Ultrasonographic Assessment of Regional Fat Distribution and Its Relationship With Body Condition in an Easy Keeper Horse Breed

• This study expands our knowledge about the distribution of regional fat deposition.
• The influence of gender and age on body condition score (BCS) and subcutaneous fat thickness measurements was observed.
• Ultrasonography may avoid overestimation of obesity in easy keeper-like horses.
• Subcutaneous fat thickness at the rump was the only site related to BCS, independent of gender and age.
• Subcutaneous fat thickness ultrasonography is a suitable technique to objectify body condition evaluation.

Body scoring system is a functional method to monitor overall adiposity. However, scorer experience, horse breed, gender, or local fat deposits are confounding factors, primarily in breeds with noticeable phenotype and tendency to subcutaneous fat deposition. Therefore, the ultrasonographic evaluation of subcutaneous fat thickness (SFT) could be an objective alternative method to assess fat distribution. The aims of this study were to characterize SFT at seven anatomic locations (over 25%, 50%, and 75% of neck length, behind the shoulder, over the ribs, over the rump, and over the tailhead), to evaluate the relationship between the body condition score (BCS) and SFT and to determine the influence of gender and age on BCS and SFT measurements. A sample of 127 Andalusian horses (78 stallions and 49 barren mares) were included. Body condition score was estimated, and SFT was measured by ultrasonography. The results showed that in the neck area, significant differences in fat accumulation over 25% and 50% of neck length were observed according to the gender and the age; however, regarding the body condition, no significant differences were found. Subcutaneous fat thickness at tailhead was the largest deposit and the most positively correlated parameter with BCS with influence of gender and age. However, SFT at the rump was the only measurement related to the body condition, independent of gender and age. Therefore, the assessment of localized fat deposits by ultrasonography suggests that preferred anatomic sites for fat deposition are evident and BCS systems should be adjusted according to breed-specific criteria.