Supplementary Tests

3. Supplementary Tests

Diet History

Collecting an accurate and complete diet history should be done for every patient and can prove to be very helpful in determining the length and degree of anorexia. Clients should be carefully questioned not only about the brand and type of food offered, but also about the amount and the feeding frequency. The diet history should include enough detail to allow for the total daily caloric intake to be determined and compared to the calculated caloric requirement. The determination of food intake is often complicated by the fact that many clients have moved away from the patients' typical diets to novel foods in an attempt to entice their pets to eat. The new foods are frequently higher in moisture and/or fat content. The loss of an easy comparison makes interpreting unintentional weight loss difficult. There is a natural tendency to assume that the patient's food consumption has been adequate, since that would imply a better prognosis to the client and that the veterinarian would not need to intercede with nutritional support. However, this assumption must be proven quantitatively.

Fortunately, the advent of the internet has made previously difficult to find energy density data more accessible to anyone with computer access. Many pet food manufacturers' websites provide kilocalories per volume or kilogram often not found on their product labels. In addition, product guides are readily available from many manufacturers. Energy density data for human foods can be easily obtained from the USDA Nutrient Database for Standard Reference, which is available at www.nal.usda.gov. The lead author's (SJD) website (www.balanceit.com) is also designed to provide information for petfood as well as for human food. With these tools, accurate and complete diet histories can be evaluated in all patients and used to determine the degree and length of patient anorexia.

Body Weight

Determination of a patient's body weight, adjusted for hydration status, is an important clinical measurement. However, for the critically ill patient in need of nutritional support, its value is diminished unless recent body weight data is available. Comparisons should only be made based on readings from the same scale, since scale-to-scale variation can be misleading.

Every animal should be weighed, and weight readings should be recorded daily during hospitalization. Intervention that only occurs when the patient has lost weight while hospitalized is a poor management strategy. Ideally, all hospitalized patients will remain relatively weight stable or, if indicated, gain weight during their stay. Weight gain should be interpreted cautiously as most patients will gain weight upon rehydration. Thus, every patient should be weighed daily to ensure that nutritional intervention is appropriate. The routine occurrence of weight loss in hospitalized patients should be a clear sign to the clinician that nutritional intervention is not adequate or has not been instituted soon enough.

Body Composition

Clinical assessment of body composition is limited to a validated system of using visual and tactile cues for assessing adiposity (Laflamme et al., 1994). Although the body condition scoring system has limitations, such as in its inability to quantify lean body mass, it requires minimal training and no special patient preparation or equipment.

More precise experimental methods of determining body composition such as dual energy X-ray absorptiometry (DEXA), bioelectrical impedance, and stable isotope dilution, are technically and economically demanding, limiting their clinical use.

Thus, the use of a body condition score (BCS) is the most practical method of quantifying a patient's body composition (Figure 1 and see Chapter 1). It is also an excellent tool to convey a "picture" of the animal to colleagues in the same practice or to referring veterinarians. Although subtle changes over several days cannot be detected by weight loss. even the most experienced clinician, the use of a BCS does provide an insight into the patient’s overall nutritional status that cannot be achieved by measuring body weight alone. Therefore, a BCS should be used as a measure of the "chronic" condition, and daily body weight changes should be used as indicators of the more "acute" condition.

Beauceron on the scale. A body weight that was recorded years or even months earlier cannot be used to determine the rate of unintentional weight loss. (© Royal Canin).

Body weight and BCS are usually not dynamic enough for daily evaluations and adjustments, but rather they are a better indicator of an animal's long-term response to nutritional support.

Albumin Status

Approximately 50% of all daily protein synthesis is committed to the production of albumin. Inadequate intake of dietary protein can impair that production. However, given that albumin's half-life in the dog is approximately eight days, reflective changes in albumin status can take days to occur (Kaneko et al., 1997). An example of the discrepancy between albumin status and caloric intake is provided in a paper by De Bruijne (1979). In this study, no changes in blood albumin concentrations were detected in healthy dogs undergoing simple starvation for 21 days. In another study, admission serum albumin concentration of 105 hospitalized dogs was shown to have a statistically significant predictive value regarding clinical outcome (Michel, 1993). Thus, reductions in albumin should be seen as evidence that production is severely decreased, or may not be keeping up with demand, or that losses are excessive. Consequently, normoalbuminemia should not be used as justification for foregoing nutritional intervention.

Other Biomarkers

Currently, no single clinical pathology or biochemical marker exists that helps to determine the nutritional status of dogs. Leukopenia, creatine kinase in cats and proteins such as C-reactive protein, prealbumin, transferrin and retinol binding protein in humans have all been investigated as measures of nutritional status. However, all of these biomarkers are affected by multiple other factors that render their interpretation difficult (Phang & Aeberhardt, 1996; Fascetti et al., 1997).

At this time, the clinician's best tools for nutritionally assessing their patients are:
- Complete medical and dietary histories
- Physical examinations
- Body weights
- Current and historical BCSs
- And routine blood work.