Page 2680 - Cote clinical veterinary advisor dogs and cats 4th

1382 SNAP Tests Sodium

to a reference laboratory. Physical analysis Relative Cost: $$ (physical analysis); $ and may exceed the sensitivity of many in-
(color, morphology, sperm count): 1 mL semen (alkaline phosphatase) clinic instruments.
VetBooks.ir Include volume of sperm-rich fraction col- Pearls AUTHOR & EDITOR: Lois Roth-Johnson, DVM, PhD,
from sperm-rich fraction in sterile container.
DACVP
• History is an important aspect of fertility
lected. Alkaline phosphatase: 1 mL semen in
sterile container. Store at room temperature.
error.
Specimens < 2 hours old are considered best. assessment; relying on a single test invites
Maximum collection to examination interval • Semen alkaline phosphatase concentration is
is 72 hours. significantly greater than serum concentration

SNAP Tests

Definition Next Diagnostic Steps to Consider Pearls
Point-of-care testing based on ELISA technol- if Levels are High • SNAP® tests are in-clinic screening tests. Tests
ogy designed for a wide variety of common SNAP® tests are often used as screening tools may also be run at reference laboratories, but
small animal infections and biomarkers. for various diseases. Depending on the clinical the advantage of obtaining a rapid response
presentation, confirmatory testing, such as PCR, is lost.
Physiology culture and sensitivity, and advanced imaging, • Common SNAP tests include metabolic/
Proprietary (IDEXX Laboratories, Inc., may be necessary for confirmation of diagnosis. biomarker (fPL, cPL, feline and canine
Westbrook, Maine) test kits contain conjugate proBNP, canine and feline total T 4, canine
solution, tube for sample-conjugate incubation, Lab Artifacts cortisol, and canine and feline bile acids),
and a SNAP® device. Depending on the test These test kits are susceptible to improper vector borne (Anaplasma spp, Ehrlichia spp,
type, feces, serum, plasma, and whole blood are storage and shipping. Mishandling of reagents heartworm [canine and feline], Lyme) infec-
incubated with the conjugate solution and then and/ or kits may result in false-positives or tions, diarrheal (giardiasis, canine parvovirus),
poured into the test well of the SNAP device. false-negatives, depending on the test. Improper leptospirosis, and retroviral diseases (feline
The conjugate-sample solution diffuses across mixing of conjugate with patient sample may leukemia and feline immunodeficiency
the test window until it reaches an “activation result in false-positive or false-negative test virus).
circle” and is then depressed or “snapped” to results. • The term SNAP is specific to the tests and
release the wash solution and substrate in reverse testing devices made by IDEXX Laboratories,
flow across the same testing window. A color Specimen Collection and Handling Inc., but the term is sometimes used colloqui-
change spot, generally blue, within the testing Anticoagulated whole blood (lavender or green ally for any point-of-care diagnostic test.
window will appear and is compared to the top tube), serum (red top tube; separated),
product insert for interpretation. plasma (lavender or green top tube), or feces, AUTHOR: Erin N. Burton, DVM, MS, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
depending on tests. Follow manufacturer’s
Reference Interval instructions.
Varies depending on the specific test. Results
may be positive or negative. For some tests, the Relative Cost: Packs that include multiple
degree or darkness of the color change observed test kits: $$$-$$$$; kits for individual tests
may correlate to a semiquantitative value. when purchased in bulk: $

Sodium

Definition tract. Serum [Na ] depends on circulating Causes of Abnormally High Levels
+
Major extracellular fluid (ECF) cation. Serum blood volume and plasma osmolality. With • Water deficit (most common)
+
+
+
[Na ] essentially equals ECF [Na ]. Serum hypovolemia, aldosterone promotes renal Na ○ Loss of hypotonic fluid: via respiratory
+
[Na ] is relative to hydration status and ECF resorption and antidiuretic hormone (ADH, (fever, panting), gastrointestinal (vomiting,
+
volume but does not indicate total body Na vasopressin) promotes renal water resorption. diarrhea), or renal system (any cause of
content. Hypo-osmolality causes decreased water intake, polyuria, including osmotic diuresis, renal
increased renal water excretion. Hypervolemia disease, central/nephrogenic diabetes
Synonyms reduces Na resorption. Hyperosmolality insipidus) or uncommonly with cutaneous
+
Na, Na + promotes water intake, ADH-mediated renal (severe burns), third space loss (pancre-
water resorption. Osmotic water shifting from atitis, peritonitis), or toxicosis (paintball
Physiology ICF to ECF dilutes serum [Na ]. ingestion, phosphate enema)
+
+
Serum [Na ] is net balance of oral intake, ○ Decreased intake: neurologic disease
excretion, and water shifts between ECF and Reference Interval causing decreased thirst response (primary
+
ICF (intracellular fluid). Na and water are Dogs: 144-152 mEq/L. Cats: 150-160 mEq/L. adipsia/hypodipsia), lack of access to
lost via kidneys, intestine, skin, and respiratory Unit conversion: 1 mEq/L = 1 mmol/L. water
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