The objective of this study was to describe how information about the whole lifetime of the cow can be used when defining nonhuman animal-based criteria of the welfare of animals on the farm. Often measured over a short period, disease occurrence provides information relevant for assessing the current welfare state of the herd. Arguably, however, if disease records are to be used as ethically relevant welfare indicators, it is also important to record disease occurrence over the individual animal's entire life span. Thus, it matters ethically whether the burden of an outbreak of disease or other condition affecting animal welfare is carried by a few individuals or is distributed more evenly. To illustrate this principle, the study obtained data on disease treatment records and production from 392,287 cows from the Danish Cattle Database. The average cow had lived for 5 years and produced more than 22,000 L of milk. The medium number of treatments a cow had received for any disease was 2, but 10% of the cows had received more than 8 treatments for a disease. The study concluded that lifetime description provides a measure of disease occurrence that gives added value of ethical relevance to single-point prevalence or short-term incidence.