Final answer:
Ivermectin should not be used in Greyhounds due to their sensitivity caused by a mutation in the MDR1 gene, while Propofol and Thiopental are safe injectable anesthetics for the breed. Morphine should only be used with caution.
Step-by-step explanation:
Among the drugs listed, Ivermectin should not be used in Greyhounds. Greyhounds are known to be sensitive to certain drugs, including Ivermectin, which is commonly used to prevent heartworm and treat certain parasites in other dog breeds. This sensitivity is due to a mutation in the MDR1 gene that affects the drug's transport across the blood-brain barrier, leading to an increased risk of neurotoxicity in affected individuals. The breed can safely receive Propofol and Thiopental, which are both injectable anesthetics.
Morphine, while not contraindicated, should be used with caution in Greyhounds as they may exhibit increased sensitivity to the drug's sedative effects. Careful monitoring and dosage adjustments are necessary when administering morphine to Greyhounds to prevent adverse effects.