Which health issue is often associated with livestock that are not adequately vaccinated?

Respiratory disease is a common health issue in livestock that are not adequately vaccinated. Vaccination plays a crucial role in preventing infectious diseases that can affect the respiratory system of animals, particularly in herds where stress factors, such as overcrowding or poor ventilation, may increase susceptibility. Diseases like infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), and others can result in severe respiratory distress and can be effectively mitigated through proper vaccination protocols.

In contrast, while foot rot, muscle wasting, and overheating may affect livestock, they are not primarily related to vaccination status. Foot rot is usually caused by bacterial infections associated with poor hygiene and environmental conditions. Muscle wasting can be attributed to nutritional deficiencies or chronic disease states rather than a lack of vaccination. Overheating, often a result of environmental factors or excessive heat stress, doesn't relate directly to vaccination practices either. Thus, inadequate vaccination is most closely linked to respiratory disease among the given options.