Zoonotic parasites associated with predation by dogs and cats

One of the most common behaviors of cats that have an indoor/outdoor lifestyle is to bring hunted "gifts" to their owners, represented by small mammals, reptiles and birds. Access to the outdoors by dogs and cats may represent a problematic issue, since they may be at risk of diseases, traffic accidents and ingestion of toxins. Yet, the impact of this population of roaming dogs and cats predating wildlife is another concerning issue that receives less attention. Despite these risks, most owners still prefer to give outdoor access to their pets to allow them to express their "natural instincts," such as hunting. Therefore, with a growing population of > 470 million dogs and 373 million cats worldwide, predation not only represents a threat to wildlife, but also a door of transmission for parasitic diseases, some of them of zoonotic concern. In this review, the role played by dogs, and especially cats, in the perpetuation of the biological life cycle of zoonotic parasites through the predation of rodents, reptiles and birds is discussed. Feral and domestics dogs and cats have contributed to the population collapse or extinction of > 63 species of reptiles, mammals and birds. Although the ecological impact of predation on wild populations is well documented, the zoonotic risk of transmission of parasitic diseases has not received significant attention. The parasitic diseases associated to predation vary from protozoan agents, such as toxoplasmosis, to cestodes like sparganosis and even nematodes such as toxocariasis. Raising awareness about predation as a risk of zoonotic parasitic infections in dogs and cats will aid to create responsible ownership and proper actions for controlling feral and free-roaming cat and dog populations worldwide.