Answer :
The healthy animal may have natural immunity or genetic resistance to the pathogen, preventing illness despite exposure.
When an animal remains healthy after being injected with a pathogen isolated from a sick animal, it indicates that the animal may have some form of natural immunity or resistance to the pathogen. This resistance could be due to various factors, including:
1. Previous Exposure: The animal may have been previously exposed to a similar pathogen or a related strain, leading to the development of immunity.
2. Genetic Resistance: The animal may possess genetic factors that confer resistance to the pathogen, preventing infection or reducing its severity.
3. Innate Immune Response: The animal's innate immune system may be particularly effective at recognizing and eliminating the pathogen before it can cause illness.
4. Environmental Factors: The animal's environment or management practices may reduce its exposure to the pathogen, decreasing the likelihood of infection.
Overall, the ability of an animal to remain healthy after exposure to a pathogen isolated from a sick animal suggests the presence of some form of protective immunity or resistance, which can be beneficial for disease control and management strategies.
I think what is indicated when, in spite of being injected with a pathogen isolated from a sick animal, another animal remains healthy; is that the animal could be immune to that particular pathogen or may be the pathogen was not pathogenic. A pathogen is an agent that causes a disease;;according to Koch postulates when isolated pathogen is injected into a healthy animal, animals must develop disease, which if the disease is not developed, then the pathogen is not pathogenic or may be the animal is immune.