Focal metatarsal sinus tracts in a Weimaraner successfully managed with ciclosporin

Focal metatarsal fistulae syndrome affecting a greyhound dog successfully treated with topical 0.1% tacrolimus ointment

Metatarsal fistulation is an uncommon cutaneous condition reported almost exclusively in German shepherd dogs and their cross-breeds. To the best of the authors' knowledge this is the first reported case of focal metatarsal fistulae syndrome affecting a greyhound. Remission was obtained within 6 weeks of commencing treatment using compounded 0.1% tacrolimus ointment twice daily and the dog remained stable for another 6 months with twice weekly application before treatment was discontinued. The dog remained in remission at the time of writing, which is 1 year after treatment withdrawal.

Ciclosporin 10 years on: indications and efficacy

Ciclosporin is a lipophilic cyclic polypeptide with powerful immunosuppressive and immunomodulatory properties that has been used in veterinary medicine for two decades. It is a calcineurin inhibitor whose principal mode of action is to inhibit T cell activation. The drug is principally absorbed from the small intestine and is metabolised in the intestine and liver by the cytochrome P450 enzyme system. Ciclosporin is known to interact with a wide range of pharmacological agents. Numerous studies have demonstrated good efficacy for the management of canine atopic dermatitis and this has been a licensed indication since 2003. In addition to the treatment of atopic dermatitis, it has been used as an aid in the management of numerous other dermatological conditions in animals including perianal fistulation, sebaceous adenitis, pododermatitis, chronic otitis externa and pemphigus foliaceus. This article reviews the mode of action, pharmacokinetics, indications for use and efficacy of ciclosporin in veterinary dermatology.

The use of ciclosporin A in veterinary dermatology

Ciclosporin A (CsA) has potent immunosuppressive and immunomodulatory activity that has been exploited in human medicine to prevent the rejection of transplanted organs and to manage atopic dermatitis and psoriasis. Over the past decade, CsA has been employed more frequently in veterinary dermatology and its value in the management of several canine and feline dermatoses is now well established. CsA inhibits calcineurin phosphatase, suppressing T cell activation and the synthesis of T cell cytokines consequently impairing the activity of B cells, antigen-presenting cells, mast cells, basophils and eosinophils. The pharmacokinetics of CsA are similar in humans, dogs and cats and the drug has a wide safety margin in dogs, cats and rabbits. Adverse effects, principally transient vomiting and soft faeces/diarrhoea, may be seen shortly after instituting treatment but often resolve despite continuing treatment. Gingival hyperplasia and cutaneous effects such as hirsutism may occur after prolonged treatment.