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1394 Warfarin Zinc, Serum Level

Warfarin
VetBooks.ir Definition Drug Effects

in dog plasma is 14.5 hours; the half-life of
Warfarin and related second-generation ingested over several days. Warfarin half-life Oxyphenbutazone, phenylbutazone, diphenyl-
compounds have been a commonly used diphacinone is suspected to be days. Brodifa- hydantoin, sulfonamides, and corticosteroids
rodenticides but are being phased out of use; coum is assumed to be similar or longer than increase susceptibility to toxicity.
similar compounds are also used to treat people that of diphacinone. The differences in residual
with hypercoagulable states. Warfarin testing half-lives have important therapeutic implica- Specimen Collection and Handling
is typically for retrospective confirmation tions. Compounds interfere with coagulation Chemical detection of specific anticoagulants
(e.g., identification and prevention of future by decreasing active coagulation factors II, VII, in vomitus or baits. Liver tissue (frozen) for
reintoxication or for legal purposes). Animals IX, and X (competitive inhibition of vitamin postmortem diagnosis. Unclotted blood,
suspected of active hemorrhage due to ingestion K epoxide-reductase). stomach contents, intestinal content, feces,
of warfarin or other anticoagulant intoxicants spleen, and kidney may also be submitted.
should be evaluated with prothrombin time Reference Interval
(PT) or assessment of proteins inhibited by Consult laboratory for reference interval and for Relative Cost: $$ (Send out test for most
vitamin K absence/antagonism (PIVKA) because inclusion of both first- and second-generation veterinary reference laboratories; additional fees
turnaround time for warfarin assay is long. compounds in test panel. may apply.)
Synonyms Causes of Abnormally High Levels Pearls
First-generation compounds: warfarin (i.e., Ingestion of compounds or animals that have Conditions enhancing susceptibility are high
Coumadin), indanedione-containing rodenticides consumed compounds. Relay toxicosis (incurred dietary fat (fatty acids displace the plasma
Second-generation compounds: coumarin- from consumption of prey [e.g., rodents] protein-bound anticoagulant), prolonged oral
based generics (brodifacoum, difenacoum, bro- that have eaten warfarin) rarely occurs with antibiotic therapy, biliary obstruction, liver
madiolone) and the indanedione, diphacinone second-generation anticoagulants other than disease, hypoalbuminemia (warfarin is highly
diphacinone. plasma protein bound), renal disease.
Physiology Most veterinary reference laboratories do not
Well but slowly absorbed following oral admin- Next Diagnostic Steps to Consider do rodenticide testing. When testing is offered,
istration; plasma levels peak in 6-12 hours. Most if Levels Are High results are usually not available for several days
is protein bound, but high concentrations in Inquire about potential exposure to rodenti- or weeks. Testing is typically confirmatory rather
liver, spleen, kidney. Elimination rate via hepatic cide or human drugs; remove source; admin- than proactively diagnostic.
metabolism depends on compound, amount ister vitamin K; whole blood transfusion
ingested; may accumulate if small amounts (p. 69) AUTHOR & EDITOR: Lois Roth-Johnson, DVM, PhD,
DACVP

Zinc, Serum Level

Definition Next Diagnostic Steps to Consider Drug Effects
Zinc is an essential trace mineral required for if Levels are High Chelation therapy may decrease serum zinc
proper function of many enzyme systems. History, specifically regarding exposure to zinc- concentrations
Deficiency and toxicosis are imbalances that containing creams and rodenticides; abdominal
can be seen clinically. radiography (for ingested metal). Hemolysis Specimen Collection and Handling
and multiorgan failure can be sequelae of zinc • Serum: avoid tubes with rubber tops (contain
Physiology poisoning. See pp. 1051 and 1053. zinc stearate).
Dietary zinc is absorbed in the intestine, • Tissue: liver, kidney, GI contents can be
metabolized in the liver, and exported to Causes of Abnormally Low Levels used to rule out intoxication; skin biopsy
peripheral tissues for use and storage. Zinc- Malnutrition, malabsorption, animals receiving for suspected zinc-deficient dermatosis
responsive dermatosis is a deficiency of zinc total parenteral nutrition
presenting as a dermatologic disorder in dogs. Relative Cost: $$$
Zinc toxicity typically occurs following inges- Next Diagnostic Steps to Consider
tion of zinc-containing products. if Levels are Low Pearls
See Zinc-Responsive Dermatosis (web edition). • CAUTION: In zinc phosphide intoxication,
Reference Interval there may be a characteristic acetylene
Normal serum zinc concentration is < 2 mcg/ Important Interspecies Differences odor to the gastric contents (which may be
mL; liver wet weight is < 30-70 ppm. Check with • Zinc-responsive dermatosis occurs as a bloody), and this gas is harmful to humans.
laboratory for values consistent with intoxication. familial form (plush-coated northern dog Zinc phosphide causes emesis in dogs and
breeds) and in puppies fed zinc-deficient cats, so fatal intoxication is not frequent.
Causes of Abnormally High Levels diets (or those containing excessive calcium).
Ingestion of metal pieces, zinc-containing • Lethal acrodermatitis is a rare inherited AUTHOR: Carrie L. Flint, DVM, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
topical ointments (e.g., diaper creams), zinc disorder of zinc metabolism in bull terriers
phosphide rodenticides, or U.S. pennies minted that does not respond to zinc supplementa-
after 1982. tion and is invariably fatal.

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