Profiling of the microRNA transcriptome in feline whole blood

Circulating microRNAs (miRNAs) are potential biomarkers for numerous diseases. Characterization of the whole blood (WB) miRNA-transcriptome (miRNome) in cats is lacking, which limits the potential use of miRNAs as biomarkers for diseases such as feline cardiovascular disease. The aims of the present study were to profile and evaluate circulating miRNAs in feline WB by high-throughput sequencing of the total miRNome in WB from twelve domestic mixed breed (DOM) and Norwegian Forest (NFO) cats stringently diagnosed with or without preclinical hypertrophic cardiomyopathy (HCM). A total of 459 mature miRNAs were identified in feline WB, of which 40 were potential novel feline miRNAs. A majority, 85.3%, of the miRNAs showed sequence similarity with human miRNAs. An effect of breed was found, with up to thirteen WB miRNAs being differentially abundant between breeds. The majority of the significant breed-specific miRNAs in feline WB could be associated with regulation of haematopoietic cells. One miRNA, miR-204-5p, was potentially associated with preclinical HCM in NFO cats, but the results need to be confirmed in a larger and sex-unbiased cohort. In conclusion, here we used miRNome-sequencing to identify hundreds of circulating miRNAs in feline WB. Breed should be considered when evaluating the miRNome in feline WB.