- Disease treatment refers to medicating an animal or group of animals that have a particular disease.
- Disease prevention refers to medicating an animal or group of animals that are likely to contract a disease when the animals are in situations in which a particular disease has historically occurred.
- Disease control refers to medicating an animal or group of animals that are in situations in which they will likely be exposed to or contract a particular disease.
Antibiotic use: Prevention vs. control
These two terms may seem similar (six of one, half-dozen of the other), but it seems to me, in the eyes of the world, the term “control” seems to be more targeted to addressing livestock welfare without as much concern for indiscriminate antibiotic use.
Current label wording will be changed to meet the new VFD requirements. Considering the “control” wording changes, feed-grade antibiotic use to deal with cattle liver abscesses will likely be an example of label revisions.
Feed-grade antibiotics approved for cattle are labeled to aid in the “reduction of liver condemnations due to liver abscesses.” This type of wording will likely be changed to “aid in the control of liver abscesses caused by Fusobacterium necrophorum and Trueperella pyogenes.”
The most notable cattle disease that currently has feed-grade antibiotics labeled for control is anaplasmosis caused by Anaplasma marginale.
Understanding anaplasmosis
Anaplasma marginale is a blood parasite that is devastating to older cattle. Youngstock, while they can be infected and be carriers of the parasite, seldom show clinical signs. The parasite is transferred between animals by blood contamination.
The parasite transfer is often via blood-sucking insects, and because these types of insects are more common in the South, the prevalence of the disease in cattle is higher in southern U.S. latitudes. In some parts of the U.S., the occurrence of clinical anaplasmosis can occur year-round (See ‘Minimizing transfer’ below).
The feed-grade antibiotic chlortetracycline is approved to control anaplasmosis, and the dose of 50 milligrams per hundredweight fed daily, as instructed on the label, seems very effective.
The FDA indicates 180 days will be the maximum length of time a VFD order can be effective. If chlortetracycline, the feed-grade antibiotic approved for anaplasmosis control, is assigned 180 days, some parts of the U.S. will require two VFD orders to responsibly meet the needs of cattle to control anaplasmosis in endemic areas.
The FDA is making it very clear they are working with every state to address concerns about the availability of licensed veterinarians in the state in which the cattle reside to write VFD orders. Anaplasmosis control must be a high priority.
To avoid gaps in coverage in critical disease management, the FDA will allow the VFD order “effective date” to be at a future time from the date the veterinarian writes the VFD order.
While anaplasmosis may not currently be an issue in your area, cattle producers should have a conversation with a veterinarian in their area now about feed-grade antibiotic usage and VFD orders. Their feed suppliers are an additional source of information about VFD requirements and can help them make contact with a veterinarian in their area. 
Dee Griffin is the director of the Texas Veterinary Medical Center partnership at Texas A&M University. Email Dee Griffin.
Prescription vs. Order
For what it is worth, VFD regulations avoid use of the word “prescription” and instead uses the word “orders.” While this may seem trivial, the word “prescription” has a much more restrictive and controlling regulatory definition than the word “order” as it applies to drug use.
Believe it or not, the FDA Center for Veterinary Medicine is a friend of cattle raisers and has for decades fought off agencies from other countries, as well as a few agencies in the U.S., that want to place even more restrictive controls on availabilities of livestock medications.
Minimizing transfer
Besides insects, humans can play a serious role in transferring the disease between cattle during vaccination, dehorning, castration and rectal palpation.
However, it is reasonably easy to minimize the transfer when working cattle by rinsing instruments in water between cattle. Water will rupture the red blood cells that carry the parasite and effectively prevent transfer.
