Zinc Poisoning in Dogs

Many household items cause zinc poisoning, one of the most common being the penny. The exact amount of zinc ingestion that leads to toxicity is not well known, nor is the duration between ingestion and the onset of clinical signs. The source of the toxicity can be eliminated through the stool or vomit before symptoms fully appear. Though the release rate and effects of the toxin can vary depending upon how much food is in the stomach at the time of ingestion, the PH of the stomach and the length of time the toxin is in the body, all incidents of zinc consumption should be treated promptly.

Acute zinc poisoning is a relatively common source of poisoning in dogs. When canines ingest certain types of zinc, there is a formation of toxic zinc salts. These salts are rapidly distributed to the pancreas, bones, muscles, prostate, liver and kidneys. While zinc toxicosis has been documented most often in small breed canines, all dogs are susceptible to the serious dangers caused by the ingestion of the metal.

Because ingestion of zinc has lead to the death of many canines, it is imperative that you bring your furry family member to the veterinary clinic without delay if you suspect zinc toxicity or see any of the symptoms listed:

• Lack of appetite (anorexia)
• Abdominal pain
• Depression
• Vomiting
• Diarrhea
• Lethargy
• Pale mucous membranes
• Dehydration
• Reddish colored urine
• Fever
• Jaundice (icterus)

In advanced stages of zinc poisoning, there can be seizures and death.

The zinc salts that form in the stomach as a result of zinc poisoning irritate and corrode tissue, cause red blood cell abnormalities, and interrupt renal function. Zinc toxicity is a very real and serious issue; illness can result from the ingestion of as little as one penny.

• The U.S. Lincoln penny minted since 1983 are 97.5% zinc by weight
• The Canadian penny was made of zinc between 1997 and 2001; some UK coins contain 25% zinc
• Many paints contain zinc
• Batteries
• Calamine lotion and zinc oxide cream
• Vitamin and mineral supplements
• Household medicine cabinet contents like suppositories, antiseptics, shampoos
• Fertilizers and fungicides
• Galvanized wire
• Screws and nuts (as in plumbing supplies or as found on pet carriers or cages)
• Some board games pieces
• Zipper pulls
• Automotive parts

There are types of cookware and pipes that contain zinc. Also, if a dog spends any time in an industrial type setting, there may be toxicosis related to exposure to zinc dust.

It should be noted that zinc poisoning in the early stages can be mistaken for gastrointestinal upset or disease. This is further proof that as a dog owner, self-diagnosis at home is not a great idea. Zinc poisoning must be treated promptly and aggressively in order to ensure a good prognosis.

Upon arrival at the clinic, the veterinarian will ask for a history of your pet’s behavior of late. If you suspect zinc ingestion or have witnessed your dog eating something that may contain zinc, notify a quality veterinarian immediately. A complete physical examination of your dog may reveal muscle weakness, a sign found in cases of toxicity. Other physical signs might be tachycardia (rapid heart rate) and dyspnea (labored breathing).

A radiograph of the gastrointestinal tract will show evidence of a foreign body if one is still present. The foreign body may have been removed through the process of defecation or vomiting, but not before the toxic effects have begun.

Confirmation of zinc poisoning can be verified through various tests. A biochemistry profile, complete blood count (hemogram), coagulation profile, serum chemistry and urinalysis will show toxicity to the system. Some results may be:

• Bilirubinemia (too much serum bilirubin due to red cell breakdown)
• Heinz bodies (anemia granules present in blood)
• Polychromasia (variation in the red blood cells)
• Transaminases (enzymes that indicate liver damage)
• Hemoglobinuria (oxygen transport protein hemoglobin is found in high concentrations in the urine)
• Intravascular hemolysis (rupture of red blood cells)
• Lymphopenia (abnormally low white blood cells)

Successful treatment will start with the removal of the item containing zinc. Attempts at inducing vomiting (emesis) may or may not work. Zinc objects can have a tendency to adhere to the gastric mucosa. Surgery (laparotomy), or endoscopy (flexible tube with a camera attached) may be necessary in order to remove the item.

Intravenous therapy will be started to stimulate the urine process (and thus eliminate zinc from the kidneys) and balance the electrolytes. If needed, oxygen will be provided. Medications to inhibit the further formation of zinc salts, gastroprotectants to ease ulcerations, and drugs to combat nausea are all part of the treatment for toxicity. Continual monitoring of the therapy provided, along with the results seen on retesting of serum and CBC tests, will be done by the veterinarian.

Often, a blood transfusion is required in cases of severe anemia.

Early treatment is essential to a favorable prognosis, as are other factors like the severity of organ damage resulting from the toxicity, and how well your dog responds to therapy.

Complications that can occur during or after treatment are:

• Chronic pancreatitis
• Severe anemia
• Kidney damage
• Liver problems
• Intravascular coagulation - this is when proteins that control blood clotting become overactive, resulting in chances of spontaneous bleeding, high risk of heavy bleeding, and lack of blood flow to organs.

The veterinarian will want to check your dog regularly in order to ensure system levels are normal. If you have a pet who is curious about mouthing or ingesting household items, be vigilant with safe storage and encourage a family member to clean up work or play areas, taking care not to leave any toxic items within your dog’s reach.