You’d be hard-pressed to find a veterinarian or producer who hasn’t been frustrated with a diagnostic result. When it comes to herd health, good diagnostics are like detective work, but even the best tests can’t help if the wrong evidence is collected.
Sampling isn’t just grabbing what’s handy; it’s a deliberate process that links a clear question to the right animal, tissue and timing. Getting that process right saves money, reduces frustration and leads to faster, more confident decisions.
Here are five practical ways producers and veterinarians can work together to improve sample collection on the farm so that every diagnostic submission counts.
1. Start With the Right Question
Before taking a single sample, step back and ask: What do we want to know?
“Your diagnostic question really drives everything from sample selection to animal selection,” says Drew Magstadt of the Iowa State University Diagnostic lab. “If we don’t define the problem — What are you seeing? What’s going on? Why are you calling the lab? — we can’t really formulate a differential diagnosis list that we ask a diagnostic question.”
Taking samples “just to see what turns up” often leads to inconclusive results and wasted effort.
Field tip: Include your diagnostic question on your submission form. This helps the lab choose the best testing pathway and increases your chances of getting actionable answers.
2. Choose the Right Animals To Sample
When disease strikes, not all animals tell the same story. Aim to collect from animals showing early or typical clinical signs, not just those that are terminally ill.
“The answer isn’t always ‘the dead one that’s in front of us,’” stresses Magstadt. “Focus on acutely affected, untreated and representative animals.”
For herd investigations, sample several animals within the same group or age class to capture variation. In some cases, sampling a few seemingly healthy herdmates could provide valuable comparison data. Sampling only the worst looking survivors or those already treated with antibiotics could mask the cause of disease or send you down the wrong diagnostic path.
Field tip: For mortality events, select the freshest animals possible for necropsy. Early submissions preserve tissue integrity and increase the odds of a meaningful result.
3. Take the Correct Sample Type and Handle It Properly
Even the perfect sample loses its value if it degrades before reaching the lab. The sample type, container and preservation method matter just as much as the collection itself. Each diagnostic test has its own validated sample requirements. Using the wrong media, failing to chill samples or letting tissues autolyze can render tests useless.
On an episode of “DocTalk,” Dan Thompson highlighted some considerations for sample collection: “Being able to take the size of the sample from the right spot so that you have healthy tissue next to diseased tissue for histology. Getting the proper sample so that if you’re going to isolate pathogens you can. Whether you [need] fixed or fresh tissue. You need to work with your veterinarian who will know exactly what [you] want to have.”
A few extra minutes of planning can save days of waiting for a “sample unsatisfactory” call.
Field tip: Check your diagnostic lab’s sampling guide before collection and label everything clearly (animal ID, tissue, date).
4. Record Good Clinical and Herd Information
Providing accurate clinical histories and observations helps diagnosticians interpret findings in context. Include information such as onset and duration of illness, number of animals affected, treatments used, feed changes and vaccination history. Consider including photos if applicable.
This kind of supporting information allows labs to match findings with disease patterns and may even prompt recommendations for additional or alternative testing.
The Beef Cattle Research Council has put together a great resource for anyone interested in leveling up their animal health record-keeping.
Field tip: Use your herd health software to standardize the process. The more detail you include, the better.
5. Sample Early and Sometimes More Than Once
Timing matters. By the time a sick animal has been treated, recovered or died, diagnostic clues may have vanished.
Magstadt stressed that it’s possible to get a negative diagnostic test in a positive animal based on when a sample was taken. You must take into account “the timing of disease, when we would expect large amounts of the pathogen to be there, when we wouldn’t, and the different pathogens [involved].”
Whenever possible, collect samples early in the course of disease — ideally before antimicrobial or anti-inflammatory treatment. For diseases with intermittent shedding, repeat sampling over several days increases detection odds. Also consider whether pooled or composite sampling might make sense for your diagnostic goals.
Field tip: Keep sampling supplies ready on-farm so you can act immediately when new cases appear. Rapid responses can mean the difference between inconclusive results and a valuable diagnosis.
