Which of the following diseases is NOT commonly associated with elderly animals?

Congenital diseases are conditions that are present at birth and typically arise during fetal development due to genetic mutations, environmental factors, or a combination of both. These diseases are not directly related to the age of the animal, meaning they can affect animals of any age, including young or mature individuals.

In contrast, degenerative diseases, cancers, and heart diseases are often more prevalent in elderly animals as they tend to develop over time due to age-related changes, wear and tear of bodily systems, or increased likelihood of mutation accumulation. As animals age, they become more susceptible to these conditions, which are commonly observed in geriatric populations. Thus, congenital diseases stand apart as they are not age-related and are not more frequently seen in older animals, making them the correct choice in this question.