Page 434 - Small Animal Clinical Nutrition 5th Edition

448 Small Animal Clinical Nutrition

Box 25-2. Future Laboratory Tests for Nutritional Assessment.
VetBooks.ir DELAYED-TYPE HYPERSENSITIVITY TESTING proteins have relatively short half-lives (two hours to 10 days) in

The delayed-type hypersensitivity (DTH) skin test has been promot- people, and have been suggested as indicators of the patient’s
ed as an inexpensive and simple bedside preoperative test for peo- energy and protein status. The half-lives of these proteins are
ple with sepsis-related mortality risk, again relating the close tie unknown in cats and dogs but are assumed to be relatively short
between immunocompetence and patient outcome. Patients who and related to the nutritional status of the patient.
did not have an appropriate skin reaction to a multi-antigen intra-
dermal injection had a sepsis rate of 34% and a mortality rate of GENE EXPRESSION TESTING
38% vs. a 7% sepsis rate and 3% mortality rate for patients who Gene expression of metabolic enzymes and hormones in the fed vs.
reacted to the test injection. Several diseases and drugs, however, fasted state can be differentiated. The means by which food affects
may alter the specificity of this test as an indicator of malnutrition. genetic activity probably differs among responding organs but also
Delayed-type intradermal hypersensitivity testing is not currently depends on the duration of the fast and the composition of the
used in dogs and cats; however, some preliminary work in cats has refeeding food. Many nutritional studies using animals have demon-
shown promise. Cats infected with feline leukemia and feline strated the expression of enzymatic genes using a three-day fast
immunodeficiency viruses had a DTH response less than that of followed by refeeding specific dietary formulations. For example,
normal cats. In another study, healthy cats receiving no food had a this starvation-refeeding paradigm has demonstrated that fasting
significantly reduced response to an intradermal injection of feline causes adaptive increases in the concentrations of many hepatic
rhinotracheitis-calicivirus-panleukopenia antigens on Day 4 vs. and renal enzymes that convert amino acids to precursors of glu-
when they received food daily. a cose and fatty acids. Conversely, feeding a carbohydrate diet
decreases the activity of those enzymes involved in gluconeogene-
LYMPHOCYTE FUNCTION TESTING sis and amino acid catabolism. Fasting and refeeding alter the
Other promising indicators of nutritional status in the development structure of chromatin in regions near the structural genes involved
stage for dogs and cats are specific immune function tests. A bat- in metabolic regulation.The alterations in chromatin also depend on
tery of immune function tests has been developed for use in cats, the amount of carbohydrate, protein and fat in the refeeding food.
including: 1) immunophenotyping to identify relationships between The method of refeeding affects transcriptional regulation of certain
immunosuppressor and helper cells, 2) measuring membrane cal- genes. In the future, it should be possible to more accurately assess
cium flux to evaluate membrane function, 3) immunophenotyping to the metabolic state (i.e., nutritional status) of animal patients by
identify cells expressing major histocompatibility class II surface measuring the activities of specific enzymes, cell receptors and
antigen, 4) measuring phagocytic capabilities of monocytes and 5) gene signaling pathways and then to administer an appropriate
assessing neutrophil activation. Preliminary data indicate differ- refeeding formulation.
ences in these lymphocyte function tests among normal-fed, nor-
mal-fasted and ill anorectic cats. b ENDNOTES
a. Saker KE, Virginia-Maryland Regional College of Veterinary
ACUTE-PHASE PROTEIN TESTING Medicine, Blacksburg,VA, USA. Unpublished data. October 1997.
Laboratory tests available in other species, but not yet fully investi- b. Saker KE, Remillard RL, Virginia-Maryland Regional College of
gated as parameters of nutritional assessment in dogs and cats Veterinary Medicine, Blacksburg, VA, USA, and Angell Memorial
include serum prealbumin, transferrin, retinol-binding protein, Animal Hospital, Boston, MA, USA. Unpublished data. January
fibronectin and cholesterol concentrations and total iron-binding 1997.
capacity. A group of down-regulated proteins (prealbumin, transfer-
rin, fibronectin and retinol-binding protein) and up-regulated pro- The Bibliography for Box 25-2 can be found at
teins (ceruloplasmin, α-1-antitrypsin, α-1-acid glycoprotein and C- www.markmorris.org.
reactive protein) may prove useful in nutritional assessment. These

[DM] protein) with adequate caloric intake (19% DM fat) had ment protocol for veterinary patients, such as the Subjective
below normal serum albumin and total protein levels but nor- Global Assessment used in people, would provide a valuable
mal globulin concentrations after four weeks (Davenport et al, tool for veterinary practitioners.
1994). As an indicator of morbidity and mortality, serum albu- Decreased serum protein levels may occur in more acute
min concentration is a reliable tool (Mendez et al, 2005). states of inadequate protein intake relative to a large protein
Numerous studies in people have demonstrated that a low loss (e.g., protein-losing enteropathies, open abdomen). In
serum albumin value correlates with complications during starving animals, loss of muscle mass decreases the body’s pro-
recovery. It is not recommended, however, to use serum albu- tein reserves and, together with a slower rate of protein
min levels alone to determine nutritional status in critical care turnover in the remaining muscle, decreases the body’s ability
patients, because multiple factors can lead to hypoalbuminemia to synthesize proteins in response to metabolic needs
without malnutrition (Makhija and Baker, 2008). (Tomkins et al, 1983). Such patients are poor surgical candi-
Establishment of an accurate and sensitive nutritional assess- dates because the body’s protein reserves (muscle mass) have