Testing eye temperature assessed with infrared thermography to evaluate stress in meat goats raised in a semi-intensive farming system: a pilot study

Whether animals have emotions was historically a long-lasting question but, today, nobody disputes that they do. However, how to assess them and how to guarantee animals their welfare have become important research topics in the last 20 years. Infrared thermography (IRT) is a method to record the electromagnetic radiation emitted by bodies. It can indirectly assess sympathetic and parasympathetic activity via the modification of temperature of different body areas, caused by different phenomena such as stress-induced hyperthermia or variation in blood flow. Compared to other emotional activation assessment methods, IRT has the advantage of being noninvasive, allowing use without the risk of influencing animals’ behavior or physiological responses. This review describes general principles of IRT functioning, as well as its applications in studies regarding emotional reactions of domestic animals, with a brief section dedicated to the experiments on wildlife; it analyzes potentialities and possible flaws, confronting the results obtained in different taxa, and discusses further opportunities for IRT in studies about animal emotions.

Section: Discussionmentioning

confidence: 99%

Section: Applicationsmentioning

confidence: 99%

Infrared Thermography in the Study of Animals’ Emotional Responses: A Critical Review

Travain

Valsecchi

2021

“…As with the EEG responses, environmental factors likely influenced IRT results, as a similar trend was observed over time, with no treatment interaction. Changes in eye temperature have been used to indirectly measure autonomic nervous system activation in livestock including cattle [11,22] and stress inducing scenarios in goats [23] and sheep [24,25]. Stress-induced hyperthermia occurs as an initial decrease in surface temperature followed by an increase in core body temperature as a result of a stressful stimulant [26].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Electroencephalography, Behaviour and Eye Temperature in Response to Surgical Castration in Sheep

Harris

White

Hall

et al. 2021

Castration has been demonstrated to cause pain in sheep. However, it is routinely performed for management purposes. Electroencephalography (EEG) has been used successfully to measure pain in lambs in response to castration and other husbandry procedures in livestock. The aim of this study was to evaluate the use of EEG as a measure of pain and analgesia in conscious lambs undergoing castration on farm over a 24 h period. EEG responses were compared to behavioural observations and changes in ocular temperature via infrared thermography. Twenty-four merino ram lambs (18.63 ± 2.06 kg) were used in this study. Lambs were randomly allocated to one of the following treatment groups: (1) castration with pre-surgical administration of meloxicam (0.5 mg/kg Metacam 20 mg/mL injected subcutaneously into the skin of the neck 15 min prior to recording) and lignocaine (applied via intra-testicular injection five minutes prior to castration, 2 mL lignocaine hydrochloride 20 mg/mL, Troy/Ilium) (CML, n = 8); (2) castration only (C, n = 8); (3) sham castration, handling only (SC, n = 8). EEG was recorded for 5 mins pre-procedure (prior to any intervention), and for 5 mins post-procedure at 0, 1, 4 and 24 h. Behavioural reactions to the procedure were scored, and behaviours were scan sampled at 5 min intervals at the above time points, by blinded observers. Eye temperature was measured for five-minute intervals at each time point. EEG decreased from baseline to 0 h for CML and C groups (p < 0.001), C group values returned similar to baseline at 24 h. Eye temperature increased post-castration at 0 h for C group, no initial change was seen for CML or SC groups. CML and C groups were more likely to have higher reaction scores and showed more abnormal behaviours (p = 0.017). CML and C groups had similar results, indicating minimal effect of analgesic intervention. Lambs in SC group showed significant EEG changes, suggesting that stress from handling also impacted EEG results.

“…According to Siebert et al [ 41 ], goats do not habituate to social isolation, which implies that the generally higher heart rate at two weeks, compared to two months, was probably not a habituation effect. Adult goats have lower heart rate than goat kids [ 58 ], thus, the lower heart rate at two months may be an age effect.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Mother Goat Presence during Rearing on Kids’ Response to Isolation and to an Arena Test

Walter

Forkman

Högberg

et al. 2021

The aim of the study was to examine how early permanent separation, separation during the day only, or full-time access to the mother goat affected goat kids during social isolation with a sudden sound of a dog bark at two weeks and two months, and a novel arena test with a novel object at two months. Kids permanently separated reduced their vocalization earlier and had a higher heart rate before and after dog bark during isolation at two weeks, no effect was found on the daytime separated kids. Daytime separated kids bleated more at two weeks and decreased heart rate after dog barking at two months. Daytime separated kids showed the strongest fear reaction in the arena test, no effect was found on the permanently separated kids. Kids separated early vocalized more before novel object and showed more explorative behavior afterwards. Our study shows different responses in goat kids separated early permanent, daytime separated, or kept full-time with mother, which demonstrates the importance of if and how the mother is present, and the impact of using a wide variety of physiological and behavioral measures when evaluating stress in animal welfare research.