Final answer:
The EIA test referred to in the context of horses entering NH from outside states is known as the Coggins test.
Step-by-step explanation:
Horses coming into the state of NH from outside states must have health certificates with a negative Equine Infectious Anemia test. The EIA test is more commonly referred to as the Coggins test. The Equine Infectious Anemia (EIA) is a viral disease that affects horses and is tested by the Coggins test to ensure that the horses are not carriers of the virus. The EIA virus is transmitted through blood-feeding insects and can pose a serious health risk to the horse population.