^Well, in most cases, I would say yes. Poisons, like I said, are vastly different. Not just in ingredients, but in how they are “delivered.” Some poisons need to be ingested, some work through skin contact, some need to be inhaled, others only work when in the bloodstream.
Anatomy, and physiology also play a role. Some animals don’t have the ability to absorb certain chemicals. Metabolic rates, and weight are also important factors. Take a spider’s venom,let’s say a neurotoxin, like a black widow. If a small child is bitten, paralysis of the diaphragm could lead to asphyxiation, and death. If a fully grown person is bitten, it could have no effect, or just make them sick. When the spider bites a smaller insect, it is extremely deadly.
Some animals have a really high metabolic rate. So it takes higher doses of a drug/chemical to be effective. A 25 mg benadryl/diphenhydramine is effective for allergy relief, and makes me (a 300 lb man) tired. My 50 lb pit bull needs 50 mgs to get the same effect.
Some things are poisonous to some animals, and not to others. You and I can enjoy a bag of grapes. But grapes are toxic to dogs…
There are many variables in regards to toxind/poisons, and how they affect an animal.