Validity of indicators of dehydration in working horses: a longitudinal study of changes in skin tent duration, mucous membrane dryness and drinking behaviour.

This research study aims to understand the validity of various indicators of dehydration in working horses. Researchers observed that despite common indicators like skin elasticity and mucous membrane dryness, water intake and the frequency and duration of drinking periods were the most reliable indicators of a horse’s hydration status.

Understanding Dehydration in Working Horses

• The research focuses on the issue of dehydration in working horses, particularly in developing countries. This issue presents a huge welfare concern as horses are essential work animals in these regions.
• The researchers aimed to establish a valid and practical indicator of dehydration that would facilitate more rapid treatment and prevention measures.
• The study utilised fifty horses, all showing signs of dehydration (positive skin tent test) and working in environments with temperatures between 30-44 degrees Celsius in Pakistan.
• The horses were given a chance to rest and offered water to drink freely. During this period, their body weight, clinical and blood parameters, mucous membrane dryness, drinking behaviour, and skin tent duration at six anatomical locations were measured periodically.

Key Findings

• The study found that skin tent duration, initially considered an indicator of hydration state, was influenced by the side of the animal, anatomical location, and coat moisture – but not related significantly to either fluid intake or plasma osmolality (P(osm)), a ‘gold standard’ criterion of hydration.
• Those horses with higher P(osm) drank more water and had longer and frequent drinking sessions – indicating a link between plasma osmolality and water intake.
• The study didn’t find any significant association between P(osm), water intake, and measures of mucous membrane dryness.

Conclusions

• The findings concluded that conventional methods of determining hydration such as the skin tent test and checking mucous membrane dryness were not reliable or valid indicators of dehydration when compared with plasma osmolality.
• Instead, the volume of water consumed and the indicators related to drinking behaviour such as frequency and duration of drinking bouts presented more reliable hydration status indicators for working horses.
• The researchers suggest that offering palatable water to drink freely helps both for diagnosing and treating dehydration in working horses in these environments.