Diagnostic Analgesia

Question 1

What local is commonly used for diagnostic anaesthesia?

Answer 1

Mepivicaine - onset 5-10 mins

Lasts up to an hour

Question 2

Contraindications for diagnostic analgesia

Answer 2

Suspect fracture
Cellulitis
Lymphangitis
Uncooperative horse

Question 3

What size needles should you use of intra-articular anaesthesia?

Answer 3

20g 1.5 inch (yellow) - DIPJ

18g spinal needle - navicular bursa

Question 4

What conditions are too painful to be blocked out?

Answer 4

Sub solar abscess
Distal phalanx fracture
Subchondral bone pain in OA

Question 5

Palmar digital nerve block

Answer 5

Just proximal to the collateral cartilages and abaxial to the DDFT

Non-weightbearing limb
Palpate the neurovascular bundle
Place the needle pointing distally

1.5-2ml 25g 5/8 needle

Question 6

Structures desensitised by the palmar digital nerve block

Answer 6

Navicular bone
Navicular bursa
Collateral suspensory ligaments
Distal sesamoidean / impar ligaments 
Distal DDFT 
Digital cushion 
Palmar 1/3 of lamellar corium and the sole 
Palmar process of the pedal bone 
Collateral cartilage 
\+/- collateral cartilage the DIPJ
Palmar pouch of the DIPJ
Proximal interphalangeal joint analgesia

Question 7

Abaxial sesamoid block

Answer 7

Immediately Palmar to the neurovascular bundle and abaxial to the proximal sesamoids

Non-weight bearing
Palpate neurovascular bundle with thumb
Insert needle distal and parallel to the bundle

25g 5/8 inch needle

Question 8

What structures are dense situated by the abaxial sesamoid block?

Answer 8

As for palmar digital 
DP, MP and palmar aspect of PP 
Collateral ligaments of the DIPJ and PIPJ
Distal sesamoidean ligaments
Lamellar corium and coronary band 
Distal digital extensor tendons 
Dorsal branch of the suspensory ligament

Question 9

DIPJ block

Answer 9

Weight bearing limb mid line
Palpate the depression 1-2cm above the coronary band on the dorsal aspect of the pastern
Insert the needle vertically through skin and extensor tendon

20g 1.5 inch needle - 6ml

Question 10

DIPJ block desensitises

Answer 10

DIPJ
Navicular bursa
Collateral ligaments of DIPJ
Toe region of sole

Question 11

Navicular bursa block

Answer 11

Palmar approach - between the heel bulbs
Horizontal, midline through the DDFT
Radiographic confirmation of placement required

18g spinal needle 2-4 ml