Peer-reviewed veterinary case report
Ulcers on skin and tongue linked to leflunomide in three dogs
By Roussille, Louis F et al.·Published in Journal of veterinary internal medicine·2026·Department of Clinical Sciences, United States·View original on PubMed →
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Original publication title: Cutaneous and mucosal ulceration associated with the use of leflunomide in three dogs.
- Species:
- dog
Plain-English summary
Three dogs, including a 1.5-year-old Bernese Mountain Dog, a 7-year-old Australian Shepherd, and a 1-year-old mixed breed, developed painful ulcers on their tongues and skin after being treated with the medication leflunomide for immune-related issues. One of the dogs also experienced serious liver problems due to the medication. After stopping leflunomide, the ulcers healed within weeks, and the liver issues improved over a few months. This highlights that while leflunomide can be helpful, it may also cause serious side effects in some dogs.
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Abstract
Oral and cutaneous ulceration and drug-induced liver injury (DILI) are uncommon adverse drug reactions (ADRs) to leflunomide use in humans. Reports of leflunomide hepatotoxicity in dogs exist but ulceration has not been described in animals. This case series includes a 1.5-year-old male neutered Bernese Mountain Dog, a 7-year-old female spayed Australian Shepherd, and a 1-year-old male neutered mixed-breed dog that were administered leflunomide for immune-mediated conditions. All developed deep ulcerated lesions affecting either the tongue, skin, or both. One dog had concurrent severe DILI. The Naranjo probability scale for ADR suggested the signs were possibly (n = 1) or probably (n = 2) attributed to leflunomide administration. Ulcerated lesions resolved within weeks and hepatotoxicosis within months after discontinuation of leflunomide administration. This case series indicates that oral and cutaneous ulcers are potential ADRs to leflunomide and provides histological documentation of a leflunomide-induced liver injury.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41742543/