RUMINANTS
The protocol for on-farm postmortems performed under the Small Ruminant Adult Mortality Project includes submission of the intact head, in addition to a list of fresh and formalin-fixed tissues. Upon receipt at the AHL, pathologists split the head, examine and photograph it, and collect the brain for ancillary testing. If lesions are identified in the oral or nasal cavities, these are described and samples are obtained for analysis. Above are 4 recent examples. Answers below.
Answers to What is your diagnosis?
a) 2-year-old ewe: nasal adenocarcinoma, caused by enzootic nasal tumor virus (ENTV).
b) 6-year-old ewe: nasal abscess.
c) 6-year-old ewe: severe dental disease causing emaciation.
d) 6-year-old ewe: pituitary adenoma.
Salmonella Dublin ELISA now verified and available
Jim Fairles, Davor Ojkic
With the use of both confirmed positive and negative sera received from another AAVLD-accredited lab (Animal Health Diagnostic Centre, Cornell University), and positive and negative sera results confirmed in an interlaboratory comparison with the same lab, the AHL has now verified the Prionics Salmonella Dublin antibody ELISA in-house and is accepting samples.
Salmonella Dublin antibody ELISA
Fee - $9.50
Sample - 1mL serum
Code - salmdel
Turnaround time- 1-5 business days
Coxiella burnetii in bovine abortion submissions
Andrew Brooks, Murray Hazlett, Beverly McEwen, Janet Shapiro, Josepha DeLay, Maria Spinato, Margaret Stalker, Andrew Vince, Emily Brouwer
From 2011 to 2017, Coxiella burnetii was detected in 15 submissions to the AHL that involved bovine reproductive losses. The majority of cases (10 of 15) involved abortions in dairy cattle. Two cases were stillbirths and one case involved a weak calf that died shortly after delivery.
C. burnetii is an obligate intracellular bacterial pathogen that is often associated with abortion in sheep and goats, but there are few reports of this organism causing abortion in cattle. Determining the significance of C. burnetii in cases of bovine abortion can be challenging. Serologic evidence suggests that the organism may be widespread in Ontario cattle herds, and asymptomatically infected cows can shed the organism in the placenta during normal parturition.
Pathologists interpreted the presence of C. burnetii as either suspicious or significant in 10 cases in this series. In the remaining cases, the organism was considered to be an incidental finding or to have questionable significance.
Placentitis was the lesion most frequently associated with C. burnetii, characterized by various degrees of necrosis, fibrin exudation, and neutrophil or mononuclear leukocyte infiltration (Fig. 1). In many submissions, other pathogens were also present that may have contributed to the placentitis, including Ureaplasma, Bacillus licheniformis, Mycoplasma spp., Streptococcus pluranimalium, E. coli, and Klebsiella pneumoniae.
C. burnetii was detected by quantitative PCR (qPCR) performed on the placenta in 13 submissions. In 2 submissions that lacked placenta, the organism was detected by qPCR performed on fetal lung or stomach content. In some cases, the organism was visible in placental trophoblasts in routine H&E-stained sections and was detected in modified acid-fast stains of placental smears.
The range of C. burnetii concentrations in the placenta, fetal lung, or stomach content, as measured by qPCR, varied considerably from 100 to 107 copies/µL. The highest concentrations of C. burnetii were generally found in the placenta, and concentrations tended to be greater in those cases where the pathologist concluded that the organism was significant or suspicious. However, further research is required to determine whether there are correlations between C. burnetii concentration, placental pathology, and abortifacient role. C. burnetii test results in cases of bovine abortion must be interpreted in light of the pathology findings and presence or absence of other abortifacient pathogens.
As the cause of Q fever, C. burnetii is an important zoonotic pathogen. The presence of C. burnetii in fetal and placental tissues from bovine abortions highlights the potential zoonotic risk associated with handling these materials. The AHL will continue to monitor for C. burnetii in bovine abortion submissions. Please contact the AHL if you have any questions about sample or test selection for abortion cases - helpful guidelines are published in the AHL User’s Guide and sample collection templates are available from the Ontario Animal Health Network. AHL
References
Bildfell RJ, et al. Coxiella burnetii infection is associated with placentitis in cases of bovine abortion. J Vet Diagn Invest 2000;12:419-425.
Agerholm JS. Coxiella burnetii associated reproductive disorders in domestic animals – a critical review. Acta Vet Scand 2013;55:13.
