Rumenotomy is indicated for vagal indigestion, hardware disease, rumen acidosis, and some forms of choke. Rumenotomy allows exploration of the rumen, reticulum, and parts of the omasum.
A. Relevant anatomy:
The rumen is a large fermentation vat. The layers should be gas (dorsal), recent fiber, older fiber, and fluid (ventral). The reticulum is sac off the dorsal aspect. The esophagus empties into the rumen from the dorsal cranial wall while the reticulum empties into the omasum on the medial wall just above the pillar separating the rumen and reticulum. The omasum and abomasum are often palpable through the rumen wall.
B. Preoperative management:
- Food restrictions: If possible the cow should be held off feed for 24 hours prior to rumenotomy.
- NSAIDs/analgesic: Recommended preoperatively. Flunixin meglumine 1.1-2.2 mg/kg iv is standard.
- Antibiotics: Recommended. If milking, ceftiofur 2.2 mg/kg IM is standard. In beef or non-lactating cattle, other options do exist. Pencillin is often effective; however, remember that the label dose of procaine penicillin is ineffective!
- Others: If possible, plan on rumen transfaunation.
C. Instrument required for Rumenotomy:
- Extra sleeves and gloves
- Additional laceration or surgery pack is ideal
- Sterile saline for lavage
- Rumen board – optional
- Wound drape – optional
- 2 suture on a cutting needle for securing rumen
- 2-0 or 0 absorbable suture for closing rumenotomy
- Wet-dry vac -optional
- Standard surgery pack
- Sterile sleeves for internal palpation
- Scalpel blade and handle
- 2 or 3 absorbable suture material for muscle closure
- 3+ nonabsorbable suture material for skin closure
D. Surgical procedures:
- Rumen exteriorized and temporarily tacked to skin After exploring the rumen is tacked to the body wall to hold it in position. This will minimize the work needed to hold it up and decrease the risk of peritoneal contamination.
- To tack the rumen: insert the needle (attached to #2 suture) through the skin away from the incision into the abdominal cavity.
- Grab a large bite of rumen away from the proposed rumen incision.
- Drive the needle back through the skin near the original insertion and tie.
- Repeat until the rumen is held in position by the tacking sutures.
E.Contamination management:
It is important to control contamination. This can be via the use of a rumen board, rumen protector, or by creating a water-tight seal through inverting suture pattern. The latter is the most effective. To create a water-tight seal, secure the rumen to the skin using a continuous Cushing pattern of 2 sutures on a cutting needle. When completed accurately, no suture should be visible. Any gaps should be closed with a mattress suture, especially at the ventral aspect.
NOTE that the rumen should be poofed out a bit. However, too much poof leads to a poor match with the skin and more gaps. The rumen is attached to the skin using a Cushing pattern to create a water-tight seal. To minimize contamination, separate rumenotomy instruments (scalpel, saline, gauzes, needle holders, suture, scissors) from closure instruments. Cover closure instruments to keep sterile and move them away from the area. Consider adding protective gear to minimize lingering smells. Garbage bags are good protection. At this stage, the procedure is not a sterile one.
F. Rumenotomy:
- Incise the rumen.
- Remove ingesta along the path to the reticulum for hardware (or all of it if the animal has rumen acidosis).
- A wound protector can minimize trauma to the rumen surface.
- Another option would be to tack the rumen open or temporarily suture it open to minimize exposure to the serosal surface.
- Explore the reticulum, esophageal opening, and omasal opening.
- If the reticulum does not move, investigate the adhered area for penetrating foreign bodies.
- Palpate through the wall for any abscesses that need drainage.
- Hardware should be removed as should any extra magnets.
- One magnet should be left or placed.
- Rumen transformation is easiest at this stage.
- In case of an abscess, it can be drained into the rumen through the area adhered to.
- Any incision that extends beyond that area will leak ingesta into the peritoneum.
Note: Pus does not drain uphill well. And if you lose a scalpel blade, you have to find it. Tie it to your wrist before taking it into the rumen. If contamination occurs or in case of peritonitis, DO NOT lavage the abdomen. Cows can wall off infection if localized.
G. Rumen closures:
The rumen drapes or shields are removed and the rumen surface cleaned. The rumenotomy incision is closed in two layers with an inverting pattern uppermost. After the first layer is closed and the rumen surface cleaned, the garbage bags are removed from the surgeons, gloves changed, and the clean instruments used for the second layer. After two-layer closure, the rumen is slowly released from the body wall so that it can be cleaned well prior to returning to the abdominal cavity.