IACUC Learning Module - Swine

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ANIMAL HEALTH CONCERNS

Regardless of the source of the pigs, at least a five-day conditioning period should be observed to allow pigs to recover from the stress of shipment. (At UAC facilities, if pigs are to be used before the end of the conditioning period, a special form must be signed by the investigator in which they waive all rights of getting a refund for an ill pig).

Most suppliers will periodically worm their herd, however, internal parasites, especially roundworms, are a serious problem because they migrate through the lungs, liver and other organs where they cause considerable harm. Routinely, UAC administers ivermectin to control this parasite. If pigs are maintained for any time, it may also be necessary to establish a vaccination program for agents such as: Bordetella, Pasteurella, Erysipelas, Hemophilus, Clostridium, Parvo virus of swine, Transmissible gastroenteritis and Rotavirus.

MATING, GESTATION and PARTURITION

Gilts (virgin females) may be first bred at sexual maturity, about 8 months of age. The sow cycles about every 21 days, throughout the whole year, except when she is pregnant or nursing. Estrus, the actual period when the sow will accept the boar, is about 2-3 days in length and can be recognized by a mucoid, vaginal discharge; swollen, moist, congested external genitalia; and mounting of herdmates.

Mating is preceded by courtship behavior. A boar approaches the female in estrus and presses his snout against her head and gradually moves it to her genital-anal region where the nuzzling becomes more intense. Several mountings may take place before intromission (penetration). The penis is shaped like a corkscrew and quite muscular. Until about 16 months of age, boars should be limited to mating once per day, in order to increase the likelihood of fertile ejaculate.

Gestation, or pregnancy, lasts about 114 days. Litter size is 8-10 for farm breeds; 5-6 for miniature breeds. Within 12-24 hrs after birth, piglets usually have their needle teeth cut off, their tails cut short to prevent cannibalism, their ears notched for identification, their navels dipped in iodine to prevent infection, given iron dextran (100 mg IM) to prevent anemia, and administered the C. perfringens vaccine. Males are born with descended testicles. Unless being kept for breeding purposes, most are castrated within a few days after birth. Castration at less than one week of age has many advantages: less trauma and pain, rapid recovery, less effect on growth rates. Castration, ear notching and tail docking of piglets, without anesthesia, are acceptable management practices when performed in a sanitary manner in the first week of life. (AVMA Animal Welfare Positions). Weaning usually occurs at 4-8 weeks.

MALIGNANT HYPERTHERMIA

Since pigs are prone to laryngospasm and fluid tends to accumulate in the pharyngeal region, endotracheal intubation should be performed whenever the pig is anesthetized.

Atropine (0.05 mg/kg) can be given intramuscularly about five minutes before intubation to help dry secretions and make the placement of the endotracheal tube easier.

It is easiest to intubate by placing the pig in ventral recumbency, that is, with the pig on it's stomach, although dorsal recumbency is not that difficult with practice.

For a 10-25 kg pig, a 6-7 mm diameter endotracheal tube is usually used.

The upper and lower jaws are held open and the tongue grasped with gauze sponges and pulled forward.

The epiglottis is opened with the end of the laryngoscope to reveal the larynx. When the larynx is visualized, spray it lightly with a topical anesthetic. A laryngoscope is needed; blade size depends on weight of a pig, but 195 mm is usually adequate for pigs up to 30 kg. Some persons like using a rigid stylet inside the endotracheal tube to keep it from bending. A) The endotracheal tube will readily enter the proximal larynx, but gets obstructed about midway. B) At this point, gently rotate the entire endotracheal tube 90 and apply gentle pressure. C) This will usually allow the endotracheal tube to pass through the area of obstruction.

ANESTHESIA

Pigs may become apneic (will not breathe) when barbiturates are used, so a respirator is needed. The short acting barbiturates, such as thiopental (7 mg/kg) are often used for general anesthesia. Intramuscular injections of Ketamine (20 mg/kg) and Xylazine (2 mg/kg) in combination also work well for short procedures. For long procedures, inhalant agents such as Isoflurane or Metafane are recommended. Since many pigs are sensitive to Halothane (which may initiate malignant hyperthermia), it's use is discouraged.

Important Link: IACUC Approved Analgesics, Anesthetics & Sedatives

ADMINISTRATION of MEDICATIONS

Subcutaneous (SQ) Injections are usually made in the loose skin where the neck and shoulder join.

Intramuscular (IM) Injections are given in the thigh muscles, or sometime, in the large muscles along the side of the neck.

Intravenous (IV) injections are usually done in the marginal ear vein. IV injections may also, with practice, be made in the jugular vein using a "blind stick" method. Except on very young pigs, the vein cannot be seen.

BLOOD COLLECTION

Remove the rubberband, as soon as the needle or catheter is seated!

Blood may be collected from the large vessel, entering the heart, the anterior vena cava. The pig must be anesthetized, to prevent movement and tearing of the vessel wall. Find the notch between the manubrium and the first rib on the right side; the needle should enter here and be aimed at the left shoulder. For pigs less than 40 kg, use a 1.5 inch long, 21 gauge needle.

EUTHANASIA and DISPOSAL of BODY

Since pigs can be big and heavy, UAC allows only one dead pig placed into each red barrel in the necropsy freezer.

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