Effects of Different Temperatures on the Development and Viability of Toxocara canis Eggs and Larvae

Objective: This study aimed to determine the effects of different temperature levels on the development of Toxocara canis eggs and the viability of larvae developing from these eggs.Materials and Methods: Eggs isolated from adult female T. canis obtained from naturally infected dogs were suspended in physiological saline solution at a concentration of approximately 4,000 eggs per sample and incubated at 0, 4, 10, 20, 25, 30, and 35°C for seven weeks. Egg development was monitored daily under a light microscope and classified as degenerated eggs, undeveloped eggs, eggs exhibiting blastomere division, embryonated eggs containing larvae, and free larvae. At the end of the incubation period, larval viability was evaluated.Results: No developmental progression was observed in eggs incubated at 0°C, and all eggs showed structural degeneration. At 4°C, blastomere division occurred; however, larval development did not occur. At 10°C, limited larval development (28%) was observed; however, the viability rate was low (10%). At 20°C and above, larval development increased markedly, reaching the highest level at 30°C (91%). Larval viability was also highest at 30°C (97%). At 35°C, both development (21%) and viability (43%) decreased significantly.Conclusion: In conclusion, temperature was identified as a determining factor in the development and larval viability of T. canis eggs. Optimal conditions for development and viability were observed at approximately 30°C, whereas very low and high temperatures were found to adversely affect the development and survival of the parasite.