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Zinc Toxicity in Dogs

Zinc is one of the most important minerals for maintaining a healthy body, but excessive zinc can be harmful and can cause toxicity. More commonly referred to as zinc toxicity, it occurs when animals ingest an exorbitant amount of zinc-containing materials. Though mostly reported in small breed dogs, zinc toxicity can affect dogs of all sizes.

Symptoms and Types

• Lack of appetite
• Vomiting
• Diarrhea
• Lethargy
• Depression
• Excessive hemoglobin levels in blood
• Excessive hemoglobin levels in urine
• Jaundice
• Orange colored feces

Causes

Ingestion of zinc-containing materials, such as:

• Nuts
• Bolts
• Staples
• Nails
• Board game pieces
• Zippers
• Some toys
• Jewelry
• Pennies
• Certain lozenge brands
• Some lotions

Diagnosis

Your veterinarian will take a detailed history of your dog, including any incident of ingestion of unusual materials which may have precipitated the symptoms. He or she will also perform a complete physical examination on the animal. Routine laboratory tests include biochemistry profile, electrolytes, urinalysis, and a complete blood count. The complete blood count may reveal anemia due to zinc-related destructions of Red Blood Cells (RBCs) with possible formation of Heinz bodies, or granules present in the red blood cells. The complete blood count may also reveal variations in red blood cells coloration known as polychromasia.

The biochemistry profile, meanwhile, may reveal abnormally high levels of hemoglobin and bilirubin in blood. If biochemistry profile shows derangements -- like high levels of blood urea nitrogen, creatinine, liver enzymes, and pancreatic enzymes -- it will indicate multiple organ failure, which is not a good sign.

While examining your dog's blood, the veterinarian may also note abnormal red blood cells with an unusual dark ring surrounding a dark center known as target cells; this is associated with anemia.

Due to rapid destruction of red blood cells, your veterinarian will administer a test called packed cell volume (PCV), which will calculate the number of viable red blood cells. This test is important in determining whether a blood transfusion is required.

To confirm the diagnosis, however, your veterinarian will order laboratory tests to measure the levels of zinc in your dog's blood. These tests can also help evaluate your dog's blood clotting mechanism, an indicator of zinc toxicity. In addition, X-rays are often used to confirm if your dog has ingested zinc-containing materials.