ERDYN US 
Dogs and cats are the most common companion animals encountered in veterinary practice and represent the primary focus of innovation in veterinary dermatology. The conditions discussed in this article were selected because they are among the most prevalent dermatological diseases affecting these two species and because they continue to present significant unmet medical needs. Their chronic nature, high prevalence, and the need for long-term management also make veterinary dermatology one of the most dynamic areas for therapeutic innovation.
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Atopic Dermatitis and Feline Atopic Syndrome
Canine atopic dermatitis (CAD) and feline atopic syndrome (FAS) are chronic inflammatory diseases resulting from an exaggerated immune response to environmental allergens. In dogs, the pathogenic mechanisms involving the cytokines IL-4, IL-13, and IL-31 are now well established (1). In cats, however, the disease remains less well understood, and no specific biomarker has yet been identified (2).
The hallmark clinical sign is pruritus, which is frequently accompanied by skin lesions resulting from scratching, licking, or chewing (1). These diseases have a considerable impact on the quality of life of both affected animals and their owners because of their chronic course, frequent relapses, and the risk of secondary skin infections (3).
Management of atopic dermatitis relies on a multimodal approach combining therapies aimed at restoring the skin barrier, controlling pruritus and inflammation, and, whenever possible, addressing the underlying allergic cause (4). The main therapeutic options currently available are summarized in the table below.
| Therapeutic objective | Treatment | Mechanism of action | Target species |
|---|---|---|---|
| Restore the skin barrier |
Barrier-repair topical formulations
|
Supply of skin lipids to reinforce skin barrier integrity and reduce allergen penetration. | Dogs & Cats |
|
Dermatological nutraceuticals
(ω-3, ω-6…) |
Supply of essential fatty acids that help maintain skin barrier function and modulate inflammation. | Dogs & Cats | |
| Control pruritus and inflammation |
Glucocorticoids
|
Inhibition of the inflammatory response and suppression of pro-inflammatory cytokine production. | Dogs & Cats |
|
Cyclosporine
(calcineurin inhibitor) |
Inhibition of T-cell activation and modulation of the immune response. | Dogs & Cats | |
|
Oclacitinib
(JAK inhibitor) |
Preferential inhibition of JAK1, interrupting the signaling of cytokines involved in pruritus, particularly IL-31. | Dogs | |
|
Lokivetmab
(anti-IL-31 monoclonal antibody) |
Specific neutralization of IL-31, a key cytokine involved in the induction of pruritus. | Dogs | |
| Address the underlying allergic cause |
Allergen-specific immunotherapy
(ASIT) |
Progressive induction of immune tolerance to the causative allergens. | Dogs |
The veterinary dermatology market is largely driven by a limited number of major companies, including Zoetis (Apoquel®, Cytopoint®), Elanco (Atopica®, Zenrelia®), Virbac (Allerderm® product range), and Ceva Santé Animale (Douxo® product range), which offer solutions ranging from targeted therapies to skin barrier restoration products.
Despite the availability of several therapeutic options, important unmet medical needs remain. Current treatments generally provide effective control of pruritus and inflammation; however, relapses are common, some animals exhibit an inadequate response or develop refractory disease, and relatively few therapies have been specifically validated for cats.
Among the most promising therapeutic avenues are biologics targeting the IL-4/IL-13 signaling pathway, whose central role in the Th2 immune response makes it an attractive therapeutic target (1). Although these approaches are currently being developed primarily for human medicine, they hold considerable translational potential for veterinary dermatology and may ultimately enable a more personalized management of atopic dermatitis (7).
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Flea Allergy Dermatitis (FAD)
Flea allergy dermatitis (FAD) is a hypersensitivity reaction to proteins present in flea saliva. Unlike simple mechanical irritation, FAD results from an exaggerated immune response that may be triggered by only a very small number of flea bites. Affecting both dogs and cats, it is one of the leading causes of pruritic skin disease in veterinary medicine (8).
The disease is characterized primarily by intense pruritus, which may lead to skin lesions, excoriations, and excessive grooming, particularly in cats. Without appropriate management, lesions may worsen and predispose affected animals to secondary skin infections. Because of its recurrent nature, FAD significantly impairs the animal’s quality of life and requires rigorous ectoparasite control by the owner, including treatment of all animals within the household and, when necessary, environmental decontamination to prevent reinfestation.
Management of FAD relies primarily on the complete elimination of fleas to interrupt exposure to salivary allergens. The principal therapeutic options currently available are summarized in the table below.
| Therapeutic objective | Treatment | Mechanism of action / Therapeutic role | Target species |
|---|---|---|---|
| Eliminate fleas |
Isoxazolines
(fluralaner, afoxolaner, sarolaner, lotilaner) |
Rapid and sustained elimination of fleas through inhibition of GABA- and glutamate-gated chloride channels. | Dogs & Cats |
| Control pruritus and inflammation |
Glucocorticoids
|
Rapid suppression of the inflammatory response. | Dogs & Cats |
(8)
The market is dominated by major animal health companies such as Zoetis, Elanco, Boehringer Ingelheim, and Merck Animal Health, which market both systemic and topical antiparasitic products based primarily on the isoxazoline class. Owing to their high efficacy and prolonged duration of action, isoxazolines have become the reference treatment for flea infestation control (9).
Despite the effectiveness of currently available antiparasitic products, the main unmet needs now concern the long-term prevention of reinfestation and disease recurrence. Successful management remains dependent on the simultaneous treatment of all animals within the household, as well as the environment, where most immature flea stages reside. Consequently, current developments are focused less on introducing new therapeutic classes than on optimizing prevention strategies, extending the duration of protection, and improving treatment compliance (10).
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Secondary Skin Infections: Pyoderma and Malassezia Dermatitis
Secondary skin infections generally develop as a consequence of an underlying primary disorder, such as allergic dermatitis or impairment of the skin barrier. These alterations promote the proliferation of opportunistic microorganisms, mainly bacteria and yeasts, which perpetuate inflammation, exacerbate pruritus, and contribute to disease recurrence (11).
Pyoderma refers to bacterial skin infections, most commonly caused by Staphylococcus pseudintermedius, whereas Malassezia dermatitis results from the excessive proliferation of Malassezia pachydermatis, a commensal yeast that becomes pathogenic when the normal cutaneous balance is disrupted (11).
Pyoderma typically presents with pustules, crusts, erosions, erythematous or exudative lesions, frequently associated with pruritus of variable severity (12). In contrast, Malassezia dermatitis is characterized by chronic pruritus, marked erythema, scaling, greasy seborrhea, and a distinctive malodorous skin odor (11).
These infections have a substantial impact on animal welfare because of the chronic discomfort they cause. Persistent pruritus promotes self-inflicted trauma resulting from excessive scratching and licking, thereby worsening skin lesions (12). Their frequently recurrent nature also leads to repeated veterinary consultations and prolonged treatment courses (11).
Management primarily focuses on treating the underlying disease while controlling bacterial and/or fungal infections whenever present. The principal therapeutic options currently available are summarized in the table below.
| Therapeutic objective | Treatment | Mechanism of action | Target species |
|---|---|---|---|
| Control bacterial infections |
Chlorhexidine
(topical antiseptic) |
Reduces the cutaneous bacterial load; first-line treatment for superficial pyoderma. | Dogs & Cats |
|
Systemic antibiotics
(amoxicillin-clavulanic acid, cephalexin, etc.) |
Elimination of bacteria responsible for extensive or deep pyoderma. | Dogs & Cats | |
| Control fungal infections |
Topical miconazole + chlorhexidine
|
Antifungal and antiseptic activity against Malassezia. | Dogs & Cats |
|
Systemic antifungals
(itraconazole, etc.) |
Inhibition of ergosterol synthesis; treatment of generalized or refractory infections. | Dogs & Cats |
The market is primarily driven by companies such as Dechra, Ceva Santé Animale, Virbac, Elanco, and Zoetis, which commercialize antiseptic, antibiotic, and antifungal products for the management of pyoderma and Malassezia dermatitis.
Despite the availability of these therapies, several unmet medical needs remain. Disease recurrence is common when the underlying primary condition is not adequately controlled, while the repeated use of antibiotics and antifungal agents contributes to the emergence of antimicrobial resistance. Consequently, current research is increasingly focused on strategies that reduce reliance on antimicrobial drugs while ensuring long-term infection control.
Among the most promising approaches is phage therapy, which is being investigated as an alternative or adjunct to antibiotics for the treatment of antimicrobial-resistant bacterial infections. However, its application in veterinary dermatology remains at the research stage (13, 14).
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Translational Dermatology: A Growing Dialogue Between Human and Veterinary Medicine
Veterinary and human dermatology are now closely interconnected, with canine atopic dermatitis (CAD) widely recognized as one of the most relevant spontaneous animal models of human atopic dermatitis. Both conditions share numerous clinical, histopathological, and immunological features, including impairment of the skin barrier, a Th2-skewed immune response, and the involvement of cytokines such as IL-4, IL-13, and IL-31 (15, 16).
This close relationship has fostered a substantial transfer of knowledge between the two disciplines. Advances in human medicine regarding the pathophysiology of atopic dermatitis—particularly those related to skin barrier dysfunction and Th2 cytokine signaling—have directly guided the development of targeted therapies in veterinary medicine, including Janus kinase (JAK) inhibitors and anti-IL-31 monoclonal antibodies (6).
Conversely, canine models of atopic dermatitis have provided valuable insights into the natural history of the disease and have enabled the early evaluation of novel therapeutic strategies under conditions that closely resemble clinical practice in humans. These models have notably contributed to elucidating the role of IL-31 in pruritus, characterizing abnormalities of the skin barrier, and assessing interventions aimed at restoring barrier function (16).
Thus, translational dermatology extends beyond the adaptation of treatments from one species to another. It also advances our understanding of disease pathophysiology through the study of naturally occurring animal models that share many biological and immunological characteristics with human diseases.
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References
[1] Banovic F. (2025). Updated insights into the molecular pathogenesis of canine atopic dermatitis.
https://doi.org/10.1111/vde.13300
[2] Mueller RS. et al. (2021). Treatment of the feline atopic syndrome: A systematic review.
https://doi.org/10.1111/vde.12933
[3] Gedon NKY., Mueller RS. (2018). Atopic dermatitis in cats and dogs: A difficult disease for animals and owners.
https://doi.org/10.1186/s13601-018-0228-5
[4] Olivry T. et al. (2015). Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA).
https://doi.org/10.1186/s12917-015-0514-6
[5] Forster S. et al. (2025). Comparative efficacy and safety of ilunocitinib and oclacitinib for the control of pruritus and associated skin lesions in dogs with atopic dermatitis.
https://doi.org/10.1111/vde.13319
[6] Wichtowska A., Olejnik M. (2025). Anti-Cytokine Drugs in the Treatment of Canine Atopic Dermatitis.
https://doi.org/10.3390/ijms262210990
[7] de Bruin-Weller MS. et al. (2026). Biologics to Treat Atopic Dermatitis: Effectiveness, Safety, and Future Directions.
https://doi.org/10.1111/all.70061
[8] Zhou X., Hohman AE., Hsu WH. (2022). Current review of isoxazoline ectoparasiticides used in veterinary medicine.
https://doi.org/10.1111/jvp.12959
[9] Future Market Insights. (2036). Canine Flea Allergy Dermatitis Market | Global Market Analysis Report.
https://www.futuremarketinsights.com/reports/canine-flea-allergy-dermatitis-market
[10] Dryden M., Blakemore JC. (1989). A review of flea allergy dermatitis in the dog and cat.
https://www.researchgate.net/publication/285521532
[11] Bond R. et al. (2020). Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats.
https://doi.org/10.1111/vde.12809
[12] Merck Veterinary Manual. Pyoderma in Dogs and Cats.
https://www.merckvetmanual.com/integumentary-system/pyoderma/pyoderma-in-dogs-and-cats
[13] Loponte R. et al. (2021). Phage Therapy in Veterinary Medicine.
https://doi.org/10.3390/antibiotics10040421
[14] Squires RA. (2021). Bacteriophage therapy for challenging bacterial infections: achievements, limitations and prospects for future clinical use by veterinary dermatologists.
https://doi.org/10.1111/vde.12958
[15] Freudenberg JM. et al. (2019). The Comparison of Skin Transcriptomes Confirms Canine Atopic Dermatitis Is a Natural Homologue to the Human Disease.
https://doi.org/10.1016/j.jid.2018.10.018
[16] Marsella R., Girolomoni G. (2009). Canine Models of Atopic Dermatitis: A Useful Tool with Untapped Potential.
https://doi.org/10.1038/jid.2009.98
