How are infections characterized when no clinical signs are present?

Infections that occur without any observable clinical signs are characterized as subclinical. These types of infections can still be present in an organism, but the host may not exhibit symptoms or noticeable changes in behavior or physiology. This can make subclinical infections particularly intriguing and often challenging in both veterinary and human medicine, as the host may carry and transmit the infection without showing any outward signs of illness.

In contrast, acute infections are typically marked by sudden onset and pronounced symptoms, which would not align with the condition described in the question. Chronic infections persist over a longer period, often with ongoing symptoms, and systemic infections impact the entire body, affecting multiple systems or organs. Therefore, subclinical is distinctly appropriate, as it reflects a state where the infection exists without causing the animal to look or feel sick, potentially leading to unnoticed transmission and management issues in a laboratory setting.