Rumenatomy Lecture Notes PDF

A CRASH COURSE IN RUMENOTOMY CF Omar Bernardino D. Domingo, DVM, MSc  Relevant Anatomy The rumen and reticulum accommodate most of the microbial fermentation during digestion. They are divided from each other by the same mechanism that the rumen itself is partitioned, by the internal p...

A CRASH COURSE IN RUMENOTOMY CF Omar Bernardino D. Domingo, DVM, MSc  Relevant Anatomy The rumen and reticulum accommodate most of the microbial fermentation during digestion. They are divided from each other by the same mechanism that the rumen itself is partitioned, by the internal pillae formed by internal projections of the rumenal wall. Externally, the pillae appear as grooves. Loading…  The ruminoreticular fold demarcates the rumen from the reticulum. The rumen itself is divided into dorsal and ventral sacs by the ruminal pillars, and cranial and caudal blind sacs by the coronary pillars. A cranial pillar further divides the dorsal sac into a ruminal atrium, which is most closely associated with the reticulum. Loading…  The reticular-omasal and esophageal orifices are located in the reticular groove, which runs down the right internal surface of the reticulum from the cardia to the fundus. The mucosal lining of the reticulum is characterized by honeycomb shaped ridges that house a collection of short papillae. This honeycombed appearance subsides at the ruminoreticular fold as it merges into the papillated mucosa of the rumen. These projections are associated with a subepithelial capillary plexus that facilitates the absorption of the volatile fatty acid by-products of microbial fermentation.  Indications Removal of metallic foreign bodies traumatic reticulitis or traumatic reticuloperitonitis, Removal of materials (twine or plastic bags ) that are obstructing the reticulo-omasal orifice Removal of foreign bodies lodged in the distal esophagus or over the base of the heart.  Indications Evacuation of rumen contents Rumen impaction Impaction and atony of the omasum or abomasum Traumatic Reticuloperitonitis (hardware disease)  Swallowed metallic objects, such as nails or pieces of wire, fall directly into the reticulum or pass into the rumen and are subsequently carried over the ruminoreticular fold into the cranioventral part of the reticulum by ruminal contractions. Contractions of the reticulum promote penetration of the wall by the foreign object. Perforation of the wall of the reticulum allows leakage of ingesta and bacteria, which contaminates the peritoneal cavity. The resulting peritonitis is generally localized and frequently results in adhesions. The object can penetrate the diaphragm and enter the thoracic cavity (causing pleuritis and sometimes pulmonary abscessation) and the pericardial sac (causing pericarditis, sometimes followed by myocarditis). cessation, or septicemia can develop.  Loading… Esophageal obstruction Rumen impaction  There are several techniques described for performing a rumenotomy Suturing the rumen to the skin prior to rumenotomy The use of fixation devices such as Weingarth’s ring The use of stay sutures The use of towel clamps to fix the rumen to the skin.  Rumenotomy by rumen skin suturing fixation. a) Skin incision. b) First suture bite through the rumen and skin. c) Completed suture, rumen is incised. Right square: Enlarged schematic of the suture pattern. Lower square: Suture pattern at dorsal and ventral comissures for better peritoneal seal.  Image : Dehghani, et al. 1995 Weingarth's ring rumenotomy. a) Application of Weingarth's ring, the rumen is anchored to the ring dorsally and ventrally. b) b) Rumen is incised and fixed to either side of the ring by hooks. Images: http://veterinarysciencehub.com/ Dehghani, et al. 1995 Stay suture rumenotomy The rumen is sutured to the skin ventrally, dorsally, cranially, and caudally prior to being incised. Image : Dehghani, et al. 1995  Rumenotomy by rumen skin clamp fixation a) The rumen is fixed to the skin dorsally and ventrally by 2 towel clamps. b) The rumen is incised and fixed to skin on either side. c) The ruminal incision is extended and fixed to the skin by more clamps. Lower square: Towel clamps properly applied to overlap rumen wall over the skin.  Anesthesia and Surgical Preparation The left-flank area is prepared for aseptic surgery in a routine manner, and local anesthesia is instituted by line block, inverted L block, or paravertebral block. Inverted L block  In a “line block” the analgesic agent is infiltrated along the line of incision. The infiltration of the analgesic agent into the incision line may cause edema and may affect wound healing Inverted L Block is the simplest technique of regional anesthesia for laparotomy and laparoscopy in large animals. It may be used to facilitate flank or paramedian interventions. Local anesthetic agent is administered nonspecifically in the form of an inverted L with a goal of blocking nerves within the surgical field. It is generally recommended that a dose of local anesthetic is limited to 2 mg/kg. The vertical portion of the inverted L is caudal to the last rib, and the horizontal portion is just ventral to the transverse processes of the lumbar vertebrae. 10-15 minutes should be allowed for the drug to take effect. Paravertebral Block  Paravertebral Block Described and utilized to desensitize the flank area for standing procedures in horses, cattle, sheep, and goats. In ruminants, the 13th thoracic nerve (T13), the 1st and 2nd lumbar nerves (L1 and L2), and the dorsolateral branch of the 3rd lumbar nerve (L3) supply innervation to the skin, fascia, muscles, and peritoneum of the flank. Regional analgesia of these nerves is the basis of the paravertebral block.  Surgical Technique Rumenotomy is performed through a left paralumbar incision (a 20- cm incision generally is sufficient) with the animal standing. In large cows, the flank incisions for rumenotomies sometimes are made just caudal and parallel to the last rib, to place the incision closer to the reticulum. It is essential, however, to leave sufficient tissue caudal to the last rib for suturing. (The incision should be approximately 5 cm [2 inches] caudal to the last rib.)  A continuous inverting suture pattern (similar to a Cushing pattern) is used, to pull the rumen over the edge of the skin incision.  Two large, inverting sutures are placed at the ventral aspect of the incision so that the rumen projects well over the skin edge. This avoids contamination in the ventral region  The rumen is incised with a scalpel taking care to leave enough room dorsally and ventrally for closure at the end of the procedure.  The operator, wearing long rubber gloves, evacuates and explores the rumen. The inside of the rumen and the reticulum are explored; and, if a foreign body is present, it is removed.  The rumen incision is closed with a simple continuous pattern using of no. 1 or no. 2 synthetic absorbable material  A single layer can be adequate, but a double row is generally used with the second row an inverting pattern with similar suture material. The surgical site is thoroughly irrigated with polyionic fluid after closure of the lumen and any contaminated gloves, gowns, or drapes should be replaced prior to removal of the rumen-fixation suture and second layer closure. No further exploration of the abdominal cavity should be done after closure of the rumen. Closure of the laparotomy incision has been described previously.  Postoperative Management Postoperative medication varies with the indication for the rumenotomy. Although rumen overload often requires intensive fluid therapy, Loading… traumatic reticulitis requires little intensive care. Antibiotics are indicated following the removal of foreign bodies from the reticulum. Oral fluids can be administered following rumenotomy; and mild osmotic laxatives, such as magnesium hydroxide, often promote gut motility.  Complications and Prognosis Potentially fatal peritoneal contamination may occur if a fluid-tight seal is not created between the rumen and abdominal wall. Incisional swelling and infection Peritonitis is also likely if one performs exploration of the abdominal cavity after closure of the rumen, no matter how clean you believe the site to be. THANK YOU. Surgical Corrections of Abomasal Displacements and Torsion CF Omar Bernardino D. Domingo, DVM, MSc Relevant Anatomy  Relevant Anatomy In general, the exact position of the abomasum in the living animal depends on: Rate and size of contractions of the rumen and reticulum Loading… Fullness of the other stomach compartments The abomasum’s activity The presence of a pregnant uterus The age of the animal. Relevant Anatomy  Relevant Anatomy The body of the abomasum lies on the abdominal floor with the cranial aspect of the fundus anchored to the reticulum, atrium, and ventral sac by muscular attachments. Loading…  Relevant Anatomy The pyloric part of the abomasum transverses the ventral abdomen toward the right body wall.  The lining of the abomasum is comprised of thick folds of glandular mucosa. The mucosa of the body and fundus contains peptic glands while the pyloric part secretes only mucous. At the flexure of the abomasum, the folds diminish to low rugae and a large, highly vascularized, thickening of the wall, called the torus, narrows the pyloric passage. Indications  Indications Dilation or displacement of the abomasum is considered to be one of the most common surgical conditions in ruminant patients. Displacements may occur to the left or right side (LDA or RDA), although most occur to the left side and are more common during the first month after parturition.  Indications ↑ Volatile FA’s ↑ Fermentation Gas accumulation and distension Abomasal displacement!  Abomasal displacement is believed to occur secondarily to abnormally high volatile fatty acid levels and excessive fermentation that lead to gas accumulation and distention. As a result of the gas, the abomasum may float up the abdominal wall on either the left or right side. Loading… Indications  Indications Right torsion of the abomasum (RTA) may occur to varying degrees. RTA generally have more acute clinical signs. Marked electrolyte changes (Cl and K levels) Torsion > exceeds 180° = VOLVULUS!  Although less common, right torsion of the abomasum (RTA) may occur to varying degrees. If the torsion exceeds 180°, it is termed a volvulus. The etiology of RTA is not completely understood, but the condition is thought to occur secondary to some cases of right-sided displacement of the abomasum. Animals with RTA generally have more acute clinical signs. In addition, they may have marked electrolyte changes, particularly in the chloride and potassium Abomasal volvulus is a serious condition that leads to complete obstruction of the outflow of ingesta to the duodenum  Indications Both LDA and RDA may be treated with right-flank omentopexy, with or without pyloropexy, and right paramedian abomasopexy. In addition, right-flank omentopexy and right paramedian abomasopexy may be used to treat select cases of RTA.  Indications Right-flank omentopexy was developed when the only alternative was paramedian abomasopexy, which required the patient to be in dorsal recumbency. In some cows, this position was undesirable, so a surgical procedure that could be performed with the animal standing had obvious advantages. Recumbency should be avoided in animals with compromised systemic conditions, respiratory distress, distended rumens, or those that are pregnant. The subsequent development of the flank abomasopexy techniques offered a third alternative.  Indications Right paramedian abomasopexy has several advantages: The abomasum is brought into position more easily in most cases, and instantaneous repositioning commonly occurs; The abomasum is easily viewed for detailed examination and detection of ulcers; and strong, positive, long-lasting adhesions can be anticipated.  Indications Right paramedian abomasopexy also has disadvantages: Not performed in standing position like the alternative surgical treatments for abomasal displacements and requires more assistance. Possible formation of an abomasal fistula if the retaining suture penetrates the lumen of the abomasum.  Indications The main disadvantage of this approach is that it is not performed in standing position like the alternative surgical treatments for abomasal displacements and requires more assistance. Another disadvantage is the possible formation of an abomasal fistula if the retaining suture penetrates the lumen of the abomasum. Indications Left-flank and right-flank abomasopexies are used to correct LDA and RDA, respectively. Right-flank abomasopexy may also be used to treat RTA.  Indications These techniques have the advantage of: Direct fixation of the abomasum to the ventral body wall and are performed with the animal in the standing position. Adhesions or ulceration of the displaced abomasum can be visualized and treated. One disadvantage of these techniques is: Abomasal anchoring achieved with the flank approaches is not considered as secure as that achieved with the right paramedian technique  Indications Furthermore, the site for abomasal fixation to the body wall can be difficult to reach in large cows or if the surgeon has short arms. Care is necessary to avoid puncturing viscera as the needle is carried to the floor of the abdomen. In some cases, the abomasum may be lying in a cranioventral position and may be difficult to expose sufficiently for placement of the suture. Auscultation during the clinical examination prior to surgery should identify the situation, and another approach may be considered. Anesthesia and Surgical Preparation  Anesthesia and Surgical Preparation Right-flank omentopexy, right-flank pyloropexy (pyloroomentopexy), and right- and left-flank abomasopexies are performed with the animal standing. The right or left paralumbar area is clipped and is prepared surgically.  Anesthesia and Surgical Preparation Local anesthesia is instituted by performing a paravertebral block, inverted L block, or a line block. If a left-flank abomasopexy is to be performed, an area from the xiphoid process to the umbilicus and from the midline to the right subcutaneous abdominal vein is also prepared surgically. Proximall paravertebral nerve block / Distal paravertebral nerve block / Farquharson technique Magda-Cakala technique  Anesthesia and Surgical Preparation Right paramedian abomasopexy is performed in dorsal recumbency. The animal is sedated (xylazine HCl 15–30 mg IV) and is cast in dorsal recumbency. Acepromazine or butorphanol tartate are also appropriate sedatives. The animal’s legs are tied, and its body is supported by a trough or weighted side frames. The patient should be tilted slightly to the right, to facilitate later closure of the incision  An area from the xiphoid process to the umbilicus is clipped and is surgically prepared in a routine manner. Local anesthesia is administered by local infiltration along the proposed incision or an inverted L block of the right paramedian area.  Loading… Surgical Technique Left-flank Abomasopexy  Left-flank Abomasopexy A left-flank laparotomy is performed using a 20- to 25-cm incision in the paralumbar fossa. Caution should be exercised when entering the abdomen because a distended abomasum may lie immediately within the incision area. Usually, the abomasum is visible through the incision.  Left-flank Abomasopexy An 8- to 12-cm simple continuous or interlocking suture line of heavy polymerized caprolactam, nylon, or polypropylene, is placed in the greater curvature of the abomasum 5–7 cm from the attachment of the greater omentum.  Left-flank Abomasopexy The serosa may be rubbed with a dry surgical sponge to mildly irritate the area and enhance adhesion formation. The suture bites pass through the submucosa, and a length of suture material should extend from each end of the suture line. Hemostats are placed on these suture ends in such a fashion that the cranial and caudal ends are easily identified. The abomasum may then be deflated using a 12-gauge needle and rubber tubing, if necessary. The needle is placed into the dorsal portion of the abomasum and is inserted at an angle to obviate leakage when the needle is withdrawn.  Left-flank Abomasopexy The cranial end of the suture is attached to a large, straight, cutting needle or to an S-curved cutting needle; This needle is carried along the internal body wall to a position right of midline, but medial to the subcutaneous abdominal vein and 15 cm caudal to the xiphoid process. The forefinger protects the end of the needle, and the lateral fingers reflect the viscera away from the body wall and ahead of the needle.  Left-flank Abomasopexy An assistant can apply upward pressure on the abdominal wall in the area where the needles are to be inserted through the body wall. An empty syringe case works well for this purpose Left-flank Abomasopexy  Left-flank Abomasopexy The caudal suture is placed through the body wall 8–12 cm caudal to the cranial suture. When the sutured area of the abomasum is lying against the floor of the abdomen, the assistant ties the suture ends together.  Left-flank Abomasopexy The assistant then grasps the two suture ends and applies gentle traction; at the same time, the surgeon pushes the deflated abomasum into its normal position. Care should be taken to tie the retention suture with appropriate tension. The surgeon should be able to have one finger snuggly between the abomasum and body wall when tied. Too loose may allow intestine to become entrapped in the suture loop while too tight may lead to tearing of the suture out of the abomasum.  Left-flank Abomasopexy The flank laparotomy incision is closed routinely. The suture is left in place for 4 weeks; the ends are then cut as close to the skin as possible. This time is considered necessary to allow the development of adhesions sufficient to prevent redisplacement. Surgical Technique Right Paramedian Abomasopexy  Right Paramedian Abomasopexy A 20-cm incision is made between the midline and the right subcutaneous abdominal vein, starting approximately 8 cm behind the xiphoid process and ending immediately cranial to the umbilicus  Right Paramedian Abomasopexy The small branches of the subcutaneous abdominal vein that are cut when incising the skin and subcutaneous tissue need to be ligated because the lack of muscle tissue in this region inhibits natural hemostasis and may result in hematoma and seroma formation.  Right Paramedian Abomasopexy The incision is continued through the external rectus sheath (aponeuroses of external and internal abdominal oblique muscles) and the rectus abdominis muscle.  Right Paramedian Abomasopexy The transverse abdominal aponeurosis and peritoneum are incised.  Right Paramedian Abomasopexy Rarely, in the case of an RDA or RTA, it may be appropriate to empty gas with a 12-gauge needle and rubber tubing (Figure 13.7E).  Right Paramedian Abomasopexy Once the correct position of the abomasum has been ascertained, the lateral aspect of the greater curvature of the abomasum (where it is free of omentum) is incorporated with the peritoneum and internal rectus sheath in a simple continuous suture pattern.  Right Paramedian Abomasopexy The heavy, external rectus sheath is closed with a simple continuous pattern and the skin is closed with a Ford interlocking suture (Figure 13.5G). Postoperative Management  Postoperative Management Postoperative management depends on the individual case. Some animals require little or no aftercare; other animals may have septic metritis, mastitis, or ketosis and may also have been deprived of feed and water. DEHORNING THE MATURE GOAT CF Omar Bernardino D. Domingo, DVM, MSc VSUR 153 Indications The mature goat is dehorned either to reduce the danger to man and other animals or if its horn(s) are broken. Some breed societies require dehorning to register the goat, although flock goats are generally left horned as protection from predators. Dehorning of male goats is sometimes combined with removal of the scent (horn) glands to reduce odor. Relevant Anatomy The cornual branch of the lacrimal nerve runs superficially across the supraorbital process and may be blocked halfway between the lateral canthus of the eye and the lateral base of the horn. The infratrochlear nerve may be blocked in between the medial canthus of the eye and the base of the horn on the medial side. Anesthesia and Surgical Preparation As with other ruminants, food should be withheld from the goat for 12–24 hours before surgery to avoid ruminal tympany, regurgitation, and possible aspiration pneumonia if general anesthesia is administered. Goats do not tolerate pain associated with even minor surgical procedures and can die of shock if sufficient analgesia is not provided. Although the exact cause of this shock is not known, it is believed to be a reaction to intense fear or fright from a combination of restraint and pain. All goats should be anesthetized or deeply sedated before dehorning. Cornual Blocks in Goats and Sheep Sedation needs to be supplemented with local analgesia of the horn. Once the goat is recumbent, the head region is clipped and prepared for a cornual nerve block and infratrochlear nerve block. The cornual branch of the lacrimal nerve is blocked by injecting 2 ml of local anesthetic as close as possible to the caudal ridge of the root of the supraorbital process to a depth of 1–1.5 cm. The cornual branch of the infratrochlear nerve is also blocked by injecting 2 ml of local anesthetic at the dorsomedial margin of the orbit. Cornual Blocks in Goats and Sheep In larger goats, a ring block around the entire base of the horn may be necessary Lidocaine should be used judiciously in goats to avoid toxicity; the minimal dose should be used. While the anesthesia is taking effect, the area around the horn is prepared for aseptic surgery. In larger goats, a ring block around the entire base of the horn may be necessary Lidocaine should be used judiciously in goats to avoid toxicity; the minimal dose should be used. While the anesthesia is taking effect, the area around the horn is prepared for aseptic surgery Instrumentation General surgery pack Obstetric wire saw, Gigli wire saw, or dehorning saw Rongeur (for cosmetic dehorning) Hemostats Surgical Technique The skin is incised 1 cm from the base of the horn. Enough skin must be removed from the caudolateral and caudomedial areas, where scurs are likely to occur. Surgical Technique While an assistant supports the goat’s head, the surgeon seats an obstetric wire saw or Gigli wire saw in the caudomedial aspect of the incision and removes the horn by directing the saw in a craniolateral direction Surgical Technique In male goats, the scent glands are located at the base of each horn (caudal and medial) and generally are removed during the dehorning procedure. Surgical Technique Hemorrhage from the superficial temporal artery can be severe and should be stopped by ligating the artery or by pulling and twisting it with a hemostat. Surgical Technique When a goat is dehorned correctly, its frontal sinuses are exposed because of the extensive communication between the lumen of the cornual process and the frontal sinus. Prior to bandaging, a topical antibacterial solution is applied onto the dehorning site Surgical Technique The head may be bandaged postoperatively to prevent both myiasis and the collection of foreign material in the sinus. Bandaging is not accepted by everyone. Some surgeons believe that the wound should not be covered and should be allowed to remain dry. If the wound is neglected, myiasis can develop under the bandage, and the consequences may be more serious than if the wound was left open. Cosmetic Dehorning Cosmetic dehorning has been described as a method to avoid the need for extensive postoperative management of an open sinus with bandages and wound monitoring. After horn removal, a rongeur is used to remove frontal bone to thus allow skin closure over the surgical site. The skin at the incision edges is undermined; release incisions may also be needed in the skin between where the horns were located in order to relieve enough tension to allow primary closure of the surgical site. The skin incisions are then closed with simple interrupted sutures. In some cases it is difficult to completely close the surgical site. However, the open segment of the partially closed wound left to heal by secondary intention is greatly reduced in size and the healing is much quicker. Skinsutures should be removed in 3 weeks. Postoperative Management Tetanus prophylaxis should be performed. If the animal’s head is bandaged, the first bandage should be changed on the second postoperative day and replaced. The second bandage is left on for an additional 5–6 days. Many animals will require bandages for extended periods before the sinus closes. In the summer, when flies are a problem, prevention of myiasis is important for several more weeks. Complications and Prognosis Dehorning can result in a reduction in milk production, impairment of spermatogenesis, sinusitis, myiasis, and loss of social status in the herd. The surgery should be planned to minimize these effects. For prevention of myiasis, the procedure should be reserved for the cooler months. Life threatening complications are rare and the prognosis is good. THANK YOU.