The effect of topical lidocaine on intradermal testing in atopic dogs.

BACKGROUND: Intradermal testing (IDT) most often requires sedation. Topical lidocaine offers an adjunct or alternative to sedation. HYPOTHESIS/OBJECTIVES: We hypothesized that topical lidocaine would significantly reduce reactions to intradermal injections and that atopic dogs treated with topical lidocaine would have similar results with IDT to atopic dogs tested without topical lidocaine. ANIMALS: Fifteen client-owned atopic dogs. METHODS: In Part I, a 5% lidocaine patch, 5% lidocaine cream and a control with no active ingredients were compared. The lowest pain score during intradermal injection was established in six atopic dogs. Fifteen atopic dogs were enrolled in Part II, and lidocaine cream (found to be most effective in Part 1) was applied randomly to a single side of the thorax. An IDT was performed on each side of the chest. Subjective and objective scores of the control and lidocaine treatment sides were compared 15 and 30 min post-injection. RESULTS: The 5% lidocaine cream had the greatest reduction in pain score associated with intradermal injection. There were no significant differences in mean wheal diameter for any evaluated allergen at any time point between the control and lidocaine-treated sides. There was high agreement between the two groups when assessing the subjective score for all but one allergen. CONCLUSIONS AND CLINICAL IMPORTANCE: Topical lidocaine may be used as adjunctive analgesia during IDT with caution in interpretation of subjective house dust scoring. Lidocaine cream appeared to reduce pain score and may allow reduction in concurrent sedation.

Urticaria pigmentosa-like skin disease in a domestic shorthair cat.

CASE SUMMARY: A 14-month-old castrated male domestic shorthair cat presented with an 8 month history of severe pruritus, alopecia, papules and excoriations. Initial evaluation and treatment prior to referral included skin scrape, cytology, two strict food trials, dermatophyte culture, and bacterial culture and sensitivity, as well as antibiotic therapy, empiric treatment for mites, steroids and ciclosporin A (Atopica; Elanco). The cat was referred to the Dermatology and Otology Clinic at the University of Illinois Veterinary Teaching Hospital for further diagnostics and treatment. Skin scrapes were unremarkable. Cytology showed rare bacteria and moderate neutrophils. The cat was given an injection of triamcinolone acetonide, which was ineffective. Oclacitinib (Apoquel; Zoetis) was given for 4 weeks with no improvement. A skin biopsy was performed, and histopathology showed large numbers of well-differentiated monomorphic mast cells with fewer eosinophils that diffusely infiltrated the superficial dermis, supportive of urticaria pigmentosa. Oral dexamethasone and cetirizine hydrochloride were initiated, and the cat responded favorably. At the time of writing, the cat continues to do well on cetirizine hydrochloride with only intermittent tapering courses of dexamethasone. RELEVANCE AND NOVEL INFORMATION: To the best of our knowledge, this is the first reported case of urticaria pigmentosa in a domestic shorthair cat. This case also highlights the importance of biopsy after a thorough, systematic work-up in a cat with severe, intractable pruritus to reveal an uncommon disease pattern, as well as the efficacy of oral dexamethasone and cetirizine hydrochloride as a potential management option.

Comparing dermoscopy and histological examination of normal equine skin.

BACKGROUND: Dermoscopy is a noninvasive diagnostic technique that allows visualization of structures of the superficial dermis not visible with the naked eye. HYPOTHESIS/OBJECTIVES: To assess the usefulness and applicability of dermoscopy for evaluation of healthy equine skin. ANIMALS: Twelve healthy horses from a research herd. METHODS: Five regions (cheek, lateral neck, dorsum, flank and abdomen) were examined with contact dermoscopy using both nonpolarized and polarized light at both 17-fold and 24-fold magnification. These findings were compared to histological features of skin biopsies cut both longitudinally and transversely. RESULTS: Using a hand-held dermatoscope with nonpolarized light, epidermal ridges were observed. Using polarized light, follicular openings and distinctly separate epidermal openings of sweat gland ducts were observed in some but not all individuals. Similarities were noted between histological and dermoscopic results. CONCLUSIONS: Although not ideal for visualizing many structures in the superficial dermis of healthy equine skin, dermoscopy allowed visualization of epidermal ridges, hair shafts in the infundibular portion of the hair follicles and sweat gland duct openings. Dermoscopy could potentially be useful in the evaluation of diseases affecting the sweat glands, epidermis and hair shaft.