Although domestic cats are one of the most popular companion animals, current knowledge on the fate of micronutrients in cats according to their age, sex, and health is very limited. In this study, 72 whole blood and 54 plasma samples from cats of different ages and sex were collected at three veterinary offices in the Czech Republic, and the copper (Cu), selenium (Se), and zinc (Zn) concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that Cu was significantly (P < 0.05) higher in both plasma and whole blood of males (980 and 958 μg L−1 in plasma and whole blood, respectively) than in females (741 and 766 μg L−1 in plasma and whole blood, respectively), whereas no significant differences between males and females were found for Se and Zn. Similarly, no significant differences were recorded for any of the three elements according to age, although animals older than 7 years tended to have lower plasma concentrations of all three elements. Hypertrophic cardiomyopathy (HCM) is one of the most prevalent diseases of domestic cats. The potential relationship between the essential microelement status in the blood of cats with HCM vs. cats with no clinical signs of HCM was taken into account, but the limited number of HCM-positive individuals did not allow any clear conclusion. Thus, the potential relationships between micronutrient status in cats and the incidence of HCM should be elucidated in further research.