Salivary and fecal cortisol as measures of stress in horses

Tamsin Hughes/Young et al. — Wed, 05 Sep 2012 04:27:29 PDT

Valid measures of stress are needed in horses to determine over-all stress levels and to identify stress triggers, used to ensure management is kept within the animals’ ability to cope and welfare is not compromised. Levels of circulating cortisol reflect HPA-axis activity, and excretion into saliva and faeces allow non-invasive sampling. We validated an enzyme-linked immunoassay (ELISA) for horse salivary and faecal cortisol and validated these as indicators of acute and over-all stress levels in riding horses. Saliva was swabbed every 30-minutes over three days in N=15 horses with eight in light exercise. Faeces were collected from N=9 working horses on stabled workdays and at rest at grass for three consecutive weeks. Immunological validity of the ELISA was demonstrated by high specificity, accuracy, precision and sensitivity. Biological validity of salivary cortisol was demonstrated by diurnal decline and elevation post-exercise both mirroring known patterns in plasma cortisol; and by a trend towards elevation following 10 minute exposure to a known stressor. Faecal cortisol was biologically validated by decline between working and rest days. Large individual differences in assay values were found and not all individuals followed the group means. Salivary cortisol was labile, and although it has a close temporal relationship to circulating cortisol, measures may be confounded by environmental disturbance, pulsatile release patterns and diurnal rhythm. Careful sampling protocols are therefore needed. Faecal cortisol as an index of circulating cortisol has a 24-hour time lag to excretion, and collection protocols must evenly sample total faecal mass due to uneven hormone distribution and be frozen immediately post-excretion to avoid degradation. With careful sampling, salivary cortisol may be used to measure acute stress responses to identify stress triggers, and faecal cortisol may be used to compare over-all stress levels over longer-term conditions.

A novel scale of behavioural indicators of stress for use with domestic horses

Tamsin Young et al. — Tue, 31 Jul 2012 03:44:24 PDT

Behaviour scores (BS) offer non-invasive, objective and easy to use ways of assessing welfare in animals. Their development has, however, largely focused on behavioural reactions to stressful events (often induced), and little use of physiological measures has been made to underpin and validate the behavioural measures. This study aimed to develop a physiologically validated scale of behavioural indicators of stress for the purpose of welfare assessment in stabled domestic horses. To achieve this, behavioural and physiological data were collected from 32 horses that underwent routine husbandry procedures. Principal component analysis (PCA) of the behavioural and physiological data revealed three meaningful components that were used as the basis of the scale. Analysis of video clips of the horses’ responses to the husbandry procedures was undertaken by a panel of equestrian industry professionals using a free choice profiling (FCP) methodology. These results were added to the scale along with key definitions from relevant literature. Salivary cortisol levels were significantly correlated with the BS confirming the scale was meaningful and reflected physiological stress. The scale offers an easy to use ‘tool’ for rapid, reliable non-invasive welfare assessment in horses, and reduces the need for potentially invasive physiological measures.

Natural Environment

Salivary and fecal cortisol as measures of stress in horses

A novel scale of behavioural indicators of stress for use with domestic horses