Discoid Lupus Erythematosus in a Dog

Introduction. Autoimmune dermatoses in dogs account for only 2–3 % of all skin and coat pathologies encountered in veterinary dermatology practice. Discoid lupus erythematosus (DLE) in dogs is a chronic autoimmune disease. This condition was first described in dogs in 1965, but it was not until the 1970s that cutaneous variants were officially documented in dogs that developed chronic dermatitis following prolonged sun exposure. Lesions may be confined solely to the muzzle, the so-called facial form of discoid lupus erythematosus, or may be localized to other areas of the body the generalized form of DLE. Olivry et al. developed a histopathological classification for DLE. It was also established that the histopathology of lupus shows similarities to the microscopic lesions present in cutaneous lupus erythematosus in humans. For veterinary specialists, this group of diseases raises many questions regarding diagnosis, selection of therapeutic methods, and monitoring of the patient's condition.

Case Description. A 5-year-old mixed-breed dog was presented to the veterinary clinic with lesions on the nasal planum, without systemic clinical abnormalities. The diagnosis of discoid lupus erythematosus was based on history, clinical examination, cytological examination, complete blood count and serum biochemistry, and histopathological examination of biopsy samples from the nasal planum. For cytological examination, impression smears were taken from ulcerated skin areas. The smears were fixed, stained with Diahem-Diff-Quick stain (Russia), and examined under a microscope at ×100 magnification using an Olympus CX23 microscope (Japan). To establish the definitive diagnosis, a punch biopsy was performed under general anesthesia using a 3-mm punch; three tissue samples were obtained from the nasal planum and nasal wings. Histopathological examination was performed by veterinary pathologist I.V. Bogomolova.

Discussion. The presented clinical case illustrates the typical facial form of discoid lupus erythematosus (DLE) in a dog. The localization of lesions exclusively to the nasal planum, the absence of systemic symptoms, and normal blood parameters are consistent with the classic course of FDLE, highlighting the importance of differentiating this form from generalized and systemic lupus erythematosus. The diagnosis was verified based on histopathological examination, the gold standard for DLE diagnosis. The identified changes allowed the exclusion of other autoimmune dermatoses, particularly pemphigus, despite the presence of acantholytic cells on cytology. This finding confirms that cytological examination cannot serve as the sole diagnostic criterion.

Conclusion. The treatment outcomes and photographic materials presented in this article may be useful for practicing veterinarians in the diagnosis of discoid lupus erythematosus. The applied combination therapy proved to be effective.

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