Natural infections of guinea-pigs

Abstract

The guinea-pig (Cavia porcellus) is an important laboratory animal whose susceptibility to a wide range of pathogens has made it extremely useful in research and diagnosis. In the United States about 600000 guineapigs are used each year; only mice and rats are more common (ILAR, 1972). Guinea-pigs are thought to have originated in the mountains of Peru, and little is known about the diseases which they suffer in their natural habitat. In the artificial environment of the animal colony a number of infectious agents may cause disease problems. These are most likely to occur when the animals are under stress because of overcrowding, a breakdown in sanitation, or abrupt changes in temperature, humidity, or diet. Such infections may be either sporadic or epizootic, and often produce a high mortality. In this discussion, they are grouped under the heading 'spontaneous infectious diseases'. Most of the agents involved have been isolated and well-characterized, and methods have been devised for their control. With careful management, including routine surveillance to detect and eliminate infected animals, they need not cause many serious problems. Good management practices have been described (for example, Lane-Petter & Pearson, ]971; UFAW, 1972) and will not be repeated here. BasicalIy they consist of common sense; if an infectious disease does cause losses, most often it is due to a lapse of attention to the management routine. Inapparent infections pose a different type of problem. In these cases a balanced relationship exists between parasite and host: the infected host remains healthy and the pathogen is almost always undetected. However, when stress such as experimental infection disturbs this balance, the pathogen may multiply or exert its effects. Infected animals may respond unpredictably to experimental treatments, yielding inconclusive or misleading results. In recent years the increased recognition of the importance of healthy animals for diagnosis and research has stimulated progress in identifying and characterizing such infettions (Baker, Cassell & Lindsey, 1971; Irving, 1972).