Are You Collecting the Right Samples? Diagnosing Infectious Bovine Perinatal Mortality in the Field

When investigating a case of bovine perinatal mortality, the quality of the diagnosis often depends on the quality of the samples submitted. Even the most advanced laboratory testing cannot compensate for poor sample selection, improper handling or failure to collect key tissues. 

Because infectious causes account for a smaller proportion of perinatal mortality cases than non-infectious causes, it is particularly important to gather evidence that can help distinguish infection from conditions such as dystocia, trauma or asphyxia. A systematic sampling approach can significantly increase the likelihood of reaching a meaningful diagnosis. 

Start Before the Necropsy Begins 

An infectious disease investigation starts long before samples are collected. 

A detailed herd history can provide valuable clues regarding possible infectious risks. Information such as recent vaccination protocols, introduction of new animals, movement of pregnant cattle, grazing practices, and previous reproductive losses may help narrow the list of potential pathogens². 

Examination of affected and unaffected animals within the same group can also provide useful information regarding exposure patterns and herd-level disease risks². 

The Placenta: Often Missing but Extremely Valuable 

One of the biggest challenges in investigating bovine perinatal mortality is that the placenta is frequently unavailable. In many cases, it is never recovered or is too contaminated for meaningful examination. 

When available, however, placental evaluation can be extremely informative. 

Gross evidence of placentitis may include discolored or necrotic cotyledons, exudation, edema and thickening of intercotyledonary tissues³. Placental sampling is particularly valuable when pathogens such as Coxiella burnetii or Chlamydia species are suspected⁴. 

Ideally, several abnormal cotyledonary and intercotyledonary tissue samples should be collected for microbiological and histopathological examination². 

Why Abomasal Contents Matter 

Among all samples collected from a perinatal mortality case, abomasal contents are considered one of the most important. 

The fetus continuously swallows amniotic fluid during gestation. As a result, the abomasal contents may contain microorganisms present within the intrauterine environment². 

Aseptic collection is essential. The abomasal wall can be seared with a heated blade before aspiration of contents into a sterile container to reduce contamination². 

If abomasal contents cannot be obtained because of scavenging, decomposition or postnatal colostrum ingestion, alternative tissues such as lung, liver, or brain may provide useful diagnostic information, especially when septicemia is suspected⁵. 

Do Not Ignore Gross Lesions 

A careful internal examination can reveal important indicators of infection. 

Common findings associated with infectious processes include: 

• Pneumonia 

• Pericarditis 

• Peritonitis 

• Meningitis 

• Septicemia 

• Hepatitis 

• Omphalophlebitis¹ 

These lesions may help direct laboratory testing and increase confidence in attributing infection as a cause of death. 

Importantly, microbiological samples should be collected before extensive organ manipulation to minimize contamination during necropsy². 

Histopathology Completes the Picture 

A negative culture result does not necessarily exclude infection. 

Autolysis, prior degradation of pathogens and sampling limitations can all reduce pathogen detection rates. Histopathological examination can provide evidence of inflammatory responses even when a specific pathogen cannot be identified^1,6. 

Routine tissue collection should include organs such as the lung, liver, heart and brain, particularly when gross lesions are present¹. 

The brain deserves special attention because of its value in diagnosing conditions such as neosporosis. Tissue samples should include both normal and abnormal areas and be appropriately sized to allow proper laboratory processing². 

The Importance of Proper Storage 

Even excellent samples can lose diagnostic value if handled incorrectly. 

When immediate laboratory submission is not possible, samples intended for culture, serology and histopathology should be refrigerated at approximately 4°C. Samples intended for PCR testing should be frozen at approximately −20°C². 

Failure to maintain proper storage conditions can lead to bacterial overgrowth, tissue degradation, and compromised results. 

Practical Take-Home Message 

Successful diagnosis of infectious bovine perinatal mortality relies on collecting the right samples at the right time and handling them correctly. 

Whenever possible, prioritize: 

• Abomasal contents 

• Placental tissues 

• Lung, liver, heart and brain samples 

• Appropriate microbiology and histopathology submissions 

Combining a thorough herd history, careful necropsy examination, and strategic sample collection provides the strongest opportunity to identify infectious causes and guide future herd health decisions. In many cases, the answer is not found through a single test, but through the combined interpretation of clinical history, pathology, and laboratory findings.  

References 

1. Mee JF, Jawor P, Stefaniak T. Role of infection and immunity in bovine perinatal mortality: Part 1. Causes and current diagnostic approaches. Animals. 2021 Apr 6;11(4):1033. https://www.mdpi.com/2076-2615/11/4/1033 

2. Mee JF. Investigation of bovine abortion and stillbirth/perinatal mortality-similar diagnostic challenges, different approaches. Irish Veterinary Journal. 2020 Sep 4;73(1):20. https://link.springer.com/content/pdf/10.1186/s13620-020-00172-0.pdf 

3. Mee JF, Ley R. How to set up a postmortem facility in a farm animal practice. Livestock. 2021 Jul 2;26(4):196-201. https://www.magonlinelibrary.com/doi/pdf/10.12968/live.2021.26.4.196 

4. Mock T, Mee JF, Dettwiler M, Rodriguez-Campos S, Hüsler J, Michel B, Häfliger IM, Drögemüller C, Bodmer M, Hirsbrunner G. Evaluation of an investigative model in dairy herds with high calf perinatal mortality rates in Switzerland. Theriogenology. 2020 May 1;148:48-59. https://t-stor.teagasc.ie/bitstreams/6dae9bce-19ef-4563-8f17-8752c5865439/download 

5. Clothier K, Anderson M. Evaluation of bovine abortion cases and tissue suitability for identification of infectious agents in California diagnostic laboratory cases from 2007 to 2012. Theriogenology. 2016 Mar 15;85(5):933-8. https://www.ccfruitandnuts.ucanr.edu/sites/default/files/2023-05/384244.pdf 
6. Norquay R, Orr J, Norquay B, Ellis KA, Mee JF, Reeves A, Scholes S, Geraghty T. Perinatal mortality in 23 beef herds in Orkney: incidence, risk factors and aetiology. Veterinary Record. 2020 Jul;187(1):28. https://bvajournals.onlinelibrary.wiley.com/doi/pdfdirect/10.1136/vr.105536