In which circumstance should a lactating goat be culled due to CAEV infection?

Culling a lactating goat due to CAEV (Caprine Arthritis-Encephalitis Virus) infection is particularly indicated when the goat develops a hardbag udder. This condition is a result of chronic inflammation and scarring in the udder tissue, which significantly affects milk production and the overall health of the animal. A hardbag can lead to substantial discomfort, making it difficult for the goat to nurse or produce milk effectively.

In the context of CAEV, the udder can become hard and firm due to the chronic nature of the infection, indicating a severe health issue that needs to be addressed. The decision to cull is also often influenced by the implications for the herd's health and productivity, as animals with advanced CAEV infection can act as reservoirs for the virus, potentially affecting other goats.

While the other conditions listed, such as arthritis (which can affect mobility), aggression (which may relate to other stressors), or weight loss (an indication of overall health decline), may warrant consideration, the presence of a hardbag udder is a more definitive sign that the goat is suffering from a significant and chronic issue directly linked to CAEV, typically leading to a recommendation for culling to maintain herd health and productivity.