Every animal born on your operation starts its record at zero — you were there, you wrote the birth down, and everything since is yours. An animal you buy arrives already carrying a history: treatments, vaccinations, maybe a withdrawal window still open, maybe none of that because it was never recorded by whoever had the animal before you. That history does not transfer automatically just because the animal did. It transfers only if someone asks for it, writes down the answer, and treats a shrug as an answer worth recording too.
Purchased animals are where the discipline of the rest of a farm's recordkeeping is tested against a stranger's, and the honest starting point is that you usually cannot verify what you are told. What you can do is record what you asked, what you were told, and what you observed, so the gap between "known" and "unknown" is visible rather than quietly erased.
The seller's record is not yours to certify. When a purchased animal arrives, there is no way for you to independently confirm a treatment history you were not present for, including whether it currently sits inside an active withdrawal window. This page is about documenting what you asked and what you were told — not about verifying it. If an animal's history is uncertain, the safe assumption and the right isolation practice are questions for your veterinarian, not a guess made at the trailer.
The purchase record starts with what you don't know
The instinct when an animal arrives is to start the record the day it shows up — weight on arrival, group assigned, first observation — and treat everything before that as someone else's problem now solved. That instinct erases the most important fact about a purchased animal: there is a gap in its history, and the gap is not the same as a clean history. An animal with no known treatments and an animal whose treatments were simply never asked about look identical in a record that starts on arrival day. They are not the same animal from a risk standpoint, and only a record that captures the asking, not just the answer, can tell them apart later.
The same problem shows up at a different scale in a sale barn purchase, where a lot may pass through several hands and a ring before it reaches you, and any documentation that existed further back in that chain has likely already thinned to nothing. A private-treaty purchase from a single known seller is the easier case, because there is one person to ask and one answer to record. A sale-barn lot is the harder case, and it is exactly the case where writing down "source: sale barn, no prior history available" earns its keep — it tells a future reader of the record that the gap was noted, not overlooked.
Ask for the history even when you expect nothing
Most private-treaty and sale-barn purchases come with little or no documentation, and it is tempting to skip asking because the answer is predictable. Ask anyway, and record the date you asked and what you were told, including "nothing was provided." The value is not in extracting a perfect record from a seller who does not have one — it is in creating your own record of due diligence, which is the thing you will actually be able to produce later if a question comes up about an animal's history before it was yours.
Where documentation does exist, the specific field that matters most is whether any treatment administered by the previous owner puts the animal inside an active withdrawal window on arrival. This is squarely the subject of withdrawal and residue records, and it deserves its own line in a purchase record rather than being buried in a general note, because it is the one fact that can turn an otherwise routine sale of that animal, weeks later, into a residue problem you inherited without knowing it.
An unrecorded history is not a clean history
It is easy to treat "the seller didn't mention anything" as equivalent to "there is nothing to mention." Those are different claims, and conflating them is where risk hides. A record that distinguishes "confirmed no recent treatment" from "no information was provided" gives whoever manages that animal going forward, including a future version of you, the ability to apply appropriate caution to the second case instead of extending it the same confidence as the first.
This distinction earns its keep at exactly the moment a purchased animal comes up for sale again. A buyer, a certifier, or your own sale workflow asking "is this animal clear to sell" needs a real answer, and "we were never told otherwise" is a materially weaker answer than "confirmed clear on arrival, and nothing administered since." Only a record that kept the two apart from the start can produce the stronger answer honestly.
The animal's own identity may need to be reconciled, not assumed
A purchased animal may arrive with an existing tag from the previous owner, a new tag you apply on arrival, or both. Recording which tag or tags the animal carries at the point of purchase, and linking any new tag you apply back to whatever identifier accompanied the sale paperwork, is what keeps the animal's pre-purchase documentation — if any exists — connected to the record you build from here forward, rather than starting a second, disconnected identity the moment it crosses your gate.
Where the purchase record fits from here
Once an animal is on the farm, it needs the same ongoing records as any other — a group assignment, a weight, eventually a breeding history — and the purchase record's job is largely done once it has established what came before and what is currently open or unknown. Farm40 gives every animal a purchase-and-origin field alongside its ongoing history, and one of the twelve one-click CSV exports pulls a full purchase log — date, source, price, and whatever health notes were entered — for the season or the year. The limit is the same one that applies to every export: it is a view of what was entered at the time. It cannot verify a seller's claim, and it cannot recover a history that was never asked for in the first place.
Purchases are one entry point into the broader discipline described in the livestock management guide, and the one most likely to be treated as a transaction rather than the start of a record — which is exactly backwards, since the animal's history did not start the day you bought it, even if your knowledge of it did.