Veterinary Controlled Substance Log: Requirements, Types & Free Template (2026 Guide)

If your veterinary practice holds a DEA registration, you are required to keep complete and current records of every controlled substance you receive, administer, dispense, and dispose of. The controlled substance log is where most of that record-keeping happens — and incomplete or inaccurate logs are among the most common violations the DEA cites during an inspection.

This guide explains what a controlled substance log is, what it must contain, the different logs your practice needs, how to fill them out correctly, and the mistakes that turn a routine inspection into a list of findings. You can download a free, ready-to-use template further down.

What is a controlled substance log?

A controlled substance log is the running record a veterinary practice keeps to account for every controlled drug in its possession. It documents the full chain of custody for each drug — from the moment a shipment arrives, through every dose administered or dispensed and every amount wasted, down to the final empty container.

The principle behind it is simple: as a DEA registrant, your practice must be able to account for every unit of every controlled substance, at any time. The log is how you prove it. When a DEA investigator arrives, they will take a physical count of a drug and reconcile it against your log. If the two don’t match — or the log has gaps — that is a finding.

Does your veterinary practice legally need one?

Yes. Under federal law (21 CFR Part 1304), every DEA registrant must maintain complete and accurate records of controlled substances on a current basis. Veterinary practices are registrants. This applies to every practice that orders, stocks, administers, or dispenses Schedule II–V drugs — which is nearly every practice that performs surgery, anesthesia, or euthanasia.

There is no small-practice exemption and no grace period. The obligation begins the day your DEA registration is active, and it sits with the registrant — the person or practice whose name is on the registration.

What a controlled substance log must contain

Each entry must capture enough detail that an inspector can reconcile the log against physical stock and trace any single dose. At a minimum, an entry should record:

The date of the transaction
The drug name, strength, and dosage form
The container or bottle the drug came from
Patient and client identification
The amount administered, dispensed, and wasted
The running balance remaining in the container
The person responsible — and, for any waste, a witness

The running balance is the single most important field. After every transaction, the log should show exactly how much drug is left — and that figure should always match what is physically in the container.

The controlled substance logs your practice needs

A common mistake is treating “the log” as one document. A complete record-keeping system usually involves several:

Opened-container log — the daily running log for each bottle currently in use, tracked down to empty. This is the workhorse, and the one most people mean by “controlled substance log.”
Unopened-stock record — what is held in the safe but not yet opened, so your total on-hand count is always known.
Receipt records — invoices, and DEA Form 222s for Schedule II purchases, proving what came into the practice and when.
Biennial inventory — the full physical count of all controlled substances, taken at least once every two years.
Authorized personnel record — a written list of who is permitted to access controlled substances.

Each answers a different question an inspector will ask. Together they form a system an inspector can follow end to end — from the invoice that brought a drug in, to the entry that took the last dose out.

Schedule II vs. Schedule III–V: how the records differ

Not all controlled substances are recorded the same way. The schedule of a drug changes how it is ordered and how its records are kept:

Schedule II (for example, certain opioids used in veterinary medicine) must be ordered on a DEA Form 222 or through the electronic CSOS system, and the records for Schedule II drugs must be kept physically separate from all other records.
Schedule III–V (for example, many sedatives and the controlled substances most common in general practice) may be ordered with a standard invoice, and their records must be kept either separately or in a form that is readily retrievable from the practice’s other business records.

In practice, the cleanest approach is to keep a distinct log for every controlled substance regardless of schedule, and to file Schedule II records separately. That way you never have to argue with an inspector about whether your records are “readily retrievable.”

How to fill out a controlled substance log correctly

Three rules separate a log that protects you from one that creates findings:

Record every transaction immediately. Not at the end of the shift, and never reconstructed from memory. A log filled in later is, by definition, not kept “on a current basis.”
Witness and document all waste. Any amount drawn up but not administered — partial doses, excess in the syringe — must be recorded and initialed by a second authorized person.
Reconcile the balance. The log balance must always match the physical count in the container. If it doesn’t, stop and investigate immediately, and document what you found. An unexplained discrepancy is the single biggest red flag in a DEA inspection.

A worked example

Say your practice opens a new 10 mL vial of a Schedule III injectable controlled substance.

You start a fresh opened-container log for that vial, record its details (drug, strength, lot, container ID), and enter a beginning balance of 10 mL.
A patient, “Bella,” is sedated and receives 0.6 mL. You enter the date, the patient, 0.6 mL administered, and a new balance of 9.4 mL, and you initial the entry.
Later, a 1.0 mL dose is drawn up for another patient but only 0.8 mL is used. The remaining 0.2 mL is wasted — you record 0.8 mL administered and 0.2 mL wasted, a second staff member witnesses and initials the waste, and the balance drops to 8.4 mL.
At any point, an inspector (or you) can pull the vial, measure it, and confirm it holds 8.4 mL — exactly what the log says.

That last step is the entire point. The log is only as good as its agreement with the physical drug.

Six controlled substance log mistakes that get practices cited

Gaps in the log — missing entries, or entries clearly written in later in the same pen and handwriting.
No witness on waste — wasted drug recorded with only one signature, or not recorded at all.
A balance that doesn’t match the count — the most common, and most damaging, finding.
One shared log for everything — instead of a separate log per opened container, which makes reconciliation impossible.
Loose-leaf pages — pages that can be removed or replaced, with no tamper evidence.
Logs not retained, or stored off-site — records that aren’t kept for the required period, at the registered location.

What a DEA inspector looks for in your log

During an inspection, an investigator typically does three things with your logs:

Picks a drug and counts it. They physically measure or count a controlled substance and compare it to the running balance. This is the core test.
Follows the paper trail. They trace a drug from its receipt record (invoice or Form 222) through the log to its current balance, looking for breaks in the chain.
Reads the log critically. They look for gaps, un-witnessed waste, entries in inconsistent ink or handwriting, and balances that were “corrected” without explanation.

A clean, current, reconciled log answers all three before they are even asked. A messy one invites every follow-up question an inspector has.

How long to keep controlled substance logs

Federal rules require controlled substance records to be kept for at least two years, at the registered practice location, and available for DEA inspection. Several states require a longer retention period — confirm the requirement with your state veterinary board.

Paper vs. digital logs

Both are acceptable. Paper logs are traditionally kept in bound logbooks, because bound pages provide a clearer, harder-to-alter paper trail than loose sheets. Digital logs are acceptable if they are tamper-evident and timestamped.

A spreadsheet template sits usefully in between: it can be printed and used on paper, or kept digitally, and it calculates the running balance automatically — which directly prevents the most common citation, a balance that doesn’t match the physical count.

Download a free controlled substance log template {#lead-magnet}

We’ve built a free Veterinary Controlled Substance Log Template you can use today — a clean opened-container log with an automatic running balance, a built-in instructions sheet, and the legal basis explained. Enter your email and we’ll send it over, free.

Get the free Controlled Substance Log Template →

Frequently asked questions

Is a controlled substance log a legal requirement? Yes. Federal law (21 CFR Part 1304) requires every DEA registrant, including veterinary practices, to keep complete and current records of the controlled substances they handle.

Can I use a spreadsheet or does it have to be a bound book? Both are acceptable. A bound logbook gives a strong paper trail; a digital or spreadsheet log is acceptable if it is tamper-evident and timestamped. The requirement is accuracy and completeness, not a specific format.

Who can make entries in the controlled substance log? Authorized personnel who are part of the practice’s controlled-substance handling. Waste in particular must be witnessed and initialed by a second authorized person.

How long do I have to keep controlled substance logs? At least two years under federal rules, kept at the registered location. Some states require longer — check your state veterinary board.

What happens if my log doesn’t match my physical count? An unexplained discrepancy is a serious red flag and a common DEA finding. Investigate immediately, document what you found, and — if a loss or theft is involved — follow the reporting requirements.

A log is one piece — not the whole picture

A complete, accurate controlled substance log is necessary. But it is not, on its own, enough to pass a DEA inspection — an investigator checks dozens of items beyond your logs: how drugs are stored, who has access, whether a biennial inventory was done, how losses are reported, and whether your staff are trained.

To see where your practice actually stands, run our free DEA Self-Audit Checklist — the 39 items an inspector checks, as a self-scoring worksheet. And when you’re ready to close the gaps, the Vet Compliance HQ DEA Controlled Substance Compliance System gives you the logs, SOPs, staff training records, and templates to do it.

Vet Compliance HQ provides educational compliance resources for veterinary practices. This article is not legal advice. DEA and state requirements change and vary by state — verify current requirements with the DEA and your state veterinary board.