iCatCare Talks Science: Stress sensitivity and welfare assessment

What is animal welfare?

An animal’s welfare refers to both its physical health and its psychological well-being. Good welfare is achieved when an animal is physically healthy and experiencing positive emotional well-being (ie, experiencing more positive emotions and experiences than negative ones, also known as a good ‘quality of life’).

In order to determine whether an animal is experiencing good welfare or not, we need to be able to measure it. This is important so that we know if we need to make improvements to an animal’s welfare.

How do we measure welfare?

Unfortunately, there is no ‘welfare thermometer’ – no single method or test we can use to reliably determine an animal’s overall health and quality of life. Therefore, we must rely on multiple methods of welfare assessment (termed animal welfare indicators). The more indicators we have, the more complete a picture we can build of an animal’s overall welfare.

In order to determine whether an assessment method is actually measuring what we want it to measure, it needs to be validated. Validation can be achieved by comparing the new method of measurement to an already established method that gives us an accurate measurement of the property of interest. For example, we might want to test the validity of a food measuring cup supplied with a pack of dry cat food which states that one full cup is equal to 30g of food. We could validate this by weighing the amount of food from one full measuring cup. We are validating the measurement from the cup against the measurement from the weighing scales.

Stress and welfare

Stress is key factor which can lead to poor welfare in animals. Stress is a normal and healthy part of an animal’s life. However, severe and/or prolonged stress can lead to distress. Distress is a negative emotional state, which can tip the balance between the positive and negative emotional states experienced by the animal, leading to a poor quality of life and poor welfare.

There are many aspects of an animal’s environment that can cause stress; these are known as stressors. It is important to recognise that individual differences in personality, or temperament as it is referred to in animals, can affect how individuals cope with different stressors. If welfare is measured by the presence of potential stressors, then this will not take into account individual responses to these stressors. Therefore, methods of welfare assessment should take into account these individual differences in an animal’s response to stress. How responsive an animal is to stressors is also known as stress sensitivity.

To find out more about stress in cats, how to recognise it, and ways to help relieve or prevent it, visit our website: https://icatcare.org/advice/problem-behaviour/stressed-cats.

In addition, the International Society for Feline Medicine (ISFM), iCatCare’s veterinary branch, has published an excellent guide on feline stress and health:

https://icatcare.org/shop/publications/isfm-guide-feline-stress-and-health.

What did this study set out to do?

The aim of this study was to investigate whether a questionnaire-based assessment called the Feline Temperament Profile (FTP) could measure an individual cat’s stress sensitivity (ie, how easily they become stressed) in a cattery environment (ie, when confined in pens). This questionnaire-based assessment tool was validated against a measurement of stress in the form of core eye temperature, which has been found to be linked to stress response in dogs.

What did they do?

The investigators carried out their research using 34 cats at three rehoming centres. Some of these cats were singly-housed, ie, housed alone in individual pens, and some were group-housed, ie, housed in groups.

The FTP consists of putting a cat in ten situations involving human actions and interactions; a summary of these is provided in the table below. The person testing the cat then records the cat’s reaction to each situation. The reactions are categorised as either acceptable (ie, do not indicate negative emotions such as fear and anxiety) or questionable (ie, may indicate negative emotions).

Core eye temperature was measured using a thermal image reading. Measurements were taken before the FTP was carried out, straight after the FTP was completed, and an hour after the first reading was taken, and these three readings were averaged. Average core eye temperature was compared to scores from the FTP for each cat to see if these scores correlated with each other.

What did they find?

There was a significant negative correlation between eye temperature and acceptable FTP scores, ie, the higher a cat’s core eye temperature, the lower the number of acceptable reactions it showed to the ten situations in the FTP test. From this the authors concluded that the FTP outcome accurately reflected individuals showing increased stress responses in a cattery environment.

The authors also found a significant positive correlation between core eye temperature and age, ie, the older the cat, the higher their core eye temperature was. Finally, it was revealed that cats housed alone had higher eye temperatures than cats housed in groups. The authors therefore concluded that older cats and singly housed cats find a cattery environment more stressful than young cats and group housed cats respectively.

Are these results reliable?

There are some limitations to this study that affect the strength of any conclusions drawn. To start with, the use of core eye temperature to validate FTP as measure of stress sensitivity is questionable, as core eye temperature itself has not been validated as a measure of stress in cats; the authors only offer one piece of evidence to support the use of core eye temperature as a measure of stress and it comes from a study with dogs.

It is also unclear why FTP, which involves human interaction, was used as a potential predictor of how stressful a cat found a cattery environment. The cattery environment and human interactions are two different, separate stressors which cats may react to in different ways.

Nor is it clear why the authors chose to take three measures of FTP and average them. If the authors were interested in how stressful a cat found the cattery environment, then the core eye temperature taken before the FTP was carried out would be of interest. If they were interested in how stressful cats found interactions with humans, then temperatures taken during and after the FTP test would be of interest. Alternatively, temperature before the FTP could be taken as a baseline measure of stress and compared to temperature taken during/after the FTP test, to see by how much stress has increased, and so how reactive the cat is to a potentially stressful situation of human interaction. However, averaging three temperatures taken before, straight after and an hour later loses this useful detail and it becomes unclear what the core eye temperature measurement used in the analysis actually tells us.

Furthermore, only taking one core eye temperature at the very end of the FTP test does not give us a complete picture of how stressful cats find different kinds of interactions with humans. Rather, a measure of stress at the end of the test is only likely to reflect how stressful the cats find the last two situations in the test which many cats would find very stressful: having their tail pulled and having a loud noise made behind them. It would instead be better to take core eye temperature readings throughout the FTP test, to determine a cat’s sensitivity to different levels of the potential stressor of human interaction.

There is also the question of how ethical using the FTP test is. This test subjects cats to two considerably unpleasant interactions with humans (having their tail pulled and having a loud noise made unexpectedly behind them). This has the potential to cause a great deal of fear in some cats, and could even have long-lasting effects in how aversive a cat views humans.

In terms of the results, the correlations observed are weak. This suggests that there is not a strong relationship between core eye temperature and acceptable FTP scores, nor with cat age. This means that there is not strong support for the use of FTP as a measure of stress sensitivity if we take core eye temperature as validation.

Based on their finding that group housed cats had lower core eye temperatures than singly housed cats, the authors concluded that singly housed cats may find a cattery environment more aversive than group housed cats. However, there is no background information supplied on the groups of cats, ie, if the cats were familiar with each other and accepted each other as belonging to the same social group. If this is the case, they will not find being housed in a group as stressful as if they were unfamiliar with each other. This information is needed before being able to investigate whether being housed in a single pen is more stressful for a cat than being housed in a group.

What can we take from this study?

The evidence from this study that the Feline Temperament Profile can be used as a measure of stress sensitivity in cats, and that older cats and singly housed cats find cattery environments more stressful than younger cats and group housed cats respectively, is not very robust. This study has a strong start in discussing the importance of developing welfare measures that take into account the individuality of the animals being assessed, and is an area that deserves further research.

International Cat Care will continue to provide you with interpretations and summaries of the latest cat science studies – objectively critiqued and intelligently communicated to you by dedicated cat-loving feline scientists, professionals and veterinarians.

Reference:

Foster S, Ijichi C. The association between infrared thermal imagery of core eye temperature, personality, age and housing in cats. Applied Animal Behaviour Science 2017; 189: 79-84.

About International Cat Care:

International Cat Care works to create a world in which ‘all cats, owned and unowned, are treated with care, compassion and understanding’ International Cat Care is a charity with the vision of a world where all cats, owned and unowned, are treated with care, compassion, and understanding. We work closely with the veterinary profession through our veterinary division, the International Society of Feline Medicine. All our work is reliant on donations and legacies.

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