Veterinary · Clinical · also MSVE VSR-421
Surgery region by region, head to tail, in large and small animals, including rumenotomy, abomasal displacement, caesarean section and ovariohysterectomy.
In the exams: SAVC spay DOPS (bitch ovariohysterectomy); AVE Surgery OSCE (canine OHE on a model); NEB ovariohysterectomy requirement; ICAR AICE-JRF core group 07
Regional veterinary surgery is surgery organised by body region, head to tail, in large and small animals. Where general surgery teaches wound healing, asepsis, sutures and haemostasis, this subject applies those principles to particular operations: dehorning a heifer, replacing a cherry eye, ablating a diseased ear canal, opening a rumen to remove wire, fixing a displaced abomasum, delivering a calf by caesarean section, relieving a blocked urethra, castrating a colt, amputating a tail and spaying a bitch. For each procedure the practitioner needs the same six things: the indications, how to prepare the patient, the anaesthesia and approach, the principles of the technique, the complications, and the aftercare.
The subject matters because it is what most practising veterinarians do with a scalpel. In rural practice across South Asia, Africa and Latin America, rumenotomy, caesarean section, urolithiasis surgery and castration are routine standing field operations; dairy practice everywhere deals with abomasal displacement; companion-animal practice does spays, castrations, cystotomies, enterotomies and gastropexies every day. Dehorning, castration, tail docking and ear cropping are regulated differently by country, and the manual says so where it matters.
Exams test the subject in two ways. Written papers, from India's ICAR and state service tests to NAVLE, BCSE, the RCVS examination and national licensing tests, ask about anatomy relevant to nerve blocks, the names and steps of operations, and complications. Practical licensing assessments test one operation directly: the bitch spay is observed and scored in South Africa's registration examination and on a model in the Australasian examination, and certification of foreign graduates in North America requires it. This manual covers orthopaedic surgery only where a soft-tissue procedure involves the limbs; fractures and lameness belong to the separate orthopaedics subject.
Horns are removed to protect handlers and herd-mates from injury, to reduce bruising of carcasses and to let horned animals share feed faces and transport safely. Breeding for the polled gene removes the need altogether and is the welfare-preferred long-term answer where the breed allows it. Disbudding means destroying the horn bud in a young animal before the horn has attached to the skull; dehorning means removing an established horn. In the calf the horn bud is free-floating in the skin for roughly the first two months of life, after which the horn core grows from the frontal bone and the frontal sinus extends into it as the cornual diverticulum. That anatomical change is the reason age matters so much: disbudding a young calf is a skin-level procedure, while dehorning an older animal opens the frontal sinus. Kids should be disbudded within the first one to two weeks of life because their horn buds grow quickly. Their skull is thin, so prolonged contact with a hot iron can cause thermal injury to the brain, and the iron must be applied for short periods only. Laws on disbudding and dehorning differ by country: several jurisdictions require local anaesthesia, set age limits for each method, or restrict who may perform the procedure. Welfare codes also expect longer-lasting analgesia, usually a non-steroidal anti-inflammatory drug.
In cattle the horn is supplied by the cornual nerve, a branch of the zygomaticotemporal (lacrimal) nerve from the ophthalmic division of the trigeminal nerve. The nerve runs along the lateral edge of the frontal bone beneath the frontal (temporal) crest. The block is placed on the upper third of that crest, about midway between the lateral canthus of the eye and the base of the horn, inserting the needle just beneath the ridge of the crest, to a shallow depth that depends on the size of the animal. A commonly taught volume for an adult cow is 5 to 10 mL of 2% lidocaine per side — confirm against the product label and your national formulary. In mature cattle with large horns a ring block around the horn base supplements the cornual block, because some cervical nerve branches also supply the caudal skin. In goats the horn has a double nerve supply: the cornual branch of the lacrimal nerve and the cornual branch of the infratrochlear nerve. Both must be blocked, the second dorsomedial to the eye on the dorsomedial margin of the orbit. Goats are more sensitive to lidocaine toxicity than cattle, so the total dose is calculated on body weight and the drug is often diluted for kids. Lidocaine and other local anaesthetics have restricted or extra-label status for food animals in some countries, with withdrawal periods that vary.
Disbudding methods are thermal cautery with a hot iron, which destroys a ring of germinal tissue around the bud, and chemical cautery with caustic paste, which is permitted only in very young calves in some jurisdictions because it can burn the eyes and skin of the calf or its herd-mates. Dehorning methods for established horns include the gouge (Barnes-type dehorner) for smaller horns, the embryotomy wire (obstetric wire saw) and the dehorning saw for large horns, and a cosmetic dehorning in which skin flaps are raised and sutured over the opened sinus so it heals by first intention. Whatever the method, a ring of about 1 cm of skin around the horn base must be removed, or scurs (small, loosely attached horn regrowths) form. The main artery of the horn is the cornual artery, a branch of the superficial temporal artery, running along the same line as the nerve; it is controlled by pulling it out with forceps, by ligation or by cautery. The important complications are haemorrhage, frontal sinusitis (which may present weeks later with nasal discharge, head pressing or a draining sinus at the horn base and is treated by trephination and lavage), fly strike, scurs, and tetanus in unvaccinated animals. Horn cancer (squamous cell carcinoma of the horn core, mainly in zebu-type working cattle) and horn fractures are treated by amputation.
Ophthalmic surgery needs akinesia and analgesia. Akinesia of the eyelids comes from blocking the auriculopalpebral nerve, a branch of the facial nerve, where it crosses the zygomatic arch; this stops blinking but gives no sensation loss. Sensory block of the globe and orbit in cattle uses either the Peterson block, which deposits local anaesthetic near the foramen orbitorotundum to block the oculomotor, trochlear and abducens nerves and the ophthalmic and maxillary divisions of the trigeminal nerve together, or the four-point retrobulbar block, in which anaesthetic is injected at the dorsal, ventral, medial and lateral points of the orbit. Both carry risks: penetration of the globe, retrobulbar haemorrhage, injection into the optic nerve sheath with spread to the brainstem, and the oculocardiac reflex (bradycardia from traction on the globe). Small animals have general anaesthesia. At the eyelid margin, alignment is everything, because a step or a suture end touching the cornea causes ulceration.
Entropion is inward rolling of the eyelid margin so hair rubs the cornea; it may be primary (conformational, common in some dog breeds and in lambs) or secondary to pain (spastic). Lambs often respond to eversion with sutures, staples or an injected bleb; conformational entropion in dogs is corrected with the Hotz-Celsus procedure, in which an elliptical strip of skin and orbicularis oculi is removed parallel to the margin and the edges sutured. Ectropion, outward rolling of the margin, is corrected by wedge resection or by shortening procedures such as the Kuhnt-Szymanowski technique. Eyelid lacerations are repaired promptly in two layers, with a figure-of-eight suture at the margin so no knot touches the cornea; the eyelids are so vascular that even ragged flaps should be preserved, not trimmed. Prolapse of the gland of the third eyelid (cherry eye) is replaced, not removed, because the gland produces a large share of the tear film and excision predisposes to keratoconjunctivitis sicca; the pocket technique buries the gland in a conjunctival pocket. Third eyelid flaps and temporary tarsorrhaphy protect the cornea after injury or proptosis. Deep or melting corneal ulcers are supported with conjunctival pedicle grafts. Traumatic proptosis of the globe, common in brachycephalic dogs, is an emergency: the globe is replaced under anaesthesia and the lids are closed with a temporary tarsorrhaphy using stents, and the owner is warned that vision is often lost.
Enucleation means removal of the globe; exenteration removes the globe with orbital contents. Indications include a blind and painful eye (end-stage glaucoma), irreparable rupture, intraocular neoplasia, severe endophthalmitis and, in cattle, ocular squamous cell carcinoma (cancer eye), which is most common in cattle with unpigmented periocular skin, such as Herefords, and is promoted by ultraviolet light. Early small plaques of squamous cell carcinoma can be removed locally, with cryotherapy or by third eyelid excision if confined to it; extensive tumours need enucleation or exenteration. Two approaches are used. In the transpalpebral approach the eyelids are first sutured together and the whole of the lids, conjunctiva and globe are removed together; it is preferred for infection and neoplasia because the conjunctival sac is never opened. In the subconjunctival approach the incision is made at the limbus through the conjunctiva, the globe is dissected out within Tenon's capsule, and the eyelid margins are excised afterwards; it causes less bleeding and less tissue loss. In both, the eyelid margins and the third eyelid with its gland, and the conjunctiva, must be removed completely or a secreting cyst forms. Traction on the optic nerve must be avoided, particularly in cats, because the short optic nerve and chiasm transmit traction to the other eye and can blind it.
An aural haematoma is a blood-filled swelling of the pinna, forming within or beneath the auricular cartilage, usually on the concave surface. It is most common in dogs and cats that shake their heads or scratch their ears, so it nearly always signals an underlying problem: otitis externa, ear mites, atopic skin disease or a foreign body in the canal. Treating the haematoma without finding and treating the cause gives recurrence. Options range from drainage by needle aspiration (simple but high recurrence), placement of a drain or teat cannula, to surgical incision. The classic surgical method opens the haematoma with a straight or S-shaped incision on the concave surface, removes the clot and fibrin, and closes the dead space with through-and-through mattress sutures placed parallel to the main auricular vessels, tied over stents or not too tight so the pinna is not strangled. The incision is left open to drain.
The dog's external ear canal has a vertical part and a horizontal part, ending at the tympanic membrane, beyond which lies the middle ear in the tympanic bulla. Surgery is chosen by how far disease has spread. Lateral wall resection (often called the Zepp procedure) removes the lateral wall of the vertical canal to improve drainage and ventilation; it suits early disease in which the horizontal canal is still healthy, and it fails when the underlying skin disease is not controlled. Vertical canal ablation removes the vertical canal when it alone is diseased or holds a tumour. Total ear canal ablation with lateral bulla osteotomy is the procedure for end-stage otitis externa with calcified, stenotic canals, for middle-ear disease, and for canal tumours that cannot be removed by lesser procedures. All the epithelium of the canal and the lining of the bulla must be removed, or a deep abscess or draining tract follows months later. Hearing on that side is lost. Cosmetic ear cropping is prohibited or restricted in many countries. In cats, inflammatory polyps arising from the middle ear or nasopharynx are removed by traction-avulsion or, if they recur, by ventral bulla osteotomy. Facial nerve paralysis is the commonest important complication of total ear canal ablation, because the facial nerve leaves the stylomastoid foramen caudal to the horizontal canal and curves around it; the nerve must be identified and protected, and loss of the blink reflex needs lubrication of the eye while function returns. Horner's syndrome (miosis, ptosis, enophthalmos and third eyelid protrusion) follows damage to the sympathetic fibres that run through the middle ear and is more common in cats undergoing bulla surgery. Vestibular signs such as head tilt and nystagmus follow damage to the inner ear. Haemorrhage from the retroglenoid vein, which lies rostral to the external acoustic meatus, can be heavy.
Cleft palate is a congenital failure of the palatine shelves to fuse. A primary cleft involves the lip and premaxilla (cleft lip); a secondary cleft involves the hard and soft palate. Puppies and kittens with secondary clefts cannot suckle effectively and are at risk of aspiration pneumonia, so they are tube-fed until repair, which is usually delayed until the animal is about three to four months old, when the tissues are larger and anaesthesia is safer. The two standard repairs are the medially repositioned bipedicle flap technique, in which mucoperiosteal flaps are elevated from each side of the hard palate and slid to the midline, and the overlapping flap technique, in which a flap is hinged from one side and tucked under the opposite mucoperiosteum. Success depends on three rules that apply to all oral surgery: closure without tension, preservation of the major palatine arteries, and suture lines that do not lie directly over a defect. Acquired oronasal fistulas, often after extraction of a maxillary canine tooth, are closed with a mucoperiosteal or buccal mucosal flap following the same rules. Common oral tumours in dogs are melanoma, squamous cell carcinoma, fibrosarcoma and the acanthomatous ameloblastoma (formerly acanthomatous epulis), which is benign but locally invasive into bone. In cats squamous cell carcinoma predominates and carries a poor prognosis. A biopsy and imaging of the jaw (ideally computed tomography) precede definitive surgery, because the decision between local excision and partial mandibulectomy or maxillectomy depends on tumour type and bone involvement. Commonly taught margins are about 1 cm for benign but invasive tumours and about 2 cm for malignant ones. The tongue heals rapidly; lacerations are closed in layers with absorbable suture, and partial glossectomy is tolerated if less than about half the mobile tongue is removed. In cattle, a hard, swollen tongue with nodules and ulcers (wooden tongue) is actinobacillosis and is treated medically, not by surgery.
A salivary mucocele is a collection of saliva in tissues after leakage from a damaged gland or duct, lined by granulation tissue rather than epithelium. In dogs the sublingual gland is the usual source. It may appear as a cervical swelling, a sublingual swelling (ranula) or a pharyngeal swelling that can obstruct the airway. Drainage alone recurs; the treatment is removal of the mandibular and sublingual salivary glands on the affected side, which must be identified correctly. A ranula may also be marsupialised. A tracheostomy is an opening into the trachea through the ventral neck to bypass an upper-airway obstruction: an emergency temporary tube is placed through a transverse incision between tracheal rings that does not exceed half the tracheal circumference, and the tube needs constant suction and cleaning because it blocks with mucus. Oesophagotomy in the cervical region removes foreign bodies that cannot be retrieved by endoscopy. The oesophagus heals poorly because it has no serosa, a segmental blood supply and constant movement, so it is closed in two layers, the submucosa being the holding layer, and leakage leads to cellulitis and mediastinitis.
Opening the thorax collapses the lungs, so positive-pressure ventilation is mandatory from the moment the pleura is breached until the chest is closed and the pleural space evacuated. Lateral (intercostal) thoracotomy gives good access to one side and a defined region; the intercostal space is chosen from the target organ, for example the left fourth space for a patent ductus arteriosus and the heart base, and caudal spaces for the caudal oesophagus. The incision follows the middle of the space, through the latissimus dorsi, serratus ventralis or scalenus, and intercostal muscles, staying away from the caudal border of the cranial rib where the intercostal vessels and nerve run. Median sternotomy splits the sternum lengthwise, gives access to both hemithoraces and is used for exploration, cranial mediastinal masses and bilateral disease; it is closed with orthopaedic wire or heavy suture around or through the sternebrae. Before closure, a thoracostomy tube is placed through a separate tunnelled skin incision, entering the chest a few spaces from the skin entry so that air does not leak around it. Pain after thoracotomy is severe and reduces ventilation, so intercostal nerve blocks, intrapleural local anaesthetic and systemic opioids are used together.
Pneumothorax may be traumatic, spontaneous (often from ruptured bullae) or iatrogenic, and tension pneumothorax, in which air enters but cannot leave, is an emergency relieved by needle thoracocentesis. Traumatic diaphragmatic hernia, usually after road accidents, displaces abdominal organs into the thorax; the liver, stomach and intestine are the usual contents. Animals are stabilised before surgery unless the stomach is trapped and distending. Repair is through a ventral midline coeliotomy, which gives access to all of the diaphragm; contents are returned, the edges debrided only minimally and the tear sutured, then air is evacuated. Chronic hernias carry the risk of re-expansion pulmonary oedema, so collapsed lungs are allowed to re-expand slowly rather than forced. Patent ductus arteriosus is ligated via left fourth intercostal thoracotomy, taking care to identify and protect the vagus and recurrent laryngeal nerves that loop around the ductus. A sharp metal object swallowed by a cow lodges in the reticulum, which lies against the diaphragm close to the heart. Penetration causes traumatic reticuloperitonitis, and if the object passes through the diaphragm it may cause traumatic pericarditis. Early reticuloperitonitis is treated conservatively with a magnet, antimicrobials and confinement, or by rumenotomy to remove the object. Once pericarditis develops, with muffled heart sounds, splashing sounds, jugular distension, brisket oedema and a high heart rate, the prognosis is poor. Pericardiotomy by resection of the left fifth rib and drainage of the pericardial sac has been described and occasionally saves valuable animals, but most cases are culled, and the decision weighs welfare and economics. Prevention by magnets and good feed hygiene is more effective than any operation.
Rumenotomy means opening the rumen through a left flank laparotomy, usually in the standing animal. The commonest indication is traumatic reticuloperitonitis, where the surgeon empties enough of the rumen to reach the reticulum, palpates for and removes penetrating metal, and often leaves a magnet. Other indications are rumen impaction with indigestible material (plastic bags and ropes, a common problem where cattle scavenge in towns), grain overload when the rumen must be emptied quickly, toxic plant ingestion, and exploration of the forestomachs, including vagal indigestion and abscesses near the reticulum. A rumen fistula (rumenostomy) is a related procedure used for chronic recurrent bloat in calves and to provide access in research animals. Anaesthesia is regional: a proximal or distal paravertebral block of the thirteenth thoracic and first and second lumbar spinal nerves, or an inverted-L block, in which local anaesthetic is infiltrated along the caudal border of the last rib and the ventral border of the lumbar transverse processes. The paravertebral block gives a wider, more uniform field with less drug and no distortion of the incision line; the inverted L is simpler. Typical paravertebral volumes are 10 to 20 mL of 2% lidocaine per nerve in adult cattle — confirm against the product label and your national formulary.
A vertical skin incision of about 20 to 25 cm is made in the left paralumbar fossa, a hand's width caudal to the last rib and starting a little below the transverse processes. The external oblique, internal oblique and transversus abdominis muscles and the peritoneum are divided in turn. The abdomen is explored before the rumen is opened, and adhesions of the reticulum are noted. The key surgical principle is to keep rumen contents out of the peritoneal cavity and the wound. The rumen wall is fixed to the edges of the skin incision before it is opened, using a rumenotomy frame (Weingarth frame) with hooks, a rubber ring or sleeve, or a continuous suture between the rumen wall and the skin. The rumen is then incised, contents removed as needed, and the reticulum explored through the rumen with a gloved arm. Foreign bodies are removed, the reticulum wall and its adhesions are felt, and abscesses adherent to the wall may be drained into the reticulum. The rumen is closed with absorbable suture in two inverting layers, often a Cushing then a Lembert pattern, after which the fixation is released, the rumen surface cleaned and the gloves and instruments changed before the body wall is closed in layers (peritoneum with transversus, internal oblique, external oblique, then skin). The commonest complication is incisional infection, followed by localised or generalised peritonitis from contamination or leakage. After surgery, animals receive analgesia and, usually, antimicrobials chosen with the drug's food-animal status and withdrawal periods in mind. Fluid and electrolyte support continues if the animal is dehydrated or has a metabolic disorder, and rumen transfaunation with fluid from a healthy donor may restore microbial activity after grain overload. Prognosis depends on the original condition more than on the operation.
The abomasum normally lies on the ventral abdominal floor, right of the midline. When it loses tone and fills with gas it can float up. In left displacement (LDA) it moves between the rumen and the left abdominal wall; in right displacement (RDA) it moves up the right side, and it can twist about its mesenteric axis to form an abomasal volvulus (AV), which compromises blood supply and becomes an emergency. Most LDAs occur in high-yielding dairy cows within the first weeks after calving. Risk factors include a high-concentrate, low-fibre ration, reduced feed intake around calving, hypocalcaemia, ketosis, metritis, retained placenta and twins. Diagnosis rests on simultaneous auscultation and percussion: a high-pitched resonant ping over the left side between about the ninth and thirteenth ribs in LDA, or over the right side in RDA. A right-sided ping has other causes, such as gas in the caecum, spiral colon or rectum, so its location and shape matter. Cows with LDA have a reduced appetite, falling milk yield and often ketosis. Sequestration of hydrochloric acid in the obstructed abomasum causes hypochloraemic, hypokalaemic metabolic alkalosis; in severe cases the kidney conserves sodium and excretes hydrogen ions, producing paradoxical aciduria. In AV the cow is more ill, with dehydration, a rapid heart rate, scant dark faeces and a distended right flank; a high heart rate and severe dehydration are associated with a worse outcome.
Several methods exist and the choice depends on the surgeon, the facilities and the cow. Rolling the cow (casting her on her right side, rolling onto her back and rocking) can return the abomasum but recurrence is common without fixation. Closed methods fix the abomasum without opening the abdomen: in the toggle-pin technique, the cow is rolled into dorsal recumbency, the abomasum located by ping and a toggle passed through the ventral body wall into it; the blind-stitch technique passes a suture through the body wall and the abomasum. Both are quick and cheap but may catch the wrong viscus. Open surgical methods are more reliable. Right flank pyloro-omentopexy (the Hannover method), done standing through the right flank, brings the abomasum back by reaching across, deflating it if needed, and sutures the greater omentum near the pylorus to the body wall. Left flank abomasopexy (the Utrecht method) is done standing through the left flank: a suture is placed in the greater curvature of the abomasum and its ends are passed out through the ventral abdominal wall, right of the midline, and tied, fixing the abomasum in its normal position. Right paramedian abomasopexy in dorsal recumbency sutures the abomasum directly to the ventral wall and allows good visualisation. Laparoscopic techniques also exist. Concurrent ketosis, hypocalcaemia and metritis must be treated. RDA and AV are approached through the right flank with the cow standing. The distended abomasum is first decompressed with a needle attached to tubing, then the direction of twist is determined and the abomasum is derotated, often by working around the omasum and returning the pylorus to its normal position. The abomasum is then fixed, usually by pyloro-omentopexy. Post-operative care includes oral or intravenous fluids rich in chloride and potassium, calcium, and attention to appetite and rumen function. Cows with AV may still die after successful surgery from vagal nerve damage or abomasal necrosis. Herd prevention aims at transition-cow management: adequate effective fibre, a gradual change to the lactation ration, avoiding over-conditioned dry cows, controlling hypocalcaemia and ketosis, and good cow comfort.
A laparotomy (coeliotomy) is a surgical opening of the abdomen. In dogs and cats the standard approach is the ventral midline through the linea alba, which can be extended from the xiphoid to the pubis and gives access to every organ. Ruminants are usually operated standing through the right or left flank, under regional anaesthesia, because general anaesthesia risks regurgitation and bloat; ventral midline and paramedian approaches in dorsal recumbency are used for calves, for some abomasal and caesarean operations and when the abdomen must be explored widely. Exploration is systematic, organ by organ, so that nothing is missed. The linea alba is closed with a continuous or interrupted pattern that takes the external rectus sheath, the holding layer; a suture length at least four times the wound length in continuous closure (the 4:1 rule) reduces the risk of dehiscence. A hernia is the protrusion of an organ or tissue through an opening in the wall that normally contains it; a true hernia has a sac of peritoneum, a ring and contents. Umbilical hernias are common in calves and puppies and may be congenital; in calves they must be distinguished from umbilical infection (omphalitis, umbilical abscess, infected urachus or umbilical vessels), which is confirmed by palpation and ultrasound and may coexist. A reducible hernia with a soft, non-painful swelling is repaired electively by closing the ring after freshening its edges, with or without opening the sac; large rings in calves may need mesh. An incarcerated or strangulated hernia, hot, painful and irreducible, is an emergency. Inguinal and scrotal hernias occur in piglets, stallions, bulls and dogs; in pigs they must be recognised before castration, because castrating a ruptured piglet by the open method lets intestine eventrate.
Enterotomy, an incision into the intestine, is used mainly to remove foreign bodies and to take full-thickness biopsies. The loop is exteriorised, packed off and occluded on either side. The incision is made on the antimesenteric border, in healthy tissue just aboral (distal) to the foreign body, and closed with a single layer of appositional sutures, interrupted or continuous, in monofilament absorbable material; inverting patterns narrow the lumen of small intestine and are avoided there. A leak test, by injecting saline into the occluded segment, and covering the closure with omentum or a serosal patch add security. Linear foreign bodies, such as string anchored under the tongue in cats or at the pylorus in dogs, plicate the intestine and saw through the mesenteric border; the anchor is cut first, and multiple enterotomies or a gastrotomy may be needed. Where intestine is non-viable, judged by colour, wall thickness, peristalsis, arterial pulsation and bleeding when cut, the segment is resected and the ends joined by end-to-end anastomosis, with the smaller end cut more obliquely or spatulated if their diameters differ, and the mesenteric defect closed. The most dangerous complication is leakage and septic peritonitis, typically three to five days after surgery; risk is higher with pre-existing septic peritonitis, low serum albumin and poor tissue viability. Intussusception, common in young dogs and calves and often ileocolic, is reduced manually if possible or resected if not.
Gastric dilatation-volvulus (GDV) is distension of the stomach with gas and fluid followed by rotation about its long axis, most often in large and giant deep-chested dog breeds. The rotation is usually clockwise when viewed from the caudal end of a dog lying in dorsal recumbency, so the pylorus moves from the right side ventrally and to the left, dragging the spleen with it. Compression of the caudal vena cava and portal vein causes obstructive shock; gastric necrosis and arrhythmias follow. A right lateral radiograph showing a compartmentalised stomach with a displaced pylorus confirms it. Treatment begins with resuscitation, intravenous fluids and gastric decompression by orogastric tube or trocarisation. Surgery follows as soon as the dog is stable: the stomach is derotated through a ventral midline coeliotomy, its wall is assessed and non-viable parts are resected or invaginated, the spleen is removed if it is infarcted or its vessels thrombosed, and a permanent right-sided gastropexy is made. Without gastropexy, recurrence is very common; with it, recurrence is uncommon. In incisional gastropexy, a seromuscular incision in the pyloric antrum is sutured to an incision in the right transversus abdominis muscle caudal to the last rib; belt-loop, circumcostal and tube methods are alternatives. Prophylactic gastropexy, often laparoscopically assisted or done at the time of neutering, is offered for at-risk breeds. Ventricular arrhythmias are common in the first one to three days after surgery and are monitored by electrocardiography.
Caesarean section (hysterotomy) is indicated when vaginal delivery is impossible or more dangerous than surgery. Common indications in cattle are fetopelvic disproportion (an oversized calf or a small pelvis), incomplete cervical dilatation, uterine torsion that cannot be corrected by rolling or per vaginam, fetal monsters and malpositions that cannot be corrected, and uterine rupture. A live calf favours surgery; a dead calf that can be removed by a few cuts may be better delivered by fetotomy, and a dead, emphysematous calf raises the risk of peritonitis whatever the method. The standard approach is the left flank with the cow standing, under paravertebral or line block, because the rumen holds the intestines away from the field. Alternatives are the right flank (useful when the rumen is very distended), the left oblique ventrolateral approach with the cow in right lateral recumbency (useful for an emphysematous calf because the uterus can be exteriorised and contamination kept outside), and the ventral midline or paramedian in dorsal recumbency. Caudal epidural anaesthesia at the sacrococcygeal or first intercoccygeal space reduces straining but does not desensitise the flank, and a high epidural that makes the cow go down must be avoided in standing surgery.
Through a vertical incision in the left paralumbar fossa, the surgeon finds the pregnant horn and grasps a fetal limb through the uterine wall to bring the greater curvature of the horn into the incision. The uterus is incised along the greater curvature, over the fetal limbs, avoiding caruncles and large vessels and making the incision long enough to deliver the calf without tearing. The calf is delivered with chains on its limbs and its airway cleared. The placenta is removed only where it separates easily; forceful removal causes bleeding. The uterus is closed with absorbable suture in an inverting pattern; the Utrecht pattern (a continuous inverting suture with oblique bites that buries the knot) and the Cushing or Lembert patterns are standard, sometimes as two layers. The uterine surface is cleaned of blood and fluid before the uterus is returned, and the body wall is closed in layers. Oxytocin is commonly given to promote uterine involution and expulsion of the placenta, at a dose taken from the product label — confirm against the product label and your national formulary. Antimicrobials and an anti-inflammatory analgesic are given, with attention to withdrawal periods. Complications include peritonitis, adhesions, retained placenta, metritis, wound infection and reduced later fertility. In ewes and does the same principles apply; incomplete cervical dilatation (ringwomb) and fetal oversize are common indications, and the left flank or ventral approach is used.
Indications include primary uterine inertia, secondary inertia after prolonged labour, obstructive dystocia from fetal oversize or malposition, a narrow birth canal, and fetal distress shown by a sustained low fetal heart rate on ultrasound or Doppler. Brachycephalic breeds often need elective surgery. Anaesthesia is chosen so that drugs depress the puppies as little as possible: preoxygenation, a short-acting induction agent, inhalant maintenance, and local infiltration of the incision line are typical, while alpha-2 adrenoceptor agonists are usually avoided because they are linked with poorer neonatal survival; opioids given before delivery can be reversed in the neonates. The approach is ventral midline with the bitch clipped and prepared before induction to shorten the time the puppies are exposed to anaesthetic. The uterus is exteriorised and a single incision made in the uterine body or near the bifurcation, through which each puppy is milked toward the incision, the membranes removed and the cord clamped. The uterus is closed with absorbable suture, often two layers, the second inverting. Ovariohysterectomy can be done at the same time if the owner does not want further litters, or an en bloc technique can remove the whole gravid uterus quickly, with a team ready to extract and resuscitate the puppies within about a minute. Neonates are dried, suctioned, rubbed, kept warm and put to suck early.
Obstructive urolithiasis is a disease of male ruminants, especially castrated feedlot steers, wethers and bucks, because castration before puberty leaves the urethra narrower. The usual obstruction sites are the distal sigmoid flexure in cattle and the urethral process (the vermiform appendage) and sigmoid flexure in sheep and goats. Phosphate stones (struvite and calcium phosphate) form on high-concentrate, high-phosphorus rations with low calcium-to-phosphorus ratios; silica stones form on pasture in some arid regions; calcium carbonate stones are linked with legume-rich, high-calcium forage; oxalate stones with oxalate-rich plants. Affected animals strain, kick at the abdomen, swish the tail and dribble blood-tinged urine; the urethra may pulsate below the anus. Untreated, the urethra ruptures, causing subcutaneous urine accumulation along the prepuce and ventral abdomen ('water belly'), or the bladder ruptures, causing uroperitoneum. Uroperitoneum is confirmed when peritoneal fluid creatinine is at least twice the serum creatinine. Treatment depends on the animal's value and purpose. Amputating the urethral process in small ruminants often relieves obstruction temporarily, but stones higher up commonly recur. Tube cystostomy, placing a Foley catheter into the bladder through a paramedian laparotomy and out through the skin, preserves breeding ability and has a better long-term outcome; normograde flushing and medical acidification may dissolve some stones. Perineal or ischial urethrostomy creates a new urethral opening above the obstruction and is a salvage procedure for animals destined for slaughter, with frequent stricture. Prevention: a calcium-to-phosphorus ratio of about 2:1, urine acidifiers such as ammonium chloride for phosphate stones, salt in the ration to raise water intake, and easy access to clean water.
In dogs the commonest uroliths are struvite (magnesium ammonium phosphate, usually induced by urease-producing bacterial infection) and calcium oxalate; urate stones occur in breeds with a defect in uric acid metabolism and in dogs with portosystemic shunts; cystine stones are inherited. In cats struvite and calcium oxalate predominate and struvite is usually sterile. Struvite can often be dissolved medically with a calculolytic diet, plus antimicrobials when infection is present; calcium oxalate cannot, and must be removed. In male dogs, stones lodge commonly just caudal to the os penis. They are pushed back into the bladder by retrograde urohydropulsion and removed by cystotomy. Prescrotal urethrotomy removes stones that will not move and may be left to heal by second intention, with some bleeding for days. Scrotal urethrostomy, with castration and scrotal ablation, is used for recurrent obstruction because the urethra there is wide and superficial. Male cats with urethral obstruction are stabilised first: hyperkalaemia causes bradycardia and arrhythmias and must be treated before anaesthesia. Perineal urethrostomy is reserved for recurrent obstruction or irreparable distal urethral damage. The penile urethra is dissected free, the ischiocavernosus and ischiourethralis muscles are cut at their ischial attachments, and the urethra is opened up to the bulbourethral glands, where it is wide, and sutured to the skin. Stricture, urinary tract infection and incontinence are the main complications.
Cystotomy is an incision into the urinary bladder, done to remove calculi, to biopsy or excise masses, to repair trauma or to explore ectopic ureters. Through a caudal ventral midline coeliotomy (parapreputial skin incision in males), the bladder is exteriorised, packed off with moist swabs and held with stay sutures. The incision is usually made in the ventral or dorsal wall away from the trigone, where the ureters enter. Stones are removed with a spoon or by suction; the urethra is flushed normograde from the bladder and retrograde from the external orifice so that no stone remains. Stones go for quantitative analysis and a piece of mucosa or a stone for culture. Post-operative radiographs confirm that all radio-opaque stones are out, because incomplete removal is a well-recognised error. The bladder heals quickly, regaining near-normal strength within about two to three weeks. It is closed with monofilament absorbable suture in a single appositional layer or with one or two inverting layers; sutures should not enter the lumen if avoidable, and non-absorbable material is avoided because it can act as a nidus for new stones.
Castration is removal or destruction of the testes. It is done to control breeding, reduce aggression, improve handling and, in pigs, to avoid boar taint. It is painful whatever the method, and many countries now require anaesthesia or analgesia, restrict methods by age, or restrict who may castrate; for example, rubber rings are limited in several jurisdictions to the first days of life. Three methods exist in farm species. Open surgical castration incises the scrotum, exteriorises each testis and removes it by traction, by an emasculator or by ligation; it is certain, but leaves an open wound with risks of haemorrhage, infection, myiasis and tetanus. Bloodless (closed) castration with an emasculatome (a heavy crushing clamp) crushes each spermatic cord separately through intact skin, high on the neck of the scrotum; the two crushes should not meet across the midline, so that the scrotal blood supply in the median septum is preserved and the scrotum does not slough. It suits fly-prone and tetanus-prone areas but has a failure rate if the cord slips, so checking for testicular atrophy weeks later is advised. Rubber ring (elastrator) castration in young lambs and calves causes ischaemic necrosis of the scrotum and testes. Piglets are castrated through two scrotal incisions in the first days of life, after checking for scrotal hernia. Tetanus prophylaxis matters in all species. Vasectomy, removing a section of each vas deferens through incisions on the neck of the scrotum, produces a teaser ram or bull that retains libido for oestrus detection.
Colts are castrated standing under sedation and local anaesthesia, with local anaesthetic injected into the testis and spermatic cord and along the incision, or in lateral or dorsal recumbency under short general anaesthesia. Both testes must be palpable in the scrotum; a horse with a retained testis (cryptorchid, 'rig') needs a different operation, often by an inguinal or laparoscopic approach. Three techniques are described. In the open technique the vaginal tunic is incised and the testis and cord exteriorised without the tunic; it is quick but leaves the tunic open, giving a route for herniation. In the closed technique the vaginal tunic is not opened; the testis is removed inside the tunic and a ligature can be placed around the whole cord, reducing the risk of eventration; it suits older horses and those with large inguinal rings. The half-closed (semi-closed) technique opens the tunic only to check its contents, then closes the tunic around the cord. The emasculator is applied 'nut to nut', with the wing nut toward the testis, so that the crushing part sits proximally and the cutting edge distally; it is held for a few minutes. Scrotal incisions are left open to drain, and exercise reduces swelling. The main complications are haemorrhage, usually from the testicular artery; oedema; infection and funiculitis; scirrhous cord (chronic infection of the cord stump, often staphylococcal), which presents as a draining tract weeks later and needs excision of the stump; hydrocele; persistent stallion-like behaviour; and eventration, prolapse of intestine or omentum through the inguinal canal, a life-threatening emergency needing immediate surgery.
In dogs a single prescrotal incision on the midline just cranial to the scrotum is standard. Each testis is pushed into the incision, and in the closed technique the vaginal tunic is left intact and the whole cord is ligated; in the open technique the tunic is incised and the vessels and ductus are ligated separately. Tom cats are castrated through two scrotal incisions left open, the cord being tied on itself or ligated. Cryptorchidism, failure of one or both testes to descend, is heritable, so affected animals should not be bred and both testes should be removed; retained testes in dogs carry a higher risk of Sertoli cell tumour and of torsion. A retained testis is located by palpation of the inguinal region and by ultrasound, and abdominal ones are removed through a parapreputial or midline incision; the ductus deferens leads from the prostate to the testis. In bulls, chronic preputial prolapse (common in some Bos indicus and polled breeds) is treated by circumcision (reefing), and penile haematoma from rupture of the tunica albuginea during service is treated conservatively or surgically.
Tail docking is shortening of the tail in young animals for management or appearance; tail amputation is removal for a medical reason. Prophylactic docking of dogs for appearance is banned or restricted in many countries, with exemptions in some for certified working dogs; tail docking of dairy cattle is banned in some countries and states and is not supported by evidence of benefit to udder health or hygiene. In lambs, docking reduces faecal soiling and blowfly strike, but the tail must be left long enough to cover the vulva in ewe lambs and of similar length in males, because very short docking increases the risk of rectal prolapse. Rubber rings are commonly restricted to the first days of life, and requirements for anaesthesia differ by jurisdiction. Tail amputation in dogs and cats is indicated for severe trauma, non-healing tail-tip injuries ('happy tail'), neoplasia and tail-fold intertrigo in screw-tailed breeds. The tail is amputated through an intervertebral space, not through a vertebral body, after creating dorsal and ventral skin flaps long enough to close without tension. The median caudal artery on the ventral surface and the lateral caudal vessels are ligated. A tail avulsion in a cat can damage the sacral and caudal nerves; urinary and faecal continence must be assessed before amputation, because recovery depends on nerve injury rather than on the tail. In cattle, caudal epidural anaesthesia at the sacrococcygeal or first intercoccygeal space desensitises the tail, perineum, anus and vulva for tail and perineal procedures.
Perineal hernia is a failure of the pelvic diaphragm, the levator ani and coccygeus muscles, that lets rectal, pelvic and sometimes abdominal contents bulge beside the anus. It is a disease of older, intact male dogs, and hormonal influences, chronic straining from prostatic disease or constipation, and muscle atrophy all contribute. If the bladder is retroflexed into the hernia the dog cannot urinate, an emergency in which the bladder is decompressed by catheter or cystocentesis and the animal stabilised before surgery. The standard repair is internal obturator muscle transposition, in which the internal obturator muscle is elevated from the ischium and folded dorsally to fill the ventral part of the defect, then sutured to the external anal sphincter, coccygeus and levator ani remnants and the sacrotuberous ligament. Sutures placed around the sacrotuberous ligament must not catch the sciatic nerve, which lies just deep to it. Castration at the same time reduces recurrence. Complications include infection, faecal incontinence, rectal prolapse, sciatic nerve entrapment and recurrence.
Anal sacculectomy is done for recurrent anal sac infection or abscess and for anal sac neoplasia. Apocrine gland anal sac adenocarcinoma in dogs can cause hypercalcaemia of malignancy and spreads early to the sublumbar lymph nodes, so staging precedes surgery. In the closed technique the sac is dissected out intact from the external anal sphincter; damage to the sphincter or to the caudal rectal nerve causes faecal incontinence. Rectal prolapse occurs in young animals after straining from diarrhoea, parasites or tenesmus, and in piglets and calves; the cause must be treated. A viable, reducible prolapse is replaced and held with a loose purse-string suture around the anus that allows soft faeces to pass; a necrotic prolapse is amputated and the two layers sutured, and recurrent cases may need colopexy. Vaginal prolapse occurs in cows and ewes in late pregnancy. After cleaning, lubricating and replacing the prolapsed tissue under caudal epidural anaesthesia, it is retained by a Buhner suture, a buried purse-string of heavy tape placed subcutaneously around the vulva, tightened enough to admit about two fingers. The suture must be removed at the onset of parturition, or the vulva will tear. Because a predisposition to vaginal prolapse can recur in later pregnancies, many affected animals are culled.
Ovariohysterectomy (OHE) removes both ovaries and the uterus; ovariectomy (OVE) removes the ovaries only. Elective neutering prevents oestrus, unwanted litters and pyometra, and reduces the risk of mammary tumours in the bitch. Ovariectomy is widely practised in Europe and comparative studies in healthy bitches have not shown more pyometra or urinary incontinence after OVE than after OHE, provided all ovarian tissue is removed and no progestogens are given later; OHE remains the norm in many countries and the standard on which licensing practicals are assessed. Therapeutic OHE treats pyometra, uterine neoplasia, uterine torsion or prolapse, and some ovarian disease. Timing is debated. The often-quoted classic figures are that bitches spayed before the first oestrus have a much lower risk of mammary tumours than those spayed after one or two cycles, but systematic reviews have judged the evidence weak. Studies in some large and giant breeds have linked neutering before skeletal maturity with higher rates of some joint disorders and cancers, while other breeds show little effect. A balanced recommendation therefore depends on breed, size, lifestyle and the owner's ability to prevent mating. Surgery during oestrus or pregnancy is technically harder, with more friable, enlarged vessels and more bleeding.
The bitch is in dorsal recumbency. The skin incision is on the ventral midline, beginning just caudal to the umbilicus and running caudally in the cranial third of the caudal abdomen, because the ovaries lie well cranially in the bitch; in the queen the incision is in the middle third. After the linea alba is incised, the left uterine horn is found, often with a spay hook slid along the body wall, and followed to the ovary. The suspensory ligament, running from the ovary to the last ribs, is stretched or broken near the kidney so that the ovary can be exteriorised; this must be done without tearing the ovarian vessels. A window is made in the broad ligament just caudal to the ovarian pedicle. In the three-clamp technique, clamps are placed across the pedicle proximal to the ovary, the most proximal clamp is removed, and a circumferential ligature is placed in its crush; a second, often transfixing, ligature is placed, and the pedicle is cut between the remaining clamp and the ovary so the whole ovary comes away. The pedicle is grasped with forceps before the clamp is released and inspected for bleeding before it is returned. The same is done on the right side, where the ovary lies more cranially and is harder to reach. The broad ligament is torn or ligated if vascular, and the uterine body is ligated just cranial to the cervix, including the uterine vessels on each side, then transected. The cut ovaries are checked to confirm they are complete. The abdomen is inspected for bleeding and closed in three layers: the external rectus sheath, subcutaneous tissue and skin. Absorbable ligatures are used; braided non-absorbable material has been associated with granulomas and draining sinus tracts.
Haemorrhage is the commonest serious complication, usually from a slipped or loose ligature on an ovarian pedicle, or from the uterine vessels or broad ligament in a bitch in heat. Ovarian remnant syndrome, return of oestrous signs after spaying, follows incomplete removal of ovarian tissue; it is reported more often on the right, which lies more cranially and is harder to exteriorise, and it is diagnosed by hormone testing or by inducing ovulation, then confirmed at re-operation, preferably during oestrus or dioestrus when the remnant is easier to see. Stump pyometra and stump granulomas follow residual uterine tissue under progesterone influence or reactive suture material. Accidental ligation of a ureter, close to the uterine body or the caudal ovarian pedicle, causes hydronephrosis. Urinary incontinence from urethral sphincter mechanism incompetence develops in a proportion of spayed bitches, especially larger breeds, months or years later. Licensing practicals (South Africa, Australasia, North American certification) test the spay directly, and examiners score preparation and asepsis, gentle tissue handling, secure ligation, haemostasis checks, closure and post-operative planning, not speed. Pyometra is a progesterone-dependent infection of the uterus, usually in middle-aged and older intact bitches a few weeks after oestrus, and less often in queens. The cervix may be open, with a vaginal discharge, or closed, with a distended uterus that may rupture. Septic animals are stabilised with intravenous fluids and antimicrobials before prompt OHE. The uterus is handled gently because it tears easily, it is packed off from the abdomen, the vessels are ligated as for a routine spay, and the uterine body is ligated and transected with care to avoid spilling pus. Abdominal lavage is used if contamination occurs. Medical treatment is reserved for selected breeding bitches with open-cervix pyometra, and recurrence is common. In the queen, the flank approach is popular in some countries, especially in shelter programmes, while the ventral midline is preferred for pregnant or diseased cats; the small ovarian pedicle may be ligated or tied on itself.
As a student you will be expected to describe and, in clinics, to assist with or perform the core operations: a bitch or queen spay, a dog castration, a cornual block and disbudding, a standing left flank laparotomy on a cow, and a caesarean section. Learn the nerve block landmarks, because written papers ask them and in practice a poor block makes every step harder. Learn the steps of the spay until you can talk through them: incision site, finding the horn, breaking the suspensory ligament, the three-clamp technique, checking the pedicle, ligating the uterine body and the three-layer closure. Practical licensing assessments in several countries observe exactly that. For each operation, be able to state the indications, the approach, the main complications and how to prevent them, and know the welfare law on dehorning, castration and docking in your own country.
Five years into practice, regional surgery is a set of decisions made under pressure. A cow with a left-sided ping after calving: roll and toggle in a low-value cow, or a Hannover or Utrecht fixation in a high-yielder, with her ketosis and hypocalcaemia treated alongside. A heifer in dystocia: caesarean or fetotomy, standing left flank or recumbent ventrolateral, depending on whether the calf is alive. A wether straining to urinate: amputate the urethral process for a quick fix, or offer a tube cystostomy to save a breeding buck. A blocked tomcat with a slow heart: correct the potassium first. A retching Great Dane: decompress, resuscitate, then derotate and gastropexy. You will also advise clients on herd prevention of displacement and urolithiasis, which saves more animals than surgery.
With twenty-five years behind you, the work is judgement, teaching and systems. You decide when an operation is not in the animal's interest: a cow with traumatic pericarditis, an abomasal volvulus with a racing heart and dark faeces, a valueless wether with a ruptured urethra. You audit your own complication rates for spays, castrations and abomasopexies and change technique when they drift. You train new graduates in standing flank surgery and in safe spays, and you design herd programmes so that displacements, urolithiasis and hardware disease become rare. You also keep the practice inside changing law on dehorning, castration, docking and drug use in food animals, which differs between countries and is updated often.
At research level, the open questions are comparative and evidence-based. Which abomasal fixation gives the best long-term survival and milk yield per unit cost, and how do laparoscopic methods compare? What age of neutering balances mammary tumour, orthopaedic and behavioural outcomes in each dog breed, given that the classic mammary tumour data are weak? How much do NSAIDs and local anaesthesia change pain, growth and behaviour after dehorning and castration, and how should that evidence change law? Which nutritional and genetic factors drive urolithiasis in small ruminants in arid regions? Rigorous trials, registries and outcome studies in field conditions, especially in low-income settings where most of the world's food-animal surgery is done, are where a researcher can make a difference.
This manual gives principles and the standard operations, not step-by-step operative atlases. It does not yet cover orthopaedic and lameness surgery (a separate subject), neurosurgery, intraocular surgery such as cataract surgery, detailed dental surgery, equine colic surgery, laryngeal and upper-airway surgery in horses, teat and udder surgery, abomasal and intestinal surgery in calves beyond the principles given, minimally invasive and laser techniques in detail, or surgical oncology staging. Drug doses are given only as commonly taught local anaesthetic volumes; every dose must be confirmed against the product label and national formulary, and food-animal drug use and withdrawal periods vary by country. Laws on dehorning, castration, tail docking and ear cropping are summarised only in general terms because they differ by country and change often. Figures such as tumour margins, mammary tumour risk and recurrence rates are approximations from textbooks and are debated.
Original practice questions written to the syllabus and pattern of the exams named in each question's examTags. They are not past papers and do not reproduce any board's questions.
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