Rabies is caused by a virus that infects the central nervous system in mammals. It is almost always transmitted through the bite of a rabid animal. The majority of rabies cases in the United States occur in wildlife including raccoons, skunks, foxes and bats. Rabies is invariably fatal; however, effective vaccines are available to protect people, pets and livestock.

Oral rabies vaccination (ORV) has been in use in the United States since 1990, in Canada since 1985 and in Europe since 1980. Currently there are sixteen states distributing oral vaccines for raccoons in the U.S., while Texas distributes baits for gray fox and coyote. The ORV baits currently being used in the United States are developed and manufactured by Merial, Inc. and consist of a sachet, or plastic packet containing the Raboral V-RG® rabies vaccine. To make the baits attractive, the sachets containing vaccine are sprinkled with fishmeal coating or encased inside hard fishmeal polymer baits about the size of a matchbox. When an animal finds a bait and bites into it, the sachet ruptures, allowing the animal to swallow the vaccine. Animals that swallow an adequate dose of the vaccine, develop immunity to rabies. As the number of vaccinated animals in the population increases, they act as a buffer to stop the spread of the disease to other wildlife, domestic animals, and people.

The U.S. Department of Agriculture - Wildlife Services has established the National Oral Rabies Vaccination (ORV) Program with the goal of limiting the westward expansion of raccoon rabies. This goal is being accomplished through the establishment of a "vaccine barrier" that will run from eastern Ohio (beginning at the border with Lake Erie) down the Appalachian ridge to Mobile County, Alabama, ending at the Gulf of Mexico.

In February 1995, the Texas Department of State Health Services (DSHS) initiated the ORV program as a multiyear program with a goal of creating zones of vaccinated coyotes and gray foxes along the leading edges of the epizootics, thereby halting the spread of the virus. The ORVP is a cooperative program involving DSHS; Texas Cooperative Extension Wildlife Services; US Department of Agriculture; Texas National Guard; Centers for Disease Control and Prevention; Merial Ltd.; Dynamic Aviation Group, Inc.; U.S. Army Veterinary Laboratory at Ft. Sam Houston, San Antonio, Texas; Texas A&M University System; and other local, state, and federal agencies. The aerial distribution of vaccine that occurs during each year involves King Air aircraft from the Dynamic Aviation Group, Inc. and annually results in a total flight distance equaling approximately 4 times around the world. Since 1995, the program has been responsible for the distribution of over 25.4 million individual doses of Raboral V-RG®, an oral rabies vaccine, over approximately 352,100 square miles of Texas.