When cat rescue fails — Part 1. Lion-clip shaving, enilconazole bathing and oral itraconazole treatment failed to control an iatrogenic Microsporum canis outbreak in a shelter: but a novel ophytrium-chlorhexidine shampoo and mousse treatment succeeded in the home
Authors: Addie DD , Livy J.G. 
Published: April 2024

OBJECTIVE: To identify the reason(s) for failure to prevent repeated nosocomial dermatophyte infection of shelter cats and to present alternative strategies which are less stressful to the cats and humans involved.

ANIMALS: The Dorset branch of the Royal Society for the Prevention of Cruelty to Animals (RSPCA) seized 30 of 32 Persian cats from a cat breeder on the 2nd of August 2019 and put them into Ashley Heath RSPCA shelter. Two cats and three dogs were left at home. All 30 cats were returned to their guardian in July 2020. Three cats died between 2020 and 2022, leaving 29 cats which were seized on the 8th of March 2022 and put into two RSPCA shelters. The dogs were not seized. Four cats were later euthanased.

METHODS: RSPCA Animal Treatment Reports along with photographs used for evidence in the court case against the breeder and the veterinary records of their primary veterinary surgeon were retrospectively reviewed.

RESULTS: Clinical signs of dermatophytosis occurred on the index_ _case one week after dematting with clippers in August 2019. _Microsporum canis_ (_M. canis) _was cultured from 27 of 30 (90%)_ _cats on the 39th day of the Ashley Heath shelter stay in 2019. _M. canis_ infection could only have been acquired while in RSPCA care because the incubation period from infection to development of clinical signs for _M. canis_ is one to three weeks, and there was no history of ringworm in their home.

Efforts to control the ringworm outbreak in the shelter included lion clipping, weekly enilconazole bathing and oral itraconazole (EI treatment) for five or seven weeks until culture negative. Six cats became culture positive again in 2020. Cats were housed in pairs in 2019 to 2020 and singly in 2022, therefore transmission was indirect (i.e. via fomites).

Two cats remained positive when the cats were returned to their guardian in 2020, all 30 were treated with a single ophytrium-chlorhexidine (Douxo S3 Pyo) shampoo followed by ophytrium-chlorhexidine mousse rubbed into their fur for three weeks. It was reasonable to conclude that the ophytrium-chlorhexidine treatment had cleared the _M. canis_ infection for the following six reasons: first no cat developed clinical signs of dermatophytosis during the 20 months in their home. Second, no obvious ringworm lesions were seen on the photographs taken for evidence and third, no veterinary surgeon noted in the records any lesions suspicious of dermatophytosis during the examination of the cats within days of them being seized again in March 2022. Fourth: no positive dermatophyte results were produced as evidence during the trial (ringworm charges against the owner were dropped). Fifth: three of four dermatophyte tests performed on EI untreated cats were negative and samples from the positive cat were after three months in the shelter. Sixth: no EI treatment was administered until the cats had been in the shelters again for two and a half months. Nevertheless, shelter staff assumed ringworm infection from the arrival of the cats in 2022 and again subjected them to the stressful shaving/bathing/itraconazole protocol.

CLINICAL RELEVANCE AND CONCLUSIONS: This is the first report of ophytrium-chlorhexidine for treatment and prevention of _M. canis _in cats. We recommend shelter staff be trained in basic barrier nursing and be educated regarding the difference between true dermatophyte infection versus fomite carriage.