Thermography as a tool for the assessment of stress and affective states in an avian model

Animal welfare is an important issue influencing the health, wellbeing and/or productivity of animals in a wide range of contexts such as farm, laboratory and wild animals. Effective and reliable welfare assessment techniques are essential to identify issues and make progress in this area. Current approaches to welfare assessment may be time consuming and rely primarily on measuring behavioural responses that are indicative of pain or distress such as vocalisations or more subtle changes such as suppression of normal behaviour, redirection of behaviour or changes in behaviour patterns. Physiological approaches to welfare assessment have also been used and these are based on the release of stress hormones which are usually measured in the blood. While this approach is well established, it is usually invasive (requiring a blood sample) and circulating levels of these hormones may be influenced by many biological factors other than stress. Perhaps most importantly, hormone based welfare assessment has so far focused on the measurement of negative states, and we do not currently have a measurement approach that can reliably differentiate between positive and negative mental or emotional states. New techniques are required that are more reliable and less invasive or time-consuming. During stressful events, rapid physiological changes in the body alter the pattern of blood flow, directing blood away from the periphery of the animal to its body core. This leads to warming of the body core and localised cooling of the skin and these changes occur in response to both acute (short term) stress as well as chronic (longer term) stress.

Recent advances in thermal imaging cameras provide an opportunity to develop remote methods of assessing the welfare of animals. Thermal imaging, otherwise known as infrared thermography, records the surface temperature of an animal by measuring the quantity of thermal radiation it emits. Surface temperature is therefore an indirect measurement of blood flow and has the potential to be a non invasive method of assessing physiological responses to stress without the need for blood sampling or probe attachment. Most importantly, there is evidence that this method may be able to distinguish between negative and positive mental states in animals.

The aim of this research project is to validate the use of infrared thermography as a novel, non invasive tool to provide relevant and immediate information on welfare state in birds. We will work on the domestic fowl (laying hen) which is highly relevant species because millions of birds are reared annually in the UK poultry industry. Commercial poultry may be affected by confinement, lameness, hunger, undiagnosed disease or poor handling and we need better ways of assessing their welfare.

The specific objectives of this work are to:
1. Determine the accuracy of surface temperature measures as indicators of stress by comparing surface temperature in responses to increasing severities of the same short term stressor and also examine responses to different types of stressors. We will validate this information against well established welfare measures including stress hormones, core body temperature and behaviour.
2. Establish the use of thermography as an indicator of chronic stress by examining responses to long term stressful situations and comparing these to unstressed birds.
3. Examine the extent to which body surface temperature patterns are associated with negative and positive mental states, to determine if thermal imaging could be a novel way of distinguishing good and bad welfare.

The work will lead to significant advances in our understanding of the thermal responses to stress in birds. It will develop appropriate thermographic approaches for welfare assessment and establish the potential for commercial application of this technique to monitor the welfare of birds.

Reliable measurements of stress and affective state in animals are extremely important tools for animal welfare assessment. Quantifying stress hormone levels and behaviour have been the basis of significant progress in welfare research but further methods are required that are less invasive or time-consuming. Stressors induce autonomic responses through the sympatho-adrenal axis affecting heart rate, blood flow and respiratory rate. Rapid changes in the pattern of blood flow, from the periphery to the core lead to stress-induced hyperthermia (SIH). The aim of the project is to validate the use of infrared thermography (IRT) as a novel, non invasive tool to provide relevant and immediate information on physiological, welfare and affective state in birds. In pilot experiments we recorded a decrease in surface temperature of zebra finches exposed to acute and chronic stressors, showing that stress induced temperature changes are quantifiable with IRT. In this study, we will work on the domestic fowl (laying hen) because of its strategic relevance to poultry welfare in commercial contexts. Specific objectives are to:

1. Compare quantitative measures of body surface temperature change using IRT between different severities of the same acute stressor and responses to different types of stressors, and validate these against measures of plasma corticosterone, core body temperature and behaviour.
2. Establish the use of IRT as an indicator of chronic stress by making chronic stress related measurements and examining responses to acute stress in normal and chronically stressed birds.
3. Examine the extent to which thermographic spatial patterns are associated with negative and positive affective states.

This work will lead to significant advances in our understanding of the thermal responses to stress in birds, develop appropriate thermographic protocols for welfare assessment and establish the potential for commercial application of this technique.

Animal welfare is an important international issue, and there are both ethical and economic reasons for improvement of welfare, particularly in the reduction of acute and chronic stress in farm and laboratory animals. For progress in this area, reliable and efficient techniques for the assessment of welfare are required. This project will validate the use of infrared thermography as a novel, non invasive tool to provide relevant and immediate information on the physiological welfare and mental state of birds.

The global poultry industry rears 50 billion chickens annually, is increasingly concerned with bird welfare and values methods which can distinguish different welfare states. Avian research laboratories also have a responsibility to assess welfare and maintain standards of welfare for experimental birds. However, to date there is only very limited information available on the effect of housing conditions on laboratory birds. Both of these industries will benefit from this new welfare assessment approach. Animal welfare organisations also have an interest in clear scientific advice on welfare implications of husbandry. Animal welfare has been described as 'a public good' and remains a source of passionate concern for the public. New assessment methods and the studies arising from these will allow the public to make more accurate judgments on the welfare of birds in a range of contexts.

The research team has a strong track record in effective dissemination of results at scientific meetings and in peer reviewed publications. Public engagement will be delivered through talks at local and national Science Festivals, through the University of Glasgow's community engagement programme and through the media.

At the beginning of the project we will set up a group of practitioners interested in assessing welfare in a range of contexts and the Infrared R&D Industry. Annual meetings of this group will ensure that the development of assessment protocols is taking into consideration the specific needs of practitioners that would apply these methods. This group will also be used to devise the most effective dissemination method to deliver the final measurement protocols and set up appropriate systems that will advice users about the approach.

This project has developed from previous collaborations between the researchers, the poultry industry and discussions with FLIR systems over a number of years. McKeegan will manage the project and arrange regular review meetings with the PDRA and co-investigators and the stakeholders in thermal imaging, poultry industry and general animal welfare assessment. McKeegan has very good contacts with the poultry industry and McCafferty has good contacts with the thermal imaging industry. This will provide effective knowledge exchange between all of the interested parties.

This work provides the opportunity for commercial exploitation of thermal imaging technology for welfare assessment. This can be achieved by working with the manufacturers of thermal imaging cameras and the poultry industry to develop and evaluate automated welfare monitoring systems.

The impact activities will be undertaken and delivered by the research team. The investigators have previous experience of providing presentations and reports to technical and lay audiences. McKeegan has previously presented to DEFRA, the Farm Animal Welfare Council, the European Food Safety Authority and is a member of the British Veterinary Association Welfare and Ethics Group. Nager has regularly presented public talks on his research at a number of local public science events. McCafferty coordinates public outreach activities in life sciences at the University of Glasgow. The application of thermal imaging to captive laboratory birds has already generated a co-authored fact sheet together with the thermal imaging industry.