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Zinc Toxicosis 1053

Zinc Toxicosis Client Education
Sheet
VetBooks.ir Diseases and Disorders

defecation of metallic objects; incidental finding
BASIC INFORMATION
of metallic object on abdominal palpation or is rarely needed after the source of zinc has
been removed.
Definition radiography; or investigation of hemolytic
Syndrome occurs after ingestion of zinc- anemia. Zinc levels can confirm toxicosis. Acute General Treatment
containing objects such as U.S. pennies minted Management of life-threatening abnormalities
after 1982, scrap metal pieces, galvanized wire, Differential Diagnosis if present:
and hardware (e.g., washers, nuts). Clinical signs • Other substances causing oxidative injury: • Anemia: if severe (e.g., hematocrit < 20%
consist of acute gastrointestinal (GI) irritation, onions/garlic, acetaminophen, mothballs and/or clinical signs present), consider blood
hemolysis, and/or possible renal, pancreatic and (naphthalene), local anesthetics transfusion (p. 1169).
hepatic injury. • Immune-mediated hemolytic anemia • Azotemia if concurrent with severe hemo-
• Tick-borne diseases lysis: IV fluid therapy (e.g., 90-130 mL/
Epidemiology • Microangiopathic hemolysis (p. 59) kg/h, barring pre-existing heart disease
SPECIES, AGE, SEX • Other causes of hemolysis (e.g., hypophos- [p. 23])
Toxicosis is reported mostly for dogs (all breeds, phatemia, hemolytic-uremic syndrome) • Removal of zinc source from GI tract:
any age, either sex) from ingesting zinc-containing endoscopy or gastrotomy
objects. Birds are frequently exposed by chewing Initial Database • Emesis (p. 1188): only if metallic object
on galvanized wire cages, chains, and other sources. • CBC: regenerative anemia, Heinz bodies, recognized in stomach in the absence of
hemoglobinemia, reticulocytosis, spherocy- clinical signs related to intoxication (e.g.,
Clinical Presentation tosis; neutrophilic leukocytosis witnessed consumption)
HISTORY, CHIEF COMPLAINT ○ Regenerative response requires days to • Because an acidic environment is needed
• Inappetence, lethargy, protracted vomiting, begin but is usually present by the time for zinc absorption, antacids, H2-blockers,
diarrhea zinc-related anemia is detected. and/or proton pump inhibitors given soon
• Dark-colored urine • Serum biochemistry profile: elevation in after ingestion can decrease the stomach pH
• An animal may vomit or pass metallic objects serum bilirubin, liver enzymes, amylase, and therefore decrease the amount of zinc
in the feces. lipase, azotemia (if pigment nephropathy available for absorption. Activated charcoal
occurs) is not indicated because like most metals,
PHYSICAL EXAM FINDINGS • Urinalysis: hemoglobinuria, bilirubinuria, zinc is not adsorbed well.
• Abdominal discomfort/pain on palpation proteinuria • Early and sustained use of antacids until
• Pale mucous membranes • Radiography to look for metallic object source is removed (calcium carbonate
• Tachycardia, tachypnea, soft systolic murmur 70-185 mg/kg/day PO) and/or H2-blockers
• Icterus Advanced or Confirmatory Testing (famotidine 0.5-1 mg/kg PO q 12-24h) to
• Discolored urine (hemoglobinuria) Definitive diagnosis depends on blood or tissue decrease leaching and absorption of zinc
zinc levels: Chelation therapy: most cases of zinc poisoning
Etiology and Pathophysiology • For blood collection, use special tubes (royal do not require chelation therapy. Animals with
Source: blue–top tube) and syringes without rubber zinc toxicosis usually respond well to fluid
• Metallic zinc is used in galvanizing, welding, grommets. Do not use traditional syringes, therapy and other supportive measures after
and soldering. Zinc salts are used as astringents, rubber grommets, and Vacutainer tubes, the source of zinc has been removed. Serum
antiseptics, deodorants, wood preservatives, because the rubberized surfaces contain zinc. zinc concentrations, clinical condition, hydra-
pigments, and insecticides. Zinc gluconate • Toxic levels in dogs tion status, organ function, and whether the
is ≈14% elemental zinc and often found ○ Serum: 10-54 ppm (adequate levels 0.7- source of zinc is removed should be considered
in cough drops. Zinc oxide (10%-40%) is 2 ppm) before deciding to chelate. In the rare case that
found in ointments, diaper rash creams, and ○ Whole blood: 45 ppm has been fatal requires chelation, options for chelation therapy
sunblocks or sunscreens. ○ Liver: 130-436 ppm (adequate levels 30- include
• U.S. pennies minted after 1982 weigh 2.5 g 70 ppm) • Calcium EDTA (6.6% solution = 66 mg/
and are 97.6% zinc and 2.4% copper; 1982 ○ Kidney: 175-295 ppm (adequate levels mL) in dogs: dilute to 10 mg CaEDTA/
pennies have various zinc contents, and 16-30 ppm) mL in 5% dextrose and give 25 mg/kg SQ
pennies minted earlier have negligible zinc ○ Urine: 10-25 ppm (adequate levels 2- at different sites q 6h for 2-5 days. Do not
content. Canadian pennies made between 5 ppm) exceed 2 g/day, maximum of 5 consecutive
1997 and 2001 are 96% zinc and 4% copper. days. In cats: give 27.5 mg/kg in 15 mL of
Mechanism of toxicosis: TREATMENT 5% dextrose SQ q 6h for 5 days. Use with
• Toxicosis occurs when zinc-containing caution and monitoring because of risk of
objects are retained in the GI tract. Zinc Treatment Overview nephrotoxicosis, or
leaches from metallic objects in an acidic Life-threatening abnormalities must be • Dimercaprol: 2-4 mg/kg SQ or IM q 8-12h
pH of the stomach. Zinc is absorbed into identified and managed first. Severe anemia for 2 days, or
the bloodstream, leading to oxidative damage may require transfusion, pigment nephropathy • D-penicillamine: 110 mg/kg/day PO, divided
to the erythrocytes and hemolysis. (potentially resulting in acute kidney injury) q 6-8h for 1-2 weeks
• Zinc also causes direct GI mucosal irritation. should be addressed with intravenous fluids, Supportive care:
and GI tract irritation may require treatment • IV fluids
DIAGNOSIS with antiemetics and GI protectants. After the • Control vomiting with maropitant 1 mg/
patient is stabilized, the source of zinc should be kg SQ q 24h or 2 mg/kg PO q 24h for 5
Diagnostic Overview removed from the GI tract. General supportive days, or metoclopramide 0.2-0.5 mg/kg SQ
Suspicion of zinc toxicosis arises in one of care is indicated during recovery. Chelation with q 8h if needed, provided GI obstruction is
three contexts: observed ingestion or vomiting/ calcium EDTA, dimercaprol, or D-penicillamine ruled out.

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