Surgery Flashcards
You are presented with a male horse that has no palpable testicles that the owner believes has been castrated. It is however showing marked stallion like behaviour. How would you decide whether or not this horse still had testicular tissue. The owner has a second colt for castration. What equipment and drugs would you take to anaesthatise this colt for castration in the field. Give brief reasons for your choices. Following castration, a number if possible complications can arise. List 4 complications and indicate how you would manage each complication. (4,12,4,10)
Stallion like behaviour can be a behavioural/neurological problem, but it is most likely the horse is a cryptorchid (rig)- probably bilateral, as a horse should not be castrated without two palpable testicles. If the horse is over 3 years old, a single oestrone sulphate blood sample can be taken. If the horse is under 3 years old, a stimulation test using hCG is undertaken with pre and post blood samples. A cryptorchid is likely to have a higher pre sample testosterone level and will stimulate.
We have not examined this horse before, so we are unsure if the colt is suitable for a standing castrate, or whether it will need a GA in the field. This means we must be prepared for both.
Standing- sedative drugs (romifidine/detomidine alpha 2agonists depending on preference, xylazine likely to be too short acting. Both should be combined with an opioid (torbugesic) to reduce the likelyhood of the colt kicking and to improve the sedation.
Need an NSAID- Phenylbutazone most likely- IV on the day and an oral course for about 5 days afterwards (ensure horse signed out of food chain). Prophylactic broad spectrum antibiotic cover also sensible- penicillin IM on the day and then oral TMPS for 5 days. Also need to check tetanus cover, if already vaccinated (ideal), may consider bringing the booster forwards to ensure it was within last 6 months. If not, give tetanus toxoid and tetanus antitoxin at the same time at opposite ends of the horse.
If hairy, may need to clip the scrotal area, so need an electric extension, and clippers. Then scrub site with hibiscrub (chlorhexidine) or povidine-iodine followed by surgical spirit.
Next, local anaesthetic needs to be infiltrated into the scrotal skin, spermatic cord and possibly the testicular body. Bupivicaine, lidocaine, mepivacaine or procaine possible.
The site is scrubbed again, the surgeon scrubs and opens their kit. Need a tray/table to put out kit on and a sterile drape. Kit contains buzzido emasculators to cut and crush cord, 10 blade scalpel to incise skin, scissors to extend that incision or trim tunic if necessary, multiple haemostats to clamp vessels, and to hold the cord while it is clamped. Suture material and needle holders should be available in case a vessel needs ligating, though the incision should be left open to drain in a non sterile environment.
If the horse needs a GA extra equipment(large, older than 3, difficult to handle or one testicle inguinal)- place a shirt stay catheter to maintain IV access. Acepromazine to predmedicate- long lasting sedation, if a GA is required, it is proven to improve survivability, most likely through a cardioprotective effect.
Ketamine/thiopentone/GGE to induce, ketamine needs to be topped up every 10-15 minutes. Thio/GGE can be part of a triple drip. Oesophageal ET tube to maintain airway.
Complications-
Swelling (oedema)- ensuring adequate drainage from incision, antiinflammatories and enforced exercise.
Haemorrhage- haemostasis using haemostats or ligate the vessel if possible, if not, pack the scrotum with swabs (possibly soaked in ice cold saline or phenylephrine if possible) and hold closed with haemostats, if still struggling to control may need a GA to localise vessel and ligate or referral.
Infection- immediate infection covered by antibiosis and adequate drainage from incision. Abscessation of the spermatic cord (schirrous cord) can occur between months and years after the castration, see a purulent discharge and hard swelling of the remaining cord. Treated by surgical resection of the cord.
Eviseration- owners can see many types of tissue hanging down from the scrotum after castration, the tunica albuginea is the least serious and can just be trimmed, omentum appears stringy and red and can be large, again the stump needs trimming and cleaning before the tunic is closed. Intestines are the most serious and require urgent referral for a GA and ex lap. Wrap the intestines up to the body in a moist sheet to protect them from bring trampled.
List the differential diagnoses for epistaxis in the horse. Detail your clinical exam, outlining the diagnostic tests you would perform, specifying findings that might confirm the differentials you cited. (4,8)
EIPH
Progressive ethmoid haematoma
Guttural pouch mycosis
Rupture of rectus capitus ventralis muscle
Iatrogenic ethmoid trauma (with endoscope) or other trauma
Fungal rhinitis
Sinusitis (normally secondary to purulent discharge)
Systemic status, and amount/colour of blood (if very large volume or systemic signs of hypovolaemia GP mycosis a concern) (very dark can indicate ethmoid hameatoma as haemosiderin darkens)
Unilateral/bilateral (unilateral usually rostal to the nasal septum, eg ethmoid haematoma, trauma, sinusitis,can vary)
Airflow (ethmoid hameatmoa may obstruct/partially obstruct air flow)
History of trauma/kick (rearing for rectus muscle)
Endoscopy- should visualise location of blood.
previous episodes, dysphagia, facial swelling, after exercise (eiph)
Radiography sinuses/teeth roots, ethmoid haemtomas
- List three common conditions of the guttural pouches (3 marks). For any one of these describe how you would manage this case (7 marks)?
guttural pouch empyema (strangles)
guttural pouch mycosis (aspergillus fumigatus)- haemorrhagic vs neurological (dyshagia)
stylo-hyoid arthropathy
guttural pouch tympany in foals (congenital defect where air accumulates- surgery to allow air to drain)
Guttural pouch mycosis can present as epistaxis or dysphagia.
If haemorrhagic, it is possible that the fungal plaque has invaded the internal carotid artery, this produces profuse red haemorrhage that can lead to death. This can be confirmed via endoscopy to localise the source of bleeding. This is an area that is very difficult to put pressure on and stop bleeding, so treatment options are restricted to arterial occlusion (intra-luminal balloon, ligation, coil embolism) or topical antifungals and or supportive care.
If neurological, the fungal plaques can be invading any of the cranial nerves that pass within the guttural pouch (9,10,11,12). The loss of function could require an oesophagotomy feeding tube to provide support until function improves. Again treated with topical antifungals.
Guttural pouch empyema can be acute (retrophryngeal lymphadenopathy) or chronic (chondroids) and is associated with Strep equi equi infection. Can be diagnosed by endoscopy or possibly radiography, may be associated with a nasal discharge (uni/bilateral). Can lead to dysphagia via dorsal pharyngeal compression and dyspnoea. Condroids less of an acute issue, tend to cause carriers. Solid inspissated pus, insoluble, requires surgical removal.
Supportive care and therapy and antibiotics only if acute (TMPS)
- List three different surgical techniques of castration (3 marks), indicating the advantages and disadvantages of each (7 marks)?
Standing closed castrate- requires less people and equipment (often cheaper), no associated GA risk, may be difficult depending on handling of colt, can’t be done if cryptorchid or inguinal. Increased risk of complications esp haemorrhage if older animal with larger testes.
GA closed (field)- can be done in the field assuming appropriate conditions (large open area which is relatively clean), requires more people to monitor GA and risk of GA. Can be done if inguinal cryptorchid or larger older animal as can get better visualisation for haemostasis.
GA open (only under sterile conditions)- must be done under sterile conditions and often the most expensive. Needs an operating theatre and appropriately trained personnel. Can get better ligation and can close the skin after. Could do modified closed and close tunic to reduce risk of herniation. Can do at the same time as abdominal surgery to remove a cryptorchid. GA risk.
- Outline the care of the case of post-operative colic in the first 48 hours post surgery (10 marks).
Recurrence Ileus- impaction Endotoxaemia Pain Haemorrhage Fractures in recovery Surgical site infection dehisence hernia
Rope or other assisted recovery
Allow time to reduce ataxia before moving
Stent or belly bandage to cover wound
Move to icu
Hourly checks for TPR, wound, dressing, borborygmi, mms, CRT, pulses, DPs, faecal output, water and food intake
Give bran mash or mashed nuts first until passed faeces, then give grass or soaked hay in small handfuls- slowly increase as long as faecal output normal. No dry hay or hard feed. Could put in tiny turn out paddock on second day
Continue on fluids until eating normally, monitor electrolytes
Antibiosis- pen and gent if urinating IV and metronidazole,
Pain relief- flunixin better for visceral pain, unlikely to mask surgical recurrence
Sodium iodide for endotoxaemia. Metaclopramide if non obstructive.
Describe your diagnostic approach to a 4 year old horse which shows stallion-like behaviour, but with no palpable testes and a scrotal scar (6 marks). Briefly outline possible surgical techniques (4 marks).
History- were two testicles removed, behaviour, when was it castrated (late may be learned behaviour) other signs
Clinical exam general, check scrotal scar, palpate inguinal region, could attempt rectal, large crest
Diagnostics- one blood sample to measure oestrone sulphate, if high likely to have retained testicular tissue. If under 3 stimulate using hCG
Inguinal- can be done in the field under GA if palpable, cut down, identify, exteriorise, use emasculators for 2 minutes then cut, close wound
Abdominal- needs to be done under sterile conditions via ex lap, laparoscopic
A horse presents to you with the owner complaining that it is heard to make an inspiratory noise at exercise. Describe how you would diagnose the cause of this noise (6 marks) and the treatment options you may consider (4 marks).
History- job, age, when it started, exercise intolerance, when it happens (what level of excercise), poor performance, any other signs
Clinical- general clinical exam, palpate larynx (cad atrophy makes more prominent on left), thoracic auscultation, oral exam, listen to the horse doing its normal job if possible, look if inspiratory (leg position, in air breathing in), listen for recovery time.
Endoscopic examination of larynx at rest and if normal over ground exercising endoscopy (minimal sedation).
Tie back (prosthetic laryngoplasty) fixed arertynoid open, nm pedicle graft from omohyodius, hobday (remove lateral ventricle), ventriculocordectomy (and affected vocal cord), partial aretynoidectomy, tracheostomy, retire to less athletic career.
- Describe, the surgical technique that you would use to castrate a 2 year old colt. Describe how you would modify your surgical technique for the castration of a 10 year old stallion. (12)
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- A lame horse presents with an acute 6cm transverse laceration over the distal lateral third metacarpal (‘cannon bone’). What structures in this vicinity are you concerned about being damaged? (6 marks)
Describe how this case should be evaluated, listing possible findings for each diagnostic method (6 marks).
Suspensory ligament, deep digital flexor tendon, superficial digital flexor tendon, annular ligament, fetlock joint, metacarpal three, vascular structures such as the palmar digital artery and vein, lateral palmar metacarpal nerve.
Sedate the horse, ask about tetanus, give anti toxoid if not vaccinated in the last six months.
Put on gloves and digitally explore the wound. See how far it extends, feel for any tears in underlying structures and see if it seems to extend to the fetlock. See if there is continuous bleeding suggesting vascular compromise.
Ultrasound, assess integrity of the structures present, and tears, irregular borders, hypoechoic areas etc.
Radiography, assess for any bone damage, use contrast to assess if fetlock infected and septic joint is therefore present.
Advanced imaging such as an MRI may be warranted.
- After performing a rectal examination, you notice that you have blood on your rectal sleeve. USING BULLET POINTS, DESCRIBE your approach to investigation of the source of blood (6 marks). BRIEFLY DESCRIBE the grades of rectal tear (2 marks) and BRIEFLY OUTLINE a treatment plan for 1 grade of your choice (2 marks).
A) If horse has not had it, Buscopan.
Appropriate chemical and physical restraint.
Epidural or lots of local per rectum.
Bare-arm rectal to assess bleed and location.
Carefully evacuate.
Pack oral to prevent more contamination.
B) grade 1 - mucosa only, grade 2 - muscularis only, grade 3 - mucosa and muscularis, grade 4 - all layers, abdominal contamination with faeces.
Grade 1 - antibiotics, NSAIDS, temporary rectal liner, monitor healing and prevent contamination.
- LIST THREE complications of castration in the horse (3 marks) and, for EACH, DESCRIBE how you would TREAT the complication (7 marks).
Haemorrhage - usually cutaneous vessels and self limiting, if it is the larger external pudendal or testicular artery need to address. Look at hr and mm, if greater than 30mins or stream need to take action. pack the scrotum with swabs and towel clamp skin edges and leave for 24hlurs, apply pair of haemostats to the bleeding vessel and leave on for 24hours, apply haemostats then apply a ligature above if still bleeding. Refer if still bleeding.
Infection - acute or chronic - if acute abscess, usually too early a seal, febrile horse, swollen scrotum and prepuce, very stiff hindquarters, drain, open incision, resolves in a week normally.
Chronic - schirrous cord, can be months to years later, very firm scrotal swelling and purulent draining tracts, comes and goes, dissect, ga, remove fibrous mass and resect infected cord as deep to inguinal canal as possible.
Evisceration - prolapse of intestinal viscera through inguinal canal and out the scrotal incision, usually omentum, sometimes intestine. Replace in scrotum and suture or towel clamp, appropriate sling support and refer.
- You are asked to examine an 18 year old Arabian gelding with moderate signs of colic of 4 hours duration. Describe the evaluation procedures required to determine whether or not the horse requires surgical investigation. (12 marks) Following rectal examination there is fresh blood on the rectal sleeve and a rectal tear is suspected. How should the case be evaluated further? (8 marks) What are the treatment options for a rectal tear? (10 marks)
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You are called to examine a horse with a de-gloving injury to the palmar aspect of the fetlock on the LF. Describe how you should determine the extent of the injury (7 marks) and how you should treat the skin wound (5 marks).
Assessment - sedate, clip, clean to prevent contamination of deeper structures before exploration, explore with gentle digital palpation with a gloved hand, determine synovial involvement whether a joint or tendon sheath, determine osseous damage. Determine synovial involvement by injecting saline into the join or tendon sheath, if it comes out in the wound it is septic. Can do contrast radiography to assess leaking. Can ultrasound to assess integrity of underlying tissues.
Treatment - anaesthetise with local/regional analgesia - low four block. Then debride as devitalised tissue results in prolonged healing and is a good bacterial environment. Debride grossly non viable tissue with a scalpel, curettage of exposed cortical bone, avoid excising flaps of skin that can protect deeper tissue.
Lavage, high pressure good, would prefer chlorhexidine.
Closure determined by various factors - degree of wound contamination, whether tissue is lost or not, degree of damage to deep structures, horse temperament and financial constraints. Primary, delayed primary and secondary closure are options available.
- You are called to examine a horse with unilateral purulent nasal discharge. You are suspicious of a tooth root abscess and secondary sinusitis. OUTLINE your diagnostic approach to the case (5 marks) and methods to extract a maxillary cheek tooth if indicated (3 marks). DESCRIBE how you would treat the accompanying sinusitis? (2 marks) LIST post-operative complications that you might you warn the client about? (2 marks).
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- You are called to an 18 year old pony gelding found down and rolling in the field this morning. He was last seen normal the previous evening. DESCRIBE your clinical assessment of this case (6 marks). LIST factors indicating that a horse with acute colic needs to be referred (6 marks).
History - changes in management, worming history, dental history, feeding regime, previous colics.
Clinical assessment - Buscopan (after clinical parameters assessed), IV pain relief with flunixin, systemic examination (HR, RR, CRT, mucous membrane colour, borborygmi), rectal examination (impaction, bicycle tyres, gas filled viscous), nasogastric tube for reflux, ultrasound and abdominocentesis.
Factors indicating referral - HR>80, pain signs even with intravenous pain relief, reflux of greater than 8litres, pale mucous membranes, CRT>2 seconds, abdominocentesis serosanguinous, absence of gut sounds, feeling bicycle tyres on rectal, ultrasound a small intestinal lesion.
