What are early signs of dehydration in an infant?

Dry mucus membranes and tachycardia are indeed early signs of dehydration in an infant. When an infant is dehydrated, one of the first physical signs is the lack of moisture in the mucous membranes, which can lead to noticeable dryness in the mouth and throat. This occurs because the body is losing more fluids than it is taking in, which affects the hydration status of the mucous membranes.

Tachycardia, or an increased heart rate, can also be an early indicator of dehydration. As the body's fluids diminish, the heart compensates by beating faster to maintain adequate blood circulation and ensure that oxygen and nutrients are delivered effectively to the organs. This physiological response is particularly critical in infants, who have smaller blood volumes and are more susceptible to the effects of dehydration.

In contrast, the other options listed either represent conditions that are not typical early signs of dehydration or are indicative of the opposite situation. Increased appetite would generally suggest that the infant is well-hydrated, while moist skin would indicate adequate hydration levels. Normal urine output is also not consistent with dehydration, as dehydration typically leads to decreased urine output. Thus, recognizing dry mucus membranes and tachycardia as early signs can help health care providers respond promptly to prevent further complications.