TV4001 MSAT Flashcards
Triadan System for Adult Horse
2x I3/3, C1/1, PM 3/4 (possibly wolf tooth in maxilla), M3/3
Up to 12 teeth in maxilla, and up to 11 teeth in mandible.
Quadrants start at 100 on R maxilla and move anti-clockwise → 100 = R upper, 200 = L upper, 300 = L lower, 400 = R lower
01, 02, 03 = incisors
04 = canine
05 = wolf tooth (PM1 if present)
06, 07, 08 = PM1, PM2, PM3
09, 10, 11 = M1, M2, M3
Incisor eruption times for horse teeth
Deciduous: I1 at 6d, I2 at 6wks, I3 at 6mo
Permanent: I1 at 2.5y, I2 at 3.5y, I3 at 4.5y
Permanent teeth in wear 6mo after eruption
Cup disappearance & star appearance times in horse teeth
Cups disappear from I1 at 6y, I2 at 8y, I3 at 9y
Stars appear in I1 at 9y, I2 at 10y, I3 at 11y
Horse incisor tooth shape change with age
All incisors round before 9y.
I1 round ~9y, triangle ~16y
I2 round ~10y, triangle ~11y
I3 round ~16y, triangle ~17y
All incisors rectangular after 18y.
Galvayne’s groove for aging horses
Appears on I3 around 10y, ~½way down at 15y, ~whole way down at 20y, gone by 30y
Corner incisor rule for aging horses
Look at I3
<10y is wider than tall
~10y about square
>10y taller than wide
Intra-articular carpus nerve block
20-21G 1.5” needle with 5mL local
Flex carpus to 90 degrees, insert needle either medially or laterally to common digital extensor tendon, radiocarpal joint and middle carpal joints
Radiocarpal joint does not communicate with any other joint
Middle carpal joint and carpometacarpal joint communicate (hence only need to inject middle carpal)
Intra-articular fetlock nerve block
20-21G 1.5” needle with 5mL local
Palpate palmar pouch of fetlock joint b/w suspensory ligament and palmar cannon bone, flex joint and insert needle
Can go through the collateral ligament of sesamoid b/w palmar MC3 and suspensory ligament
Intra-articular coffin nerve block
Performed weight bearing
20-21G 1.5” needle with 5mL local
Dorsal approach - 1.5cm dorsal to coronet and lateral or medial to midline, insert needle at 45deg to long axis of limb
Palmar approach - palpate laterally b/w palmar P2 and collateral cartilage, insert needle in a proximal to distal direction aiming slightly dorsally
Region blocked includes DIPJ, sole, NB
Similar to PDNB but no loss of skin sensation
Low-6 point nerve block
(hindlimb only)
Similar to low 4 point in forelimb with addition of dorsal metatarsal nerves either side of long digital extensor tendon
25G 5/8” needle with 3mL local at each site
Blocks plantar nerves either side of DDFT just proximal to DFT sheath
Blocks plantar metacarpal nerves at splint buttons
Region blocked includes fetlock, sesamoids, suspensory ligament branch and below
Test by pricking or prodding fetlock and below
Low 4 point nerve block
25G 5/8” needle with 3mL local at each site
Blocks palmar nerves either side of DDFT just proximal to DFT sheath
Blocks palmar metacarpal nerves at splint bone buttons
Region blocked includes fetlock, sesamoids, and suspensory ligament branch and distally
Test by pricking or prodding fetlock and below
Abaxial sesamoid nerve block
25G 5/8” needle with 3mL local at both sides (lateral and medial)
Palpate VAN at distal, abaxial surface of proximal sesamoid bones
Needle inserted SC and parallel to VAN (block medial and lateral side of fetlock)
Nerve blocked = digital nerve
Region blocked includes mid pastern down, and entire foot
Test by pricking or prodding foot (dorsal P1 and heel bulbs)
Palmar digital nerve block
25G 5/8” needle with 1.5mL local in each site (medial and lateral)
Palpate VAN just proximal to collateral cartilages on palmar pastern
Insert needle SC and parallel to VAN (medial and lateral bundles)
Nerve blocked is palmar digital nerve
Region blocked includes caudal ⅓ of foot (heels), NB, P3, some sole, DIPJ
Test by pricking / prodding heels
Lameness Grading
Grade 0 = not detectably lame
Grade 1 = inconsistently lame at trot on circle
Grade 2 = inconsistently lame at trot on straight, consistently lame at trot on circle
Grade 3 = consistently lame at trot on straight line
Grade 4 = lame at walk
Grade 5 = non-weight bearing
Picking lame leg
Forelimb lameness - head goes up when lame leg hits ground
Hindlimb lameness - point of hip moves up and down MORE when the lame leg hits the ground (hip hike = vertical displacement)
Other signs = shortened cranial phase to stride, arc of flight of hoof
Lameness examination steps
- History, breed, age, and use of horse
- Examination from a distance
- Examination at trot in hand / lunge
- Pick the lame leg and apply hoof testers (heel, quarter, toe, toe, quarter, heel, frog x2, heels)
- Palpate each limb, joint, and soft tissue structure
- Flexion tests
- Nerve blocks
- Diagnostic imaging
- Treatment plan
Forelimb distal limb flexion test
Flexing fetlock, PIPJ, DIPJ and navicular apparatus
Cannon bone must be perpendicular to ground surface (avoid flexing carpus)
Carpal flexion test
Flexing carpus (may also be positive if lameness originates from proximal MC3 or distal radius)
Grasp pastern and pull so hoof is lateral to elbow - pull up on pastern and push down on distal radius
Shoulder / elbow flexion test
Hard to completely isolate shoulder and elbow dt Lacertus fibrosis
Pull limb forward holding under fetlock or distal cannon (flex elbow, extend shoulder)
Pull limb back holding fetlock and carpus (extend elbow, flex shoulder)
Hindlimb distal limb flexion test
Flexes fetlock, PIPJ, DIPJ and navicular apparatus
Grasp toe of hoof and pull up and grasp distal cannon and push it down
Can pull it out behind horse if safe
Spavin flexion test
Flexes hock, stifle and hip (may flex fetlock a bit)
Grasp fetlock / toe of hoof and lift leg so cannon bone parallel to ground
Equine NGT indications, tube type and technique
Confirmation of correct placement?
- Indications = admin of medication, gastric decompression & lavage, assist in Dx & Tx of choke, enteral nutrition & fluid therapy
- Tube type = various diameters / materials but smaller better tolerated (can be hard to pass - warm tube up to make more bendy)
-
Technique = physical +/- chemical restraint, free end looped around you, lube end put into nose, stand on left of horse (NOT in front)
- Fingers over nasal bones and thumb into nostril and ventral meatus - tube passed under thumb and guided into VM → touch pharyngeal wall to help them swallow, feel some resistance in oesophagus
- No air aspirated if in oesophagus
- Correct placement = visual confirmation, gas w/ smell of ingesta, palpation of tube (should be 2 tubes), won’t be any resistance if in trachea
Horse PE parameters
Horse blood sampling, injection and catheterisation sites
Jugular v.
Cephalic v.
Lateral thoracic v. (on belly)
Medial saphenous v. (dangerous)
Transverse facial venous sinus (for collection only)
Equine peritoneal fluid analysis
- Protein - normal <20/25g/L, marked >30g/L (possibly dt intestinal injury)
-
Cytology - normal = macrophages, some lymphocytes, a few nondegenerate neutrophils, TCC <5 x109 cells/L
- Peritoneal inflamm → neutrophilia, TNCC >5 x109 cells/L
- Bacterial peritonitis → toxic / degenerate neutrophils, TNCC >25 x109 cells/L
- Haemorrhage → RBC’s
-
Lactate - normal <2mmol/L
- If peritoneal lactate >1.5x plasma lactate → ischaemic GIT
Equine pulse palpation
- Carotid a. - ventral aspect of neck deep in jugular groove, cranial to thoracic inlet
- Facial a. - ventral aspect of mandible just rostral to masseter m. for cordlike structure about thickness of a straw, fairly mobile under skin
- Transverse facial v. - dorsal and caudal to line bisecting medial and lateral canthus of eye (picture)
Equine FLASH U/S technique
1-4 = Left side. 5-7 = Right side.
- Ventral abdomen - probe just caudal to sternum, move caudally to assess most ventral area. See SI & large colon. Looking for SI strangulating lesion.
- Gastric window - visualise stomach at level of 10th-15th ICS in middle third of abdomen, move probe 2-3 ICS cranial and caudal to 10th. See liver and stomach dorsal to spleen.
- Spleno-renal window - place probe b/w dorsal and middle third of abdomen at level of 17th ICS. See left kidney (deep to spleen). Looking for obstruction of left kidney by large colon nephro-splenic entrapment (verify by rectal).
- Left middle third of abdomen - freely move probe around middle third of abdomen. See SI loops.
- Duodenal window - place probe in 14th-15th right ICS in dorsal part of middle third (dorso-ventrally) of abdomen. See liver, duodenum and right dorsal colon. Looking for wall thickness >4mm (irregular).
- RHS middle third of abdomen - freely move probe around middle third. See caecum (more motile than colon).
- Cranial ventral thorac - place probe on cranial ventral thorac just caudal to triceps m. See liver. Looking for pleural effusion or diaphragmatic herniation.
Cornual nerve block
- What does it block?
- What needle and local?
- Landmarks and procedure
- Checking it worked
- For dehorning / disbudding - blocks CN 5 (trigeminal)
- 18-19G 1.5” needle with 10-20mL syringe and 5-10mL local
- Draw line from lateral canthus of eye to horn bud along facial crest dorsal to temporal fossa and inject ½way along the line
- Draw back to check not in vessel, inject slowly and in an arc
- Success = drooping of upper eyelid
Auriculopalpebral nerve block
- What does it block?
- What needle and local?
- Landmarks and procedure
- Checking it worked
- Blocks CN 7 (facial)
- Nerve supplies motor innervation for orbicularis oculi m. (can’t close eye when successful; does NOT provide analgesia to eye / eyelids)
- 18-19G 1.5” needle with 10-20mL syringe and 10-15mL local
- Nerve runs from base of ear along dorsal border of zygomatic arch
- Inject where it crosses superior margin of zygomatic arch
- Success = can’t close their eye
Petersons nerve block
- What does it block?
- What needle and local?
- Landmarks and procedure
- Checking it worked
- Used for examining and proptosing the eyeball and carrying out surgery of orbit including eye enucleation - blocks CN 3 (oculomotor), 4 (trochlear), 5 (trigeminal), and 6 (abducens)
- Can precede this block with auriculopalpebral block prior (stop eyelids moving)
- Place 3-5mL local SC at notch formed by supraorbital process cranially, zygomatic arch ventrally and coronoid process of mandible caudally
- 20-21G 1” needle, 5-10mL syringe, 18-19G 4” spinal needle with 25-35mL local
- Insert needle horizontal and slightly caudal, when reach coronoid process walk the needle off it rostrally then push needle in further
- Draw back to ensure not in blood vessel, inject then pull back and redirect upwards, repeat in all directions
- Success = mild proptosis of eyeball and mydriasis
Single point retrobulbar nerve block
- What does it block?
- What needle and local?
- Landmarks and procedure
- Checking it worked
- For enucleation of eyeball; blocks nerves to ocular m. causing paralysis of eyeball, as well as analgesia CN 5 (trigeminal)
- 18-19G 4” spinal needle with 40mL local (up to 10mL for each site)
- Insert forefinger either into medial or lateral canthus, b/w eyeball and conjunctival sac. Alongside finger pass curved (bend to almost a ½ circle), needle through fornix of conjunctiva until point of needle is retrobulbar.
- Ensure that needle point does not enter optic foramen (which carries risk of intrathecal [→ CSF] injection), and carry out aspiration check.
- Anaesthetize upper and lower eyelids by means of local infiltration as required.
If eyelids not adequately blocked, a line block of upper and lower eyelids can be carried out, using a 20-21 G × 1.5” long needle, from lateral canthus along eyelid margin to medial canthus, using 5mL local per eyelid.
Bovine Epidural
- Use
- Pros and Cons
- Location and landmarks
- Materials
- Method
- Signs of success
- Used for obstetrical manipulations, surgical procedures involving tail, perineum, anus, rectum, vulva & vagina & caudal aspects of thighs (no loss of motor control)
- Pros = simple and inexpensive; Cons = landmarks hard to find on fat cow, high dose can cause ataxia +/- recumbency
-
Location and landmarks = sacrococcygeal from S2 to S5, intercoccygeal from S3 to S5
- → sacrococcygeal = anterior border of ileum (palpate each side) and draw imaginary line joining points, crosses spinous process of last lumbar vertebrae, needle directly behind that
- → intercoccygeal = pump tail up and down, obvious articulation caudal to sacrum (first intercoccygeal space)
- Materials = chlorhex / alcohol swabs, 19-20G 1-1.5” needle with 4-6mL local
- Method = insert needle perpendicular to skin in midline, minimal resistance following proper placement in epidural space, can attempt hanging drop technique, should be no blood, inject local
- Signs of success = tail relaxed and floppy, sensory innervation lost, anal sphincter relaxes and posterior part of anus balloons
Bovine inverted L block
- Use
- Pros and Cons
- Location and landmarks
- Materials
- Method
- Signs of success
- Used for anaesthesia of PLF and abdominal wall (for GIT surgery and C-section)
- Pros = simple, does not interfere w/ walking, deposition away from incision site, no oedema or haematoma formation, no scoliosis
- Cons = incomplete analgesia and muscle relaxation as deeper layers of abdominal wall, large volumes of local can cause toxicity
-
Landmarks = 2 linear infiltrations whole thickness body wall → 1 anterior and 1 above line incision (branches of L depend on length and placement of incision)
- PLF & abdo wall - deposited in L running caudal to last rib (13th) and ventral to transverse processes of lumbar vertebrae
- Materials = chlorhex / alcohol swabs, 18-19G 1.5” needle with 20mL syringe or vaccination gun (need 80-100mL local)
-
Method = clip, wash, scrub, wipe. Bleb corned of inverted L caudal to last rib and ventral to transverse process of 1st LV.
- Advance full length needle under skin in caudal direction, inject small amounts of anaesthetic as needle advances
- Move along line ventral to transverse processes, re-enter end of 1st bleb
- Return to starting point and continue line parallel and caudal to last rib
- Do it all again with deeper injection
- Signs of success = loss of skin sensation caudal and ventral to blocked L
Bovine paravertebral block
- Use
- Pros and Cons
- Location and landmarks
- Materials
- Method
- Signs of success
- Used for anaesthesia of PLF and abdominal wall for GIT Sx and C-section
- Pros = complete uniform desensitisation, improved muscle relaxation, decreased intra-abdominal pressure, simple & safe, shorter post Sx block, need less local, absence of local from incision site
- Cons = muscle spasm in loins during needle insertion, causes scoliosis, weak ipsilateral pelvic limb can cause ataxia when released from crush
-
Location and landmarks = 1st transverse process in front of tuber toxae (that is LV5) → count forwards to L2. 5cm away from dorsal midline:
- Block T13 point cranial edge of L1
- Block L1 point caudal edge of L1
- Block L2 point caudal edge of L2
- Materials = chlorhex / alcohol swabs, 18-19G 1.5” needle and 10-20mL syringe with 6mL local for blebs, and 18G 4” spinal needle with ~80mL local for nerves
-
Method = clip hair over an area from last rib to LT4, and from dorsal midline to just below ends of transverse processes. Scrub area with surgical scrub until it is clean.
- Locate landmarks and mark needle insertion points then apply final skin preparation with chlorhexidine/alcohol swabs
- Using 18-19 G × 1”5 needle, make 2mL bleb of local on caudal edge of LT2, about 5-6cm (one matchbox) from dorsal midline. Redirect needle perpendicular to LT2 and inject 3 ml into underlying fascia and muscle.
- Remove 18-19 G × 1.5” needle and insert spinal needle into desensitized area perpendicular to transverse process. Injecting small amounts of local solution as needle is advanced towards bone will help prevent muscle spasm.
- When needle hits caudal edge of LT2, withdraw slightly and redirect so it ‘walks’ off caudal edge of LT2 and perforates intertransverse ligament (should be able to feel needle go through ligament).
- Needle can be advanced too far and enter peritoneal cavity. Aspiration can be used to check needle placement – should not be possible to aspirate.
- Inject 10mL of local below ligament. Withdraw needle 1cm and inject further 5mL above ligament. Repeat process to block L1 by injecting off caudal edge of L1.
- Repeat this process to block T13 by injecting off cranial edge of L1. This injection is least well tolerated by cows and should be done last.
- Onset of analgesia will be within 5-10min and will last ~90min
- Signs of success = increased temp of skin on flank (vasodilation), analgesia of skin / muscle / peritoneum / PLF, scoliosis towards desensitised side (muscles contracting on ipsilateral lumbar column)
Cattle PE parameters
Aging cattle with teeth
Bovine intravenous regional anaesthesia of distal limb
can be in the midline below fetlock using venous plexus OR on / just below lateral fetlock using lateral digital vein
- Indications
- Pros and Cons
- Landmarks
- Materials
- Method
- Used for most digital surgical procedures
- Pros → superior to superficial nerve blocks or a ring block, don’t need detailed anatomy knowledge; Cons → may be difficult if severe swelling / cellulitis
- Landmarks → use dorsal common digital vein OR tap into venous plexus on palmar / plantar aspect of limb exactly in midline and 2-3cm below fetlock joint at level of PIPJ
- Materials = gloves, clippers, chlorhex scrubs etc.; tourniquet, 21G butterfly catheter OR 20-21G 1-1.5” needle with 20-30mL local
-
Method = place tourniquet distal to carpus / tarsus and within working distance of surgical site. Palpate engorged veins, clip and scrub area with surgical scrub, prep site. Inject 20-30mL local into vein.
- Anaesthesia of limb complete in 5-10min, lasts as long as tourniquet left here (leave it for at least 15min then slowly remove)
Cranial nerves
