Study Evaluates Unintentional Weight Loss in Horses

Study Evaluates Unintentional Weight Loss in Horses

Researchers pinpointed a definitive cause of weight loss in 60% of evaluated cases, however the remaining 40% were classified as idiopathic (of unknown cause) weight loss.


Unintentional weight loss in horses is frustrating to both owners and veterinarians, especially when the horse is still eating well. Numerous causes are possible but often difficult to pinpoint. Due to the lack of descriptive information on this condition, a group of Irish researchers recently set out to establish a link between clinical findings and outcome (survival vs. nonsurvival) of horses.

"Even when establishing that a horse's appetite is normal, there are management conditions to consider; these need to be ruled out before jumping to disease conditions," relayed researcher Lisa Katz, DVM, MS, PhD, DipACVIM, DipECEIM, MRCVS, a lecturer in the School of Veterinary Medicine at University College Dublin (UCD).

In their retrospective study, Katz and colleagues evaluated medical records from 40 horses presented to the UCD Veterinary Teaching Hospital between 2002 and 2011 for investigation due to weight loss despite a good appetite.

Sixty percent of evaluated cases received a definitive diagnosis (nine through post mortem evaluation), while the remaining 40% were classified as idiopathic (of unknown cause) weight loss. Of the cases with definitive causes, the team reported that "the mechanisms of weight loss were predominately inadequate absorption/increased loss of nutrients (due to conditions such as inflammatory bowel disease or intestinal lymphosarcoma) followed by increased nutritional utilization (due to infection)."

The researchers noted that gender, age, breed, and disease duration were not associated with outcome. However, they did find three factors associated with nonsurvival:

  • Poor body condition score (BCS);
  • Low blood protein; and
  • Low levels of albumin (a specific protein in blood plasma).

The team suggested that albumin could be "a potentially more reliable prognostic indicator for survival since total protein is made up of multiple components."

These findings led researchers to conclude that, "BCS in conjunction with albumin concentration can possibly be used as a prognostic indicator for survival for horses with weight loss despite a good appetite."

Katz recommends that owners of horses experiencing weight loss, "speak with a veterinarian as soon as (they) notice a problem, rather than hoping it will resolve itself. Conditions such as management issues or parasitism have the most favorable prognosis, but other conditions may have better outcomes if caught and treated early."

The study, "A retrospective study of horses investigated for weight loss despite a good appetite (2002-2011)," will appear in an upcoming issue of the Equine Veterinary Journal. The abstract is available online.

About the Author

Casie Bazay, NBCAAM

Casie Bazay holds a bachelor of science degree in education from Oklahoma State University. She taught middle school for ten years, but now is a nationally certified equine acupressure practitioner and freelance writer. She has owned Quarter Horses nearly her entire life and has participated in a variety of horse events including Western and English pleasure, trail riding, and speed events. She was a competitive barrel racer for many years and hopes to pursue the sport again soon.

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