# A Review of Assessment of Sow Pain During Farrowing Using Grimace Scores

## TL;DR

This review discusses how pain during pig birth can be measured using facial expressions to improve sow and piglet welfare.

## Contribution

The paper introduces and evaluates the newly developed sow grimace scale as a practical tool for pain assessment during farrowing.

## Key findings

- Facial grimace scales are effective for detecting pain in sows during farrowing.
- Improved pain assessment can enhance sow and piglet health and welfare.
- The grimace scale offers a simple and feasible method for pain measurement in livestock.

## Abstract

As the public demand for improved animal welfare in meat production systems continues to increase, better management of farm animal pain is essential. Farrowing, the process of giving birth in pigs, is known to be painful, yet the amount of pain experienced by sows that is considered “normal” and how to measure this pain is poorly understood. This review explores how pain during farrowing affects the health and welfare of both sows and their piglets, and why improved understanding and management of pain is important for animal welfare and farm productivity. A key focus was the use of facial grimace scales, a tool that can be used to assess pain by observing changes in facial expressions. The review examines the newly developed sow grimace scale that has been described as a simple and promising way to detect and score the pain experience during farrowing. Accurately identifying pain in sows could lead to improved care during birth and enhanced sow and piglet health and welfare, ultimately optimising productivity. Understanding and managing farrowing pain is not just important for ethical reasons but also benefits society by improving the productivity and sustainability of food production systems.

Reproduction is one of the most important considerations for the livestock industry, presenting significant economic and animal health and welfare pressures for producers. Parturition, the process of giving birth, is known to be highly painful in many mammalian species, but the understanding of parturient pain in sows is limited. Farrowing, the process of parturition in pigs, is understudied compared to other livestock species, with very little research available specifically regarding pain. Pain can be detrimental to animal wellbeing; hence, it is vital for it to be reliably detected and managed in such a way that improves both sow and piglet health and welfare. Grimace scales have been developed as a method for pain detection and quantification in animals via observations of facial expression changes in response to painful stimuli. This presents a unique opportunity for improved pain assessment during farrowing, increasing the current understanding of farrowing dynamics and potentially enhancing farrowing management decisions to prioritise sow welfare. This review synthesises and critically analyses the current knowledge on sow parturient pain and the ability for the application of facial grimace scoring to measure pain severity. Grimace scoring was found to be an effective, simple and feasible method of pain assessment in a number of domestic species, and its recent application to farrowing is a promising development in the understanding and management of sow welfare during parturition.