Page 523 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

490 SECTION | V Metals and Micronutrients

VetBooks.ir TABLE 36.1 Uses and Purposes of Zinc Its purpose is:

Zinc is used in:
Galvanized steel Prevents corrosion
Parkerized steel Prevents rust and corrosion
Used in numerous metal alloys Brass, nickeled silver, typewriter metal, various soldering formulas, German silver
Primary metal American pennies, nuts, and bolts
Die casting Automotive industry
Zinc oxide Paints, sun protectants, rubber activator, diaper rash ointments
Wall tiles Germicidal properties
Zinc chloride Wood preservative and deodorant
Zinc methyl (Zn(CH 3 ) 2 ) Number of organic syntheses
Zinc stearate A lubricative plastic additive

The ingestion of pennies, which are 96% zinc intoxication are pancreatitis and acute arthritis. Also, non-
(Latimer et al., 1989) and may be as high as 97.5% zinc viable newborns may be observed with zinc intoxication.
(https://www.usmint.gov/coins/coin-medal-programs/cir- Foals are susceptible to zinc intoxication. It appears to
culating-coins/penny), by dogs has resulted in the devel- be a chronic zinc toxicosis. Initially, the foals have non-
opment of a subacute zinc toxicosis. The pennies remain painful joint enlargement lasting 7 21 days. They are
in the acidic environment of the stomach and slowly reluctant to rise and have stiff gait and increased joint
release metallic zinc. It is unclear how many pennies are fluid (Gunson et al., 1982).
required to produce a toxicosis. The size of the animal, Other livestock have early signs of lethargy and
lack of food in the stomach, and the number of pennies anorexia followed by diarrhea. Later, they display a
will all be factors in how quickly zinc toxicities develop. decreased rate of gain or decreased milk production. As
The pennies can be vomited or passed in the feces prior the toxic condition progresses, the animals have anemia
to presentation at the veterinary clinic. and icterus. Other signs include exophthalmia, polydipsia,
Other forms of zinc-containing hardware such as polyphagia, and seizures.
transport kennel bolts or machine nuts and bolts have Generally most species display some degree of hemo-
caused problems in animals. Analysis of these objects has lytic anemia, often with an erythrocytic regenerative
shown them to be about 97% zinc (Breitschwerdt et al., response. Additionally, there is renal damage with hema-
1986; Torrance and Fulton, 1987). They remain in the turia, urinary casts, and proteinuria. Diagnostically, there
stomach, producing a subclinical toxicosis or are vomited may be a radiodense area in the gastrointestinal tract indi-
or passed out prior to the animal’s presentation. cating the presence of zinc or some other metal such as
Other sources of toxicity have been galvanized wire lead. Postmortem lesions include renal tubular necrosis,
used in cages in aviaries (Reece et al., 1986)and for hous- hepatocyte necrosis, and gastroenteritis.
ing ferrets (Straube et al., 1980). The toys an animal selects
may be made almost entirely of zinc (Bexfield et al., TREATMENT
2007), and may not necessarily be a toy designed for ani-
mals. In addition to galvanized wire, avian food dishes and As with many metal intoxications, removal of the source
toys such as bells and other shiny toys may contain zinc. of the toxin from the animal, followed by supportive ther-
Birds, such as parrots may be able to chip the exterior of apy, are critical to the patient’s recovery. This procedure
the feeding container or bend the toy bells and be exposed with zinc will result in dramatic drops in serum and
to zinc (Center for Avian & Exotic Medicine). tissue levels within a relatively short time. Removal of
An additional component of zinc toxicosis is acute the source will allow the normal excretory pathways to
renal failure observed in some dogs (Breitschwerdt et al., work appropriately.
1986). The clinical findings include hypercreatinemia, Particularly when treating foals it is important to evalu-
azotemia, hyperphosphatemia, and granular casts in the ate the copper status of the animal. Copper and zinc seem
urine (Breitschwerdt et al., 1986; Torrance and Fulton, to work in tandem and adding copper to copper-deficient
1987; Latimer et al., 1989). Other signs of acute animals may help decrease the overriding effects of zinc.