Final answer:
Ivermectin should not be used in Greyhounds due to a gene mutation that leads to a higher risk of toxicity. Other drugs like Propofol, Morphine, and Thiopental are safe when administered by a veterinarian.
Step-by-step explanation:
The drug among Propofol, Ivermectin, Morphine, and Thiopental that should not be used in Greyhounds is Ivermectin. This medication is often used as an anti-parasitic treatment in many breeds of dogs, but Greyhounds have a higher sensitivity to Ivermectin due to a mutation in the multidrug resistance gene (MDR1), which can lead to increased risk of toxicity and severe adverse effects.
Other breeds with similar sensitivities include Collies, Shetland Sheepdogs, and Australian Shepherds. It is crucial for vets and pet owners to be aware of breed-specific drug sensitivities when treating their pets. Drugs like Propofol, Morphine, and Thiopental can be used with proper veterinary supervision in Greyhounds for anesthetic purposes as they are common induction and maintenance anesthetics; While Propofol and Thiopental are intravenously injected barbiturates, Morphine is a widely used opioid for pain relief.