Horses 3 Flashcards
Locating source of lameness what are the 3 main presentations and what to do
1. Pain and swelling • Tendon injury and septic arthritis • NO NERVE BLOCK -> ultrasound to confirm -> WILL BE LAME ON BOTH SOFT AND HARD SURFACE 2. Swelling not associated with pain • Effusion in joint, tendon sheath swelling 3. No pain no swelling • Most common • Pain but nothing externally
What are the 5 main diagnostic techniques and what good for
- Radiography - cheap, easily available
○ Osteoarthritis -> osteophytes present, arthritic change -> BUT IS IT CAUSING THE ISSUE? - Ultrasound - soft tissue but can only image small areas at the time - miss the pathology
○ To ultrasound the whole limb can take days -> NOT A GOOD SCREENING MODALITY - CT - soft tissue but same as ultrasound -> only small areas
- MRI
- Scintigraphy - highly sensitive and can do the whole limb
○ Show lots of hot spots but how do we know which is important
Golden rules for lameness diagnostic
- Allow plenty of time - can take hours and days
- Follow a routine
- Avoid cutting corners
- Use nerve blocks
What are the 6 main steps in the diagnostic approach
1) history
2) clinical examination
3) diagnostic analgesia
4) imaging
5) further diagnostic analgesia
6) response to therapy
History with lameness examination
○ Signalment § Race horses different to hobby horses § Ponies -> laminitis ○ Duration ○ Onset § Associated with work § Sudden/gradual ○ Shoeing § Often if recent will be the issue ○ Changes with work § Often gets worse with work ○ Response to treatment
What are the main aspects of the clinical examination in a lamness examination
Observe and palpate
1) examine at rest
2) examine moving (gait)
3) flexion test
clinical examination lameness what are the general steps
i. Observe □ Symmetry - need to get the horse to stand square ® Muscle mass ® Conformation ® Feet □ Swelling ® Synovial structures □ Feet ® Shoeing and Balance ii. Palpate □ Joint capsules □ Tendons and suspensory ligament □ Muscles □ Bony prominences iii. Flex and extend - NOT FLEXION TEST □ Testing for -Range of motion, Pain iv. Hoof testers □ Apply across hoof wall and sole, frog □ Repeatability, unreliable - soft feet false +ve, hard feet false -ve
What is involved with the lameness examination at rest and moving (gait)
○ Examine at rest § Quiet confined area - important § Examine whole horse - all the legs ○ Examine moving (gait) § Straight line - walk, trot § Lung - walk, trot, canter □ Soft and hard surfaces □ Allows more time to examine lameness □ Lower limb problems often worse § Ridden - some lameness only observed when ridden § Tips □ Keep it simple □ Take your time □ Practice
What are the 3 steps in giat examination for lameness and describe
- Determine the lame legs or legs - ALWAYS STEP 1
® Which leg is the horse unweighting
◊ Forelimbs -> head, forequarter drops of the non-lame limb
} Subtle lameness may not have head nod looks at forequarter
◊ Hindlimbs -> lifts hindquarter on lame limb
} Look at the midline at base of tail will go up higher when on lame limb
◊ Lower limb issues generally don’t like turning and worse on hard lunge - Characterise the lameness
® Foot flight
® Length of stride - Lameness grade
0 – no lameness
1 – subtle lameness - no real head bob
2 – obvious consistent lameness - can tell straight away
3 – pronounced unweighting
4 – severe lameness, difficult to trot
5 – non weightbearing
What is involved with an objective assessment of lameness
□ Inertial sensors -> lameness locator - sensor on head and rump
□ Measure asymmetry, allows objective comparison over time and between nerve blocks
Again not always the best with subtle lameness
What is involved with flexion tests, which joint and how to perform
§ Following joints
□ Fetlocks
□ Carpi
□ Hindlimbs
§ Hold flexed for 1 minute then trot off
§ Difficult to interpret
Many sound horses have positive flexion tests
Nerve block what does it do, types and what time needed to give
§ Only objective means of determining site of pain § Types □ Regional -> preferred □ Intra-articular ® Pain may be extra-articular ® More invasive - needle in synovial structure risk of infection or reaction ® More proximal limbs have to do here § Allow appropriate time □ Lower limb - 10 and 30mins □ Upper limb - 20 and 40mins □ Intraarticular 5-10mins □ Why you don't want to do too many in the field -> have to stay there
How to test for adequate anaglesia with nerve block and which nerve blocks for pleasure and racehorse
□ Deep pain
® Hoof testers
® Suspensory palpation
® Skin sensation - may not be the best indicator
Pleasure horse
1. palmar digital 2. abaxial 3. low 4 point 4. subcarpal 5. median/ulnar
Racehorse
1. pastern ring block 2. low 4 point 3. midcarpal 4. subcarpal 5. median/ulna
Carpus what also called, bones in proximal and distal row and the synovial structures
(knee)
Bones
Knee
- Proximal row -> (medial to lateral) -> radial, intermediate, ulnar and accessory
- Distal row -> first to forth carpal bones
○ The first is small and inconstant
Synovial structures
- Carpal sheath - surrounds both the superficial and deep digital flexor tendon as they pass the carpus
- Extensor tendon sheaths
What are the 3 joints in the carpus and the pouches with how high motion
- Antebrachiocarpal joint (radiocarpal) -> high motion joint so will be able to feel
○ Palmar pouch - lateral aspect immediate palmar to the radius and proximal to accessory carpal bone - Mid carpal joint -> high motion joint so will be able to feel
- Carpometacarpal joint -> low motion joint so won’t be able to feel (communicates with mid-carpal joint)
Fetlock synovial structures and joint with pouches
Synovial structures
- Digital sheath - contains the deep digital and superficial digital flexor tendons as they pass the fetlock joint
○ Swelling will be palmar to the suspensory ligament and dorsal to the flexor tendons
Joints
- Metacarpo-phalangeal joint - has dorsal and palmar pouches
○ Palmar pouch -> between the third metacarpal bone and suspensory branch - most commonly see swelling here first
§ Common injuries -> suspensory branch tears, sesamoid fractures, palmar osteochondral disease
○ Dorsal pouch -> either side of the sagittal ridge of the third metacarpal bone -> swelling when more severe
Pastern what joint and its pouch
- Proximal interphalangeal joint - a small dorsal pouch with large palmar pouch between branches of SDFT and P1
What is the main synovial structures in the hoof and pouches and the joint with its pouches
- Navicular bursa - lies between the DDFT and the navicular bone
○ Proximal pouch - proximally on the dorsal aspect of the DDFT
○ Lateral and medial pouches - can be penetrated by deep wounds to the heel
Joints
1. Coffin joint (distal interphalangeal joint) - lies mostly within joint capsule
○ Dorsal pouch - extends above the coronary band axially 2cm
○ Palmar pouch - immediately dorsal to palmar pouch of navicular bursa
Palmar digital nerve block what nerve blocking, what blocks and how to perform
blocking the palmar digital nerve - 2mls
○ Blocks -> whole sole, all the foot and the contents EXCEPT for the dorsal coronary band
a. Left thumb is placed on the ergot and is pulled proximally to tense the ligaments of the ergot which passes distally to the collateral cartilages - palpate these
b. Injection site is the intersection of the collateral cartilage and the palmar aspect of the pastern
Pastern ring block what nerve blocked, what blocks and how to perform
palmar digital nerve and its dorsal branch
○ Blocks -> whole foot and distal and proximal interphalangeal joint
a. Blocked mid pastern where the palmar digital nerve comes out from under the ligament of the ergot
b. 2 ml is injected at this site and needle is partially withdrawn and redirected dorsally injecting slowly as needle is pushed to expand the subcutaneous space
c. Another 2ml is deposited dorsal to the first injection site to block the dorsal branch
Abaxial sesamoid nerve block what nerve blocks, what blocks and how to perform
palmar nerve - 2-3mls
○ Blocks -> whole foot, distal and proximal interphalangeal joint, proximal sesamoid bones
a. Palmar vein, artery and nerve are palpated on the abaxial surface of the sesamoid bone and the needle is placed parallel and immediately palmar to them
Low four point nerve block what nerve block, what blocks and how to perform
palmar and palmar metacarpal nerves are blocked
○ Blocks -> mid metacarpus all the way down to the hoof
a. Block palmar nerve are blocked mid metacarpus in the groove between the suspensory ligament and the flexor tendon
b. Palmar metacarpal nerve are then blocked where they emerge from under the buttons of the splint bones -> proximally to hit the button of the splint bone
Subcarpal nerve block what nerve block, what blocks and how to perform
lateral palmar metacarpal nerve
○ Blocks -> metacarpal bone
a. The level of injection just below the level of the carpometacarpal joint where the flexor tendons are pushed axially and needle passes axial to the splint bone to hit palmar aspect of the metacarpus at its junction to splint bone
b. 3ml injects at both lateral and medial sites
How to perform nerve block in the distal interphalangeal joint
- dorsal pouch of the joint (above the coronary band of the midline)
a. Horse weight bearing on the limb with needle placed axially 10mm above coronary band, perpendicular to the skin, passed through common digital flexor tendon and onto dorsal aspect of P2
b. If unable to inject withdraw slightly until fluid goes in easily
c. Inject 5mls of local anaesthetic
How to perform nerve block in the proximal interphalangeal joint and fetlock joint
Proximal interphalangeal joint
a. Palpate the V formed by the lateral branch of the SDFT and the palmar aspect of P1, the depression in the distal part of this V is the injection site
b. Pass needle axially and slightly distally so you hit palmar aspect of P1 -> should be nearly full length of needle
Fetlock joint
a. Place a needle between the lateral proximal sesamoid bone and the third metacarpal bone with the limb flexed
How to perform nerve block in digital sheath and midcarpal and antebrachiocarpal joint
Digital sheath
a. Method involves passing a needle along the abaxial surface of a proximal sesamoid bone
Midcarpal and Antebrachiocarpal joints
a. Flex the limb and place the needle either lateral or medial indentation either side of the extensor carpi radialis tendon
b. Pass needle until you hit the cartilage
Stifle what are the 3 joints, how interact and palpate
- Femoropatellar joint - swelling can be palpable between and overlying the patellar ligaments
- Medial femorotibial joint - palpated medial to the medial patellar ligament and cranial to medial collateral ligament
- Lateral femorotibial joint - deep so generally not possible to palpate swelling
What is the stay apparatus of the hindlimb and the 3 things it consists of
The stay apparatus is defined as the combination of structures, and especially the elastic tendons and ligaments, which allow horses to rest while standing up -> passively support the trunk against gravity
- Horse limb can only undergo extension and flexion -> resisted by the stay apparatus
Consists of :
1. medial patellar ligament
2. reciprocal apparatus - (ties the movement of the hock and the stifle together so reciprocal movement occurs ○ (SDFT (superficial digital extensor tendon) +peroneus tertius (from the region of the extensor fossa of femur down to metatarsus))
3. suspensory apparatus (interoessweous ligament)
Tarsus (hock joint) what bones are present
- Proximal row -> talus (has trochlea that articulate with cochlea of tibia) and calcaneus (sustentaculum tali -> DDFT)
- Middle row -> central tarsal bone
- Distal row -> tarsal bones 1-4 of which the first and second are fused, third rests on large metatarsal bone and forth is lateral and projects proximally into the level of the middle row
What are the 4 joints in the tarsus joint and where sweling
- Tarsocrural joint - largest joint space and only one that will notice swelling from
○ Swelling noticed on the dorsal aspect -> medial and lateral to extensor tendons and palmar aspect -> between calcaneus and the tibia laterally and medially - Proximal intertarsal joint - communicate with tarsocrural joint -> Don’t need to block separately
- Distal intertarsal joint - very small
- Tarsometatarsal joint -
Syonvial structure and ligaments and tendons within the tarsus
Synovial structures
- Tarsal sheath - through which the DDFT runs
○ Swelling is seen cranial, lateral and medial to the gastrocnemius and SFT tendons
- Calcaneal bursa - SDFT runs within
Ligaments and tendons
- Superficial and deep digital flexor tendons
- Plantar ligament - calcaneus to head of 2nd metatarsal bone
- Collateral ligaments - either side of tarsal joint
What are the different nerve blocks with the tarsus compared to carpus
- Similar to forelimb
1. Palmar digital block - same
2. Pastern ring block - same
3. Abaxial sesamoid block - same
4. Low 6-point block - slightly different
5. Subtarsal block - similar
What tendons run the palmar aspect of the distal hindlimb and how does their shape change as move distally
Green -> superficial digital flexor tendon
- As move distally it becomes more bow shaped as become thinner
Blue -> deep digital flexor tendon
- As move distally it becomes more rounded and larger
Yellow -> Inferior check ligament (Accessory ligament of the deep digital flexor tendon)
- As move distally merges into the deep digital flexor tendon
Red -> interosseous ligament (suspensory ligament)
As move distally the ligament splits into medial and lateral as insert onto sesamoids
For lameness exam what is involved with clinical examination of the hoof
- Shape and symmetry ○ Collapsed heel (hoof almost parallel to surface), upright feet - Shoeing - Digital pulse - Coronary band Test with: - Hoof testers - Hoof knife ○ Need to remove stuff from the bottom of the Swelling - Hoof capsule rigid - Often pushed up limb
For hoof lamness what is important with the gait examination
- Surfaces most foot pain worse on hard surface
- Usually also worse on the turn -> lunging
What are the 3 nerve block that are important for hoof lameness
1) palmar digital nerve block
2) distal interphalangeal joint block
3) navicular bursa block
Radiography of hoof lameness, what is important for foot preparation and the 5 main views and why
○ Foot preparation - IMPORTANT
§ Remove shoes
§ Remove debris
§ Dress foot
§ Pack sulci within the frog - playdo to prevent shadows from the grooves
○ Views
1) Lateromedial - place metal onto hoof to determine slope
2) sanding dorsopalmar - assessment of balance
3) upright pedal bone - navicular and pedal bone exposure
4) obliques - fractures
5) skyline of navicular bone
