Evaluation of regional adiposity in the neck area of andalusian horses

Reasons for performing study:

Adipose tissue deposited along the crest of the neck has been associated with altered metabolic states and with an increased risk of laminitis in equids. Thickness of the neck is a phenotipic characteristic in Andalusians; however, there are no studies evaluating this condition in this breed.

Objectives:

To evaluate morphometric and ultrasonographic measurements in the neck area for assessment of neck adiposity and its associations with adiposity scores and biochemical variables.

Study design:

A sample of 115 Andalusian horses (46 barren mares and 69 stallions, 2–15 years old) was evaluated in a cross-sectional study.

Methods:

Cresty neck score (CNS) was determined. Two groups were created: cresty neck (CNS≥3) and noncresty neck (CNS<3) horses. Neck circumference (NC) (cm) and ultrasonography (US) of subcutaneous fat (mm) at 25% (NC0.25– US0.25), 50% (NC0.50–US0.50) and 75% (NC0.75–US0.75) of neck length were measured. Middle neck circumference (NC), neck length and height at the withers were taken to calculate neck ratios (NC0.50:height, NC0.50:neck length). Plasma was analysed for insulin and leptin. Hyperinsulinemia was defined as insulin ≥20 µiu/ml. Correlations using Pearson and Spearman coefficients were evaluated. Mean comparisons were carried out with Student’s t or Mann-Whitney tests.

Results:

Cresty neck condition was present in 73.9% (n = 85) of the horses and 2.6% (n = 3) were hyperinsulinaemic. Cresty neck horses had significantly higher plasma leptin, morphometric and ultrasonographic measurements. NC0.50:height was the most correlated parameter with CNS. Insulin was correlated with leptin levels and all morphometric measurements. Insulin and leptin were correlated only with US0.75.

Conclusions:

Andalusian horses’ neck score, despite their thick necks in the majority of individuals, does not have a good correlation with plasma insulin and leptin levels. Since in Andalusian horses, neck scores may be overestimating obesity, further studies on ultrasonographic fat measurements are needed.