Bilateral mastocytic and fibroblastic nodular proliferative dermatosis affecting ear margins in three domestic cats.

This case series describes the clinical appearance, histopathological findings and therapeutic trials of proliferative nodular lesions on bilateral ear margins of three domestic cats including two littermates. All therapeutic trials were unsuccessful. While the aetiology remains unclear, this report highlights different hypotheses in presenting this unusual inflammatory and fibroblastic dermatosis in cats.

Dermal arteritis of the nasal philtrum: a retrospective study of 23 dogs.

BACKGROUND: Dermal arteritis of the nasal philtrum (DANP) is a cutaneous vascular condition that selectively targets large vessels of the nasal philtrum of dogs; little information is published about this disease. OBJECTIVE: The aim of this study was to report the signalment, clinical signs, treatment options and outcome of dogs with DANP, and to propose a rationale for the clinical diagnosis. ANIMALS: Twenty-three dogs from four referral veterinary clinics from January 2002 to July 2018. METHODS AND MATERIALS: Retrospective analysis of medical records of dogs with diagnosis of DANP. RESULTS: The mean age at disease onset was 5.3 years. Nineteen dogs were pure-bred (11 different breeds) and four were mixed breed. Twenty-three dogs had a clinical diagnosis of DANP and three of these had histopathological confirmation. Eight dogs had episodes of profuse arterial bleeding from the lesion, nine had minor bleeding and six no bleeding. Twenty dogs were managed medically with monotherapy or combined therapy of topical tacrolimus, prednisolone, doxycycline and niacinamide, and/or pentoxifylline. Long-term tacrolimus was prescribed for 15 cases, eight of those cases as sole therapy. Treatment was declined for three dogs and four dogs were lost to follow-up. The lesion was satisfactorily controlled in 12 dogs and well-controlled in four dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: The distinctive presentation of DANP substantiates the clinical diagnosis. Medical treatment seems to be effective in controlling DANP and tacrolimus used as sole or adjunctive therapy appears to manage the disease satisfactorily.

Identification of 5α-reductase isoenzymes in canine skin.

BACKGROUND: Alopecia X in dogs is a noninflammatory alopecia that may be caused by a hormonal dysfunction. It may be similar to androgenic alopecia in men that is caused by the effect of dihydrotestosterone (DHT). The 5α-reductase isoenzymes, 5αR1 and 5αR2, and a recently described 5αR3, are responsible for the conversion of testosterone into DHT. However, which 5α-reductases are present in canine skin has not yet been described. OBJECTIVES: The main objective of this study was to determine the pattern of expression of 5α-reductase genes in canine skin. METHODS: Skin biopsies were obtained from healthy, intact young-mature beagles (three males, four females) at three anatomical sites normally affected by alopecia X (dorsal neck, back of thighs and base of tail) and two sites generally unaffected (dorsal head and ventral thorax). Prostate samples (n = 3) were collected as positive controls for 5α-reductase mRNA abundance measurement by real-time PCR. RESULTS: We detected mRNA encoding 5αR1 and 5αR3 but not 5αR2. There were no significant differences in 5αR1 and 5αR3 mRNA levels between the different anatomical sites, irrespective of gender (P > 0.05). Moreover, the mean mRNA abundance in each anatomical site did not differ between males and females (P > 0.05). CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first study demonstrating the expression of 5α-reductases in canine skin and the expression of 5αR3 in this tissue. These results may help to elucidate the pathogenesis of alopecia X and to determine more appropriate treatments for this disorder.