Disease diagnosis is a challenge. Hogs can’t explain what’s wrong or how they feel, so it requires you and your veterinarian to investigate. Along with reviewing records and observing animals, getting a diagnosis today often means digging deeper — conducting necropsy exams.
In the past, veterinarians would conduct all the on-farm necropsies. But with increasingly busy schedules — yours and your veterinarians’ — along with the complexity and financial impact of today’s diseases, more producers are overseeing the process themselves. Certainly, on-farm necropsies can help expedite diagnosis and treatment, which is everyone’s goal.
If you haven’t done so already, set up an appointment with your veterinarian to come on-site and conduct a training session about when and how to conduct necropsy exams.
There are two main reasons to learn to perform necropsies, according to Alex Ramirez, DVM, veterinary diagnostic and production animal medicine department, Iowa State University. One is to learn more about diseases that may surface within your herd. The second is for farm personnel to gain a clear understanding of which tissues are needed to assist with the diagnosis. They also need to learn how to collect and, if necessary, further prepare the tissues as well as how to submit them to your veterinarian.
“It is almost impossible for your veterinarian to be on your farm to post every pig that dies, but you can start collecting information,” Ramirez says. “By obtaining key tissue samples from a pig that died of an illness or that was euthanized for humane reasons and submitting those samples, you can provide important assistance in receiving a prompt diagnosis. Treatments could begin earlier and that could mean fewer mortalities.”
With experience, you may be able to identify a pattern in pig mortalities and establish the need for veterinary assistance earlier in the disease progression.
To perform a necropsy, you need a sharp knife, latex/rubber gloves and sample collection bags. The bags should be “Whirl-Packs,” which you should be able to get from your veterinarian. These tools, along with some basic training and a well-lit area are all that you’ll need to begin contributing to a quick and accurate diagnosis.
Don’t be nervous about not knowing enough. Your veterinarian can provide more specific guidance on the necropsy process and which tissues are most useful in diagnosing health problems. There is really no substitute for hands-on training here. Remember that your role is not to make a diagnosis but rather to work with your veterinarian so that he or she can make the diagnosis.
Suppose you find a dead pig or decide to euthanize one and you suspect respiratory disease; your veterinarian would want a sample of lung tissue, roughly the size of a deck of cards. Providing a sample of both healthy and diseased tissues from your herd is actually helpful.
Other samples for respiratory illness that may be requested for submission are one or more lymph nodes. For enteric illnesses, samples from the stomach, colon and the ileum may be required.
“We collect two types of samples for diagnosis,” Ramirez says. “When collecting fresh samples for culture and sensitivity, a single organ sample is placed in each bag. For a diagnosis that requires viewing under a microscope, a smaller sample is needed but it must be fixed with formalin prior to submission.”
If samples are submitted in formalin, they should be no more than 1/4-inch thick or the tissue may not be properly fixed, warns Ramirez. For those smaller samples, you can place more than one organ sample in a single bag. You would then add a 10 percent buffered formalin solution to the bag. Your veterinarian can help supply you with formalin or offer advice on where to get it.
Minimize leaking by rolling the bag several folds before securing the closure tabs.
Once you collect the tissue sample, don’t absent-mindedly lay it down on a surface, as you will contaminate it. Place it immediately in a clean Whirl-Pack bag and place it on ice in an insulated container. You should avoid freezing tissue samples. Once the necropsy is complete, get the samples to your veterinarian as soon as possible for submission to a diagnostic laboratory.
As many other details as you can supply about herd history and animal behavior prior to death are helpful and should accompany the tissue samples. Include symptoms, the animal’s age, rectal temperature prior to death if possible, whether there are other sick pigs in the group, percent of total herd showing similar symptoms and duration of symptoms. Other factors such as commingling history, the unit’s disease background and vaccination history also are useful.
Digital photos or video of affected animals and of the necropsy being performed also can be informative as your veterinarian works on the diagnosis. It will help him or her get a targeted treatment started sooner and hopefully save more pigs.
Ask your veterinarian for a booklet entitled A Guide for Swine Necropsy, prepared by Elanco Animal Health. (See below.) By learning the basics of necropsy, which organs are most useful in determining an accurate diagnosis and the best procedures for submitting samples, you can help your veterinarian help you.
Preparing for Submission
These tissue samples are commonly needed to diagnose diseases in your herd. Your veterinarian can help you determine which samples should be submitted for a particular disease problem.
A: Lung, B: Heart, C: Liver, D: Lymph nodes, E: Kidney
F: These Whirl-Pack bags are the preferred packaging for submitting tissue samples, says Alex Ramirez, DVM, Iowa State University. Talk to your veterinarian about obtaining a supply.
Help is Available
The Guide For Swine Necropsy is intended to aid swine veterinarians as they discuss the importance of necropsies and sample procedures with their clients. The guide should be used only in consultation with your veterinarian.