Laboratory Animals

1. Laboratory Animals Part 2

2. The DogCanisfamiliaris • They have been used as experimental subjects since the 17th century. • Valuable for research in physiology, pharmacology, surgery, nutrition and behavior studies, heart surgery, and diabetes • Obtained from municipal animal pounds • Since they are stray, it can be expected that they are infested with internal and external parasites and possibly other disease-producing organisms

3. The Dog • Beagle is the most used as research animals • Dogs are usually devocalized when brought into a facility to prevent excessive barking • The procedure is where they partially remove vocal cords with an instrument inserted through mouth • Cords may repair or grow again and procedure might be repeated

4. The CatFeliscatus • Used as research animals towards the end of the 19th century • Used for physiological, anatomical, pharmacological and behavioral studies • Short haired types are used more than long haired breeds

5. Nonhuman Primates • Used since they closely relate to humans • Reproduce poorly under domesticated or laboratory conditions and must be captured in the wild • Most difficult of the animals to handle in a laboratory • Long gestation period and only one child is produced per pregnancy

6. Nonhuman Primates • Belong to the order Primata meaning first • Rhesus monkey (macacamulatta) is most widely used in research

7. Main Groups • Simians • Baboons • The great apes • Gorilla • Chimpanzee • Orangutan • Gibbon

8. Main Groups • Monkeys • Prosimians • Tree shrews; lemurs and other of family Lemuridae; Lorises and Tarsiers • Geographical Groups • Old world monkeys • Macaca species and usually weigh 5-14 kilograms • Vervet or African green monkey, Sykes monkey, Mangebeys • New world monkeys • Squirrel, owl, ringtail, spider, wooley monkeys; Tamarins and marmosets

9. Old World Monkeys • Apes are the largest and have no tail • Chimpanzee (Pan troglodytes) is used most often • Gorillas and chimpanzees are primarily terrestrial but nest in trees • Apes are herbivorous and frugivorous (fruit eating) and also eat insects • Native to Asia, Africa and South Pacific islands • Can get tuberculosis and carriers of B-virus • Some have cheek pouches and do not have prehensile tails ( can grab with tails)

10. Baboons • Baboons are smaller than apes (male 20kg; female 10kg) • Primarily terrestrial • Very hardy • Live in closed social systems • Essentially vegetarian but eat insects and small animals

11. New world monkeys • Native to Central and South America • Do not have cheek pouches and have prehensile tails • All are aboreal (living in trees) • Resistant to tuberculosis and do not carry B-virus

12. Prosimians • Found in Asia and Africa • Relatively small animals • Nongregarious – do not live in groups • Mature rapidly • Two or three pairs of mammary glands • Dentition (teeth) specialized for grooming • Cutaceous glands specialized for territorial mating

13. How do they pick the animals? • Animals should not be selected randomly for an experiment but should be chosen on the basis of certain principles which would provide the most appropriate animal model. • One basis for the selection of a species is the general anatomical and physiological relationship of the small animal to the large animal of interest.

14. How do they pick the animals? • The second guideline is an animal or species may be selected for an experiment on the basis of specific characteristic which provides the desirable model for a certain type of experiment. • The third guideline used relates to the previous history of the use of the species for a prescribed type of experiment.

15. Modified Animal Models • Modification of the microbial environment • Keeping animals in isolation • Germ-free (axenic) animals are obtained under sterile conditions by Cesarean section from pregnant females • Young are fed artificially on a special sterile diet and must be maintained in sterile isolators • The air, water, food, bedding and any other items in isolator must be sterile

16. Modified Animal Models • Pathogen-free animals • Organisms that are free of pathogens ( infections) • Environment is not sterile but keep pathogen free • Obtained by Cesarean section under aseptic conditions • Housing should be maintained so pathogenic organisms may not enter and there should be periodic checks of the facility

17. Modified Animal Models • Specific pathogen free animals • Identified by the International Committee on Laboratory Animals as those that are free of specified microorganisms and parasites, but not necessarily free of others not named • Maintained like the pathogen-free animals • Gnotobiotic – known biota • Conventional Animals • Normal animals which are not obtained or maintained with any special microbial protection

18. Animal Models Developed by Breeding Techniques • Application of genetic and breeding techniques has made possible the production of a large number of inbred strains. • An animal is considered inbred after 20 generations of consecutive brother x sister or parent x child mating. • Animals which are not inbred are referred to as non-inbred

19. Animal Models Developed by Breeding Techniques • Different biological models which have been developed: • Low incidence of lung cancer • High incidence of leukemia • Hairlessness • Susceptibility to salmonella infection • High incidence of gastric tumors • Low incidence of mammary tumors • Susceptibility to tuberculosis • Resistance or susceptibility to certain tumor transplants • Resistance or susceptibility to dental caries • Susceptibility or resistance to chemical carcinogens

20. Surgical and Physiological Modification • Removal or partial removal of a gland, organ, or tissue • Nutritional alterations • Diseased states • If a modification interferes with essential life processes, some artificial means of maintaining these processes must be provided • These alterations make possible effective research and may shorten the time required for results