Validity of indicators of dehydration in working horses: a longitudinal study of changes in skin tent duration, mucous membrane dryness and drinking behaviour.
Authors: Pritchard J C, Burn C C, Barr A R S, Whay H R
Journal: Equine veterinary journal
Summary
# Editorial Summary Dehydration poses a significant welfare threat to working horses, particularly in hot climates, yet field practitioners lack reliable, practical assessment tools to guide treatment decisions. Pritchard and colleagues conducted a longitudinal study of 50 dehydrated working horses in Pakistan (environmental temperatures 30–44°C), measuring changes in bodyweight, clinical signs, blood parameters and skin tent duration across seven time points during a four-hour rehydration period, using plasma osmolality as their gold-standard criterion for hydration status. The standardised skin tent test proved unreliable, confounded by anatomical location, coat moisture, animal age and laterality, with no meaningful correlation to plasma osmolality; similarly, qualitative assessment of mucous membrane dryness failed to correlate with dehydration severity. Instead, drinking behaviour emerged as the most valid indicator: horses with elevated plasma osmolality consumed significantly more water overall and displayed longer, more frequent drinking bouts—findings that directly translate to clinical observation in the field. For practitioners managing working horses in hot conditions, actively observing drinking patterns and offering palatable water ad libitum provides both diagnostic clarity and immediate therapeutic benefit, whilst the skin tent test and membrane assessment should not be relied upon as standalone dehydration markers.
Read the full abstract on PubMed
Practical Takeaways
- •Do not rely on skin tent duration or mucous membrane appearance to assess dehydration in working horses—these clinical tests lack validity compared to actual hydration markers
- •Observe drinking behaviour as the most practical field indicator: horses that are truly dehydrated will drink more frequently and for longer when offered palatable water ad libitum
- •Simply providing unlimited access to palatable water serves both as diagnostic tool (dehydrated horses will drink heavily) and treatment in hot climates, making it the most practical management strategy for working horses
Key Findings
- •Skin tent duration was not a valid indicator of dehydration when compared to plasma osmolality as gold standard, being affected instead by anatomical location, coat moisture, animal age and side of body
- •Mucous membrane dryness measurements showed no significant association with plasma osmolality or water intake
- •Horses with higher plasma osmolality drank significantly more water with longer and more frequent drinking bouts (P<0.001 and P=0.001 respectively)
- •Water consumption volume and drinking bout frequency/duration were the most reliable field indicators of hydration status in mature working horses