THE GUINEA PIG " O 



and water bowls and the pens should be sterilized and disinfected 

 once or twice a year. 



Reproduction and Growth 



The female guinea pig becomes sexually mature in 30 to 45 days and 

 will breed at this age. The male is not sexually mature until about 

 2 months of age. When the young guinea pigs are 40 to 50 days old 

 the males should be placed in separate pens from the females. 



The estrous cycle of the guinea pig varies from 14 to 17 days, averag- 

 ing 1514 days. Estrus lasts about 24 hours,. The female comes into 

 estrus immediately after giving birth to a litter and usually mates 

 within 10 to 12 hours. Therefore the breeder male and females should 

 be left together in the cage to insure regular mating. A vigorous 

 female should produce four to five litters a year. The gestation period 

 of the guinea pig varies from 65 to 70 days, the average being 68 days. 

 The average number of young per litter is three, but sometimes there 

 are as many as five or six and even more. The young are fully haired, 

 with eyes open, and with teeth. They will start running around within 

 an hour after birth. In 2 or 3 days' time they will start eating solid 

 food and gain rapidly, reaching nearly half a pound by 30 days. The 

 young should be left with the mother 3 to 4 weeks. Growth continues 

 at a decreasing rate for about 18 months, when an adult weight of 1% 

 to 2% pounds may be reached by males. The weight of the female 

 varies; depending on whether she is pregnant and how far she is 

 advanced in pregnancy. Unbred females are usually about 2 ounces 

 lighter than males at 18 months of age. Guinea pigs will continue to 

 produce young up to 5 years of age, but after 3 years there is more 

 or less irregularity of breeding. Guinea pigs have been known to 

 live past 7 years of age. 



Diseases 



Guinea pigs are susceptible to a variety of diseases. These may 

 be classified according to their cause. 



Bacterial Disease 



Paratyphoid. — This disease is caused by Salmonella typhimunum 

 or S. enteritidis and may be carried by rats or mice. Female guinea 

 pigs may also act as carriers and serve as a continued source of infec- 

 tion to the colony. Infection usually takes place through the eating 

 of contaminated food to which wild mice or rats have had access. 

 Animals may die 48 to 72 hours after infection ; others may live several 

 weeks. Mortality rates may exceed 75 percent. In guinea-pig colo- 

 nies the disease may make its appearance during the breeding season, 

 and many animals will abort their young and die of purulent endome- 

 tritis. There often is congestion of the viscera and enlargement of 

 the liver, spleen, and mesenteric lymph nodes. If the disease is slow- 

 in its progress, the guinea pig will show pronounced loss of weight. 

 The prevention and control of paratyphoid is difficult. Various sulfa 

 drugs, particularly sulfamethazine, have been beneficial in treatment. 

 Once a colony is infected, the most effective method of eradication is 

 to destroy the animals, thoroughly disinfect the premises, and obtain 

 new healthy stock. Making the building and feed room proof against 

 the entrance of rats and mice will aid in prevention of the disease. 



