Another skinny horse with a normal physical exam: Now what? (Proceedings)

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Another skinny horse with a normal physical exam: Now what? (Proceedings)

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Apr 01, 2010

Weight loss or ill thrift is a common presenting complaint for many medical problems of horses. These cases can be frustrating because physical exam findings, including rectal palpation, are often unremarkable. However, an ordered approach to further evaluation is useful for equine practitioners to diagnose many medical disorders as well as to determine when referral to a hospital may be the next logical step. In addition, a standardized approach to horses with weight loss allows the practitioner a more realistic expectation of what services a referral hospital may or may not be able to provide for their clients.

History and physical examination

During performance of the physical exam on horses with weight loss, it is important to collect a complete history while also attempting to document the magnitude and time course of weight loss. A helpful tool can be implementation of body weight measurement (weight tape) and body condition scoring (BCS) during semiannual or annual preventive care visits. Having this information within the past few months would allow a practitioner to have a comparison basis to better document weight loss.

Performance of a rectal examination on horses with weight loss, especially when results of the remainder of the physical exam are unremarkable, cannot be overemphasized. Rectal palpation can reveal abdominal masses including neoplasia or abscesses due to metastatic Streptococcus equi subspecies equi or Corynebacterium pseudotuberculosis infections. In addition, abnormal kidneys and ureteroliths can be palpated in some horses with chronic renal 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.


Figure 1. A stick can be seen lodged between the upper dental arcades in the oral cavity of a horse that presented for weight loss over the past week along with a decreased appetite (left); dental abnormalities such as the large hook on the caudal upper cheek tooth (right) can also lead to weight loss and a decreased appetite.
Next, performing a complete oral exam also cannot be overemphasized. For example, horses referred for evaluation of a poor appetite have had a stick lodged between diastemata of the upper dental arcades (Figure 1). A complete dental exam is also essential, especially in horses 15 years of age and older in which poor dentition may be the primary problem (Figure 1).

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 and 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 or not, 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 aggressiveness of eating can also be assessed.