Seventy-three blood samples, representing blood from 67 cats sampled during 2007–2008 were used. Forty-six of the samples had been collected from patients at the University Hospital for Companion Animals, Faculty of Health and Medical Sciences, University of Copenhagen. The remaining 27 blood samples were collected at veterinary clinics throughout Denmark. The blood samples were collected from both diseased cats and cats attending the clinics for routine health checks. From four of the cats from the University Hospital we had samples in duplicate or triplicate. These samples were used as controls for the PCR reaction to confirm that we obtained identical results on repeated testing. For 62 cats, information on age, breed and gender was available. Anamnesis and clinical findings were available for all cats admitted to the University Hospital and from ten samples from the other clinics. The blood samples were obtained by venal puncture and stored in 2.5 ml EDTA-vials at −80 °C. Blood samples obtained from the University Hospital were all subjected to haematological examination using the ADVIA 120 haematology system including erythrocyte count, haemoglobin-, haematocrit- and mean cell volume (MCV) values.