1 Introduction  
2 Survey Scope and Structure  
3 Research on Affective States and Pain in Non-human Animals  
4 Meta-analysis of Computer Vision-Based Approaches for Classification of Affective States and Pain  
4.1 Data Collection and Annotation  
4.2 Data Analysis  
4.3 Parts-based vs. Holistic Methods  
4.4 Increasing Explainability: Intermediate Representations  
4.5 Going Deep: Black-Box Approaches  
4.6 Performance Evaluation  
5 Best Practice Recommendations  
5.1 Data Imbalance  
5.2 Cross-Validation  
5.3 Domain Transfer  
6 Conclusions and Future Work