, hair lipids were fractionated by thin layer chromatography after extraction of plucked hair samples. Significant improvements were found in hair coat glossiness and softness in all dogs fed the higher fat diets in relation to the acclimation diet. Improvements as a result of fat type were also seen but only at 12 weeks. A parallel finding was a marked increase in hair cholesteryl ester content determined at the end of the study at which time SHC scores were significantly improved. Skin and hair coat condition improvements may thus be related to increased cholesteryl ester deposited on the hair shaft surface when high fat diets are fed. Whereas this finding is preliminary, hair lipid analysis may be a useful, non-invasive technique with which to help assess dietary effects on canine SHC.     

A study of skin diseases in dogs and cats. III. III. Microflora of the skin of dogs with chronic eczema

The microflora of the skin was studied in 10 dogs with chronic eczema without clinical signs of secondary infection (Table I). The skin surface was swabbed at 7 different sites, making a total of 70 swabs, 25 of which were taken from visibly inflamed areas and 45 from apparently unaffected skin (Table II). Staph. aureus, Staph. epidermidis, micrococci, alpha-hemolytic streptococci, and Acinetobacter spp. were found consistently. Ten different Gram-negative bacteria, 3 different Gram-positive bacteria, and 2 yeasts were found to occur sporadically (Table III). Compared to a group of 10 healthy dogs a more prolific growth of aerobic microorganisms, a greater number of sites carrying Staph. aureus, and a higher recovery of Gram-negative transients were found in dogs with eczema (Table IV--VII). Within the group of dogs with eczema the growth of Staph. aureus was significantly heavier from eczematous skin areas than from clinically normal skin (Table VIII). In dogs with non-infective dermatitides the colonization of the skin by potentially pathogenic microorganisms may have to be considered in the clinical handling of these diseases.     

Lymphoid follicles in the gastric mucosa of dogs. Distribution and lymphocyte phenotypes

The occurrence and distribution of lymphoid follicles within the stomachs of 36 dogs that dis not have macroscopic gastric lesions are presented. The dogs ranged in age from less than 1 year to over 13 years. The number of follicles varied between the different regions of the stomach, being most numerous (15.6 follicles cm⁻²) and uniform in size (about 1 mm in diameter) in the fundus. The number and size of follicles in the antrum varied widely between dogs. Age-related changes in the distribution of follicles were not found following simple linear regression analysis. The phenotypes of lymphocytes in gastric lymphoid follicles of nine dogs aged from less than 1 year to 5 years were determined using monoclonal antibodies specific for canine leucocyte antigens and an indirect immunoperoxidase technique. The follicles had an organized distribution of lymphocytes subsets in that a predominantly B cell area contained some CD4+ cells and very few CD8+ cells and was adjacent to an area containing mostly T cells. Computer-assisted morphometric analysis was used to quantify the overall presence of the various lymphocyte subpopulations. Follicles in the fundus and body regions possessed similar percentages of lymphocytes averaging 42%, 22% and 3% of the area occupied by B cells, CD4+ and CD8+ cells, respectively. It is concluded that lymphoid follicles are a normal constituent of the canine gastric mucosa and possess a lymphocyte composition similar to that reported by others for solitary intestinal follicles.     

辽宁绒山羊皮肤毛囊miR-1298-5p靶基因预测及验证

以辽宁绒山羊不同发育时期皮肤毛囊组织为材料,用生物信息学方法预测miR-1298-5p的靶基因,采用RTPCR对miR-1298-5p与其潜在靶基因TGF-βR1进行核酸水平表达检测,利用Weston blot对潜在靶基因TGF-βR1进行蛋白水平表达检测。生物信息学预测结果表明TGF-βR1的3′UTR存在miR-1298-5p种子区结合位点;miR-1298-5p在皮肤毛囊不同发育时期呈现差异性表达;TGF-βR1在皮肤毛囊不同发育时期无论在核酸水平还是蛋白水平均呈现差异性表达;miR-1298-5p与其潜在靶基因之间呈现一种负调控趋势,说明miR-1298-5p可能通过负调控TGF-βR1,从而对毛囊周期性发育起到调节作用。结合靶基因预测结果、miR-1298-5p在核酸水平表达规律及TGFβR1在核酸水平表达规律和蛋白水平表达规律初步确定TGF-βR1为miR-1298-5p的靶基因。本实验旨在探讨辽宁绒山羊皮肤毛囊不同发育时期miR-1298-5p与其靶基因的调控作用及其与靶基因的潜在关系,为miR-1298-5p与其靶基因对皮肤毛囊发育作用提供理论研究数据。     

Methicillin resistance of staphylococci isolated from the skin of dogs with pyoderma

OBJECTIVE: To determine the methicillin-resistant profile of staphylococcal isolates from the skin of dogs with pyoderma. ANIMALS: 90 dogs with pyoderma. PROCEDURE: Staphylococci isolated from dogs with pyoderma were tested for susceptibility to methicillin by use of a standard disk diffusion test with oxacillin disks. The DNA extracted from the isolates was tested for the mecA gene that encodes the penicillin-binding protein 2a (PBP2a) by use of a polymerase chain reaction (PCR) assay. The expression of PBP2a was determined with a commercial latex agglutination assay. Species of staphylococcal isolates were identified by use of morphologic, biochemical, and enzymatic tests. RESULTS: Most of the isolated staphylococci were methicillin-susceptible, coagulase-positive Staphylococcus intermedius isolates. Whereas only 2 of 57 S. intermedius isolates were resistant to methicillin, approximately half of the isolates had the mecA gene and produced PBP2a. Staphylococcus schleiferi was the second most common isolate. Widespread resistance to methicillin was found among S. schleiferi isolates. More coagulase-negative S. schleiferi isolates were identified with mecA gene-mediated resistance to methicillin, compared with coagulase-positive S. schleiferi isolates. CONCLUSIONS AND CLINICAL RELEVANCE: The latex agglutination assay for the detection of PBP2a expression coupled with the PCR assay for the mecA gene may provide new information about emerging antimicrobial resistance among staphylococcal isolates.     

Quantification of mRNA encoding cytokines and chemokines in nasal biopsies from dogs with sino-nasal aspergillosis

Canine sino-nasal aspergillosis is usually caused by Aspergillus fumigatus and is similar to human chronic erosive non-invasive fungal sinusitis. The pathogenesis of the disease is poorly understood. We investigated the nature of the local immune response mounted in canine sino-nasal aspergillosis. Quantitative RT-PCR was carried out on RNA isolated from nasal biopsies from diseased and control dogs, using specific assays designed to amplify mRNA encoding a panel of cytokines and chemokines. Canine sino-nasal aspergillosis was associated with significantly increased expression of mRNA encoding MCP-1, -2, -3 and -4, IL-8, IL-10, IL-18 and TNF-alpha relative to controls (P<0.01) but there was no difference between groups with respect to IL-4, IL-5, IL-6, IL-12, TGF-beta, and eotaxin-2 and -3. The up-regulation of proinflammatory cytokines and chemokines related to the influx of phagocytic cells might account for the localisation of this infection to the upper respiratory tract. The up-regulation of the expression of the immunomodulatory cytokine IL-10 in nasal tissue from affected dogs might be important in limiting the extent of local tissue destruction, but might also account for the fact that infected dogs are generally unable to clear this infection spontaneously.     

Immunoglobulin-E-bearing cells in skin biopsies of horses with insect bite hypersensitivity.

The aim of the present study was to investigate, with immunohistochemistry and in situ hybridisation, if immunoglobulin-E (IgE) and mast cells are involved in the pathogenesis of insect bite hypersensitivity (IBH), an allergic dermatitis of horses. In tissue sections fixed in paraformaldehyde (PFA) for <24 h, significantly more IgE protein-bearing cells were found in the dermis and epidermis of acute and chronic IBH lesions than in skin biopsies from healthy horses (medians = 466, 236 and 110 cells/mm2, respectively; P < or = 0.01). More IgE-mRNA positive (+) cells were observed in the dermis of acute IBH lesions than in the dermis of healthy skin (median = 2.8 vs. 0.0 cells/mm2; P < or = 0.01). Significantly, more mast cells were detected with metachromatic (median = 160 vs. 62 cells/mm2; P < or = 0.001) and tryptase-specific stainings (median = 120 vs. 69 cells/mm2; P < or = 0.001) in the dermis of acute IBH biopsies compared to healthy skin. No chymase+ mast cells were found in any skin biopsy. IBH lesions fixed in PFA for >24 h were compared to dermatomycosis (DM) lesions; IBH biopsies contained a similar number of IgE-protein+ cells to DM biopsies (median = 249 vs. 192 cells/mm2; P = 0.08) but had significantly more IgE-mRNA+, metachromatic and tryptase+ mast cells than DM biopsies. This study suggests an involvement of IgE-mediated immune reactions in the pathogenesis of IBH as well as, sometimes, in dermatomycosis. Using double labelling, cells which expressed IgE protein and contained mast cell enzymes were detected.     

Determination of plasma and skin concentrations of orbifloxacin in dogs with clinically normal skin and dogs with pyoderma

Plasma and skin concentrations of orbifloxacin (Orbax tablets, Schering-Plough Animal Health) were assessed in 14 clinically normal dogs and 14 dogs with pyoderma following oral administration of the drug at 7.5 mg/kg once daily for 5 to 7 days. Skin biopsies and whole blood samples were obtained before dosing and at the time of the expected maximum concentration in skin (3 hours after dosing) on the first and on the fifth to seventh day of dosing. Skin biopsies and plasma were analyzed for orbifloxacin concentrations by high-performance liquid chromatography. Dogs with pyoderma had significantly higher mean skin concentrations of orbifloxacin within 3 hours of administration (Day 0: 7.80 +/- 3.40 mcg/g, Days 4 to 6: 9.47 +/- 6.23 mcg/g) than did dogs with normal skin (Day 0: 3.85 +/- 1.08 mcg/g, Days 4 to 6: 5.43 +/- 1.02 mcg/g). After dosing on Day 0 and after five to seven daily treatments, dogs with pyoderma had significantly higher mean orbifloxacin skin:plasma ratios (1.40 and 1.44, respectively) than did clinically normal dogs (0.81 and 0.96, respectively). The accumulation of orbifloxacin in diseased skin may contribute to the efficacy of this compound for the treatment of bacterial skin infections.