The breastfeeding by humans of animals is a practice that is widely attested historically and continues to be practised today by some cultures. The reasons for this are varied: to feed young animals, to drain a woman's breasts, to promote lactation, to harden the nipples before a baby is born, to prevent conception, and so on.

English and German physicians between the 16th and 18th centuries recommended using puppies to "draw" the mother's breasts, and in 1799 the German Friedrich Benjamin Osiander reported that in Göttingen women suckled young dogs to dislodge nodules from their breasts. An example of the practice being used for health reasons comes from late 18th century England. When the writer Mary Wollstonecraft was dying of puerperal fever following the birth of her second daughter, the doctor ordered that puppies be applied to her breasts to draw off the milk, possibly with the intention of helping her womb to contract to expel the infected placenta that was slowly poisoning her.

Animals have widely been used to toughen the nipples and maintain the mother's milk supply. In Persia and Turkey puppies were used for this purpose. The same method was practised in the United States in the early 19th century; William Potts Dewees recommended in 1825 that from the eighth month of pregnancy, expectant mothers should regularly use a puppy to harden the nipples, improve breast secretion and prevent inflammation of the breasts. The practice seems to have fallen out of favour by 1847, as Dewees suggested using a nurse or some other skilled person to carry out this task rather than an animal.

The Bruce Effect implied that every male mouse smells different to every other male mouse, at least to female mice, and that he produces a spectrum of odours that vary slightly between individuals of the same strain and differ markedly between individuals of different strains. With lateral thinking on how to prove their theory, Bruce and Parkes turned to Boake, a world famous perfumery.

Knowing how skilful perfumers must be in distinguishing between thousands of different odours, they persuaded some Boake representatives to visit NIMR for the purpose of smelling the mice. They invited them to sniff at pieces of cloth that had each been exposed to different cages of various mouse strains. The perfumers had no difficulty in distinguishing the different strains as all had a unique aroma; they even commented that four of the strains were quite similar – all of which had been bred from one original colony at Hampstead. They also noted that the CBA mouse strain, which was fairly new to NIMR, had a wonderful and pleasantly musky smell that could be of commercial interest in perfume manufacture!