Bordetella bronchiseptica from aborted equine foetus.

The study reports on a preterm abortion case in a thoroughbred mare in which Bordetella bronchiseptica was isolated from the foetal organs, suggesting in utero infection and eventual abortion.

Context and Case Study

• The research is centered around a late-term abortion in a thoroughbred mare from a stud near Harare. The mare had received a killed vaccine shot for Equine Herpes Virus 1 (EHV1) periodically during its pregnancy.
• The bacteria, Bordetella bronchiseptica, typically associated with respiratory diseases in various animal species, was isolated from foetal stomach content, liver, and lungs. The placenta cultures, however, were contaminated.
• No other bacteria of pathological significance were identified, nor were rickettsial or chlamydial cells evident in the stained smears of foetal organs and placenta.

Research Findings

• Post isolation, the bacteria underwent more than 40 tests for detailed characterization, affirming it to be Bordetella bronchiseptica. The bacteria strain showed an unusual resistance to cetyltrimethyl ammonium bromide (commonly known as Cetrimide).
• The bacteria strain proved lethal to two groups of four mice each – infected intraperitoneally (within the peritoneum) and subcutaneously (under the skin) with a third passage of 18 hours old broth culture.
• Few mice died the following day after the inoculation. The observed lesions were petechial haemorrhages on heart, spleen and liver, with exudation in pleural cavity and marginally atrophied spleen.

Conclusions

• The researchers observed no gross or microscopic lesions in the foetus and its organs with the exception of lung and placental oedema. The absence of certain features, along with the mare’s vaccination history, helped rule out the possibility of an EHV1 infection, which is a common cause of equine abortion.
• Even though Bordetella bronchiseptica has been found to cause conditions like pneumonia, sinusitis, and guttural pouch lesions in horses, there have been no documented reports of it causing equine abortion or being isolated from an aborted foetus of any animal species.
• The isolation of Bordetella bronchiseptica from the foetal organs of the aborted horse foetus strongly suggests it could cause an in utero infection leading to abortion. However, more research is needed to confirm this hypothesis.