Final answer:
Option (A), Basophilic stippling of RBCs is a sign of lead poisoning in dogs, signifying the presence of granules from disrupted RNA metabolism within the red blood cells, which is detectable with specific staining techniques.
Step-by-step explanation:
Basophilic stippling of red blood cells (RBCs) is a characteristic finding in lead poisoning in dogs. Basophilic stippling refers to the appearance of small, dark blue granules (stipples) in red blood cells, which can be spotted under a microscope with a blood stain. These granules represent aggregates of ribosomal RNA and are typically seen when there is impaired RNA metabolism, often due to toxins like lead affecting heme synthesis.
Option A, lead poisoning in dogs, is correct. In the context of veterinary medicine, lead poisoning is known to cause basophilic stippling in RBCs. Therefore, Option B relating to anemia in horses, Option C involving acetaminophen toxicity in cats, and Option D regarding healthy avian blood, are not typically associated with this specific blood smear finding.