Salmonella abortion in a dog
Rebecca Egan, Hanna Sonek
Animal Health Laboratory, University of Guelph, Guelph, ON (Egan); Aylmer Veterinary Clinic, Aylmer, ON (Sonek).
AHL Newsletter 2022;26(3):26.
A three-year-old golden retriever dog was presented to a veterinarian approximately 2 weeks prior to the expected due date, following the onset of labour and subsequent stillbirth of the entire litter. The first stillborn puppy and accompanying placenta were then submitted to the AHL for postmortem examination. Gross examination identified pale mucous membranes, pulmonary atelectasis, and scattered discrete subcapsular foci of congestion in kidneys of the fetus. The placental surface was coated by green-brown-black slightly mucoid exudate, and slight thickening of chorioallantois was appreciable. Microscopically, the placenta contained neutrophilic inflammation accompanied by necrosis, accumulation of fibrin, thrombi, mineralization, and trophoblasts containing intracytoplasmic rod-shaped bacteria (Fig. 1). In the fetus, microscopic examination revealed subtle neutrophilic pneumonia and aspiration of amniotic fluid, along with focal renal congestion and extramedullary hematopoiesis in liver. With compatible placental lesions and isolation of high levels of Salmonella spp. from the placenta, premature stillbirth was attributed to Salmonella infection. Serotyping identified Salmonella enterica serovar München. PCR testing of pooled fetal tissues did not detect canid herpesvirus-1 or canine adenovirus-2.
In animals, Salmonella enterica serovars can cause clinical disease or may be present and shed from the gastrointestinal tract of asymptomatic carriers. Potential sources of infection include consumption of raw contaminated meat or environmental exposure. In this case, the exact source of Salmonella infection was uncertain, as there was no known exposure to raw food or livestock. However, the owner did report that the dog had been found consuming a wild bird a few weeks prior. Thus, it is possible that infection was acquired through exposure to a wild bird harbouring Salmonella, with localization of bacteria to the placenta resulting in placentitis and subsequent abortion. Acute clinical salmonellosis typically presents with diarrhea, which can progress to septicemia in some cases, but clinical signs were not reported prior to abortion in this case. AHL
Figure 1. Microscopic section of placenta (10x) containing neutrophilic inflammation accompanied by necrosis (>) and accumulation of fibrin (*). H&E stain.
References
1. Grunberg W. Salmonellosis in Animals. The Merck Veterinary Manual. Aug 2020. [cited 2022 August 15]. Available from: https://www.merckvetmanual.com/digestive-system/salmonellosis/salmonellosis-in-animals
2. Weese, S. Songbird fever: Salmonella in birds and cats. Worms and germs. April 22, 2009. Available from: https://www.wormsandgermsblog.com/2009/04/articles/diseases/salmonella/songbird-fever-salmonella-in-birds-and-cats/