Causes of pregnancy arrest in the canine species

Abstract

In the canine species, early pregnancy arrest before 30–40 days of pregnancy will induce intra‐uterine embryonic or foetal resorption, with very few clinical signs. If no genital examination by ultrasound is performed at that time, it will often remain unnoticed and the bitch will be qualified as infertile. It is only when pregnancy stops at a later stage, mostly after 40 days, that clinical signs will be seen. Expulsion of aborted foetuses or placentas may be observed, although the dam frequently eats the expelled tissues. Intra‐uterine mummification may also occur. This article reviews the causes of pregnancy termination in the bitch, both at the embryonic and the foetal stages, reported in the literature. Canine brucellosis is by far the most important disease concerned in this aspect. There is an important current concern about this disease, due to the fact that several outbreaks have been observed recently in Europe, and that it is a very contagious disease; it may be an underestimated zoonosis. Other bacterial causes of pregnancy arrest are sporadic. There is, however, a growing attention towards the microbiological content of raw food diets which are more and more popular among dog breeders and may—if badly prepared—contain abortifacient bacteria such as Campylobacter jejuni or Listeria monocytogenes. The abortifacient role of endogenous vaginal bacteria and mycoplasms remains unclear and may be related to an imbalanced vaginal flora with subsequent ascending bacterial contamination of the uterus. The role of Canine Herpesvirus on abortion is controversial and probably not frequent. Other viruses have been shown experimentally to induce abortion but their natural occurrence in this respect remains unknown. The same applies to the parasite Neospora caninum which is suspected, but not proven, potentially to induce pregnancy arrest in bitches. Among non‐infectious causes, uterine pathology such as cystic endometrial hyperplasia (CEH) or sub‐clinical post‐mating endometritis which can cause infertility and may also induce embryonic resorption. The role of luteal insufficiency in pregnancy arrest is probably overestimated.

Overview of the causes of abortion in horses, their follow‐up and management

“…In all these studies, the origin of the abortion was classified into primary non‐infectious, infectious and unknown causes (Table 1) and secondary diagnostic categories (Table 2). The involvement of pathogens in abortion in horses was also investigated by comparison with published data in humans, including zoonotic pathogens (Akter, Sansom, et al, 2021) or other species such as cattle (Mee, 2023), pigs (Maes et al, 2023) and dogs (Fontbonne, 2023).…”

“…This review will present the known causes of abortion in horses, their follow-up and the management of the most important infectious diseases. This paper is one of a series on abortion in animals commissioned by Reproduction in Domestic Animals (Fontbonne, 2023;Maes et al, 2023;Mee, 2023).…”

Invited review: Bovine abortion—Incidence, risk factors and causes

“…This paper in one of a series of papers on abortion in animals commissioned by Reproduction in Domestic Animals and includes others on abortion in horses (Leon et al, 2023), in pigs (Maes et al, 2023) and in dogs (Fontbonne, 2023).…”

“…It has recently been estimated that an abortion in a dairy and beef herd costs the farmer US$1415 and US$440, respectively, (Cantón et al, 2022). This paper in one of a series of papers on abortion in animals commissioned by Reproduction in Domestic Animals and includes others on abortion in horses (Leon et al, 2023), in pigs (Maes et al, 2023) and in dogs (Fontbonne, 2023).…”