Cell proliferation kinetic values were established for the epidermis, hair follicle epithelium, and sebaceous glands of 8 Cocker Spaniels with primary idiopathic seborrhea. Values were established by intradermal pulse labeling injections of tritiated thymidine followed by cutaneous biopsy and autoradiography.The epidermal basal cell-labeling index was 4.96 +/- 0.97%, and the epidermal nucleated cell-labeling index was 3.33 +/- 0.71%. Calculated epidermal cell renewal time for the viable layers of the epidermis was 7.85 +/- 1.80 days. The hair follicle infundibulum basal cell-labeling index was 5.48 +/- 2.01%, and the sebaceous gland basal cell-labeling index was 5.94 +/- 4.15%. When compared with previously reported cell kinetic values for Cocker Spaniels and Beagles with healthy skin, these data indicate accelerated cellular proliferation in all 3 cutaneous structures in seborrheic Cocker Spaniels.

The use of growth promoters in animal husbandry to increase weight gain and efficiency of feed conversion into muscle has been banned in the European Union since 1988, and under Directive 96/23/EC, surveillance for anabolic steroid hormones is obligatory. The hormones present in animal tissues may be of endogenous origin or may result from illegal administration. Steps have been taken to determine selected steroids in the form of esters in the alternative matrix of animal hair. Their detection in biological material is direct proof of the illegal use of anabolics. The procedure for the determination of steroid esters in animal hair, based on digestion, extraction, purification, and liquid chromatography with tandem mass spectrometry was validated under the current regulations. In total, 348 samples of animal hair were examined using this method. Good recoveries and precision values (RSD) were obtained during validation. Decision limits (CCα) and detection capabilities (CCβ) were in the ranges of 2.57–4.18 μg kg⁻¹ and 4.38–7.12 μg kg⁻¹, respectively. The method met the criteria for confirmation techniques with respect to Commission Decision 2002/657/EC. Testing for steroid esters in animal hair was introduced into the National Residue Control Programme in 2017. Steroid esters were not found in any hair samples above the CCα, which indicates that illegal use of anabolics was not confirmed.

The use of growth promoters in animal husbandry to increase weight gain and efficiency of feed conversion into muscle has been banned in the European Union since 1988, and under Directive 96/23/EC, surveillance for anabolic steroid hormones is obligatory. The hormones present in animal tissues may be of endogenous origin or may result from illegal administration. Steps have been taken to determine selected steroids in the form of esters in the alternative matrix of animal hair. Their detection in biological material is direct proof of the illegal use of anabolics.

Responses of the skin over the dorsum to solar UV irradiation (2 hours/d for 6 consecutive days) were investigated in hairless descendants of Mexican hairless dogs. Assessment of skin color changes, using a spectrophotometer, indicated that luminance values began to decrease from the third, day of UV irradiation, reached the minimal value at 3 weeks, and almost recovered 12 weeks after completion of UV irradiation. The number of the dihydroxyphenylalanine-positive melanocytes increased significantly (P < 0.01) from the third day of UV irradiation, reached its maximal value at 2 weeks, and recovered to normal at 12 weeks after completion of UV irradiation. On the second day of UV irradiation, the epidermis became focally thick, with disarrangement of component cells that had degenerative changes. In addition, a few so-called sunburn cells with pyknotic nuclei were seen in the epidermis. On the third day of UV irradiation, apparent suntan reaction developed, and a large number of epithelial cell in the epidermis were heavily pigmented with melanin granules. At 12 weeks after completion of UV irradiation, the epidermis appeared almost normal. On the other hand, significant changes were not detected in the dermis throughout the study.

In the silver fox, as in its wild ancestor, the red fox (Vulpes vulpes L.), the annual growing phase (anagen) of guard hair follicles occupies at least four months. Severe damage to the hair coat near the end of this growing period was reported in 1985 on many ranches in New Brunswick and Nova Scotia. A histological analysis of serial sections of skin biopsies showed a marked increase in nuclear aberrations in the hair matrix of anagen guard hair follicles. These nuclear aberrations indicated that cells were undergoing apoptosis, a controlled form of cell death. Tissues from affected and unaffected foxes for histological and toxicological analysis, as well as other data, were obtained during visits to 26 ranches in 1986 and 34 ranches in 1987. Histological sections of the 1987 skin samples showed the mean percentage of nuclear aberrations in 43 unaffected foxes to be 0.08 +/- 0.01 (SEM), while that for 49 affected foxes was 0.51 +/- 0.23. The four foxes with the most severe coat damage also had the highest incidences of guard hair matrix cells with nuclear aberrations, ranging from 20 to 100 times greater than the mean for unaffected foxes. The mitotic index of the hair matrix, which normally remains fairly constant during the hair growth phase, was similar for unaffected and affected foxes (1.83 + 0.06 and 1.97 +/- 0.07 respectively). Although our analyses of field data have not established a specific environmental factor associated with increased nuclear aberrations, the possible involvement of toxic agents in follicle damage may warrant further investigation.

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.

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 Beagels and 20.97 +/- 4.92 days for Cocker Spaniels. Differences between cell kinetics 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.

Cell proliferation kinetic values were established for the epidermis, hair follicle epithelium, and sebaceous glands of 8 Cocker Spaniels with primary idiopathic seborrhea. Values were established by intradermal pulse labeling injections of tritiated thymidine followed by cutaneous biopsy and autoradiography.The epidermal basal cell-labeling index was 4.96 +/- 0.97%, and the epidermal nucleated cell-labeling index was 3.33 +/- 0.71%. Calculated epidermal cell renewal time for the viable layers of the epidermis was 7.85 +/- 1.80 days. The hair follicle infundibulum basal cell-labeling index was 5.48 +/- 2.01%, and the sebaceous gland basal cell-labeling index was 5.94 +/- 4.15%. When compared with previously reported cell kinetic values for Cocker Spaniels and Beagles with healthy skin, these data indicate accelerated cellular proliferation in all 3 cutaneous structures in seborrheic Cocker Spaniels.

The fungal flora of the hair and underlying skin from 2 sites was examined qualitatively in 20 horses free of skin or ocular disease. Fungi were isolated from both the hair and the underlying skin of all 20 horses. Twenty-two genera regarded commonly as saprophytes were identified and an additional 2 fungi resembled the perfect state of the cutaneous pathogenic genera Microsporum and Trichophyton. Cladosporium spp, Penicillium spp, and Rhizopus spp were the most frequently isolated saprophytes. In general, similar fungi were isolated from the hair and underlying skin, and differences were not noted in isolates from the saddle and rump regions.

Analogues of a melanocyte-stimulating hormone (alpha-MSH) have been documented to be effective in inducing integumental melanogenesis in several species. These melanotropin analogues are more potent than the natural hormone and have prolonged biological activity, without apparent teratogenic or other toxic effects, at least in rodents. In a pilot study, a cyclic alpha-MSH analogue, Ac-[Nle4, Asp5 D-Phe7, Lys10] alpha-MSH4-10-NH2, was administered SC to a dog at a dose of 1 mg of analogue in 1 ml of 0.9% NaCl for 3 weeks, without noticeable adverse effects. There was gradual and extensive darkening of the coat, which originally was predominantly tan, with tips of black. Initially, the darkening involved face and extremities, then gradually expanded to include the trunk and tail hair. Visual pigmentation peaked approximately 2 months after injections were completed. As new hair growth continued subsequent to the injections, the original tan color appeared at the proximal end of the hair shaft, leaving a dark terminal band on all affected hairs. These observations clearly indicated that follicular melanogenesis can be induced in dogs by treatment with a melanotropic peptide.