Sheep general

Question 1

What complications are associated with short tail docking in sheep?

Answer 1

Rectal prolapse - incicdence around 7% w short tail dock. Use triangular insertions of tail folds as a loandmark for amputation. Tail should also cover the vulva of ewe lambs

Question 2

Possible causes of rectal prolapse in sheep

Answer 2

Enteritis (coccidia, Salmonella), dysuria, oestrogenic feeds, obesity, lush forages, coughing, tail docking (short)

Question 3

Usuall direction of patella luxation in small ruminants?

How does this compare to the typical direction in calves and foals?

Answer 3

Usually luxate MEDIALLY in small ruminants

Typically LATERAL in foals/cattle

Question 4

What is the desired trochlear groove depth in small ruminants on skyline rads of the stifle? What procedure is indicated for patella luxations if this depth is inadequate?

Answer 4

TG should be 4-5mm deep w biaxial triangular trochlea & uniform SCB plate

Trochleoplasty is indicated if there is inadequate depth of the groove

Question 5

Procedure for tx of grade III/IV patella luxations

Answer 5

• Usually medial so medial retinacular release & lateral imbrication (+/- tibial tuberosity alignment & sulcoplasty - see elsewhere)
• 12cm curvilinear is made, centred longitudinally over the patella w proximal & distal aspects extending 2cm lateral to midline
• vastus intermedius, patella, patellar ligament (sheep have 1 not 3), tibial tuberosity, & tibial diaphysis should form a straight line.
• Often, patellar ligament diverges medially from the line of the vastus intermedius & patella to tibial tuberosity & tibial shaft.
• If misalignment is appreciated, a tibial tuberosity transposition is recommended
• lateral capsule imbrication and a medial retinacular release: 4cm longitudinal incision at the level of the patella, through joint capsule into medial part of FPj
• Retinacular release distal to medial femoropatellar ligament, encompassing entire length of femoropatellar joint contact
• 8cm longitudinal incision from tibial plateau, 4cm lateral to patella, extending proximally through vastus lateralis & lateral FPj capsule. +/- 2cm lateral capsulectomy
• Imbrication done w several vertical mattress or Lembert sutures in deep then superficial layers within capsule & fascia of vastus lateralis. May need to incorporate gluteobiceps fascia.
• Alternatively, a vest-over-pants pattern to obliterate 2-3cm lateral periarticular space.
• In both techniques, use large nonabsorbable multifilament suture for imbrication.
• Reduction of the luxation is confirmed under a full range of motion

Question 6

Briefly describe tibial tuberosity transposition for patella luxations

Answer 6

• Use oscillating saw in frontal plane from medial to lateral to perform a tibial tuberosity osteotomy from tibial plateau distally (or osteotome/mallet)
• Aim for 1.5cm tibial tuberosity osteotomy w longitudinal length of 5-6cm
• Elevate cranial tibial mm from lateral surface of tibia & protect
• Periosteum of distal tibial tuberosity at end of osteotomy is spared & used as a hinge for rotation & an additional anchor for tension band.
• Tibial tuberosity is rotated laterally w the limb in maximal internal rotation until the patellar ligament forms a straight line w quads apparatus.
• Transposition is reduced w 2 converging 3.2-mm K-wires through tibial tuberosity & trans cortex tibial plateau (K pins)
• K-wires are cut sparing most superficial 1cm of wire.
• Ensure the articular surface of tibial plateau is not penetrated
• Tension band completed w 2.5-mm bit to make a transverse hole from medial to lateral through tibial diaphysis 3-4 cm distal to osteotomy site.
• 2x 18-gauge wires passed through the hole & around K-wires in figure-8 pattern.
• K-wire stumps are bent proximally as they exit the tibial tuberosity (stops the wire falling off, like tightening a screw onto the wire).
• Wire tightened so no slack is present. Wire ends are bent away from skin to prevent irritation.