Several diseases can pass between dogs and humans (zoonoses), with welfare implications for affected dogs and public health significance for their owners. Responsible management protects both dog welfare and human health.
Toxocara canis roundworms infect virtually all puppies through transplacental and transmammary transmission. Puppies shed enormous numbers of eggs in faeces, contaminating the environment. Larvae in contaminated soil can migrate in humans (visceral larva migrans, ocular larva migrans—rare but serious causes of vision impairment in children). Regular deworming of puppies (every 2 weeks until 12 weeks, monthly until 6 months) reduces environmental contamination. Adult dogs require quarterly deworming or regular egg count monitoring.
Dogs can carry Campylobacter jejuni and Salmonella species without clinical illness, shedding organisms in faeces. Raw meat diets significantly increase shedding of these zoonotic pathogens. Careful hand hygiene after handling dog faeces, prompt faecal disposal, and avoiding dog-to-face contact reduces transmission risk. Households with immunocompromised individuals, young children, or elderly people should exercise heightened precautions particularly with raw-fed dogs.
Dermatophyte fungi (Microsporum canis, Trichophyton mentagrophytes) cause ringworm in dogs—circular, scaly, alopecic skin lesions that are directly transmissible to humans through contact. Treatment with topical antifungals, systemic treatment (itraconazole, terbinafine) for widespread infection, and environmental decontamination of spores is required. Welfare for affected dogs includes appropriate treatment preventing spread and discomfort from skin lesions.
Zoonotic risk from dogs is real but manageable through responsible ownership: regular deworming; appropriate vaccination; hand hygiene after contact with faeces; prompt clean-up of dog faeces in public spaces; regular veterinary health checks; and seeking veterinary advice for skin conditions or unusual symptoms. Responsible ownership protects both dog welfare and human health simultaneously, reinforcing the interconnected nature of One Health approaches to disease prevention.