(original graphic by marvistavet.com)
RED BLOOD CELL DESTRUCTION
The spleen is responsible for removing old red blood cells. The spleen possesses many tortuous, winding blood vessels where red blood cells may break if they are not supple enough to pass through. The spleen then collects the hemoglobin for recycling but since hemoglobin by itself is not safe for release into the bloodstream, the hemoglobin is converted into a substance called bilirubin for transport and the iron is broken off for recycling into new hemoglobin. Bilirubin is sent to the liver to be “conjugated,” a chemical process enabling the bilirubin to be made water soluble so that it can be excreted in bile and disposed of through the intestinal tract. Bilirubin is responsible for the brown color of feces.
WHAT IS HEMOLYSIS?
Hemolysis is the destruction of red blood cells. Red blood cells may be destroyed by:
When too many red blood cells are destroyed, the body’s mechanisms for processing hemoglobin are overwhelmed and bilirubin builds up. The patient may be obviously yellow (“jaundiced” or “icteric”) when the mucous membranes are examined. The serum may be yellow when one checks a blood sample. If the blood cells are actually being destroyed in the blood stream (rather than in the spleen), the urine will turn red or rust colored. Hemoglobin is toxic to the kidneys and kidney failure is a strong possibility.
Other zinc sources include nuts, bolts, and zinc oxide based skin creams (such as diaper rash cream and sun screen). One may see a penny or other radio dense object of about the right size on a radiograph or there may be a known history of penny eating. It is important to rule out immune-mediated hemolysis as an alternative explanation as this is a common condition requiring specific treatment.
The clinical signs of zinc toxicosis include:
Vomiting and diarrhea generally precede the destruction of the red blood cells. How zinc is able to produce hemolysis is not known.
If an object possibly made of zinc is seen on a radiograph, it should be removed promptly. This might involve surgery, endoscopy or possibly the induction of vomiting if the object does not have sharp edges. Support then becomes crucial. Fluid therapy is important to keep circulation to the kidneys adequate and help prevent failure. Transfusion may be necessary to combat anemia and anti-nauseal therapy is warranted. Zinc is very corrosive to the stomach so medication to protect the stomach will be needed and antacids are helpful to reduce the absorption of zinc (which is enhanced by stomach acid). Research is looking at methods for binding excess zinc in the circulation similar to the way lead poisoning is treated.
Once the zinc source is removed, most pets are able to recover within 48-72 hours with supportive care but, of course, this depends on the severity of the poisoning.
Page last updated: 3/2/2016