Correlation between clinical signs of feline conjunctivitis and molecular detection of felid herpesvirus-1, feline calicivirus, chlamydophila felis and mycoplasma felis in cats from shelters in Rio de Janeiro

Objectives: To perform molecular diagnosis of microbial agents (FHV-1, FCV, Mycoplasma felis, and Chlamydophila felis) in kittens with conjunctivitis and correlate the clinical signs with clinical severity. Material and Methods: A total of 108 conjunctival swab were collected from kittens without (G1; n = 40) and with (G2; n = 68) clinical signs of conjunctivitis. Animals from G2 group were scored from 1 (mild) to 4 (severe) according to the severity of conjunctivitis. All samples were submitted to PCR and RT-PCR. Results: FHV-1 was detected in 62/108 (57.4%) of samples, FCV in 40/108 (37.0%), M. felis in 11/108 (10.2%) and C. felis in 26/108 (24.1%). Mixed infections were detected in 39/108 (36.1%). In G1, 28/40 (70.0%) were positive for one or more agents, in G2, 58/68 (85.3%) were positive (P = 0.03). In 1, single infections by FHV-1were found in 21/40 (52.5%) samples, FCV in 2/40 (5.0%), C. felis in 1/40 (2.5%), and no pathogens were detected in 12/40 (30%) of samples, while mixed infections accounted for 29/40 (72.5%) of the cases. In G2, single FHV-1 infections were found in 31/68 (45.6%) samples, FCV in 10/68 (14.7 %), M. felis in 2/68 (3.0%) and C. felis also in 2/68 (3.0%), and no pathogens were detected in 10/68 (14.7%) samples, while mixed infections accounted for 36/68 (52.0%) of the cases. They were categorized as grade 1, 20/68 (29.4%), grade 2, 14/68 (20.6%), grade 3, 21/68 (30.9%) and grade 4, 13/68 (19.1%). The presence of FHV-1 and FCV is equally distributed among the four categories. More severe clinical signs, scores 3 and 4, are related to coinfections by C. felis and M. felis. Conclusions: FHV-1, FCV, C. felis and M. felis were identified in feline conjunctivitis. Co-infections are related to more severe cases of conjunctivitis. Molecular diagnosis is helpful to detect asymptomatic carriers and is a rapid and accurate method to determine the pathogen of feline conjunctivitis.