The objectives of this study were to evaluate the severity of acute phase reaction and to investigate the paraoxanase-1 (PON-1) activity associated with ovariectomy (OVE) and ovariohysterectomy (OVH) in dogs. A total of 21 adult healthy dogs were included. The dogs were randomly divided into two groups and either ovariectomized (n=10) or ovariohysterectomized (n=11). Peripheral blood samples were collected preoperatively and on postoperative fourth day for serum ceruloplasmin (cp) and paraoxanase-1 activity measurements. Results were compared within and between groups. Potential correlation between paraoxanase-1 and ceruloplasmin was assessed. Preoperative mean serum ceruloplasmin levels in OVE and OVH groups were 0.80±0.17 and 1.65±0.35 U/ml, respectively (P>0.05). On postoperative 4th day, serum ceruloplasmin levels in OVH group (1.95±0.47 U/ml) was higher compared to OVE group (0.69±0.10 U/ml; P<0.05). Pre- and postoperative serum ceruloplasmin levels were not different within study groups (P>0.05). Preoperative serum paraoxanase-1 activity in OVE and OVH groups were 1001.56±44.60 U/ml and 1119.10±87.99 U/ml, respectively (P>0.05). Higher postoperative serum paraoxanase-1 activity was observed in OVH group (1065.15±46.00 U/ml) compared to OVE group (941.22±32.57 U/ml; P<0.05). Pre and postoperative serum paraoxanase-1 activity was not different within study groups (P>0.05). Paraoxanase-1 activity was not correlated with concentration of ceruloplasmin (P=.250; r=0.06). In conclusion, OVE is superior to OVH in terms of reducing the severity of postoperative acute phase response. In addition, OVE and OVH does not alter canine paraoxanase-1 activity on postoperative fourth day and paraoxanase-1 activity is not associated with serum concentration of ceruloplasmin in dogs.