1. The pathogen must be found in an animal with the disease and not in a healthy animal.
2. The pathogen must be isolated from the sick animal and grown in a laboratory culture.
3. When the isolated pathogen is injected into a healthy animal, the animal must develop the disease.
4. The pathogen should be taken from the second animal and grown in a laboratory culture. The pathogen should be the same as the original pathogen.

What is indicated when, in spite of being injected with a pathogen isolated from a sick animal, another animal remains healthy?

Koch's Postulates are a set of guidelines used to determine the causative agent of a disease. If an animal injected with a pathogen isolated from a sick animal remains healthy, there may be an issue in fulfilling one of Koch's Postulates.

Explanation:

Koch's Postulates are a set of guidelines used to determine the causative agent of a disease. If an animal injected with a pathogen isolated from a sick animal remains healthy, it indicates a potential issue in fulfilling Koch's Postulates, particularly in the step where the cultured agent must cause the same disease when inoculated into a healthy, susceptible organism.

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