The environmental impact of companion animals has received little scientific attention compared to that of livestock, even though the global dog population is rapidly increasing, particularly in urban areas. This review addresses the overlooked contribution of dogs to environmental emissions, focusing on feces, urine, packaging waste, and other care-related by-products. The current knowledge from livestock research provides useful analogies for understanding nutrient excretion and gaseous emissions from dog feces, and data on nitrogen and phosphorus inputs highlight their potential to pollute soil and water. We also examine the role of plastic waste from food packaging, waste bags, and accessories, which can degrade into microplastics, and discuss recent developments in biodegradable materials. Evidence shows that owner choices—such as diet composition, protein sources, and product selection—directly affect the environmental pawprint of dogs. Mitigation strategies include optimizing diets to reduce nutrient excretion, applying feed additives developed for livestock, and improving waste management through composting or the use of emission-reducing amendments. In conclusion, dogs should no longer be viewed merely as individual household companions but as a population with a measurable environmental pawprint. Including dogs in emission reporting systems would provide a more accurate basis for mitigation policies and sustainable urban planning.