Horses forego normal intakes of feed for a variety of reasons—prior to gastroscopy, anesthesia, post colic surgery, transport and competition, or due to serious illness that dampens appetite.
A Brazilian study of 20 horses stabled outdoors under natural conditions were deprived of food for 48 hours to ascertain if there is development of significant changes to blood and physical parameters [Di Filippo, P.A.; Duarte, B.R.; Albernaz, A.P.; Quirino, C.R. Effects of feed deprivation on physical and blood parameters of horses. Brazilian Journal of Veterinary Medicine 2021, vol. 34; doi:10.29374/2527-2179.bjvm000321].
Blood samples were obtained every six hours from the 20 horses on food restriction and from 12 control horses that had access to hay. All horses in the study had free access to water. Restricted feed did not affect a horse’s body mass or boy condition, heart rate, respiratory rate, capillary refill time or body temperature. There was a notable decrease (90%) in intestinal sound intensity in horses on feed restriction. Also, there were no significant changes in erythrocyte values or glucose.
The most significant changes during fasting were as follows:
- Leukocyte response reduction at 36-58 hours, as a typical response to stress.
- Neutrophils increased at 24–46 hours, also as a typical response to stress.
- BUN significantly increased at 24–48 hours, often associated with anorexia.
- Aspartate aminotransferase increase at 36–48 hours—this occurs due to hyperlipidemia and/or liver damage.
- Total cholesterol significantly increased at 42–48 hours.
- Triglyceride increase continuously—mobilization of peripheral fats stores causes an increase in triglycerides with hypophagia.
None of the horses displayed behavioral changes other than slight lethargy, and they remained alert. No other clinical signs changed with fasting other than the marked decrease in intestinal sounds.
The authors concluded: “The horses tolerated food restriction for 48 hours without serious clinical complications, but they developed important metabolic changes that can negatively influence treatment and prolong recovery of sick, injured and/or inappetent horses.”