Direct immunofluorescence testing of normal feline nasal planum and footpad

Direct immunofluorescence testing for IgG, IgM, and C3 was performed on nasal planum and footpad tissue from 28 normal cats. Granular deposition of IgM at the basement membrane zone of the nasal planum was demonstrated in 3 of 28 cats. Direct immunofluorescence testing of the footpad was negative in all cats. It was concluded that positive direct immunofluorescence testing of the feline nasal planum using antifeline IgM needs to be cautiously interpreted, as 11% of normal cats may be positive.