Restraint and Venipuncture

Cavia porcellus

Handling

• Guinea pigs are easy to handle as they do not move quickly, seldom bite and do not inflict injury by kicking or scratching. Their body must be supported when they are lifted or they may squeal in distress. One hand is placed under the trunk while the other supports the rear limbs

IM injection

• Intramuscular (IM) injections may be given in the quadriceps muscle, as shown here, to avoid the sciatic nerve.

IP injection

• Intraperitoneal (IP) injections can be made safely into the lower, left quadrant of the abdomen. The guinea pig is tilted with its head toward the floor, to shift the abdominal organs and help prevent inadvertent injection into the intestine.

SC injection

• Subcutaneous injections can be made by tenting the skin in the neck area.

IV, marginal ear vein

• Intravenous injection into the marginal ear vein is possible, but difficult due to the small size. Other sites are the saphenous vein and the lingual vein

IV, dorsal penile vein

• Intravenous access is also possible into the dorsal penile vein; however this is a painful procedure and premedication is necessary.

Blood collection, cranial vena cava

• Blood is sometimes collected from the cranial vena cava of the guinea pigs, as shown here. The rodent is sedated for the procedure. Other sites for collecting small amounts of blood include the orbital sinus, the marginal ear vein and the toenail bed

Blood collection, cardiac puncture

• Cardiac puncture as a method of survival blood collection carries a high risk in guinea pigs as it requires anesthesia; hemorrhage into the pericardium also may result in death due to cardiac tamponade

Review

• http://www.bva-awf.org.uk/resources/tutorials/BVA07-GPig/GPig.html

Signs of pain

• Analgesics should be administered when pain is observed or expected. Clinical signs include decreased activity, restlessness, abnormal gait or posture, rough haircoat, altered patterns of vocalization, and reduced food or water intake

Analgesics

• Analgesic drugs used in the guinea pig include buprenorphine (0.05 mg/kg SC at 8 hour intervals), morphine (10 mg/kg SC or IM every 4 hours) and meperidine (20 mg/kg, IM or SC, every two-three hours).

Pre-anesthetics

• Guinea pigs can be sedated or preanesthetized using ketamine (50-100 mg/kg IM) or diazepam (5 mg/kg IM or IP). Atropine (0.05 mg/kg SC) should be used to decrease bronchial and salivary secretions.

Anesthetics

• Anesthesia in the guinea pig is difficult for several reasons, including variability in response to various drugs and difficulty monitoring depth of anesthesia; postoperative complications also are common.

• To attain a surgical plane of anesthesia, a combination of ketamine (25-40 mg/kg) and xylazine (5-12 mg/kg) can be given IM or IP

Isoflurane

• Isoflurane is the inhalant anesthetic of choice for the guinea pig. Anesthesia can be induced in a chamber and maintained with a nose cone.

• Endotracheal intubation is very difficult in the guinea pig due to the small size of the trachea and difficulty in visualization

Post-anesthesia

• To prevent hypothermia, an anesthetized guinea pig should be kept warm on a heating pad and 10-15 ml of warmed lactated ringer's solution can be infused subcutaneously. Turning the animal every 30 minutes helps to prevent hypostatic pulmonary congestion.

Euthanasia

• Guinea pigs may be euthanatized in a carbon dioxide chamber that is pre-charged prior to use. An alternative method is intravenous or intraperitoneal injection of pentobarbital sodium

( 50 mg/kg). Intracardiac injection can be used if the animal is already under anesthesia.