A simple technique for investigating gut passage times in small New World primates was developed, which produced good results without any need for special housing or diet, or for the separation of monkeys from their groups. This technique, which allowed the administration of a faecal marker, chromium oxide, to specific individuals, was used to investigate gut passage times in five species of the genera Callithrix, Saguinus, Leontopithecus and Callimico. Overall, average gut passage time was 4.5 hours, and there were no species differences. Such nondisruptive methods could help in assessing the effects of dietary changes in captive monkeys, and therefore be of considerable value in improving captive diets and hence welfare and breeding success.

Preferences for nest box size and position were tested in two groups of common marmoset, Callithrix jacchus jacchus. In a pre-test phase two, new, wooden nest boxes were introduced to each group alongside their old metal one, so that the animals could become familiar with them, and so that any pre-existing preference could be identified. In successive experiments: i) the old metal nest box was closed so that the marmosets had to choose a preferred box from the two new nest boxes; ii) the size of the preferred nest box was systematically reduced; and iii) in one of the groups the reduced nest box was restored to full size, but its position interchanged with the non-preferred box. In a further experiment, the position of the preferred, and then of the non-preferred box was raised to the highest point in the cage. The marmosets showed strong positional preferences which could not have been predicted without performing the tests. One of the groups also showed a strong preference for the high nest box. It was concluded that marmosets may exhibit preferences for their cage furniture, the basis of which may not be clear to us. These preferences should, however, be taken into account when designing cages to maximize the welfare of the animals.

Unquestionably, the last six decades of research on various animal models have advanced our understanding of the mechanisms that underlie the many complex characteristics of amblyopia as well as provided promising new avenues for treatment. While animal models in general have served an important purpose, there nonetheless remain questions regarding the efficacy of particular models considering the differences across animal species, especially when the goal is to provide the foundations for human interventions. Our discussion of these issues culminated in three recommendations for future research to provide cohesion across animals models as well as a fourth recommendation for acceptance of a protocol for the minimum number of steps necessary for the translation of results obtained on particular animal models to human clinical trials. The three recommendations for future research arose from discussions of various issues including the specific results obtained from the use of different animal models, the degree of similarity to the human visual system, the ability to generate animal models of the different types of human amblyopia as well as the difficulty of scaling developmental timelines between different species.

The callitrichid primates, Callithrix jacchus jacchus (the marmoset) and Saguinus labiatus (the tamarin) were inoculated with infective larvae of Brugia malayi and B. pahangi. Microfilaraemia at low levels developed in 3 out of 4 C. j. jacchus infected with B. malayi and living or dead adult worms found in all 4. Only one of 4 C. j. jacchus became microfilaraemic (mf + ve) when given B. pahangi and adults were found in two. Of 4 S. labiatus given B. pahangi one became very lightly mf + ve and adults were found in 3. It is concluded that these animals are not suitable hosts for chemotherapeutic experiments.