Abdominal surgery and correction of displaced abomasum

Flank anesthesia

used for standing abdominal surgeries

goal is to block T13, L1, and L2

four main approaches - proximal paravertebral, distal paravertebral, inverted L, line block

adding xylazine improves the block

Proximal paravertebral block

blocks both dorsal and ventral nerves of T13, L1, and L2 as they exit vertebral foramen

advantages - specific nerve block, small volume of lidocaine, no lidocaine in the incision

disadvantages - technically difficult, requires 3in needle, possible laceration of aorta or caudal vena cava

How to perform proximal paravertebral block

insert needle at cranial edge of transverse process of L1 just lateral to vertebral body → advance needle ventral to process

repeat off caudal edge of L1 for L1 nerve

repeat off caudal edge of L2 for L2 nerve

Distal paravertebral block

individually block dorsal and ventral nerves of T13, L1, and L2

advantages - easier than proximal paravertebral, no lidocaine in the incision, uses routine needle sizes

disadvantages - difficult in fat dairy cows and beef cows, variability in location of L2 nerve, more lidocaine needed than proximal PV block

How to perform distal paravertebral block

insert 1.5” 18g needle directly at the end of the transverse process of L1 → slide needle dorsally over the top and insert to the hub of needle → 5ccs in this area, 5ccs cranially, 5ccs caudally → back needle to the end of the process and slide ventral → inject lidocaine as before

repeat at L2 for L1 nerve

repeat at L3 and L4 for L2 nerve

Inverted L block

regional anesthesia to most of the flank

advantages - relatively simple, larger area anesthetized than line block, no lidocaine in incision

disadvantages - less effective for deeper tissues, multiple injection, large volume of lidocaine

Line block

provides anesthesia to the tissue being cut

advantages - simplest technique

disadvantages - less effective for deeper tissues, multiple injections, anesthesia in limited area, swelling and potentially delayed healign due to liodcaine in incision

Rumenotomy

when to perform - traumatic reticuloperitonitis, rumen outflow obstruction, grain overload

done standing or in right lateral restraint

performed in left paralumbar fossa

How to perform rumenotomy

tack rumen dorsally and ventrally → circumferentially suture rumen to skin in continuous pattern → evacuate rumen contents → explore rumen to remove foreign body → clean cut edges of rumen → suture with 1.0-2.0 absorbable suture (simple continuous) → clean all ingesta from area → remove skin sutures → close abdominal wall routinely

Rumen board

used to perform a rumenotomy quickly, commonly used for production med

increases risk of peritonitis

Length of stages in parturition

stage 1 - no longer than 8 hours

stage 2 - no longer than 2 hours

should progress every 15-30 minutes

C-section indications

live calf or value of dam

fetotomy impossibel due to small birth canal or prolonged labor

incomplete cervical dilation

large fetus, fetal monsters

uterine torsion

C- section standing

good for live calf, not for dead calf due to contamination

advantages - less restraint needed, less stressful to cow, minimal tension on suture line, rumen inhibits evisceration potential intraoperatively

disadvantages - uterine contents more likely to spill intraperitoneally, requires adequate facilities to restrain cow, requires a lot of physical strength of practitioner

How to perform standing C-section

regional anesthesia → incise skin → exteriorize foot → incise uterus over hoof → cut down with metzenbaums → find both feet and place chains → pull calf out of uterus → remove or replace placenta → suture uterus 2.0-3.0 U-track pattern oversewn → close abdominal wall → close skin

C-section recumbent/dorsal/midline or paramedian

advantages - excellent exteriorization or uterus and fetus, minimizes contamination of peritoneal cavity, excellent for heifers (they like to lie down)

disadvantages - requires assistance to position and restrain cow, requires full sedation, more likely to bloat or aspirate, rumen can come through incision, causes some animals to strain more, incisional complications post-operatively

Displaced abomasum

primarily in post-partum dairy cows

most displace to the left

abomasal atony and lack of rumen fill

Causes of displaced abomasum

nutrition - hypocalcemia, hypokalemia

increased concentrates → fermentation in abomasum → gas

endotoxemia after transitioning feed after pregnancy

dystocia

Right displaced abomasum

emergency situation

volvulus cuts off blood supply and nerves → ischemic damage can become permanent

Displaced abomasum physical exam

heart rate and rhythm usually normal, severe elevations indicate a poor prognosis

overt clinical signs (indicate there’s probably a volvulus) - bruxism, shifting weight on hind feet, kicking at abdomen

percussion - ping

assess for other postpartum diseases

Differentials for percussion on left side

LDA, no fiber mat in rumen, uterus with metritis, free gas from peritonitis or surgery

rumen void - ploink hollow sound

Differentials for percussion on right side

RDA, abomasal volvulus, cecum torsion or nonpathologic, free gas from peritontiis or surgery, uterus, referred LDA, rectum from recent palpation, spiral colon (normal), small intestines (mesenteric volvulus or could be normal)

When to take DA to surgery

abomasal volvulus, cecal torsion, mesenteric volvulus

Diagnostics for abdominal pings

succussion - listen for splash where ping was found

palpation

liptak test to look at fluid and gas

blood chem analysis - look for severity of hypochloremia and metabolic alkalosis

Ping differentials based on physical exam

tachycardia, tachypnea - abomasal volvulus, peritonitis, severe metritis

fever - peritonitis, metritis

sound of rumen contractions - LDA tinkling sound, rumen ping

evidence of recent surgery

abdominal contour - right side distension, left dorsal distension, sunken left flank (rumen void)

foul vaginal discharge - metritis

Surgical correction of DA

advantages - decreased cost of antibiotics, prevent disease but doesn’t treat it, decreased milk discard, higher milk production, fewer post-op complications, animal welfare

disadvantages - cost of sterile sleeves, takes time to appropriately prep cow

Roll to correct DA

roll cow into dorsal recumbency → allow abomasum to float to ventrum and gas to escape → allow cow to stand and fill rumen w/ water

Advantages - no surgery, cheap, quick 

Disadvantages - only works ¼ of the time, possible recurrence, casting and rolling cow

Roll and toggle to correct DA

Similar to roll → abomasum trocarized and bar sutures placed → correct placement based on the smell of abomasal gas 

Advantages - quick, cheap, no incision, 80-90% success rate

Disadvantages - blind procedure, casting and rolling, fistula formation, localized peritonitis, could hit mammary vein

Cows to not do roll and toggle on

late term pregnancies, adhesions, other concurrent disease, small abomasum, small rumen, long-standing DA, RDA

Laprascopic roll and toggle to correct DA

Two-step - toggle placed via flank, cow rolled and suture retrieved 

One step - dorsal recumbency, similar to roll and toggle, laparoscopic guidance

Advantages - 95-98% success rate, no incision, quick procedure, not a blind procedure, can be done prophylactically 

Disadvantages - little exploratory, equipment cost and training, casting and rolling

Right paramedian abomasopexy to correct DA

Roll cow → incision 10cm lateral to midline and 10cm caudal to xiphoid → incorporate abomasal wall in closure of peritoneum and internal rectus sheath → suture lateral to the incision

Advantages - secure adhesion of abomasum, anatomically correct, no deflation, hidden scar, easy with short arms, can visualize abomasum, corrects RDA and LDA

Disadvantages - cast and roll cow, ventral incision → fistulas, eviscerations, milk veins, poor exploratory

Right flank omentopexy to correct DA

Incision in right flank → complete abdominal exploratory → abomasum deflated with needle → pull/push to normal position → pexy omentum near pylorus to incision

Advantages - standing, single surgeon, LDA or RDA or AV, no suture in abomasum, best exploratory, can be done prophylactically (not usually done)

Disadvantages - more difficult technically, highest recurrence rate (omentum tearing/stretching), less anatomically correct, adhesions, late-term pregnancy 

Left flank omentopexy to correct DA

Incision in left flank → suture placed into abomasum → deflation → sutures pushed through ventral abdomen → abomasum repositioned → tied by assistant 

Advantages - standing, late pregnancy, visualize abomasum, address ulcers/adhesions, access reticulum/rumen

Disadvantages - only LDA, cannot be done prophylactically, difficult on small LDA, poor exploratory, requires two people, milk veins