Royal College of Veterinary Surgeons Membership Exam (RCVS) Equine Medicine and Surgery Syllabus

What is the causative agent of tetanus, and why are horses highly susceptible?

Clostridium tetani; the neurotoxin tetanospasmin blocks inhibitory neurotransmitters (glycine/GABA) causing spastic paralysis. Horses are exquisitely sensitive; signs include 'sawhorse' stance, third eyelid prolapse, trismus (lockjaw), and risus sardonicus. Prevented by toxoid vaccination.

What is the classic stance and neurological grading concern in equine 'wobbler' syndrome (cervical vertebral stenotic myelopathy)?

Cervical vertebral malformation causes spinal cord compression giving symmetrical ataxia and proprioceptive deficits, typically worse in the hindlimbs (one grade worse behind than in front). Common in young, fast-growing Thoroughbreds; diagnosed by cervical radiography/myelography.

List the components of a systematic lameness examination in sequence.

1) History and signalment; 2) Static conformation/symmetry and limb palpation; 3) Hoof testers; 4) Dynamic exam (walk and trot in straight line, on circles, hard/soft surfaces); 5) Flexion tests; 6) Diagnostic (regional/perineural and intra-articular) analgesia; 7) Diagnostic imaging.

For a forelimb lameness, where does the head move relative to the lame limb during trot?

The head goes UP when the lame (painful) forelimb hits the ground and DOWN on the sound limb ('down on sound'). The horse offloads the painful limb by raising the head as it bears weight.

Describe the 'hip hitch'/pelvic movement asymmetry pattern indicating hindlimb lameness.

The horse shows reduced downward movement of the tuber coxae on the lame side and may 'hike' the hip (pelvic hike) on the affected side. Assessed by watching tuber coxae/sacrum rise and fall ('hip up' on the lame limb at impact).

What is the AAEP lameness grading scale and what does grade 3 mean?

AAEP scale 0-5. Grade 0 = no lameness; Grade 3 = consistently observable lameness at a trot under all circumstances; Grade 4 = obvious at a walk; Grade 5 = minimal weight-bearing or non-weight-bearing/inability to move.

What is the most common cause of forelimb lameness in horses, and which nerve block localises it?

Foot pain (e.g. navicular/podotrochlear syndrome, subsolar abscess, foot bruising) is the most common cause. A palmar digital nerve block (PD block) desensitising the heel/caudal third of the foot localises pain to the foot region.

What is a subsolar (foot) abscess, and the hallmark clinical presentation?

A focal pocket of infection beneath the sole/hoof wall. Hallmark: sudden, severe (often non-weight-bearing) lameness, increased digital pulse, heat in the foot, and a focal painful response to hoof testers. Treatment: pare and establish drainage, poultice.

Define navicular syndrome (podotrochlosis) and a typical clinical feature.

A chronic degenerative/inflammatory condition of the navicular bone, bursa and associated structures (DDFT, ligaments) of the caudal foot. Typically bilateral forelimb lameness, short/pottery gait, worse on hard ground/circles; relieved by PD or navicular bursa block; managed with corrective shoeing and bisphosphonates.

What is laminitis and the key clinical sign on examination?

Inflammation/failure of the laminae bonding the hoof wall to the distal phalanx. Key signs: bounding/increased digital pulses, the classic 'sawhorse'/rocked-back stance to offload the toes, heat in the feet, and reluctance to move; commonly affects both forefeet.

What radiographic measurements assess laminitis severity in the foot?

Founder (rotation) — angle between dorsal hoof wall and dorsal surface of P3; capsular/phalangeal rotation; sinking (increased distance from coronary band to extensor process); and dorsal hoof wall thickness (HL zone).

What is 'pedal osteitis' versus a 'keratoma' in the equine foot?

Pedal osteitis is demineralisation/inflammation of the distal phalanx (P3), often from chronic bruising/infection. A keratoma is a benign keratin mass arising from the hoof wall/sole that causes pressure, focal lameness and a characteristic lucency/notch in P3 on radiographs; treated by surgical excision.

What is osteoarthritis (degenerative joint disease) in the horse, and a hallmark radiographic sign?

Progressive degeneration of articular cartilage with secondary bone changes. Radiographic signs: osteophytes/periarticular new bone, joint space narrowing, subchondral bone sclerosis, and enthesophytes. Managed with intra-articular medication (corticosteroids, HA), systemic NSAIDs, and controlled exercise.

What is osteochondrosis (OCD) and the predilection sites in the horse?

A developmental orthopaedic disease — focal failure of endochondral ossification producing cartilage/bone flaps. Common sites: tarsocrural joint (distal intermediate ridge of tibia), femoropatellar joint (lateral trochlear ridge), and fetlock; presents as joint effusion +/- lameness in young horses; treated by arthroscopic removal.

Describe a 'bog spavin' versus a 'bone spavin'.

Bog spavin = synovial effusion/distension of the tarsocrural (hock) joint (soft swelling, often cosmetic). Bone spavin = osteoarthritis of the distal hock joints (centrodistal/tarsometatarsal) causing bony proliferation and lameness; spavin/hock flexion test positive.

What is a superficial digital flexor tendon (SDFT) injury ('bowed tendon') and a key ultrasound finding?

Strain-induced core lesion of the SDFT, common in racehorses, presenting with heat, swelling and a convex 'bowed' palmar metacarpus. Ultrasound shows a hypoechoic/anechoic core lesion with reduced cross-sectional fibre pattern; healing assessed by reduction in lesion size and fibre alignment.

What is a suspensory ligament desmitis, and how is proximal suspensory desmitis (PSD) typically blocked?

Inflammation/injury of the suspensory ligament (interosseous muscle). Proximal suspensory desmitis affects the origin at the proximal palmar/plantar cannon. Localised by a lateral palmar/deep branch lateral plantar nerve block (or local infiltration); hindlimb PSD has a guarded prognosis.

What is the 'check ligament' (accessory ligament of the DDFT) and the consequence of its desmitis?

The accessory ligament of the deep digital flexor tendon (inferior check ligament) connects palmar carpus to the DDFT. Desmitis causes localised swelling in the proximal-mid metacarpus and lameness; generally good prognosis with rest.

In diagnostic imaging of lameness, what modality is best for soft tissue (tendon/ligament) versus bone?

Ultrasonography is the first-line modality for soft tissue (tendons, ligaments, joint capsules). Radiography is best for bone (fractures, osteoarthritis, OCD). MRI images both bone and soft tissue (ideal for foot pain); scintigraphy detects active bone remodelling ('hot spots').

What is nuclear scintigraphy (bone scan) used for in equine lameness?

Scintigraphy uses technetium-99m-labelled bisphosphonate (Tc-99m MDP) that concentrates in areas of active bone turnover/inflammation, producing 'hot spots'. Useful for localising occult/multilimb lameness, stress fractures, and bone pathology not visible on radiographs.

Why is MRI considered the gold standard for investigating chronic foot pain in the horse?

MRI images both soft tissue and bone simultaneously, revealing lesions invisible to radiographs — e.g. DDFT lesions within the hoof capsule, collateral ligament injury of the DIP joint, navicular bone oedema/marrow change, and subchondral bone injury.

Name three key risks of general anaesthesia in the horse compared with small animals.

1) High mortality (~1% in healthy horses, much higher in colic) — far greater than small animals. 2) Myopathy/neuropathy from prolonged recumbency and poor perfusion (compartment pressure). 3) Hazards of recovery (fractures/injury during the violent standing phase). Also hypoventilation and V/Q mismatch/hypoxaemia in dorsal recumbency.

Describe a standard triple-drip (TIVA) for field/short equine anaesthesia.

'Triple drip' = Guaifenesin (GGE, muscle relaxant) + Ketamine (dissociative anaesthetic) + an alpha-2 agonist (xylazine/detomidine), given as a constant-rate infusion after induction. Provides short-term total intravenous anaesthesia with reasonable cardiovascular stability.

What is the typical sedation/induction protocol for equine anaesthesia?

Premedication/sedation with an alpha-2 agonist (xylazine, detomidine, or romifidine) +/- an opioid (butorphanol). Induction commonly with ketamine combined with a benzodiazepine (diazepam/midazolam) or guaifenesin; maintenance with inhalant (isoflurane/sevoflurane) or TIVA.

Why is hypoxaemia common in the anaesthetised horse in dorsal recumbency, and how is it managed?

Large abdominal viscera compress the diaphragm causing atelectasis and ventilation-perfusion (V/Q) mismatch with right-to-left shunting. Managed with intermittent positive pressure ventilation (IPPV), high inspired oxygen, and sometimes recruitment manoeuvres or beta-2 agonists (e.g. salbutamol).

What is post-anaesthetic myopathy and how is it prevented?

Muscle damage from poor perfusion/compartment pressure during prolonged recumbency, causing pain, hard swollen muscles, myoglobinuria and reluctance/inability to stand on recovery. Prevented by good padding, maintaining mean arterial pressure (>70 mmHg), avoiding hypotension and limiting anaesthesia duration.

What is a standing surgery in the horse, and name a procedure commonly done standing under sedation and local block.

Standing surgery avoids general anaesthesia risks by using heavy sedation (alpha-2 +/- opioid CRI) plus local/regional anaesthesia. Examples: castration, sinus surgery/trephination, laparoscopic ovariectomy/cryptorchidectomy, dental extractions, and some fracture repairs.

Describe the difference between open, closed and half-closed castration techniques.

Open: vaginal tunic incised, emasculator applied directly to vessels/ductus within an open tunic. Closed: tunic NOT opened, emasculator applied across the whole cord including tunic (reduces eventration risk). Half-closed: tunic incised distally but cord crushed/ligated with tunic intact proximally. Closed/ligated techniques reduce evisceration risk and are preferred in older/standing horses.

What are the two most serious complications of equine castration?

1) Evisceration (herniation of intestine/omentum through the inguinal canal/vaginal ring) — a surgical emergency. 2) Haemorrhage from the testicular artery. Other complications: scrotal/sheath swelling, infection (septic funiculitis/'scirrhous cord'), and hydrocele.

What is a cryptorchid ('rig'), and why must surgical removal be confirmed?

A cryptorchid is a horse with one or both testes not descended into the scrotum (retained abdominal or inguinal). The retained testis must be removed (often laparoscopically) because it still produces testosterone causing stallion-like behaviour; an hCG stimulation test or anti-Mullerian hormone (AMH) confirms presence of retained testicular tissue.

What is the average gestation length of the mare, and the typical oestrous cycle length?

Mean gestation is approximately 340 days (range ~320-360). The oestrous cycle averages 21 days (oestrus ~5-7 days, dioestrus ~14-15 days). Mares are seasonally polyoestrous, cycling in the long days of spring/summer (long-day breeders).

What is the optimal time to breed a mare relative to ovulation, and why?

Mares should be bred close to ovulation (within ~24-48 hours before, or shortly after) because equine sperm survive ~48 hours in the reproductive tract but the ovum is fertilisable for only a short period (~6-12 hours). Ovulation is monitored by transrectal ultrasound and induced with hCG or deslorelin.

What is a Caslick's procedure and its indication?

A Caslick's vulvoplasty is suturing of the upper vulval lips to close the dorsal vulval cleft. Indicated for poor perineal conformation (sunken/tipped vulva) that allows pneumovagina/faecal contamination causing ascending placentitis and infertility; the vulva must be opened ('episiotomy') before foaling.

What is the 'red bag' (premature placental separation) emergency at foaling?

The red velvety chorioallantois (rather than the normal translucent amnion) appears at the vulva, indicating premature separation of the placenta from the endometrium. The foal is being deprived of oxygen — the membrane must be cut immediately and the foal delivered urgently.

What is the normal IgG status check for a neonatal foal and the cut-off for failure of passive transfer?

Foals are born agammaglobulinaemic and depend on colostral antibody. Serum IgG is measured at 18-24 hours; adequate transfer is IgG >8 g/L (>800 mg/dL). Failure of passive transfer (FPT) is IgG <4 g/L (<400 mg/dL); partial 4-8 g/L. Treat with plasma transfusion if low and gut closure has occurred.

What is the dental formula of the adult male horse?

Adult male horse permanent dentition: $2(I\,\tfrac{3}{3}\;C\,\tfrac{1}{1}\;P\,\tfrac{3\text{-}4}{3}\;M\,\tfrac{3}{3}) = 40\text{-}42$ teeth. Mares often lack canines giving 36-40. The first premolar ('wolf tooth') is variable and often absent.

Why do horses develop sharp enamel points, and what routine procedure corrects them?

Horses have hypsodont (continuously erupting) teeth and anisognathic jaws (upper arcade wider than lower), so the teeth wear unevenly leaving sharp enamel overgrowths on the buccal (cheek) edge of upper molars and lingual edge of lower molars. Corrected by routine floating/rasping (odontoplasty).

What is the approximate age relevance of 'Galvayne's groove' in equine ageing?

Galvayne's groove is a longitudinal groove on the labial surface of the upper corner incisor. It appears at the gum margin around 10 years, reaches halfway down by ~15 years, extends the full length by ~20 years, and recedes from the top by ~25-30 years — used as a rough age guide.

What is an EOTRH (Equine Odontoclastic Tooth Resorption and Hypercementosis) and its typical signalment?

A painful progressive disease of older horses (>15 years) affecting incisors and canines, with resorption of tooth substance and bulbous hypercementosis, gingival recession and bulb-like swellings. Causes pain on biting; definitive treatment is extraction of affected teeth.

What core vaccinations and routine preventive care are recommended for horses in the UK?

Core vaccines: tetanus (toxoid) and equine influenza (often a combined 'flu/tet'); EHV-1/4 for at-risk/pregnant mares. Routine care: targeted strategic anthelmintic worming based on faecal egg counts, annual dental checks, and regular farriery (every 6-8 weeks).