Oct 24 (Reuters) - Elanco Animal Health ( ELAN ) said on

Friday it had received an emergency use authorization from the

U.S. Food and Drug Administration for its flea and tick drug to

treat dogs infected with a flesh-eating parasite found near the

U.S.-Mexico border.

This is the first time the FDA has granted such an

authorization for treating New World screwworm, a type of fly

whose larvae feed on the living tissue of animals. The parasite

can cause severe wounds and even death if not treated quickly.

"When it comes to emerging animal health threats, we need to

be proactive, not reactive," FDA Commissioner Marty Makary said

in a statement.

The FDA issues emergency use authorizations to allow the use

of unapproved treatments during public health threats when no

alternatives are available.

The move follows a determination by the U.S. secretary of

health and human services in August that there is significant

potential for a public health emergency involving New World

screwworm, which could affect national security or the health of

U.S. citizens abroad.

The parasite, Cochliomyia hominivorax, was eradicated from

the U.S. decades ago but has recently been detected in areas

close to the southern border. The FDA's move comes before any

confirmed cases in the United States.

Elanco said a study published in a scientific journal showed

that its drug Credelio, when given orally, cleared the parasite

in naturally infected dogs within 24 hours. However, the study

was small, involving just 11 dogs in Brazil, and lacked a

control group.

The FDA's emergency use of Credelio is temporary and only

valid while the threat of screwworm remains.

The drug is already approved in the U.S. to kill fleas and

several types of ticks in dogs.

The company warned that Credelio, part of a drug class

called isoxazolines, has been linked to side effects such as

tremors and seizures in some dogs.