Vancouver Feline Hospital - Cat Veterinary Clinic

"Positive DTM Ringworm Culture shows the fluffy white fungal colony turning the yellow medium red as it grows."

Confirm the diagnosis - recommended to do fungal culture in almost all dermatological cases because of the varied presentation - from classical expanding areas of scaling or erythema to Persian keratinisation defects (chronic infection) to military dermatitis, kerions, nodules and symmetrical alopecia - it can look like ANYTHING!

• Wood's lamp (ultraviolet light) - miss 70% of cases, positive only suggests dermatophytosis so must still do fungal assay to confirm.
• Trichogram (infected vs normal hair shaft) - may still miss the diagnosis.
• Skin biopsy - a good way to rule out mites, ringworm, eosinophilic/hypersensistivity and autoimmune differentials - don't biopsy heels, ears…biopsy is not the first step in a skin work-up, but in cats we do it sooner than later especially since skin scrapings are not always an option. Always biopsy before treating with steroids!
• Fungal assay (DTM - dermatophyte culture assay; medium turns red on first white growth; will turn red anyway after approx. ten days; contaminants often green/black coloured)
• Fungal culture and identification (send to CVL, takes about three weeks so if in-house DTM is positive start topical treatment at least)
• Collect samples using sterile/new toothbrush, sterile carpet, sterile tweezers - not cold-sterile because the germiphene residue will kill the sample.

ZOONOSIS - so topical treatment with systemic antifungals (mainstay remains bathing plus oral azoles) and environment (enilconazole weekly 4-8 times; bleach (chlorine) 1:10 soln.)

Most healthy immune-competent cats will resolve the infection spontaneously over a few months - however treatment is always recommended because this is contagious to humans and other animals. ⁸

1. Treat infected cat
2. Minimise spread of infection
3. Eliminate contamination of the environment

1. Treat infected cat

• Clipping the coat⁸ - remove infected hairs, minimise contagion - TOTAL BODY CLIP - optional in shorthairs with small localized lesions - destroy coat clippings and protective clothing immediately - will contaminate environment where clipped so if clipping in veterinary clinic/groomers MUST do rigourous environmental cleanup.
• Systemic antifungal treatment⁸ - Griseofulvin, Ketoconazole, Itraconazole
• Vaccination - will not cure, may prevent spread, no controlled studies yet that show protection against natural or challenge exposure ⁸
• Topical therapy - useful for small localized lesions, but must prevent ingestion! - best is enilconazole or combination ketoconazole/chlorhexidine shampoos.⁸ Have to do weekly/twice weekly 8-10 weeks. Topical creams or enilconazole solution topically daily also can have good result for small localized lesions - but remember you need to consider whole cat is infected, not just the raw patch you see!
• Monitor therapy methodically - cats will appear clinically normal long before they are cured mycologically (ie easy to stop treatment too soon) - spontaneous resolution 60-100 days, treated cats 28-56 days (4-8 weeks). Treat till fungal culture (done weekly, starting after 3-4 weeks of therapy) is negative on two or three successive occasions.⁸

2. Environmental Clean-Up

• Environment a reservoir of infection
• Start with aggressive cleaning - wash everything that can be washed (bedding, toys, scratching posts, brushes, anything and everything) - in severe cases, destroy whatever cannot be washed. Vacuum everything - all surfaces - ceilings, vents, floors, walls, anyplace where cat hair or dust can accumulate is a source of infection. Then clean every surface you can with a safe detergent. Colonies/ catteries - Heating/Airconditioning systems need to be cleaned and then the filters changed, weekly, till free of infection.
• Antifungals do not work in dirt - so now that the place is clean, apply antifungal disinfectants - enilconazole 1:50 dilution spray or bleach 1:10 - this can be irritating so prevent human/cat contact with these agents; catteries/colonies/vets/groomers need to do this daily/every other day for several months after cure - spores carried in air and resistant for a long time!

3. Prevent spread to other animals and people

• Identification, isolation, quarantine, monitoring - applicable mainly to catteries/colonies - individually affected cats in households there is a good chance the owners have already been infected and are being treated.
• Ringworm - cat to people but also people to cat! Identification of species can give you valuable clues as to the source of

  
  

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