Veterinarian’s Corner: View the Unseen with a Necropsy
By Dr. Rob Farruggio, Jefferson Veterinary Clinic, S.C.
Raising calves can have its challenges. The individual nature of immunity and the environment the calves are housed in play a role in many different diseases. Dairies often prevent disease by creating vaccine protocols and establishing management practices, such as proper ventilation and bedding. They also provide a quality and consistent source of nutrition, which is essential for building strong immune systems. However, illnesses, such as scours and pneumonia, are inevitable even on well-managed operations.
There are times when treatment does not seem to work, indicating treatment failure. This may be due to medication resistance or the disease we thought we were treating was different than anticipated. Producers often don’t take the steps to figure out why a given treatment didn’t work.
Many different diagnostic tests can be performed on calves while they are still alive, such as fecal samples or deep pharyngeal swabs. While these tests are valid and helpful, something could still be missing.
Necropsy – the examination of a dead animal – can assist in identifying the cause of death, but it is not utilized as often as it should be. Necropsies should be performed routinely on calves that die, especially on dairies where calves suddenly die without treatment or where calves die following multiple treatments. During a necropsy, the veterinarian will first do a gross external evaluation, and then open the calf to examine the chest and abdominal cavities. They will look for obvious abnormalities that may indicate the cause of death.
In most cases, it is too difficult to determine the cause of death without laboratory confirmation. Therefore, the veterinarian will take samples of tissues from the internal organs and submit them to a diagnostic lab. The laboratory can detect viruses, bacteria, and parasites, and look at the tissues under a microscope for any additional evidence of the cause of death. Results from the diagnostic laboratory will be reported to your veterinarian usually within two to three weeks. Your veterinarian will then interpret the results, make any suggestions for treatments and develop a plan for prevention.
If a bacterial cause is identified, the laboratory will perform an antibiotic susceptibility test to give insight into which antibiotic should be used as a treatment. For example, if a calf is diagnosed with pneumonia caused by Mannheimia haemolytica susceptible to ampicillin, florfenicol, and tulathromycin, it indicates that the bacterial infection should respond to treatment with one of these medications.
If an antibiotic is reported as resistant, it means the bacteria has developed the ability to survive even when treated with this antibiotic and, therefore, this medication should not be used. These resistant bacteria should be identified sooner since continued medication use is not judicial use, leading to treatment failures and increased numbers of chronically infected or dead calves.
As mentioned earlier, a necropsy can reveal an obvious cause of death, but it may be something unexpected and this surprising diagnosis can lead to changes on the dairy that may not have been considered.
For example, I worked with a dairy where managers thought calves had pneumonia issues, but many of the calves did not respond to treatments and ultimately died. Necropsies on several of the calves revealed they did not have pneumonia, but they all had infected navel tissue leading to a septicemia. After discussing these findings with management on the dairy, it was noted that the calving personnel inadvertently eliminated dipping navels from their processing of newborn calves. Immediately, a protocol was re-implemented to dip navels twice in the first 24 hours of life. This simple change has made a sudden difference in the health of the calves. This unseen cause, revealed through a necropsy, led to a change that had a direct impact to the success of this operation.
Other conditions that can be easily observed from a necropsy that may help to change or implement new management protocols include the following, but are not limited to:
- Birth defects, such as atresia coli (lack of a colon), atresia recti (lack of a rectum), heart defects, etc.
- Improperly tubed calves that have either milk in the lungs or a perforated esophagus
- Lack of renal (kidney) fat that may indicate malnourishment
- Pieces of metal in the reticulum, abdominal cavity or heart, indicating hardware
- Abdominal and/or chest cavities filled with blood, indicating aneurism
A necropsy is not time-consuming and should be performed as soon as possible after death to obtain samples that are fresh and not contaminated. Pictures can also be taken during the necropsy to help educate farm staff on how the care they provide impacts the calf as well as to aid the diagnostic lab in its diagnosis if needed. Many of my clients want to be present during the necropsy because they learn a lot from what they see.
Work with your herd veterinarian to develop a protocol of when a necropsy might be best for your operation. This valuable tool can help identify unknown issues on the dairy, potentially pushing overall calf health in a positive direction.
Starting Strong - Calf Care