In which of the following species can administration of penicillin be fatal?

Penicillin can be particularly dangerous when administered to certain species, specifically hamsters, guinea pigs, and rabbits. These animals have a unique digestive system and specific gut flora that can be severely disrupted by antibiotics like penicillin. This disruption can lead to a condition known as antibiotic-induced enterotoxemia, which can be fatal. Unlike some other species, these small mammals lack the necessary enzymes to effectively handle penicillin, making them highly susceptible to severe side effects from its use.

In the context of the other species listed, dogs, cats, and ferrets, while they may exhibit adverse reactions to penicillin, generally do not have the same level of risk as the highlighted rodents. Cows, pigs, and sheep similarly have been shown to tolerate penicillin, although precautions must be taken when administering it. Fish, frogs, and salamanders, on the other hand, have vastly different physiology and metabolic processes, and penicillin's effects in these aquatic or amphibian species can vary, but it does not carry the same fatal risk as in hamsters, guinea pigs, and rabbits. Consequently, penicillin's administration is particularly contraindicated in the latter group due to the potential for fatal consequences.