Lead Toxicity in Cats
By: Dr. Anne Marie Manning

Section: Veterinary Care In-depth

Diagnosis

A complete blood count (CBC) is usually done to look for changes in the red blood cells. Changes such as nucleated red blood cells (normal red blood cells do not have a nucleus) and basophilic stippling (blue granules) in the cytoplasm (area of the red blood cell surrounding the nucleus) are seen in 25 to 54 percent of animals with lead poisoning. Lead toxicity also causes anemia (decreased red blood cell count) and an elevated white blood cell count. Absence of these changes however, does not rule out lead poisoning.

A biochemistry profile is a blood test done to evaluate the function of internal organs. Elevation of liver enzymes is common in lead poisoning.

Measurement of blood lead levels is the diagnostic test of choice. A blood lead level of greater than 0.5 parts per million (ppm) is considered diagnostic. Blood levels of 0.35 to 0.5 ppm with the presence of symptoms are also considered diagnostic.

Thoracic and abdominal radiographs are done to look for lead objects in the digestive tract and to evaluate the esophagus for an increase in size (megaesophagus). Megaesophagus can lead to regurgitating and pneumonia, which may also be evident on x-rays. Negative x-ray findings do not rule out lead poisoning.

Fecal lead levels of greater than 35 ppm is suspect for lead toxicity.

X-rays of the legs may also be done to look for "lead lines" in the bone. In the area of a "lead line," the bone appears denser (whiter) than normal.