Focal necrotising hepatitis caused by Clostridium novyi in a horse.

The study reports a rare case of necrotising hepatitis in a horse caused by Clostridium novyi, a disease more commonly seen in sheep and cattle in Australia.

Background of the Study

• The researchers discuss the incidence of necrotising hepatitis in horses caused by the bacteria Clostridium novyi which is usually a common disease in sheep and cattle in Australia. They note that this occurrence is unusual, with only one other reported case of this disease in horses in Tasmania in 1939.
• The purpose of the study is to report and analyze a particular case of this disease in a 10-year-old mare and relate the findings.

Case Details and Clinical Signs

• The mare was pregnant with a foal at the time of the study. The owner noted that the horse seemed depressed and displayed a stiff gait 36 hours before death.
• Eighteen hours before death, the mare’s heart rate, respiratory rate and rectal temperature were noticed to be elevated.
• Due to the lack of other significant clinical signs, the condition was initially treated as an unknown fever. The mare was administered penicillin and streptomycin via intramuscular injections.
• The mare remained standing until about 3 minutes before its death.

Post Death Findings

• A necropsy conducted post-death revealed various abnormalities in the mare’s liver and intestines.
• Among the abnormalities were signs of coagulation necrosis in the liver tissue surrounded by an infiltration of neutrophils and eosinophils. Thrombi were present in hepatic vessels and there were fibrin tags adherent to the diaphragm adjacent to the liver lesion.
• Large sporing gram positive rods were scattered through the necrotic areas which were identified as Clostridium novyi using immunofluorescence.

Implications and Conclusion

• The authors note that the clinical signs and post-mortem findings were similar to the previous case reported in 1939.
• While necrotising hepatitis in sheep and cattle is usually associated with parasitic larvae, specifically liver fluke Fasciola hepatica, the researchers were unable to establish the role of parasite damage in equine cases.
• The researchers conclude the study by noting that while this disease shares many similarities with its counterpart in sheep and cattle, there are still many aspects of its pathogenesis that remain unknown.