Ch 21 + 22 Anaesthesia monitoring and conditions

Question 1

Describe the 5 ASA grades

Answer 1

Question 2

What is the rate of anaesthetic-related death in animals?

Answer 2

1 : 500 - 1000

Humans 1:10,000

Question 3

What medications are contraindicated in animals with cardiac disease?

Answer 3

alpha-2 agonists
Acepromazine should only be used if they can tolderate vasodilation
Caution wth ketamine in HCM (increases sympathetic activity)
Propofol/alfax should be used cautiously due to vasodilation. Etomidate is ideal.
Some animals wont be able to tolerate gas vasodilation

Question 4

What medications are contradicted in the face of thyroid disease?

Answer 4

Ketamine due to potential cardiomyopathy and possibility of thyroid storm
Avoid NSAIDs and maintain normal/slightly elevated BP due to potential for underlying renal disease
May have cardiomyopathy

Question 5

What is the hypoxic pulmonary vasoconstriction?

Answer 5

A compensatory mechanism that results in vasoconstriction of the blood flow to the alveoli that do not have an adequate oxygen supply. Helps to balance a V/Q mismatch in awake patients

Inhalant anaesthetic agents impair or eliminate this compensatory mechanism causing V/Q mismatch to worsen in the anaesthetised patient

Question 6

What are some potential benefits of ketamine when used on patients with airway disease?

Answer 6

Causing bronchodilation (good for allergic airway disease)
Maintains the respiratory center sinsitivty to PaCO2
Maintains respiration making is a useful indiction agent

Question 7

What considerations should be made when making a plan for a patient with liver disease?

Answer 7

lower doses of drugs if hypoalbuminaemic as many anaesthetic drugs are highly protein bound to albumin

Propofol has extrahepatic metabolism and so is a good choice, as is remifentanyl (plasma esterase)

Inhalants undergo very little hepatic metabolism and are also a good choice

Question 8

List some drugs which are renally excreted and therefore effects may be prolonged in patients with renal disease

Answer 8

Ketamine
benzodiazepines
opioids
acepromazine

Question 9

What anaesthetics should be avoided in renal disease?

Answer 9

Ketamine
Sevofluorane (Compound A)
Epidural contraindicated due to potential coagulopathies in severe uraemia

Question 10

What are the main risks after relieveing a urinary obstruction?

Answer 10

Post-obstructive diuresis

Dialysis disequilibrium - seen if BUN drops rapidly causing a decrease in serum osmolality and associated fluid shifts resulting in cerebral oedema

Question 11

What is the maximal allowable pressure during laparoscopy?

At what pressure is there an association with anuria and acute renal failure?

Answer 11

-14cmH20 maximum allowable

• 25cmH2O anuria, AKI

Question 12

What patient positioning is used for laparoscopic surgeries?

Answer 12

Trendelenburg positioning (head-down)

Question 13

What is the only anaesthetic drug which has been shown to adversely effect neonate survival in C-sections?

Answer 13

xylazine

Question 14

For lumbosacral epidurals, what volume is appropriate for the HLs? For abdominal/thoracic?

Answer 14

0.2ml/kg for HLs

0.3ml/kg for abdomen/thorax

Question 15

What considerations need to be made when anaesthetising for an ophtho procedure?

Answer 15

Maintaining central eye position (low dose neuromuscular blockade)

Avoiding spikes in IOP such as can be caused by propofol and ketamine

Question 16

What are the effects of hypothermia?

Answer 16

Prolonged recovery
Decreased immune defense
Prolonged healing
Altered drug metabolism
Cognitive depression
Arrhythmias

Really Inadequate Heat Does Cool Animals

Question 17

List five possible caused of hypoxaemia

Answer 17

Hypoventilation
Right-to-left shunting
Decreased inspired oxygen
Diffusion barrier impairment
V/Q mismatch

Question 18

What are the effects of hypercarbia?

Answer 18

Initial hypertension, tachycardia and tachypnoea

Eventual sympathetic collapse causing bradycardia, ventricular arrhythmias and hypotension when over 85mmHg

Question 19

List some potential cause of hypercarbia?

Answer 19

Expired or exhausted absorbent
Malfunctioning expiratory valve
Inadequate flow rate in non-rebreathing system
Increased metabolism that can occur with hyperthermia or seizure

Question 20

What is the ideal tidal volume?

Answer 20

8-12ml/kg (should not exceed 15)

Question 21

anaesthetic principles

Answer 21

Administration of drug is balanced by
* Redistribution to other areas of body
* Metabolism and excretion of drug
Lipid soluble drugs take longer to reach steady state as they rapidly redistribute (large volume of distribution)

Anaesthetic distribution in body is divided into 3 groups
* Vessel-rich group – (heart/brain/kidney) up to 75% CO + increased O2 consumption
* Muscle group
* Vessel-poor group – (fat) tissue with low metabolic rates

induction occcurs folowing rapid distribution to vessel rich group, awakening dt redistribution > both depnednet on CO
maintenance therefore dependent on constant delivery either as CRI or inhalent

minimum aveolar conc to produce anaethesia depends on: type, other drugs, pateint factors (CO, temp, ventilation + redistribution)

Question 22

circuits

Answer 22

1. rebreathing
   Use of a CO2 absorbent to remove CO2 from system, therefore allows exhaled gases to be re-inhaled (soda lime etc)
   Incorporates one way valves to prevent rebreathing of expired CO2
   increased flow rate (1L/min) creates a semi-closed circuit with pop-valve open
   closed circuit = low flow acccording to metabolic need with pop-valve closed
   dead-space in circle circuit may cause CO2 re-breathing in small patient, thus not use if <5kg
2. non-rebreathing
   prevent rebreathing of CO2 by high O2 flow rate > rebreating of expired aire reduced due to high incoming gas rate
   recommended flow rate 3 x minute volume (15ml/kg)
   offer minimal flw resistance and dead space, thus ideal for small patients
   T=piece, bain
3. ventilator
   IPPV can supplied by manual or mechanical
   indications: hypoventilation (hypercapnia)
   hypoxaemia
   atelectasis

Question 23

monitoring equipment

Answer 23

Ga must maintain:
- DO2 (CO and O2 content)
- acid-base (ventilation)
- narcosis, analgesia + muscle relax
- temperature

induction can casue apnea and hypoventilation

1.depth: (jaw/eye/hr/rr)

2.blood pressure
BP is idirect measure of CO (therefore DO2)
if BP <60mmhg, DO2 and tissue perfirsion likely insufficent to kidney and brain (prolonged hypotension result in reduce brain function and AKI)
INDIRECT: less accurate/precise, affected by (cuff size, movement, position), dopppler or oscillometric
DIRECT: arterial catherisation, complications (haemorrhage, thrombosis)

3. ECG (arrythmia, electrolyte imbalance)
4. ventilation
   drugs cause reduce ventilation > hyopventilation/hypercapnia (increase CO2)
   hypercapnia results in: resp. acidosis, vasodilation, increase ICP, arrythmias
   aveolar CO2 approx arterial CO2
   ET-CO2: capnograph, WNL 35-65mmHg, monitors vent as well as (extubation/leak, cardiac arrestm resus effort, CO2 rebreathing)
   PULSE-OX: estimates % of Hb that are saturated with O2, patient breathing 100% O2 should have spO2 100% . PaO2 checked if <98%
   inaccurate dt (vasoconstriction, reduced CO, anaemia, hypothermia, hypervolaemia)

5.CVP
indection = rik of fluid overload (heart or kideny dz), hypavolaemic
measure vascular volume (cr. vena cava via jugular)
measure indirect arterial P with manometer (0-5mmHg)

Question 24

ET CO2 + pulse Ox

Answer 24

• phase 0- inspiration, 0mm Hg
• phase 1- start expiration, increase in waveform
• phase 3- end expiration, CO2 peak
• phase 4- just before inspiration, fresh gas 0 mmHg

pulse ox: 100% inspired O2 =PaO2 500 mm Hg. Fall to less than 90 mm Hg to show a change in the pulse oximeter reading

Question 25

opiods

Answer 25

act on 3 receptors (m, k, d)
MOA: triggers influx of K+ and decrease in intracellular Ca++ > decreases substance P and glutamate which hyperpolarizes post synaptic cell > decreases pain signaling

MAC sparing in GA
pros: minimal CV effects
SE: ileus, nausea/V+, regurgitation, excitment
resp depression under GA

reverseal: naloxone or butorphanol
morphine (12-24hr epidural)
methadone
hydromorphone
fentanyl (CRI or transdermal) bradycardia/apnea after bolus
Tramadol: Codeine analogue with weak μ receptor, Analgesic effects due to serotonin and adrenergic receptor effects within the central nervous system

buprenorphoine (partial agnoists) 4-6hr
butorphanol (agonist-antagnoist) 1/2-2hr

Question 26

sedatives -benzo

Answer 26

ii. Benzodiazepines: enhance the effects of GABA channels which is an inhibitory neurotransmitter within the CNS
a. Cause muscle relaxation, narcosis, amnesia, no analgesia, anti convulsant
b. Do not cause CV or respiratory depression
c. Schedule III
d. Reversal Flumazenil

Diazepam
a. Lasts 2 hours, adsorbs to plastic tubing and sensitive to light
b. IV, IM, PO, rectal

Midazolam
a. Lasts 1 hour
b. Breakdown products not effective (unlike diazepam), better for liver disease

Question 27

Acepromazine

Answer 27

1. Depresses dopamine in the reticular activating system
2. Lasts 4-6 hours, moderate sedation, some muscle relaxation
3. α-1 antagonist: hypotension, protects the heart from some arrhythmias

Question 28

α2 agonists

Answer 28

decrease norepinephrine release in the CNS
- sedation, analgesia, muscle relaxation
- some α1 activity causes vasocontriction, hypertension, arrhythmogenecity, and paradoxical excitation, hyperglycemia, diuresis, and respiratory depression
- Can see reflex bradycardia and subsequent hypotension

Xylazine
a. α2: α1 = 160:1, lasts 12-20 mins
b. Initial hypertension followed by hypotension, induces vomiting in cats
c. 44x increase in cardiac arrest in dogs; 92X increase in complications

Medetomidine
a. α2: α1 = 1600:1, lasts 60-90 mins
b. hypertension and reflex bradycardia, can cause arousal and aggression
c. analgesia and sedation
d. Cats: minimal hypertension although HR, CO, SV decrease

Dexmedetomidine
a. Same as previous except twice as potent, may cause less sedation and last slightly shorter

Question 29

Drugs for Induction

Answer 29

Propofol:
agonism of GABA receptors
- Works in 30-60 seconds
- Rapidly redistributed and metabolized, safe for patients with liver disease
- Vasodilation/hypotension and occasionally compensatory tachycardia, apnea
- Preoxygenation prolongs effect
- Oxidative damage to red blood cells in cats

ketamine
- Antagonism of NMDA receptors
- dissociation between higher brain functions and unconscious functions
- Muscle rigidity common so often given with benzo for induction
- May induce salivation
- can increase myocardial work, increases intracranial and intraocular pressure
- In patients with shock it decreases CO
- Renal elimination
- May decrease dorsal horn windup responsible for hyperalgesia

Alphaxalone
- Steroid anesthetic enhancing GABA and glycine CNS depression
- Depresses CO but no clinical respiratory depression

Question 30

Inhalant Anesthesia

Unknown MOA: likely influence receptor lipid bilayer

Answer 30

Minimum alveolar concentration (MAC): concentration (vol/vol percent) required to prevent purposeful movement in response to standard painful stimulus in 50% of normal patients. Surgical stimulus more intense

MAC iso: 1.3-1.7 sevo: 2.1-3.1

isoflurane, sevoflurane having 0.2%, 2% of their total amount being metabolized by the liver.
Side effects:
hypotension due to decreased CO and SVR, respiratory depressant,
increased intracranial pressure,
disrupted thermoregulation,
malignant hyperthermia

Question 31

Local anaesthetics

atropine

neuromuscular blockade: atricurium

Answer 31

Lidocaine/bupivacaine
MOA: Dose and activity dependent blockade of fast sodium channels on afferent nerves

Lido: lipophilic, fast onset (5mins), lasts 45-60mins,

Bupiv: higher lipid solubility, lasts 6-8 hours, takes 45 mins to exert effect, cardio toxic IV
associated with chondrotoxicity

Can be used in thoracostomy tubes (1.5mg/kg q6-8)

Anticholinergic Agents: atropine, glycopyrrolate
Parasympatholytics: minimize vagal tone which decreases HR and BP

Question 32

Pressors and Inotropes

Answer 32

• Many anesthetics impair vascular tone and CO -> low BP
• CO can be low because
  1. low preload (hypotension)
  2. poor contractility
  3. excessive afterload (severe vasoconstriction)

Inhalent anesthetics and propofol
o Tx with positive inotropic drug
* Dobutamine (5-10mcg/kg/min) or dopamine (5-12mcg/kg/min)
* B-adrenergic agonists, Chronotropic effect on heart

Opioids -> vagally induced bradycardia
o Tx symptomatic (atropine, glycol)

Vasodilation -> relative hypovolemia
Tx
1. Usually responsive to fluid boluses
* Isotonic crystalloids (5-15ml/kg bolus) or isotonic colloid (2.5-5ml/kg bolus)
2. Decrease inhalant, use other adjunct drugs such as fentanyl
3. Reverse vasodilation a-Adrenergic vasopressors phenylephrine (0.5-1.5mcg/kg/min)

Question 33

Cardiac dz

Answer 33

aimed at preserving cardiac output and systemic O2 delivery
RAAS activated -> increased BP and increased intravascular fluid retention and hypervolemia
HCM: diastolic dysfunction
DCM: systolic dysfunction, reduce contractility
MVD: regurgitant fraction, decreasing forward CO, spectrum of presentation
PDA o Branham reflex
* Associated w ligation of PDAs
* Reflexive decrease in HR after ligation of ductus arteriosus due to an abrupt increase in afterload

consdierations:
echo before sx
pre-O2
reduce stress
reduce IVFT dt overload risk
give medication except ACEI

premed: opiod +/- benzo
NOT (ACP/ketamine/medetomadine/atropine)

induction: propofol or alfaxan (will cuase vasodilation) +/- benzo to reduce doses

maint: ideally low MAC + mutimodal agens (fentanyl CRI, nerve blocks)
positive ionotropes to increase BP
procainamide for ventricular arrythmia

Question 34

endocrine dz

Answer 34

thyroid
- carcinoma removal > monitor for laryngeal paralysis
- avoid ketamine in hyperthyroid

diabete mellitus
- 1/2 insulin dose morning
- monitor Glu q 1hr during sx (dextrose on hand)
insulinoma
- BG q 30min
- May use glucagon (5-13ng/kg/min) to help normalize BG after prolonged hypoglycemia, but may also drive insulin release

Adrenal gland
- phaechormocytoma have inc risk arrythmia/tachycardia,
- a-adrenergic blockade drugs (phenoxybenzamine) for ~1wk before anesthesia
- increased risk infection
- PU may lead to hypovoalemia
- adrenelectomy: peri-op pred
- haemorrhage risk > blood type/x-match
- * Nitroprusside for hyerptension
* Lidocaine for arrhythmias

premed: opiod + benzo (no ACP)

Question 35

Respiratory dz

Answer 35

1. Upper airway disease- difficult to intubate
2. Pleural space disease- decreased residual capacity and tidal volume; rapid hypoxia after premeds
   a. Thoracoscopy- may require higher resp rates
   b. Chronic chylothorax- fibrosing pleuritis; monitor peak airway pressures (<10cm H2O)
3. Lower airway- asthma, bronchoconstriction, expiratory dyspnea and hyperinflated lungs; use bronchodilators
4. Parenchymal disease- V/Q mismatch, hypoxemia, dyspnea, not usually hypercapneic

pre-op: rads/stabilise, blood gas (hypercapnia/hypoxia)

consdierations:
pre-oxygenate,
BOAS (no opiod, antiemetics/gastric protectants, vagal tone, delay extubate)
difficulty entubation (have tracheostomy ready)

premed: ketamine/benzo + ACP (monitor for hypovent)
induction: propofol (short actig + fast) ideal for BOAS
maint:
Thoracotomy
Bupivicaine 1.5mg/kg q8 locally; LS epidural- 0.2mg/kg morphine diluted to 0.3mL/kg volume

Likely to need PPV and PEEP
TIVA- fentanyl + propofol

Reexpansion pulmonary edema
start with peak pressure of 10cm H2O, slow inc
Post op
O2 at 100mL/kg/min via nasal cannulas = 40% FIO2
Combine sedation and analgesia for smooth recovery
monitor: ETCO2 + PaCO2 (ventilation)
SPO2 (oxygenation) + PaO2 (Hypoxaemia)

Question 36

Hepatic dz

Answer 36

Evaluate function by:
- Albumin, total bili, glucose, BUN, and cholesterol
- Pre- and post-prandial bile acids
- Coagulation profile (If coagulopathic, FFP at 10ml/kg starting dose)

• Hepatic encephalopathy d/t shunts, microvascular dysplasia, or hepatic failure
• Decreased oncotic pressure from failure to produce proteins (albumin)
  > Normal oncotic pressure = 18-22mmHg
  > reduce Blood volume

consdierations
1. Ascites
- Increased pressure on diaphragm
- decreased functional residual capacity and ETV
- Ascites at equilibrium with intravascular > rapid removal > hypovolemia
2. hypoglycaemia
3. prolonged drug effect
diazepam: sedative effects prolonged
midazolam: less, choice with hepatic disease
4. reduced protien/decrease drug bound thus less dose
> Opioids, benzos, and Propofol bind to albumin > less drug required or increased sensitivity
5.Biliary tree manipulation > increased vagal tone so have anticholinergics, pressors ready
6. blood type

Premed: hydromorphone (do not require P450 microsomal enzymes) or fentanyl + Midazolam
- ½ regular dose starting point; pre-oxygenate

Induction: propofol (extra-hepatic metab)

Maintenance: inhalants (minimal hepatic metab)
> Remi-fentanyl CRI in addition to inhalant due to metabolism by plasma esterases and not hepatic biotransformation

Question 37

Renal dz

Answer 37

Chronic renal failure
- 75% nephron dysfunction before visible on chemistry
- dehydration (polyuria, polydipsia)
- hypokalemia
- metabolic acidosis
- muscle wasting
- anemia (PCV < 20% result in reduced DO2)

Acute renal failure
- Vomiting, lethargy, overhydration,
- hyperkalemia
- metabolic acidosis

consdierations:
- 24 hr IVFT prior to anesthesia if elective
- NSAIDs contraindicated
- hypertensive or hypotensive (monitor BP)
- Caution with ketamine, benzos, opioids, and acepromazine
- Hyperkalemia (calcium gluconate 50-150mg/kg IV slowly, insulin, Glucose)
- monitor UO

Premed: opioids + acepromazine produces an effective neuroleptanalgesic effect

Induction: propofol
* Avoid ketamine unless obstruction rapidly resolved

Maintenance: inhalants

• Urine output decreased
• Mannitol 0.5g/kg IV – free rad scavenger can reduce swelling of renal epithelial cells and flush renal tubules
• Furosemide 0.2-2mg/kg IV or CRI 0.66mg/kg/hr

Question 38

sepsis

Answer 38

1. Inadequate oxygen delivery to tissues
2. Distributive shock (relative hypovolemia)
   > Compensatory shock – increased CO
   > Decompensatory shock - cardiovascular collapse

consdierations
- Relative adrenal insufficiency
- inability to generate SVR

Premed: frequently not necessary
Avoid acepromazine and alpha 2 agonists

Induction: neurolept combo
 Hydro 0.2mg/kg + diazepam 0.5mg/kg + ketamine 2mg/kg
 Propofol 0.25-1mg/kg

Maintenance: multimodal
 Fentanyl CRI 5-60mcg/kg/hr
 Ketamine or lidocaine

Question 39

• Laparoscopy

Answer 39

maximum allowable intraabdominal pressure (IAP) is 14 cm H2O
- above this threshold, renal blood flow, AKI
- increased intrathoracic pressure + hypoventilation (exacerbated by Trendelenburg (head-down) positioning)
- increased CO2 absorption may increase ETCO2 and PACO2
- reduce venous return and therefore BP

o Clinical signs of an air embolus include a sudden drop in the ETCO2 tracing, as well as a drop in blood pressure

o Therapy for air embolism:
- CPR (drive the air from the right ventricle > lungs)
- placing the patient in left lateral recumbency

Question 40

C-section and neonates

Answer 40

• Cesarean Section (C-Section)
  o only anesthetic drug that has been shown to adversely affect neonate survival is xylazine
• Neonatal Patients
• heart rate is an important determinant of cardiac output
• anticholinergics are recommended
• sensitive to the resp depressant effects of opioids and inhalant anesthetics
• food withheld 2 to 4 hours
• dextrose (2.5% to 5%) may be necessary
• poorly developed liver function and renal concentrating ability consdier drugs

full or partial opioid agonist + midazolam induction with propofol,
maintenance with isoflurane

Question 41

• ORTHOPEDIC

aggressive

Answer 41

consdierations:
potent opiod
local anaesthetic bloskcs
MAC sparing/multimodal

• total ear canal ablation or limb amputation, a soaker catheter can be fashioned

bupivicaine + morphine (0.1mg/kg) total volume 0.2 mL/kg

• procedures below the elbow are suited for local anesthesia using a brachial plexus block
• hindlimbs, lumbosacral epidural analgesia is
   0.2 mL/kg should be adequate for analgesia of the hindlimbs
   0.3 mL/kg can be used to provide adjunctive analgesia for abdominal or thoracic procedures

dexmedetomidine (0.01 to 0.02 mg/kg) and an opioid, monitor V+ and resp

Question 42

anaesthetic complications (8)

V/Q ventilation/perfusion

Answer 42

1.hypothermia: due to reduce hypthalamic regulation + vasodilation
can result in: pronlonged recovery, reduce immmune, alterned drug metab, prolonged healing
TX: warm peripherals

2.hypoxaemia
causes: R>L shunt, V/Q mismatch, hypoventilation (during recovery)
V/Q most common, result in venous admixture (Interruption of pulmonary blood flow, or areas of lung collapse from disease or atelectasis)
TX: IPPV, increase O2

3.hypotension (pressor and inotrope)

4.hypercapnia
PaCO2 >85mmHg sympathetic stim wanes and bradycardia, ventricular arrhythmias, hypotension, narcosis, circulatory collapse
ETCO2 essential (+/- PaCO2)
machine cause: exhausted soda lime, iadequate O2 flow
patient cuases: hypoventilation (reduce RR or TV)
Tidal Volume = 8-12 mL/kg

5.malignant hyperthermia
Inherited condition (deficit in ryanodine receptor – involved in calcium release in muscle)
extreme hypermetabolic state during GA
hypercarbia
hyperthermia
muscle rigidity
can lead to arrhythmias and death
Dx: abrupt increase ETCO2 with inc HR and temp
TX: TIVA, dantrolene

6.cardiac arrest
Prolonged cardiac ischemia dt hypotension, anemia, hypoxemia
ETCO2 ID cardiac arrest (no ECG)
Tx: CPR (compressions, No more than 12 breaths per minute, atropine 0.05mg/kg, adrenaline 0.01mg/kg, V-fib > electrical defibrillation

7.tracheal tears
cause pneumothorax, pneumomediastinum, subcut emphysema
more common in cats dt ETT cuff

8.reflux
cause esophagitis (stricture risk)
to prevent aspiration > suction, check pH +/-lavage
metoclopramide CRI, omeprazole

Question 42

Epidural anesthesia and analgesia in small animal practice: An update
F. Garcia-Pereira

Answer 42

extending the hind limbs cranially yielded an increase of close
to 100% on the cranial-caudal distance from the dorsal facets of the
lumbosacral space

The sacrococcygeal intervertebral space may also be used for
epidural delivery of drugs, which is beneficial, especially in cats (perineum)

assist in epidural
space identification, the two most commonly used are the
“hanging drop” and loss of resistance (LOR)

Distribution after epidural administration is not always
bilaterally homogeneous,

Question 43

Grapiprant
selective prostaglandin E2 (PGE2) receptor antagonist, and therefore its mechanism of action is distinct from the cyclooxy-
genase (COX) inhibitors.

The EP4 receptor is one of four binding
sites for PGE2. By only targeting the EP4 receptor, production of the
homeostatic prostanoids, such as PGE2 is not reduced to the extent
seen with the more traditional NSAIDs

Question 44

Meloxicam is an NSAID of
the oxicam group with a COX-1:COX-2 selectivity of 1:3–77 and a long duration of action in dogs, approximating
24 hours

Conclusion: Meloxicam was more effective than robenacoxib at controlling pain
in the population of dogs reported here.
Clinical significance: Preoperative administration of meloxicam effectively controls
pain for 24 hours after combined laparoscopic ovariectomy and laparoscopicassisted
gastropexy, but rescue analgesia may be required.

Question 45

In the context of randomized controlled clinical trials, placebo
responses are improvements documented in a negative control
group (e.g. a group with no active intervention). The improvements
can be real for the patient, such as those associated with
regression-to-the-mean or a placebo by proxy (‘better care”)
effect; or merely perceived by the caregiver, such as those
associated with a care-giver placebo effect

Answer 45

Clinical metrology instruments
Canine Brief Pain Inventory (CBPI) to assess pain relief associated with an
analgesic administered into a single joint (intraarticular, IA) may not be the best measure of the analgesic efficacy of the IA
analgesic. This is quite simply because the CBPI was developed and validated in dogs with multiple joint OA receiving a systemic
analgesic (non-steroidal anti-inflammatory, NSAID)

Quality of life
variety of canine HRQoL
assessment instruments are reported in the literature, with
reference to chronic pain, most are not validated,

Activity measurement
accelerometer or a pedometer

Gait analysis
Computationalgait analysis isan objective outcome measure that
directly measures the function of the patient. The measures can be
directly ascribed to pain and pain relief where pain is causing the
alteration in function (i.e. not in states of mechanical causes of
altered limb use, or non-painful neurological disease). In addition,
whenthebiases thatcaninfluencegait analysis
are well controlled, computational gait analysis is both precise and
accurate.However,evaluation ofclinicalstudiesusing gait analysis in
veterinary medicine over the past two decades would suggest there
is still much room for evolution in the areas of quality control and
data evaluation, interpretation and reporting.
From this it can be
concluded that a change in ground reaction forces 5.0% is unlikely and 10.0% is rare. It can be concluded therefore that changes in
ground reaction forces of this amount are clinically important
when associated with intervention because they rarely occur
spontaneously

Quantitative sensory testing (QST)
Recent work has shown that QST in companion animals is
feasible, and appears to provide information on algoplasticity (e.g.
altered sensitivity) in the sensory system that has occurred as a
result of a long-standing painful disease (Knazovicky et al., 2016).
However, the instruments used, the modalities (e.g. heat,
vibration) tested and methodology used have varied from study
to study

Nociceptive withdrawal reflex (NWR)
Work in rodents has shown that NWR is a useful and objective
biomarker of central sensitization (Kelly et al., 2013). NWRs
provide a relatively non-invasive means to capture and document
changes in sensory processing within the central nervous system,

Question 46

Intraperitoneal and incisional analgesia in small animals: simple, cost-effective techniques
P. V. M. Steagall

Answer 46

Local anaesthetics inhibit membrane depolarisation, nerve excitation and conduction primarily by blocking inward Na+ currents through voltage-gated Na+ channels

bupivicaine: should be used for any type of abdominal surgery such as intestinal foreign body removal, enterotomy, splenectomy, etc.

IP and incisional anaesthesia
are simple, safe and cost-effective adjunct methods to reduce
pain after abdominal surgery in companion animals and are not
limited by geographical drug availability. However, readers should
be aware that some of our recommendations were based on a consensus
and low-level of evidence provided by the current literature

Question 47

Glasgow feline composite measure pain scale –
and species-specific studies have advanced our
knowledge on the subject. Facial expressions have
also been shown to be different between painful
and non-painful cats, and very recently the
Feline Grimace Scale has been validated as
a tool for acute pain assessment.

Question 48

Effect of two different pre-anaesthetic omeprazole protocols on gastroesophageal reflux incidence and pH in dogs
Lotti 2021

Answer 48

Fifty-five dogs undergoing elective ovariectomy were randomly assigned

Gastroesophageal reflux was observed in 55% (11/20) of control dogs, 55% (11/20) of dogs receiving omeprazole once and 47% (7/15) of dogs receiving omeprazole twice

Omeprazole administered the evening and 3 hours before anaesthesia increased gastroesophageal reflux pH and decreased the incidence of strongly acidic reflux in dogs

Question 49

Randomized controlled trial of pregabalin for analgesia
after surgical treatment of intervertebral disc disease
in dogs
Schmierer 2020

Answer 49

Prospective, randomized, controlled clinical trial with a blinded
observer.
Animals: Forty-six client-owned\

Conclusion: Postoperative signs of pain after surgical treatment of intervertebral
disc herniation (IVDH) were reduced when dogs received perioperative
pregabalin rather than opioids alone.

Question 50

Cadaveric evaluation of fluoroscopy-assisted placement of
one-lung ventilation devices for video-assisted thoracoscopic
surgery in dogs
Mayhew

Answer 50

Experimental study.
Sample population: Canine cadavers (n = 8) weighing between 20.2 and 37.4 kg.

Advancement of a left-sided Robertshaw
double-lumen endobronchial tube (DLT) and the EZ-blocker (EZ) were evaluated

Clinical significance: Fluoroscopy-assisted placement of EZ and DLT is a useful
alternative to bronchoscopy-assisted placement of these OLV devices.