Pigs Flashcards
Restraint Techniques for Pigs
o Hog board – same height as animal, 2/3 to full length
o Sling
o Lifting hind legs (smaller pigs)
o Snout snare – not comfortable, acts like tourniquet around nose, leave on only few min
IV Access in Pigs
challenging, lack of visible superficial veins
Marginal ear veins (auricular veins)
* Central auricular vessels usually arteries (like rabbits)
Lateral, medial veins outer surface of ear in larger pigs
* LJ: central dorsal auricular vein
Cephalic: blind, visualized in small pigs
Jugular cut down, can also use anterior vena cava
Mammary
IO Route
greater tubercle of humerus or trochanteric fossa of femur
* Rate of fluid administration limited in older pigs DT presence of fat, fibrosis of medullary canal
IM Injection Sites for Pigs
base of ear = thinner fat, tissues have better perfusion
Preferred for immobilization
IM Injection Site Logistics - Pigs
Need adequate length needles so don’t inadvertently inject into fat
* Thick layer of subcutaneous fat, more so for potbellied pigs
* Adipose tissue layers in neck, rump particularly thick
Where to avoid for IM in pigs?
No thigh in growers – risk of abscess, needle breakage in edible tissue
* LJ Chp 38: recommended to inject in hamstring muscles just above hock or caudal portion of biceps femoris DT lower fat
* Gluteal ‘ham’ muscle not recommended: m inflammation, fibrosis
SQ Inj in Pigs
smaller, mini pigs
Very tight connective tissue
Lateral cervical region: flap of tissue available
Pigs - Resp
obligate nasal breathers; short, narrow airway with long soft palate
Tracheal bronchi!
Pigs - GIT
acidic stomach, pH 1.5 to 2.5 – better, faster, more predictable absorption of orally administered drugs, prone to perioperative vomiting
Very well developed torus pyloricus
Other Sedative Routes in Pigs
IN: midaz 0.2-0.4mg/kg = reliable sedation within 3-4’; ketamine 15mg/kg + climazolam 1.5mg/kg + azaperone 1.0mg/kg for castration = less effective ax vs IM but minor temp loss, shorter recovery time
o IP: requires specific training, risk of bad consequences if improperly performed
Pigs - GIT
acidic stomach, pH 1.5 to 2.5 – better, faster, more predictable absorption of orally administered drugs, prone to perioperative vomiting
Very well developed torus pyloricus
Pigs - CV
Prolonged QT Interval
Fasting Times in Pigs
Minimum 12h food
o Prolonged gastric emptying DT roughage, risk of Perioperative nausea/vomiting
o Elective GI/abdo sx: 24-48hr to empty large bowel, H2O 4-6hr if stomach/small bowel sx
o Neonates: 3h
o Remove edible bedding for 2-3d
Sedation in Pigs
Ketamine is your friend
Best combined w/ adjunctive agents to improve SkM relaxation, analgesia, decrease ket dose
o Much more resistant to a2s compared to ruminants
In general don’t become very sedate off opioids, alpha a2
Tramadol = less respiratory depression in pigs than other opioids
Which pigs generally need higher doses of sedation?
Yucatan, Yorkshire pigs, VPB
Azaperone
butyrophenone neuroleptic, safe for IM
Approved for use in swine
IV contraindicated, +/- excitation
Sedative + LA for minor sx procedures, premedicant with anxiolytic properties
Effects = dose dependent
Large boars: do not exceed 1mg/kg to decrease risk of priapism
a chloralose
- Mixed effects of dose-dependent CNS excitation, depression
- CV stability, lack of BR depression, poor analgesia when used alone
- Poor solubility
- Slow onset (15-20’)
- Causes metabolic acidosis, hyperreactivity to auditory stimulation, peritonitis, adynamic ileus
- Loading dose 40mg/kg IV, CRI 10mg/kg/hr
- CMV recommended: prevent hypercapnia, respiratory acidosis
Endotracheal intubation in Pigs - when/why
o Recommended for px > few min, dorsal recumbency – hypoxia, hypercapnia, airway obstruction
o Resp depression = significant risk bc need for heavier sedation to decrease stress level, high work of breathing by narrow upper airway
o Prone to laryngospasm, fluid tends to accumulate in pharyngeal region under GA
Anatomic Challenges Assoc with Airway Management in Pigs
Thick tongues
Long, narrow oropharyngeal spaces
Elongated soft palate
Pharyngeal diverticulum: 3-4cm in adults, 1cm in piglets – protrudes from wall of pharynx, above esophagus
* If get stuck in diverticulum – pneumediastinum
Angle btw floor of lateral ventricle, trachea, cd to opening of larynx = obtuse
ETT: R endobronchial intubation if inserted too far
* R cranial LL branches off very early – pre measured tube TRACHEAL BRONCHI
Delicate laryngeal mucosa, prone to irritation/injury (hematoma, rupture, generalized laryngeal edema)
Maintenance of GA in Pigs
o All current inhalants used safely, effectively in pigs - MH triggers (Halothane»_space;> iso)
N2O: max concentration N2O in pigs 75% with 25% O2
50-66% more common clinically
Xenon Maintenance of GA in Pigs
research, inert gas that not harmful to environment
Systemic hemodynamic stability, analgesia
MAC 119% intubated pigs, does not trigger MH
Production = cost-prohibitive, requires low FGF rates with xenon-recycling system
Telazol or Ketamine in Pigs
rough recoveries excessive paddling, multiple attempts to stand, hypersalivation, frequent vocalization, hyperthermia
* Eliminated more slowly than other species
* Tiletamine longer DOA vs zolazepam
Triple Drip in Pigs
Triple drip: 5% solution of dextrose in water w/ 50mg/mL guaifenesin, 1-2mg/mL ket, 1mg/mL xyla
Infusion rate 2.2mL/kg/hr
Opioids
Severe Resp Depression in Pigs
Excitement if non painful
Pupillary Constriction
BIS in Pigs
poor correlation with ax depth, may not predict changes in BP or HR during sx
Monitoring in Pigs
Most reliable method for assessing depth in pigs: m relaxation –> jaw tone laxity, absence of gross movement IRT pinch or stimulus at coronary band
Also reliable: palpebral, corneal reflexes
Not reliable: ocular, pupillary reflexes esp if atropine, ket in protocol
Blood Transfusions in Pigs
usually littermates, close relatives DT 16 recognized porcine blood groups
BP Treatment in Pigs
Dopamine = most effective inotropic agent in pigs!
- 15mcg/kg/min increased CI by 18%, improved GI BF by 33% in septic pigs
- Piglets: better improved BF to heart, SI vs dobutamine
FiO2 in Pigs
Pulmonary shunt fraction depends on FiO2, lower shunt fraction with FiO2 0.4 vs 0.6, 0.8
Porcine Recovery
o Pen, cage lined with soft padding to preclude injury
o 20-25* to minimize hypothermia +/- thermal blanket +/- heat lamp
o If early extubation, high risk for hypoxemia DT laryngospasm
Steroids, diuretics prophylactically prior to extubation
Phenylephrine spray on larynx vascular congestion, laryngeal edema
o Surgical incisions: do not house with other animals, will cannibalize wounds
o Behavior parameters to monitor pain: agitation, running, rooting
Main Risks Assoc with Swine Recovery?
Severe airway obstruction difficult to tx: difficult to restrain, reintubate
Extension of head can complicate air upper airway obstruction
–Also do not want to extend head for tube placement
Dorsal displacement of soft palate = airway obstruction, suffocation
OBLIGATE NASAL BREATHERS
Epidurals in Pigs
6 or 7 lumbar vertebrae
* SC terminates with conus medullaris btw sacral vertebrae 2 and 3 - SAS not easily penetrated in pigs
Consider US guidance for LS epidurals DT amt of fat (L6-S1)
- Measurement of distance from external occipital protuberance to 1st Co vertebrae may allow for more precise dosing of epidural injections DT differences in number of thoracic, lumbar vertebrae
Examples of Epidural Protocols in Pigs
For max distribution of drug into spinal canal, morph + saline = 1mL of solution for pigs with vertebral length of up to 40cm, +1.5mL saline added for Q additional 10cm vertebral length
To achieve blockade to T10 in pigs <65kg:
0.8mL/10cm 40-69cm
0.9mL/10cm 70-79
1mL/10cm 80-99
Examples of Epidural Protocols in Pigs
Seizure Dose of Lidocaine in Pigs
24mg/kg
Malignant Hyperthermia
Inherited autosomal recessive DO –> single amino acid mutation in ryanodine receptor type 1 (RYR1) assoc with calcium channels in skeletal m
When triggered, muscle not able to control Ca efflux from inside SR
Massive amt of Ca released from SR into cells, calcium activation of myosin ATPase causes excessive muscle contracture, release of heat
Cell metabolism increased: requires anaerobic, aerobic respiration = increased CO2, H+, lactate; decreased venous oxygen content
MH Triggers
any type of stress
o All commonly used VAs, halothane
Only one incidence of iso induced MH
o Depolarizing NMBAs (succinylcholine)
Pigs most predisposed to MH?
–Genertic testing now available
have high ratio of muscle to total body mass, rapid growth
o Pietran, Landrace, Spotted, Large White, Hampshire, Poland-China
PPLLHS
MH Presentation
increased body temp
m rigidity
tachycardia
tachypnea,
extreme hypercapnia (ETCO2 >70 mm Hg)
hypoxemia
metabolic acidosis
SNS activation with increased catecholamine plasma concentration
high serum Mg, Ca, Phos, K
Sequela of MH
o As progresses, cell metabolism unable to meet demands –> membrane integrity compromised –> increased d permeability (edema)
o Cardiac ischemia, decreased coronary perfusion pressure DT increased m metabolism
o Arrhythmias: decreased CO, cardiac failure with related hypotension
o Also myoglobinuria, renal failure
Prognosis of MH?
usually poor once episode initiated in spite of immediate, aggressive treatments
MH Tx/Management
- DC inhalant, ventilate 100% oxygen
Preferably change machine, at least different rubber components (hoses, bag)
Hyperventilate - Active cooling = alcohol baths, ice packs around large vessels, fans, rectal lavage with ice water
- Dantrolene
Dantrolene
IV 1-5mg/kg
Skeletal m relaxant, inhibits excessive leak of calcium by RYR1
Prevent, tx MH
Prevention: 2-5mg/kg PO 6-10hr prior to induction
Highly lipophilic, poorly water soluble
Azumolene
30x more soluble than dantrolene, reverses m contractive in pigs by decreasing opening rate of RYR1, w/o changing Ca uptake into SR
