Which statement is true of a subclinical disease?

• A. It is diagnosed by laboratory tests.
• B. It is an acute form of the disease.
• C. It does not occur in animals in the wild.
• D. Signs of the disease are apparent upon gross examination of the animal.

Answer: (A)

Subclinical disease means the animal carries an infection or disease process without showing outward clinical signs. Because there are no visible clues, diagnosis relies on laboratory testing rather than observation—tests that detect the pathogen itself or the body's response to it, such as antibodies, pathogen DNA/RNA, or abnormal lab values. That’s why the true statement is that it is diagnosed by laboratory tests.

The idea that it is an acute form is incorrect because subclinical disease lacks the rapid onset and obvious signs that define acute illness. It can occur in wild animals as well, so saying it does not occur in animals in the wild isn’t accurate. And signs aren’t apparent on gross examination for subclinical disease, since there are no noticeable external or gross changes—lab findings are what reveal the issue.