The Confidential Enquiry into Perioperative Equine Fatalities: phase 4 (CEPEF4) – a worldwide observational, prospective, multicentre cohort study in 2025.

The research article discusses the findings of a comprehensive, global study that analyzed the conditions, demographics, and anaesthetic drugs related to the deaths of horses and ponies that underwent general anesthesia. The article provides crucial data on the common causes of deaths and the factors that can potentially increase or decrease the chances of survival after anesthesia.

Study Methodology and Participants

• The research was conducted as a confidential, observational, prospective, multicentre, cohort study known as the Confidential Enquiry into Perioperative Equine Fatalities 4 (CEPEF4).
• A total of 47,396 horses and ponies that underwent general anaesthesia were included in the study.
• Data were collected from 93 centres in 28 countries, capturing a diverse range of demographics and conditions.
• 249 variables relating to each general anaesthesia procedure were collected, thereby providing a thorough and extensive analysis of the factors that could contribute to a horse or pony’s death.

Findings of the Study

• The overall death rate was 1.2%, with 0.6% for non-colic cases and 4.2% for colic cases.
• The top three causes of death in non-colic cases were identified to be fractures, abdominal complications, and central nervous system problems.
• Death rates were particularly higher in pregnant mares, older horses, thin horses, those with higher American Society of Anesthesiologists grade, urgent procedures, and procedures lasting less than one hour or longer than two hours.
• Ketamine infusions and plasma lactate measurement during maintenance were linked to increased risk of death.

Factors Reducing the Likelihood of Death

• The study found several factors that seem to reduce the risk of death, such as monitoring invasive arterial pressure, end-tidal CO, blood gases, and body temperature.
• Premedication with agonist-antagonist or partial-agonist opioids with non-steroidal anti-inflammatory drugs and the use of α-adrenoceptor agonists during recovery, alone or with acepromazine, also showed a correlation with reduced odds of death.

Conclusions

• Comparative data shows a reduction in death rates in CEPEF4 compared with the second phase of the study (CEPEF2) conducted in 2002.
• The findings will help inform future clinical decision-making and enhance the safety of horses undergoing general anesthesia, while also providing an imperative resource for future research.