Page 524 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Zinc Chapter | 36 491

VetBooks.ir teritis and anemia must be addressed. Activated charcoal intestines (Cahill-Morasco, 2016). Hence, removal of the
Supportive care is critically important as the gastroen-
offending item prior to chelation therapy is critical. The
most commonly suggested chelator is calcium disodium
is not recommended as it is ineffective at absorbing
elemental zinc. The vomiting, in species capable of EDTA. Calcium disodium EDTA is most commonly used
vomiting, has usually resulted in severe gastroenteritis. to treat lead intoxication and the dose for zinc intoxica-
Vomiting may be controlled with metoclopramide tion has thus been extrapolated (100 mg/kg and may be
(0.2 0.4 mg/kg) administered every 6 h intramuscularly given IV or SQ, divided into four doses per day for
(IM), subcutaneously (SQ) or per os. Decreasing zinc 3 days. It may be diluted in 5% dextrose or in sterile
absorption may be accomplished by decreasing gastric water to decrease local irritation) but may exacerbate
acidity (Meurs, 1995). Use of H2-receptor blockers, such zinc-induced nephrotoxicity. Especially with chelation
as famotidine (0.5 mg/kg orally, SQ, intramuscularly, or therapy, daily monitoring of the patient is essential to
intravenously (IV)) should be administered once or twice determine the length of therapy.
daily (Plumb, 1999) until the serum zinc has decreased.
Blood transfusions may be necessary to address the
anemia. Fluid therapy with a balanced solution such as CONCLUDING REMARKS
lactated Ringer’s solution is appropriate. Good supportive AND FUTURE DIRECTIONS
care includes continuous monitoring of various blood
Evidence of pancreatitis, liver, and kidney dysfunction
parameters such as red blood cells, platelets, packed cell
must be considered along with gastroenteritis and a hemo-
volume and serum chemistries including liver enzymes,
lytic event when considering the differentials. The clinical
serum urea nitrogen, and electrolytes. Treatment efforts
sign of acute gastroenteritis is common to viral and bacte-
must be directed at correcting pancreatic, renal, and/or
rial diseases, parasitic diseases, and various neoplasms.
liver dysfunctions, which are closely associated with zinc
Gastroenteritis and a hemolytic event must be differenti-
intoxication.
ated from other metal intoxications such as copper
A radiograph of the animal should help locate the
poisoning. Additional considerations include acetamino-
offending object. Removing the offending object or
phen or onion intoxication, mustard poisoning, immune-
objects is important in decreasing the serum zinc concen-
mediated diseases and certain snake bites.
trations. If the patient is asymptomatic, inducing emesis
As zinc is a very economically useful metal it is likely
may remove the object. The offending agent should be
to be found in more products that animals are exposed to
removed, either by surgery or retrieval by endoscopy.
in various fashions. It would be beneficial to have a larger
Serum zinc levels should decrease when the offending
array of safe chelation products. Unfortunately, the impor-
object is removed from the patient. However, dogs may
tance of chelation therapy outweighs the available mar-
die as a result of complications from anemia or kidney
kets for the product. Therefore it is unlikely research
failure even after a penny or other zinc object is removed
dollars will be directed at finding new chelation therapies.
(Latimer et al., 1989).
Evaluate the serum zinc levels after removal of what Online Contents
is believed to be the offending object. If the zinc levels Center for Avian &Exotic Medicine ,https://avianan-
have not dropped, then all of the offending objects have dexoticvets.com/top-toxins-to-pet-birds/..
not been removed from the gastrointestinal tract or the US Mint ,https://www.usmint.gov/coins/coin-medal-
renal insufficiency has prevented zinc excretion. If either programs/circulating-coins/penny..
of these situations is present, then chelation therapy (see
below paragraph) is inappropriate and contraindicated as REFERENCES
it may increase gastrointestinal or intestinal absorption of
any remaining zinc, and the chelated metal is potentially Abdel-Mageed, A.B., Oehme, F.W., 1990. A review of the biochemical
nephrotoxic. roles, toxicity and interactions of zinc, copper and iron: 1. Zinc. Vet.
Chelation therapy is an option in the patient’s care. Hum. Toxicol. 32 (1), 34 39.
Chelation therapy is effective but not without risk and Bexfield, N., Archer, J., Herrtage, M., 2007. Heinz body haemolytic
some controversy (see above paragraph) so must be eval- anaemia in a dog secondary to ingestion of a zinc toy: a case report.
Vet. J. 174 (2), 414 417.
uated with regard to the patient’s overall condition.
Breitschwerdt, E.B., Armstrong, P.J., Robinette, C.L., et al., 1986. Three
Patient conditions requiring evaluation include the hydra-
cases of acute zinc toxicosis in dogs. Vet. Hum. Toxicol. 28, 109.
tion status, the degree of dysfunction of the excretory
Cahill-Morasco, R., 2016. Zinc toxicosis. In: Aiello, S., Moses, M.A.
organs, especially the kidneys, and the severity of the
(Eds.), The Merck Veterinary Manual, eleventh ed. Merck & Co,
serum zinc concentration. While chelation therapy can Inc, New Jersey, pp. 3088 3089.
increase zinc elimination and speed recovery, chelation Chasapis, C.T., Loutsidou, A.C., Spiliopoulou, C.A., et al., 2012. Zinc
treatment may increase absorption of zinc from the and human health: an update. Arch. Toxicol. 86, 521 534.