Comparison of serum amyloid A (SAA) and some hematological parameters in pregnant cats and cats with pyometra

This study aimed to compare the course of serum amyloid A (SAA) concentrations during the early and early-mid stages of pregnancy in cats with those in pyometra cases, along with corresponding hematological and biochemical profiles. A total of 14 female cats were divided into two groups: a pregnant group (PG, n=7) and a pyometra group (PYG, n = 7). In the pregnant group, blood samples were collected at two time points (days 12-18 and 20-30 of gestation), while in the pyometra group, sampling was performed at the time of diagnosis. Hematological, basic biochemical, and SAA analyses were conducted on the same day. Within-group comparisons were performed using paired tests, between-group differences were evaluated using independent tests, and the combined effects of time and group were analyzed using a linear mixed model (LMM). In the pregnant group, no significant differences were detected between the two time points for SAA or for the main hematological and biochemical parameters; however, the LMM revealed decreases in red blood cell count (RBC) (β = −0.67; p = 0.03) and albumin (ALB) (β = −0.73; p = 0.01). In the between-group comparisons, cats with pyometra had significantly higher mid-cell population (MID) (p = 0.05) and mean corpuscular hemoglobin concentration (MCHC) (p = 0.01), while white blood cell count (WBC) (p = 0.07) and lymphocyte count (LYM) (p = 0.08) showed an increasing trend. The alkaline phosphatase (ALP) level was lower in the pyometra group (p = 0.07). According to the LMM results, WBC (p = 0.04), MID (p = 0.03), and MCHC (p = 0.03) were higher, whereas ALP was lower (p = 0.05) in the pyometra group. SAA levels tended to be higher in the pyometra group (p = 0.06). In conclusion, SAA concentrations remain stable and within physiological limits during the early and early-mid stages of pregnancy in cats. In contrast, pyometra is characterized by a tendency toward elevated SAA levels, a neutrophilic response, and an increase in MID values. The clinical diagnostic value of SAA is enhanced when interpreted together with hematological and biochemical panels and assessed through serial measurements.