Post-treatment interval (PTI) may bring to mind a complicated series of mathematical equations, but it really comes down to a period of time when beef producers don’t have to do much more than keep an eye on their cattle — and that downtime can even put more dollars in their pockets.
“A PTI is really just the period of time a producer can confidently wait to assess whether or not a treatment has been successful,” says Lee Bob Harper, DVM, managing veterinarian with Pfizer Animal Health. “During this interval of time, the treatment should be working to provide effective levels of medication against a disease challenge.”
When a medication can provide effective levels of therapy for a longer period of time, the cost of the treatment is spread over the duration of the interval – making better use of beef producers’ treatment dollar, Dr. Harper notes.
In a typical operation, PTI is most helpful when considering treatments for bovine respiratory disease (BRD). Traditional practices usually call for a treatment administered about every three days, until the animal recovers. Every additional treatment adds to the medical bill of a sick calf.
“In the meantime, a product with a PTI of a week or more can provide effective treatment levels without additional expenses,” Dr. Harper says. “If producers know the product is inside the animal, continuing to work, then they can focus less on the outward signs of a recovering animal that may still look a bit off.”
PTIs are determined by extensive research for each product, and it’s important to note that not all products have the ability to continue providing effective treatment levels for a week. In fact, many products remain active for a matter of hours or at most three or four days. Dr. Harper says. DRAXXIN® (tulathromycin) Injectable Solution, for example, has been proven to be effective for seven to 14 days after the first treatment. In one study, 85 percent of cattle were treated successfully after a single injection with no difference in mortality rates or average daily gain following a seven, 10 or 14 day PTI.1
“Better understanding the PTI of the treatments used for BRD can help producers improve their bottom line, and their herd’s overall health,” Dr. Harper says. “If they can use a product that works well on the first injection, and works for a longer period of time, then producers can reduce the number of doses used overall, which isn’t a complicated formula.”
Do not use in calves to be processed for veal. A pre-slaughter withdrawal time has not been determined for pre-ruminating calves. Effects on reproductive performance, pregnancy and lactation have not been determined. DRAXXIN has a pre-slaughter withdrawal time of 18 days.