We all have fair knowledge about Rats and Mice as these are very commonly used animal species for research. Today I would like to discuss about Guinea pig. In this section we will not discuss more about its housing, feeding, watering, and bedding (as you may find all the information everywhere very easily) but we will focus on some interesting facts which are really to be known as a Scientist. If you have any query beyond this please leave your comment or keep track on updation of this article on https://ghanshyamvaghasiya.wordpress.com/
Species: C. porcellus
The use of guinea pigs in scientific experimentation dates back at least to the 17th century, when the Italian biologists Marcello Malpighi and Carlo Fracassati conducted vivisections of guinea pigs in their examinations of anatomic structures. In 1780, Antoine Lavoisier used a guinea pig in his experiments with the calorimeter, a device used to measure heat production. The heat from the guinea pig’s respiration melted snow surrounding the calorimeter, showing that respiratory gas exchange is a combustion, similar to a candle burning. Guinea pigs played a major role in the establishment of germ theory in the late 19th century, through the experiments of Louis Pasteur, Émile Roux, and Robert Koch.Guinea pigs have been launched into orbital space-flight several times, first by the USSR on the Sputnik 9 biosatellite of March 9, 1961 – with a successful recovery. China also launched and recovered a biosatellite in 1990 which included guinea pigs as passengers. (Ref: Wikipedia)
Taking into consideration autoclaving or irradiation requirements, Vitamin C can be supplied in the pelleted ration (800mg/kg finished diet) or supplemented in the drinking water (1g/litre), prepared fresh daily. Fresh vegetables can also be used to provide Vitamin C and should be thoroughly washed prior to presentation.
Guinea pigs have a high dietary fibre requirement (16%) which is best met by supplying them with good quality lucerne hay. They should be provided with a diet of 20% minimal protein.
The feed should be appropriately stored to maintain active levels of Vitamin C. As a guide, one half of the Vitamin C may be lost 90 days after the diet has been commercially mixed and stored above 22ºC.
Guinea pigs are susceptible to anorexia following experimental procedures and may require special attention to resume eating. The use of a pellet mash mixed with water and hand fed to guinea pigs will often be sufficient for normal appetite to be resumed. A faecal pellet can be included to restore microbiological activity in the digestive tract after periods of anorexia.
Consideration should be given to the type or placement of the feed hopper outside the cage to control wastage of food and contamination of the feed with faeces.
In general, this species is better able to withstand cold than heat, if provided with sufficient bedding and protection from draughts. Reproductive rates will decline significantly if room temperatures are above 25ºC for any length of time. Pregnant sows are susceptible to heat stress at higher temperatures (> 30ºC) and survival of young is greatly reduced at 17ºC.
Dietary Precautions: Guinea pigs develop dietary preferences early in life and do not adapt readily to changes in the type, appearance, or presentation of their food or water. It is very important to introduce your guinea pig to variety at a young age to prevent potentially dangerous self-imposed fasting by your guinea pig. Cavies have sensitive intestinal tracts and sudden alterations in their diet (even pellet brand) may result in serious GI upset and loss of appetite.
Flight and Exploration
To unfamiliar sudden sounds they tended to freeze rather than flee.
Immobility response to sound as characterized by an arched posture with the forefeet extended, the head up, and the eyes opened wide giving the impression of exophthalmia.
In response to sudden, very loud sounds, immobility was maintained for as long as 20 minutes.
In response to sudden or unexpected movement guinea pig usually flee.
Urine plays some role in social communication
New born guinea pigs usually are incapable of voluntary micturation for several days post partum.
Maternal licking stimulates both defecation and urination during this period.
Even gentle stimulation of the lumbar region often sufficient to elicit defecation in hand reared animals.
Guinea pigs are communal animals that generally live together peacefully. Animals that are group- housed establish male-dominated social hierarchies, and once this hierarchy is formed the group is generally stable. Introduction of a new male into a stable group can lead to fighting, and should be avoided whenever possible.
Dominant animals will frequently “barber” or chew off the hair of subordinate animals. This results in a patch of hair loss with the underlying skin having a normal appearance. Barbering is also associated with boredom or the stress of overcrowding. Adult boars may sometimes chew on the ears of young within the group. In addition, fighting animals may have bite wounds on the ears or back.
The most common investigation movement is extending the snout towards other animal’s snout, ears or perineum.
In sexual or parental encounter perineal investigations may includes anogenital licking and nibbling.
The young usually may actually sit or lie on the top of the mother.
Lactating females characteristically adopt a sitting posture for nursing while the young crawl under their mother, aligned parallel to her body, to reach mamme.
Grooming of a new born by mother
Self grooming can be seen in pups on the day of birth (!!!)
Communication by 1) Olfactory and 2) Auditory
(1) Olfactory Signals
Scent marking with the anal glands is common among cavies.
The animal squats and drags the perineal region along the ground. This response occurs particularly often in mating encounters, after micturation and when animals are adjusting to strange surroundings perhaps to denote familiar territory.
The supracaudal gland of the male is also used in marking the homesite.
(2) Auditory Signals
A variety of calls has been recognized in domestic guinea pigs. Guinea pig has different 11 types of clear sound calls (See Table 1)
Male’s investigation to perineal region of unreceptive female àShe flattens her back, raise the perineum and emit a jet of urine towards the maleàMale may sniff or lick this emissionàFemale, thus, may make her escape while the male is so occupied.
When a male is attempting to mate with an unreceptive female, he may move by her with a skipping motion, throws his hind quarters towards her (sometimes making contacts) and eject a stream of urine at her.
The function of this response is unclear; the male’s scent may affect pair synchronization or serve to identify the female as member of the male’s group.
The amount of blood needed and other factors will govern the method and sites of collection. The area of collection should be preferably be cleaned with alcohol or other appropriate disinfectants. Some blood sampling procedures will require sedation or anesthesia while others may be carried out without anesthesia provided that suitable restraint is used. Always apply pressure to the site after blood collection to enhance hemostasis.
Lateral Saphenous Vein: A small amount of blood can be obtained via the lateral saphenous vein (using a 22-23 gauge needle) while applying pressure in the thigh region to create venous stasis.
Cranial Vena Cava: This is an acceptable site if you need to collect more than a one milliliter of blood repetitively. Animals must be anesthetized and restrained in dorsal recumbency. The manubrium of the sternum is palpated and needle is inserted lateral to the manubrium under the first right rib at a 30 to 35 degree angle to the horizontal axis of the animal. Insert a 22-23gauge
needle at the site, apply slight negative pressure and slowly withdraw until blood flows. If not blood is obtained, withdraw the needle and start over. Do not try to reposition the needle while inserted to avoid laceration of vessels and other vital structures. Blood should be withdrawn slowly, and the amount must be limited (up to 7 ml/kg in an adult guinea pig) unless euthanasia is indicated.
Cardiac Puncture: This is another accepted method of blood collection from guinea pigs when more than a few drops are required. However, this method also carries considerable risk to the animal and occasionally deaths occur. It is not recommended as a repetitive blood sampling procedure. Animals must be anesthetized and restrained in dorsal recumbency. Use a 20-22 gauge needle and insert it under the xyphoid cartilage slightly to the left of midline. The needle is advanced at a 20 to 30 degree angle from the horizontal axis to the sternum to enter the heart. Aspirate lightly while advancing the needle. Blood should be withdrawn slowly, and the amount must be limited (up to 7 ml/kg in an adult guinea pig) unless euthanasia is indicated.
Common Health Problems
Scurvy is the result of inadequate vitamin C in the diet. Signs of scurvy usually appear 2 weeks after guinea pigs have been deprived of vitamin C. Clinical signs include reluctance to move, unkempt appearance, swelling around the joints, pain upon movement, and sometimes hemorrhage. Affected guinea pigs should receive 50 mg/kg ascorbic acid daily until recovery is evident. Deficiencies in young animals may result in permanent skeletal defects.
Water deprivation with resulting dehydration and death may occur if animals are switched to unfamiliar watering systems. It may also be the result of a plugged water source, or territorialism by dominant individuals who prevent subordinates from drinking.
Dystocia (difficulty giving birth) may be the result of failure of the pubic symphysis to separate, excessively large or malformed fetuses, a large litter, obesity, pregnancy toxemia, or uterine inertia. Normal parturition occurs quickly, with a few minutes between the delivery of each pup. Guinea pigs should deliver their young in about 30 minutes, and may require a Cesarean section if they do not. Sows experiencing dystocia are depressed and may have a bloody or discolored vaginal discharge.
Pregnancy toxemia may occur in late pregnancy. It may be precipitated in obese sows during late pregnancy when the sows stop eating, due to changes in the feeding routine or other stressors. Affected animals become depressed, comatose, and die within 5-6 days; treatment is not usually successful. Prevention includes controlling food intake to prevent obesity and keeping other factors in the environment constant.
Heat stress is easily induced in guinea pigs because their body shape prevents dissemination of heat. Clinical signs include excessive salivation, rapid shallow breathing, hyperemia (redness) of the extremities, and elevated body temperature. Treatment consists of cooling the animal, and giving supportive nursing care.
Ulcerative pododermatitis, or “bumblefoot” occurs when lacerations on the feet become infected with bacteria. Predisposing factors include obesity, housing on wire flooring, and poor sanitation. Swollen, painful lesions develop on the bottom surface of the forefeet. Treatment consists of cleaning and bandaging the feet, and housing affected animals in solid bottom cages with soft, deep bedding.
Cervical lymphadenitis, or “lumps” is caused by bacterial infection of the lymph nodes in the neck. The lymph nodes will be swollen, but otherwise the affected animals do not appear to be ill. Treatment consists of drainage of the lymph nodes and administration of antibiotics.
Alopecia is common in guinea pigs, and may be the result of hair pulling or barbering by cagemates. Sows in advanced pregnancy and those nursing litters often have a loss of hair over the back and rump. Weanling animals also have a thinning of the hair during the transition time from “baby fur” to a more mature hair coat.