A fat scoring system for horses' necks has been developed.
Rebecca Carter and fellow workers at Virginia Tech and the Middleburg Agricultural Research and Extension Centre developed the scale.
Their "Cresty Neck Score" (CNS) assigns a score on a scale from 0 to 5. Grade 0 indicates that no crest is palpable or visible. Grade 5 indicates that the crest is so large that it permanently falls to one side.
Their new system comes at a time of growing concerns about obesity in the horse population, which carries with it increased risk of disease - in particular insulin resistance and laminitis.
In humans, accumulation of fat in the abdomen is associated with a higher risk of diabetes and cardiovascular disease. If the fat is more widely distributed it tends to cause fewer problems. Similarly in horses and ponies, it is the accumulation of fat depots in the abdomen and crest that is of more concern than a generalised obesity.
Systems such as Body Mass Index (BMI) are used in humans as a measure of overall fat deposits. Central or abdominal fat is assessed by the ratio of waist to hip measurements.
In horses and ponies, body condition score (BCS) is well established as a means of assessing the overall fat deposits. But what about regional fat deposits?
Equine Science Update reports that the researchers also identified morphometric measurements (morphometrics is the field concerned with studying variations and change in the size and shape of organisms) that were closely correlated to body condition score and cresty neck score.
Such measurements provide a more objective approach, and have the advantage of being easier for people without specialist training to determine.
They found that the ratio of girth to height was strongly correlated with body condition score.
Crest height (measured midway down the neck from the dorsal midline of the neck to the junction of the crest and the neck muscle) or the ratio of neck circumference at mid-neck (NC): height were suitable morphometrics for assessing neck fat deposits. Both showed a strong correlation with the Cresty Neck Score.
The researchers found that the relationship of the various morphometrics with the Body Condition Score, Cresty Neck Score and blood parameters differed between horses and ponies. Values for horses and ponies therefore need to be interpreted differently.
For example, a horse with a body condition score of 7/9 or more was no more likely to have raised blood insulin levels than a horse of moderate BCS. A pony with BCS or 7/9 or more was nearly 10 times more likely to be hyperinsulinemic than a pony of moderate BCS.
Having a cresty neck did not make a horse more likely to be hyperinsulinemic. But a pony with a cresty neck was 19 times more likely to be hyperinsulinemic than a pony with a moderate neck.
They suggest that the Cresty Neck Score allows a more standardised assessment of neck fat deposits, as does Body Condition Score for overall fat deposits. Objective alternatives are provided by the ratio of girth to height for overall fat deposits, and mid-neck circumference to height for regional (crest) fat deposits.