Objective: The work aimed to determine the state of lipid peroxidation products and the activity of the antioxidant system in cats with aseptic inflammation and purulent-inflammatory processes of varying severity. Materials and Methods: The intensity of the process of lipid peroxidation- antioxidant system processes in blood plasma was evaluated using commercial kits. The level of diene conjugates (DC), the content of malondialdehyde (MDA), the level of medium-weight molecules were deter¬mined from lipid peroxidation indices. The state of antioxidant protection was assessed by indi¬cators of superoxide dismutase (SOD) activity, catalase (CT), ceruloplasmin (CP) concentration, glutathione peroxidase activity, glutathione reductase (GLR), and total antioxidant activity (AOA). Results: With aseptic inflammation in the blood of cats, a slow activation of peroxidation reactions occurred. The DC indicator increased by 1.4 times, the SOD level rose by 1.38 times, the amount of GLR by 1.04 times, and the activation of total AOA by 9.06. In sepsis, the values of DC, MDA, and medium-weight molecules increased by 4.4, 8.4, and 8.8 times, respectively. With abscesses in the blood of cats, an increase in CT, CP, and GLR is observed against a background of a decrease in glutathione peroxidase. With purulent wounds, the total AOA of plasma increases by 2.5 times; with abscesses, the total AOA increases by 1.9 times, and with sepsis, it decreases by 1.5 times. Conclusion: With surgical infections in cats, deep biochemical changes or irreversible biochemical changes (in sepsis) occur that indicate a significantly enhanced catabolic orientation of metabolic processes and the accumulation of toxic metabolites, which leads to damage and a decrease in tissue regenerative capacity. [J Adv Vet Anim Res 2021; 8(2.000): 210-217]

Opioids are considered the gold standard to manage acute or chronic or mild to severe pain. Tramadol is a widely prescribed analgesic drug for dogs and cats; it has a synthetic partial agonism on μ-opioid receptors and inhibits the reuptake of norepinephrine and serotonin. However, the biotransformation and resultant metabolites differ between species and depend on cytochrome P450 interactions. Dogs mainly produce the inactive N-desmethyl tramadol metabolite, whereas cats exhibit an improved antinociceptive effect owing to rapid active O-desmethyltramadol metabolite production and a longer elimination half-life. Tapentadol, a novel opioid with dual action on μ-receptors and noradrenaline reuptake inhibitory activity, is a promising option in dogs, as it is less reliant on metabolic activation and is unaffected by cytochrome polymorphisms. Although scientific evidence on the analgesic activity of tapentadol in both species remains limited, experimental studies indicate potential benefits in animals. This review summarizes and compares the pharmacology, pharmacokinetics, and therapeutic efficacy of tramadol and tapentadol in dogs and cats with different pain conditions. According to the available data, tramadol seems a more suitable therapeutic option for cats and should preferably be used as a component of multimodal analgesia in both species, particularly dogs. Tapentadol might possess a superior analgesic profile in small animals, but additional studies are required to comprehensively evaluate the activity of this opioid to manage pain in dogs and cats. [J Adv Vet Anim Res 2021; 8(3.000): 404-422]