North American Veterinary Licensing Examination (NAVLE) Practice Test

The disease indicated by young chickens being found dead on their backs with no prior signs is associated with Flip-over disease, also known as "Sudden Death Syndrome." This condition particularly affects young broiler chickens and is characterized by sudden mortality without any apparent clinical signs. Healthy chickens can be found dead, often positioned on their backs.

The pathophysiology behind Flip-over disease relates to stress and metabolic disturbances that lead to a rapid increase in heart rate, potentially resulting in a fatal cardiac event. Factors contributing to the development of this condition include rapid growth rates, high stocking densities, and environmental stressors.

In contrast, other diseases mentioned, such as Highly pathogenic avian influenza and Newcastle disease, typically present with a range of clinical signs, including respiratory distress, neurological symptoms, or gastrointestinal signs, before death occurs. Ascites syndrome is associated with excess fluid accumulation in the abdomen and is more commonly seen in older chickens or in those exposed to certain environmental stressors, also presenting with other signs prior to mortality.