1) Livestock ownership, especially poultry, is very common in rural areas of developing countries. Keeping livestock indoors where children live is also common. 2) Observational studies found animal feces to be prevalent in households in Bangladesh, Ethiopia, and Vietnam, ranging from 38-42% of households. 3) Analysis of survey data found that keeping poultry indoors was associated with lower child height-for-age (HAZ) in Ethiopia, and presence of animal feces outside was associated with lower HAZ in Bangladesh and Ethiopia. More research is needed to understand the mechanisms and scale of the problem.