4.2 Bovine Herd Health, Medicine & Surgery
Key Takeaways
- Omentopexy is a standing right-flank procedure securing the pyloric omentum ('sow's ear') to correct left or right displaced abomasum.
- Primary horn desensitization is achieved via a cornual nerve block targeting the zygomaticotemporal nerve branch along the frontal crest.
- Proximal paravertebral block targets spinal nerves T13, L1, L2 at their intervertebral exit, producing scoliosis towards the blocked side.
- Fetotomy is preferred over C-section for a dead fetus when the maternal cervix is fully dilated, as it minimizes systemic contamination risks.
4.2 Bovine Herd Health, Medicine & Surgery
Bovine clinical practice demands proficiency in both routine surgical procedures and advanced obstetric and anesthetic techniques. Performing these procedures efficiently while optimizing animal welfare and minimizing stress is a core competency for food animal practitioners.
Surgical Management of Displaced Abomasum
Abomasal displacement, most commonly occurring within the first month post-partum, requires surgical or mechanical stabilization to return the abomasum to its normal anatomical position on the ventral abdominal floor.
Standing Left Flank Abomasopexy
Performed on the standing animal, this procedure is used for left displaced abomasum (LDA). An incision is made in the left paralumbar fossa.
- Technique: The abomasum is located, and long stay sutures (using a heavy non-absorbable suture) are placed in the abomasal wall. A long needle is passed through the ventral abdominal wall to the right of the midline (paramedian area), pulling the sutures through. The sutures are then tied externally.
- Pros and Cons: Good direct visualization of the abomasal wall on the left is achieved, but the final suture placement on the ventral abdominal floor is performed blindly, risking entrapment of the omentum or loop of intestine.
Standing Right Flank Omentopexy
This is the most common standing surgical correction for LDA and can also be used for RDA/RAV.
- Technique: A right flank laparotomy is performed. The abomasum is deflated (if LDA) and returned to its normal position. The "sow's ear" (a distinct, fat-filled fold of the greater omentum near the pylorus) is identified and sutured to the peritoneum and transverse abdominal muscle of the right flank incision.
- Pros and Cons: It allows full visualization of the right side of the abdomen and does not require the animal to be cast. However, it relies on indirect stabilization (securing the omentum rather than the abomasal wall), which has a slightly higher recurrence rate than direct abomasopexy.
Standing Right Flank Pyloropexy
Similar to the omentopexy, but the seromuscular layer of the pyloric antrum itself is sutured directly to the abdominal wall.
- Pros and Cons: Provides a highly secure, direct anchor. However, improper placement can lead to pyloric outflow obstruction or abomasal leakage if the lumen is penetrated.
Right Paramedian Abomasopexy
Performed with the cow in dorsal recumbency.
- Technique: An incision is made 5–10 cm to the right of the midline, caudal to the xiphoid. The abomasal wall (seromuscular layer only) is sutured directly to the internal abdominal fascia and peritoneum.
- Pros and Cons: Provides the strongest and most anatomically correct fixation. However, it requires casting and restraining the cow in dorsal recumbency, which can cause severe respiratory distress due to rumen pressure on the diaphragm.
Dehorning and Castration Pain Management
Modern veterinary medicine and animal welfare standards dictate that surgical procedures must be accompanied by appropriate local anesthesia and systemic analgesia.
Cornual Nerve Block for Dehorning
Innervation of the horn is supplied by the cornual branch of the zygomaticotemporal nerve (a branch of the trigeminal nerve).
- Anatomical Landmark: The nerve runs along the frontal crest, halfway between the lateral canthus of the eye and the base of the horn.
- Administration: 5–10 mL of 2% lidocaine is injected subcutaneously and subfascial at this site. In older cattle, supplementary ring blocks or block of the cornual branch of the infratrochlear nerve (dorsomedial to the eye) may be necessary due to accessory innervation.
Castration Anesthesia
Local anesthesia is achieved via:
- Intratesticular Injection: 10–15 mL of 2% lidocaine is injected directly into each testicle. The anesthetic diffuses into the spermatic cord, providing reliable anesthesia.
- Spermatic Cord Block: Infiltration of local anesthetic around the spermatic cord in the neck of the scrotum.
Systemic Analgesia
Systemic administration of non-steroidal anti-inflammatory drugs (NSAIDs) is recommended to manage post-operative pain.
- Meloxicam: Administered orally or injectably, providing long-lasting analgesia (half-life of 20–26 hours).
- Flunixin Meglumine: Commonly administered intravenously for rapid anti-inflammatory effects.
Dystocia Management
Obstetric emergencies in cattle require quick assessment to determine the safest method of delivery.
Fetotomy
A fetotomy is the surgical dissection of a dead fetus in utero to facilitate vaginal delivery.
- Indications: A dead fetus that cannot be delivered due to relative size or postural abnormalities.
- Contraindications: A live fetus, a severely narrow maternal pelvis, or incomplete cervical dilation.
- Technique: Uses a Gigli wire saw inside a Utrecht fetotome. Clean, precise cuts are made to amputate limbs, head, or trunk, minimizing maternal trauma and avoiding major abdominal surgery.
Caesarean Section (C-Section)
- Indications: A live fetus with absolute or relative oversize, incomplete cervical dilation ("ringwomb"), uterine torsion that cannot be corrected vaginally, or a dead, emphysematous fetus where a fetotomy is impossible.
- Surgical Approach: The standing left flank laparotomy is the standard. The rumen acts as a natural barrier, keeping the small intestines from prolapsing through the incision site.
Bovine Regional Anesthesia for Flank Surgery
Flank laparotomies require complete anesthesia of the skin, muscles, and peritoneum.
| Block Type | Technique | Advantages | Disadvantages |
|---|---|---|---|
| Inverted L | Non-specific infiltration of 60–100 mL lidocaine along a line cranial and dorsal to the incision. | Simple, requires no anatomical precision. | Large volume of lidocaine required; incomplete anesthesia of deep muscle/peritoneum. |
| Proximal Paravertebral | Targets T13, L1, L2 at their exit from the intervertebral foramina (cranial edge of transverse processes of L1, L2, L3). | Complete, uniform anesthesia of all layers; causes scoliosis (spine bends toward the blocked side), opening the incision. | Technically challenging; risk of penetrating major blood vessels (aorta/vena cava). |
| Distal Paravertebral | Targets T13, L1, L2 at the distal tips of the transverse processes of L1, L2, L4. | Easier and safer to perform than proximal; no scoliosis. | Requires larger volume of anesthetic per site; variable blocks if anatomical landmarks are fat-obscured. |
| Caudal Epidural | 5–10 mL lidocaine injected at S5-Co1 or Co1-Co2. | Blocks tenesmus; desensitizes perineum, vulva, and caudal vagina. | High volume causes recumbency (motor blockade of hindlimbs). |
A veterinarian is preparing to perform a standing Caesarean section on a heifer with a live calf. The clinician wants to use a regional anesthetic technique that provides uniform, deep desensitization of the skin, muscles, and peritoneum of the left flank, while also causing a characteristic lateral bending of the spine (scoliosis) towards the desensitized side. Which technique is most appropriate?
A beef producer needs to dehorn several 6-month-old calves. To provide adequate local anesthesia for the procedure, the veterinarian performs a cornual nerve block. At which anatomical site should the local anesthetic be deposited?
A dairy cow is presented with severe dystocia due to a dead, emphysematous fetus. The cervix is fully dilated, and the birth canal has adequate room for instrument manipulation. What is the most appropriate management strategy for this case, considering maternal welfare and prognosis?