ERYTHROCYTE DISORDERS

6 ERYTHROCYTE DISORDERS



Shannon Jones Hostetter, Claire B. Andreasen



1 Identify the characteristic hematologic changes secondary to lead toxicity in small animals.



a. Normal to mildly decreased hematocrit, but usually not less than 30%

b. Basophilic stippling of erythrocytes

c. Increased nucleated red blood cells (nRBCs)

d. Poikilocytosis


2 Explain the pathogenesis of lead toxicity in dogs and cats.


Lead toxicosis in small animals usually results from ingestion of lead-containing objects, such as lead-based paint chips, batteries, and lead fishing weights. Puppies under 6 months of age are at a greater risk of toxicosis than older dogs or cats, both because they are more likely to ingest foreign objects and because they absorb more lead from the gastrointestinal (GI) tract than their adult counterparts. Dogs and cats with lead toxicity develop GI and neurologic signs as well as the hematologic changes listed above. Lead inhibits several enzymes that incorporate iron into hemoglobin, causing oxidative damage to the bone marrow, which results in increased release of nRBCs from the marrow. Lead also inhibits ribosomal breakdown in erythrocytes, leading to basophilic stippling.



3 What is methemoglobin reductase deficiency in the dog?


Methemoglobin reductase deficiency is presumed to be an inherited disorder that results in persistent methemoglobinemia. Although considered a rare disorder, it has been identified in several breeds, including poodles, Chihuahuas, Eskimo dogs, Borzoi, and English setters. Affected animals typically have a normal life expectancy and exhibit minimal clinical signs.



4 List the clinical signs and laboratory findings associated with methemoglobin reductase deficiency in the dog.



Clinical Signs



a. Persistently cyanotic mucous membranes

b. Exercise intolerance

c. No clinical signs exhibited in many animals


Laboratory Findings



a. Persistently dark-brown/red venous blood samples

b. Increased methemoglobin content in the blood (greater than 12% methemoglobin)

c. Normal oxygen tension (PO2)

d. Normal to mildly increased hematocrit


5 What is phosphofructokinase deficiency, and what breeds are predisposed?


Phosphofructokinase (PFK) deficiency is a relatively uncommon disease of dogs that results from an enzyme defect. Decreased activity of PFK in affected dogs leads to decreased adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) in erythrocytes.


PFK deficiency is an inherited disorder that affects different breeds, including English springer spaniels and cocker spaniels.

Related posts:

  1. LARGE ANIMAL HEMATOLOGY
  2. MYELODYSPLASTIC SYNDROMES
  3. LABORATORY TESTING FOR THYROID DISEASE
  4. METABOLIC ACID-BASE ABNORMALITIES

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Aug 26, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on ERYTHROCYTE DISORDERS

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