Abstract: The objective of the present study was to apply supervised Machine Learning to predict severe complications after equine orchiectomy. A dataset of 612 cases of orchiectomies in stallions was used for the development of a computational model, among which in 8.5% of cases severe complications (colic, continued stallion-like behaviour, evisceration, funiculitis, haemorrhage, and scrotal infection) were diagnosed post-orchiectomy. Three supervised Machine Learning tools were employed: Logistic Regression (12 different models evaluated), Random Forest (64 models), and Gradient Boosting (8 models). For the prediction of the development of severe complications post-orchiectomy, Logistic Regression was the tool that produced the best discrimination measures, where accuracy, precision and recall were 0.9134, 0.8391, and 0.9133, respectively. The results of the analysis for SHapley Additive exPlanations values for the impact of the independent variables in the prediction of the development of complications indicated that (a) the age of the horse and (b) the surgical technique employed were the two variables that mostly influenced the prediction outcome, findings that were unambiguous in the models developed by any Machine Learning tool. The findings of this study indicate that computational models could be used as adjunct tools to support clinical decisions in the peri-operative management of horses.
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
Overview
This study developed and evaluated machine learning models to predict the risk of severe complications following orchiectomy (castration surgery) in stallions.
The goal was to support veterinarians in making informed peri-operative decisions to improve stallion outcomes.
Background and Objective
Orchiectomy in stallions can sometimes lead to serious post-surgical complications such as colic, abnormal behavior, evisceration, funiculitis, hemorrhage, and scrotal infection.
Timely prediction of these complications before or immediately after surgery could help vets manage care proactively and potentially reduce adverse outcomes.
The researchers aimed to leverage supervised machine learning methods to create a predictive computational model using clinical data from past stallion orchiectomies.
Data and Methods
The dataset consisted of 612 cases of orchiectomies performed on stallions.
Severe complications occurred in 8.5% of these surgeries.
Three supervised machine learning algorithms were tested to predict severe complications:
Logistic Regression (with 12 different model versions evaluated)
Random Forest (64 models tested)
Gradient Boosting (8 models tested)
Model Performance
Logistic Regression outperformed both Random Forest and Gradient Boosting in predicting severe complications.
Performance metrics for the best Logistic Regression model included:
Precision: 0.8391 (how many predicted complications were true complications)
Recall: 0.9133 (the model’s ability to identify all actual complications)
Interpreting Model Predictions: Explainability
The researchers used SHapley Additive exPlanations (SHAP) values to interpret how each independent variable influenced model predictions.
Two key factors consistently emerged as the strongest predictors of severe complications across all models:
Age of the horse — older or younger age possibly linked to complication risk.
Surgical technique used — differences in how the orchiectomy was conducted impacted outcomes.
This explainability provides clinicians with insights that align with clinical understanding and helps justify reliance on the predictive model.
Conclusions and Implications
The study demonstrates that machine learning models, particularly logistic regression, can effectively predict severe post-orchiectomy complications in stallions.
Using explainable AI methods like SHAP enhances trust and facilitates clinical adoption by clarifying how input factors relate to risk.
Such computational tools could serve as valuable adjuncts to support veterinary clinical decision-making, potentially improving peri-operative care plans and outcomes for horses undergoing orchiectomy.
Further validation and integration into clinical workflows would be important next steps to realize practical benefits.
Cite This Article
APA
Tyrnenopoulou P, Kalatzis D, Kiouvrekis Y, Flouraki E, Folias L, Loukopoulos E, Starras A, Chalvatzis P, Tsioli V, Mavrogianni VS, Fthenakis GC.
(2026).
Development of an Explainable Machine Learning Computational Model for the Prediction of Severe Complications After Orchiectomy in Stallions.
Animals (Basel), 16(3), 377.
https://doi.org/10.3390/ani16030377
Mason B.J., Newton J.R., Payne R.J., Pilsworth R.C. Costs and complications of equine castration: A UK practice-based study comparing “standing nonsutured” and “recumbent sutured” techniques. Equine Vet. J. 2005;37:468–472.
Basran P.S., MacLean M., Kaba S., Villiers E., Woodward A.P., Sánchez J., O’Sullivan T.L. The unmet potential of artificial intelligence in veterinary epidemiology. Am. J. Vet. Res. 2022;83:392–395.
Hooper S.E., Hecker K.G., Artemiou E. Using machine learning in veterinary medical education: An introduction for veterinary medicine educators. Vet. Sci. 2023;10:537.
Low D., Stables S., Kondrotaite L., Garland B., Rutherford S. Machine-learning-based prediction of functional recovery in deep-pain-negative dogs after decompressive thoracolumbar hemilaminectomy for acute intervertebral disc extrusion. Vet. Surg. 2025;54:665–674.
Bourganou M.V., Kiouvrekis Y., Chatzopoulos D.C., Zikas S., Katsafadou A.I., Liagka D.V., Vasileiou N.G.C., Fthenakis G.C., Lianou D.T. Assessment of published papers on the use of machine learning in diagnosis and treatment of mastitis. Information 2024;15:428.
Shaikhanova A, Kuznetsov O, Iklassova K, Tokkuliyeva A, Sugurova L. Interpretable predictive modeling for educational equity: A workload-aware decision support system for early identification of at-risk students.. Big Data Cogn. Comput. 2025;9:297.
Hastie T, Tibshirani R, Friedman JH. Boosting and additive trees.. In: Hastie T, Tibshirani R, Friedman JH, editors. The Elements of Statistical Learning: Data Mining, Inference, and Prediction. 2nd ed. Springer; New York, NY, USA: 2009. pp. 337–384.
Zhang C, Zhang Y, Shi X, Almpanidis G, Fan G, Shen X. On incremental learning for Gradient Boosting Decision Trees.. Neural Process. Lett. 2019;50:957–987.
Fukuyo R, Tokunaga M, Yamamoto H, Ueno H, Kinugasa Y. Which method best predicts postoperative complications: Deep learning, machine learning, or conventional logistic regression?. Ann. Gastroenterol. Surg. 2026. in press.
James G, Witten D, Hastie T, Tibshirani R. An Introduction to Statistical Learning with Applications in R.. Springer; New York, NY, USA: 2013.
Nakas C, Bantis L, Gatsonis C. ROC Analysis for Classification and Prediction in Practice.. CRC Press; Boca Raton, FL, USA: 2023.
Beardshall M. Understanding Explainable AI (XAI): Enhancing Transparency with SHAP and LIME.. [(accessed on 3 December 2024)]. Available online: https://www.linkedin.com/pulse/understanding-explainable-ai-xai-enhancing-shap-lime-mike-beardshall-tmjyf/.
Lundberg SM, Lee SI. A unified approach to interpreting model predictions. Proceedings of the 31st International Conference on Neural Information Processing Systems (NIPS’17); Long Beach, CA, USA. 4–9 December 2017; pp. 4768–4777.