LA-200, sold under the brand name Liquamycin LA-200, is an injectable antibiotic used in cattle and swine. Each milliliter contains 200 milligrams of oxytetracycline (that’s where the “200” comes from), making it a concentrated, ready-to-use formulation designed to fight bacterial infections in livestock. It was originally developed by Pfizer Animal Health and is one of the most widely recognized veterinary antibiotics in the United States.
What LA-200 Treats
LA-200 is FDA-approved to treat bacterial pneumonia in both cattle and swine, as well as anaplasmosis in cattle. Anaplasmosis is a tick-borne blood disease that destroys red blood cells and can be fatal if left untreated. Bacterial pneumonia, sometimes called “shipping fever,” is one of the most common and costly diseases in beef cattle, often flaring up after the stress of transport or weather changes.
The drug works as a broad-spectrum antibiotic, meaning it’s effective against a wide range of bacteria rather than just one type. It targets both gram-negative and gram-positive bacteria, which gives it versatility across different infections.
How It Works
Oxytetracycline belongs to the tetracycline family of antibiotics. It stops bacteria from growing by blocking their ability to build proteins. Without new proteins, bacteria can’t reproduce or maintain their cell functions. The drug latches onto a specific part of the bacterial machinery responsible for assembling proteins and essentially jams the process.
This binding is reversible, which means LA-200 is bacteriostatic rather than bactericidal. In plain terms, it doesn’t kill bacteria outright. Instead, it holds them in check long enough for the animal’s own immune system to clear the infection. The drug also reduces bacteria’s ability to stick to cells, which limits how aggressively an infection can spread through tissue.
Why It’s Called “Long-Acting”
The “LA” in LA-200 stands for “long-acting.” At the higher dose of 9 mg per pound of body weight, a single injection has been shown in clinical trials to be as effective as two or three daily treatments at the standard lower dose of 3 to 5 mg per pound. That’s a significant practical advantage. Handling livestock for repeated injections is stressful for the animals and time-consuming for the rancher, so a one-shot treatment option makes a real difference in day-to-day management.
Dosing and Injection Guidelines
LA-200 can be given intravenously, subcutaneously (under the skin), or intramuscularly (into the muscle). The standard daily dose is 3 to 5 mg of oxytetracycline per pound of body weight, while the single long-acting dose is 9 mg per pound.
Volume limits per injection site matter. For adult beef and dairy cattle, no more than 10 mL should go into any one intramuscular or subcutaneous site. Adult swine have a lower limit of 5 mL per intramuscular site. Small calves should receive only 1 to 2 mL per site. You need to rotate injection sites with each treatment to avoid tissue damage and reduce the chance of injection-site lesions that can lower carcass quality at processing.
Prescription Requirements
LA-200 used to be available over the counter at farm supply stores, but that changed. Under FDA Guidance for Industry #263, which took effect on June 11, 2023, medically important antimicrobials like oxytetracycline transitioned to prescription-only status. This means you now need a prescription from a licensed veterinarian to purchase LA-200.
The FDA allowed existing over-the-counter labeled stock already in distribution channels to sell through until supplies ran out, so there was a transition period. But going forward, all product entering the market carries prescription labeling. The goal behind this change is to slow the development of antibiotic-resistant bacteria by ensuring a veterinarian is involved in the decision to use these drugs. If you previously bought LA-200 off the shelf, you’ll now need to establish a veterinarian-client-patient relationship to obtain it.
Practical Considerations for Livestock Producers
Because LA-200 ends up in animal tissue, withdrawal periods apply. Treated animals cannot be sent to slaughter for human consumption until enough time has passed for the drug to clear their systems. The specific withdrawal period depends on the species, the dose given, and the route of injection, so this information appears on the product label and should be followed exactly. Using the wrong withdrawal period risks drug residue violations, which can result in regulatory penalties and condemned carcasses.
LA-200 is a sterile, ready-to-use liquid in an aqueous (water-based) vehicle. It should be stored according to the label’s temperature guidelines to maintain potency. The product has a distinctive golden-yellow color typical of tetracycline drugs, and any significant color change or cloudiness in the solution can indicate degradation. Always use a clean, sterile needle for each vial puncture to prevent contamination.