South African Equine Veterinary Association Congress 2015 Protea Hotel Stellenbosch
addition, abnormal kidneys and ureteroliths can be palpated in some horses with chronic kidney
disease. When performing a rectal exam on a horse with weight loss, it is important to attempt to
reach the mesenteric root by palpating the aorta as far cranially as possible. The root of the
mesentery contains a number of lymph nodes and is a common location for abdominal abscesses.
Assessment of management and appetite: Before more serious medical conditions that lead to
weight loss (and referral) are considered, it is essential to determine whether or not the horse is
actually consuming an adequate amount of feed daily to maintain body condition. In a group
setting dominant horses may chase younger, older, or less competitive horses away from feed and
correction of weight loss may simply require separation from the group at feeding time or
breaking the herd into smaller groups with less of a dominance hierarchy. Next, during cold
weather caloric requirements increase and if feed availability is not increased weight loss can
ensue. In this situation most of the horses in the herd are found to be thin, rather than a single
individual. Thus, when the horse in question is part of a herd, it is important to look at the
remaining horses to determine overall body condition of the group: more severe weight loss in an
individual animal would support a medical condition while an overall decrease in condition of the
herd would support a management problem. To further answer the question of whether or not a
horse is eating adequately, it is often helpful to offer the horse a flake of hay or a couple of
pounds of concentrate feed as part of the initial evaluation. “Quidding” or dropping of chewed up
hay boluses can be observed and the horse‟s vigour towards eating can also be assessed.
Initial blood work: Collection of blood samples for a complete blood count (CBC) and serum
biochemistry profile is generally warranted in horses with ill thrift. The CBC is probably the less
rewarding of these tests. Frequently, mild anaemia (packed cell volume [PCV] of 27-30%) is the
only abnormality detected. Mild anaemia may be a consequence of chronic disease but it is also
important to recognize that PCV values of 28-32% may be normal for adult horses that are not in
a regular exercise program. Occasionally, however, rare conditions such as leukaemia may only
be detected with a CBC.
Chronic kidney disease is perhaps the best example of a medical disorder leading to weight loss
that can be easily detected on serum biochemistry: detection of azotaemia with hypercalcemia is
nearly pathognomonic for chronic renal disease. Chronic liver disease is most often supported by
an increase in γ-glutamyl transferase (GGT) activity as increases in activity of this enzyme are
specific for the biliary system. Finally, it is important to look at total protein, albumin, and
globulin concentrations. Detection of either increased total protein concentration or
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