Week 4 Locomotor 3/6/14

Question 1

Properties of Lidocaine

Onset, Duration, Potency

Answer 1

Amide type local anaesthetic
Short OOA: 10-15 minutes
Duration of action: up to 2 hours

Question 2

Why is Lidocaine often combined with adrenaline>

Answer 2

Lidocaine causes vasodilation therefore often formulated with adrenaline.

Question 3

Why is Lidocaine not used in horses

Answer 3

Causes sub-cutaneous/ skin swellings.

Rarely used.

Question 4

Procaine (properties, onset, duration, potency)

Answer 4

Ester local anaesthetic.
Onset: 15-20 minutes
Duration: short 45-60 minutes
Potency: Poor

Question 5

Which is the only local anaesthetic licenced for food producing animals in the EU

Answer 5

Procaine (ester)

Question 6

Which local anaesthetic is used for diagnostic equine nerve blocks

Answer 6

Mepivacaine 
(amide)
short onset (10 minutes)
Duration of action (2 hours) 
Good potency

Question 7

Side effects of Bupivacaine

Answer 7

Amide.
Long onset (30-40 minutes)
High incidence of cardiotoxicity

Question 8

Why are local anaesthetics conjugated to hydrocloride salts

Answer 8

Because local anesthetics are weak bases they need to be solubilised for injection by conjugating with a hydrochloride salt

Question 9

How do local anaesthetics work?

Answer 9

Blocking sodium channels therefore preventing propagation of axonal action potentials

Question 10

Speed of onset is related to the the dose/ proportion of the drug in the

Answer 10

Non-ionised lipid soluble form. Determined by the dissociation constant (pKa)

Question 11

Which two local anaesthetics are used in EMLA cream

Answer 11

Prilocaine (lipid soluble –> high potency) and Lidocaine

Question 12

Which is the preferred block used for digit amputation in cows

Answer 12

Intravenous Regional Analgesia (IVRA) or Bier’s block

Question 13

Where is a caudal epidural anaesthesia most commonly performed in large animals? Why?

Answer 13

Injected in the sacro-coccygeal space. Between the first two coccygeal vertebrae.
It is used to prevent straining during parturition

Question 14

COX-1 pathway is important for…..

Answer 14

Production of prostaglandins that are important in the physiological modulation of function.

• gut mucosal barrier
• intra-renal perfusion when RBF is reduced

Question 15

When is COX-2 pathway activated?

Answer 15

• Tissue damage

- Bacterial lipopolysaccharide

Question 16

COX-2 inhibition (Suppression of inflamm, pain, fever)- what additional benefits are there?

Answer 16

Slow progression of Alzheimers disease.

Preventative against colon, pancreas, lung and transitional cell carcinoma, melanoma.

Question 17

3 types of NSAIDs

Answer 17

1. Non-selective
2. Preferential (10-40 x)
3. Selective (>100x selective for COX-2)

Question 18

Therapeutic aim for COX-2 inhibition

Answer 18

COX-2 >80% inhibition for part of the 24 h period

COX-1 < 20% inhibition to avoid side effects

Question 19

4 examples of non-selective COX inhibitors

Answer 19

1. Asprin
2. Phenylbutazone
3. Ketoprofen
4. Tolfenamic acid

Question 20

What type of NSAID is Phenylbutzaone?

Answer 20

Non-selective COX inhibitor

Question 21

What type of NSAID is Meloxicam?

Answer 21

Meloxicam is a preferential COX-2 inhibitor

Question 22

Example of selective COX-2 inhibitor

Answer 22

Firocoxib and Robenocoxib (Coxibs)

Question 23

What are Coxibs?

Answer 23

Coxibs are selective inhibitors of COX-2. Firocoxib and Robenocoxib

Question 24

What is Tepoxalin?

Answer 24

Dual inhibitor of COX and LOX.
Inhibits LOX for short periods during day.
Non selective inhibitor of COX-1 and COX-2

Question 25

Species differences for Carprofen

Answer 25

CarprofenL
DOGS: COX-2 preferential 
CAT: COX-2 preferential (longer halflife than dog!)
HORSE: Non-selective 
MAN: COX-1 preferential

Question 26

Why do you need to be careful with the carprofen dosing regime in cats?

Answer 26

Carprofen is COX-2 preferential in dogs and cats but has a much longer half life in cats.
Daily dosing = GI disaster

Question 27

Pharmacokinetics of NSAIDs

Answer 27

Weak acids so readily penetrate inflammed tissue.

Highly protein bound therefore accumulates in protein-rich inflammatory exudate

Question 28

How does Prostacycline and PGE2 maintain the protective layer of the gastric mucosa

Answer 28

• Inhibiting gastric acid secretion
• Maintaining mucosal blood flow
• Being involved in secretion and composition of muscos
• Intracellular messages for cell turnover

Question 29

How do NSAIDs affect the liver?

Answer 29

NSAIDS undergo extensive hepatic metabolism. Care with hepatic disease

Question 30

Canine Elbow Dysplasia more reproducible discomfort for OCD, MCD components of condition

Answer 30

Elbow Dysplasia: Ununited anconeal process, osteochondritis dissecans, fragmented medial cornoid process, elbow incongruity.
Suprination (external rotation) of antebrachium while elbow held in moderate flexion.

Question 31

Ununited anconeal process (UAP) =

Answer 31

failure of union bnetween anconeus and main part of ulna BEYOND 20 WEEKS OF AGE.
Anconeal process develops as part of ulnar diaphysis BUT
Some breeds (e.g. GSD, anconeal process forms as secondary ossification centre) NORMAL <20 WEEKS!

Question 32

Options for Cranial Cruicate Ligament rupture

Answer 32

Conservative <15kg
Surgery: Mimic ligament using Lateral suture
OR Modify stifle mechanics (TPLO/ TTA)

Question 33

Difference between TPLO and TTA mechanisms

Answer 33

TPLO: Anterior cruciate ligament looses its main function because
TTA: Modifies position of patellar ligament. Articular weight bearing forces are PARALLEL TO PATELLAR LIGAMENT NOT longitudinal access of tibial.
SEE IPHONE PHOTOS FOR ARTICLE.