Based on the increase of food-related disturbances in animals and the recent findings concerning the toxicity of oxytetracycline (OTC) presence within pet food, we compared the effectiveness of two commercially available diets in 36 bitches suffering from reproductive disturbances. We ran a randomized clinical evaluation over a 90-day period. Bitches were randomly assigned to receive a control diet (CD) or a nutraceutical diet (ND) and were assessed for the presence of OTC in their sera before and at the end of the study. Sixteen of 18 bitches in the ND group went into heat within an average of 35.5 ± 3.1 days, and 15 of them became pregnant. In the CD group, 12 of 18 bitches went into heat within an average of 54.1 ± 3.2 days, and 10 of them became pregnant. A significant decrease in mean OTC serum concentration was observed in bitches belonging to the CD and ND group (P < 0.01). The overall amelioration, in particular in the ND group, provides new insights for future studies involving the modification of diet in order to restore the normal physiology of bitches suffering from reproductive disturbances.