Serum concentrations of APP and

Serum concentrations of APP and antioxidants of the 10 queens with pyometra before surgery (T0), at day two (T1) and at day 10 (T2) after ovariohysterectomy are presented in Fig. 1. Concentrations of SAA and Hp were significantly lower (P < 0.01 and P < 0.05, respectively), and of albumin significantly higher (P < 0.05) at T2 in comparison with T0. At day 10 post-surgery, these 10 queens presented concentrations of SAA and albumin in the reference range; however, serum Hp, despite being significantly lower than before surgery, was still above the reference range in all queens. Regarding antioxidants, FRAP showed significantly higher concentrations at T1 in comparison with its concentration before surgery (P < 0.05), while concentrations of Thiol, CUPRAC and TEAC1 were significantly higher at T2 than at T0 (P < 0.05, P < 0.01, and P < 0.05, respectively). A tendency to increase (although not statistically significant, P = 0.065) was also observed in TEAC2 concentrations at T2 when compared with T0. When data from diseased and control queens before surgery (T0) were pooled (n = 36), Spearman correlation test revealed significant correlations between the serum antioxidants Thiol, CUPRAC and TEAC2 and APP, namely a negative correlation with SAA and Hp, and a positive correlation with albumin (Table 3).
Discussion Acute phase protein responses were already described in mares, cows and bitches with pyometra [[11], [12], [13], [14], [15]]. However, to the authors' knowledge, APP have not been evaluated in queens with pyometra. In the present study, the APP response in feline pyometra was evaluated through an APP profile that flecainide acetate included one positive major (SAA), one positive moderate (Hp) and one negative (albumin) APP. Determination of APP profiles, which should include at least one positive major, one positive moderate and one negative APP has been recommended over determination of individual APP, in order to provide a better differentiation between pathological states and more information on the evolution of the disease [43]. The obtained results indicate that an APP response occurs in feline pyometra, since significantly higher serum concentrations of SAA and Hp, and lower albumin were detected in queens with pyometra when compared with healthy control queens. These results are in accordance with previous studies, which described the occurrence of systemic inflammatory response syndrome (SIRS) and increases in inflammatory markers such as 15-keto-(13,14)-dihydro-PGF2α (PGFM) and 6-keto- PGF1α in queens with pyometra [44,45]. In the cat, SAA is considered as a positive major APP, characterized by an early and marked increase, and a rapid decline in serum concentrations after an inflammatory stimulus, while Hp is classified as a positive moderate APP, characterized by a moderate and gradual increase and decrease in serum concentrations after an inflammatory stimulus. Albumin is considered as the principal negative APP, characterized by a decrease in serum concentrations in inflammation [46,47]. In this study, magnitude of increase in concentrations of SAA was more pronounced than of Hp. Although caution should be taken if SAA is used as a unique APP, as in this study a lack of increment of this protein was detected in six queens with pyometra. Similarly, low SAA values were described in some cats with inflammatory diseases [48]. This fact could be explained by two possible hypotheses: the method used, which was initially designed for human serum presents a lower sensitivity with feline samples [30,48], and/or feline SAA possess different isoforms that could be responsible for the lack of cross-reactivity of antibodies used in the reagents, as previously described in humans and other animal species [[49], [50], [51]]. Further studies should be undertaken in order to elucidate why SAA is not increased in some cases of inflammatory feline diseases, including pyometra. However, serum Hp was increased in all these six queens at diagnosis.