Veterinary Medicine & Surgery

# Veterinary Medicine & Surgery Knowledge Pack

## Clinical Assessment

### Systematic Physical Examination
Every PE follows a consistent, head-to-tail approach to avoid missing findings:

**General assessment**: Body condition score (1-9 scale for dogs/cats; 1-5 for horses/cattle), mentation (alert, quiet, obtunded, stuporous, comatose), posture, gait, hydration status (skin turgor, mucous membrane moisture, eye position in orbit). TPR: Normal canine temp 100.5-102.5°F, HR 60-140 (size-dependent), RR 10-30. Normal feline temp 100.5-102.5°F, HR 140-220, RR 20-40. Equine temp 99-101.5°F, HR 28-44, RR 8-16.

**Mucous membranes**: Color (pink=normal, pale=anemia/poor perfusion, yellow=icterus, brick red=vasodilation/sepsis, cyanotic=hypoxemia), CRT (normal <2 seconds; >2 seconds suggests poor perfusion; <1 second suggests hyperdynamic state). Petechiae on mucous membranes indicate thrombocytopenia or vasculitis.

**Cardiovascular**: Auscultate all four quadrants (left apex, left base, right side). Grade murmurs I-VI: I (barely audible), II (soft but readily heard), III (moderate, no thrill), IV (loud with palpable thrill), V (very loud, thrill), VI (heard with stethoscope off chest). Note timing (systolic, diastolic, continuous), point of maximum intensity, and radiation. Common murmurs: mitral regurgitation (left apex, systolic) — most common acquired heart disease in dogs; subaortic stenosis (left base, systolic) — common congenital in large-breed dogs.

**Abdominal palpation**: In small animals, systematic palpation identifies organomegaly, masses, fluid, pain, and foreign bodies. Cranial abdomen: liver, stomach, spleen. Mid-abdomen: small intestines, kidneys. Caudal abdomen: bladder, colon, sublumbar lymph nodes. A palpable thickened intestinal loop raises DDx of lymphoma, inflammatory bowel disease, foreign body, or intussusception.

### Emergency Triage
The primary survey follows the ABCDE approach:

**Airway**: Patent? Obstructed by blood, vomitus, foreign body, or swelling? Brachycephalic breeds (Bulldogs, Pugs) have inherently compromised airways — laryngeal edema after trauma or anesthesia can be rapidly fatal. Intubation or emergency tracheostomy may be needed.

**Breathing**: Rate, depth, effort, pattern. Increased effort with short/shallow breaths suggests pleural space disease (pneumothorax, pleural effusion, diaphragmatic hernia). Thoracocentesis is both diagnostic and therapeutic — aspirating air or fluid from the pleural space provides immediate relief while you stabilize.

**Circulation**: HR, pulse quality, CRT, blood pressure. Shock classification: hypovolemic (hemorrhage, dehydration — tachycardia, poor pulses, prolonged CRT), distributive (sepsis, anaphylaxis — vasodilation, bounding pulses initially then decompensation), cardiogenic (heart failure — muffled heart sounds with pericardial effusion, jugular distension). Fluid resuscitation: crystalloid bolus 10-20 mL/kg IV over 15-20 minutes for dogs (reassess after each bolus — cats are more volume-sensitive, use 5-10 mL/kg).

**Dysfunction (neurological)**: Mentation, pupil size and responsiveness, ability to walk, voluntary movement of all limbs. Modified Glasgow Coma Scale for head trauma patients — serial scores track deterioration or improvement.

**Exposure**: Complete secondary survey once stabilized — clip fur to find wounds, radiograph for fractures, focused assessment with sonography for trauma (FAST scan) to detect free abdominal or thoracic fluid.

## Common Surgical Procedures

### Soft Tissue Surgery
**Ovariohysterectomy (spay)**: Most commonly performed small-animal surgery. Ventral midline approach, ligate ovarian pedicles (triple clamp technique or vessel-sealing device), ligate uterine body at cervix, remove uterus and ovaries. Complications: hemorrhage from slipped ligature (most dangerous — ovarian pedicle bleeds into abdomen; signs appear 12-48 hours post-op: weakness, pale mucous membranes, abdominal distension), ureteral ligation (iatrogenic — rare but devastating), and stump pyometra (if ovarian tissue remains).

**GDV (gastric dilatation-volvulus)**: Life-threatening emergency in deep-chested large breeds (Great Danes, German Shepherds, Standard Poodles). Stomach distends with gas and rotates 180-360° on its mesenteric axis, occluding venous return and gastric blood supply. Presentation: non-productive retching, abdominal distension, tachycardia, weak pulses, rapid decline.

Tx: Aggressive IV fluid resuscitation (90 mL/kg/hr shock rate initially), gastric decompression (trocar or orogastric tube), correct metabolic derangements (ECG monitoring — ventricular arrhythmias occur in 40% of cases, treat with lidocaine 2 mg/kg IV bolus if hemodynamically significant). Surgical correction: derotate stomach, assess gastric wall viability (black/green necrotic tissue requires partial gastrectomy — CFR increases to 35-50% with necrosis), splenectomy if splenic torsion or avulsion, and gastropexy (permanently fix stomach to body wall — without gastropexy, recurrence rate is 80%).

### Orthopedic Surgery
**Cranial cruciate ligament (CCL) rupture**: Most common orthopedic condition in dogs. Equivalent to human ACL tear but with different biomechanics — the canine tibial plateau slopes 20-30° posteriorly, creating constant cranial tibial thrust during weight-bearing. Degenerative rupture is more common than traumatic in dogs; 40-60% of dogs will rupture the contralateral CCL within 1-2 years.

Surgical options: Tibial plateau leveling osteotomy (TPLO) — rotational osteotomy of the proximal tibia to reduce tibial plateau angle to ~5°, eliminating cranial thrust. Current gold standard for medium-to-large dogs. Tibial tuberosity advancement (TTA) — advances the patellar tendon insertion point to neutralize shear forces. Lateral suture stabilization (extracapsular repair) — heavy suture from lateral fabella to tibial tuberosity, suitable for small dogs (<15 kg BW). Return to function: 90-95% achieve good to excellent outcomes with TPLO; full recovery takes 12-16 weeks with strict exercise restriction.

**Fracture repair**: Principles follow AO/ASIF guidelines. Fracture classification: open vs. closed, transverse vs. oblique vs. spiral vs. comminuted, articular vs. non-articular. Fixation methods: bone plates and screws (locking plates especially valuable in small patients and poor-quality bone), interlocking nails (long bones in medium-large dogs), external fixation (open fractures, severely contaminated wounds, or temporary stabilization). Cats heal fractures faster than dogs (typically 6-8 weeks vs. 8-12 weeks). Young animals heal faster still — puppies may consolidate fractures in 3-4 weeks.

## Anesthesia and Analgesia

### Pre-anesthetic Assessment
ASA status classification adapted for veterinary patients: ASA I (healthy), ASA II (mild systemic disease — compensated heart murmur, mild obesity), ASA III (severe systemic disease — significant cardiac disease, uncontrolled endocrine disease), ASA IV (life-threatening — GDV, hemoabdomen), ASA V (moribund, not expected to survive without surgery). Pre-anesthetic bloodwork: minimum CBC and BMP for ASA I-II; full panel including coagulation for ASA III+.

### Protocol Design
Balanced anesthesia combines multiple drug classes to minimize individual drug doses and side effects:

**Pre-medication**: Sedation + analgesia. Acepromazine (0.01-0.05 mg/kg IM — avoid in hypovolemic patients, causes vasodilation) or dexmedetomidine (5-20 mcg/kg IM — provides profound sedation and analgesia, can reverse with atipamezole, avoid in cardiac patients due to bradycardia and increased afterload). Combine with an opioid: hydromorphone (0.05-0.1 mg/kg IM) or methadone (0.3-0.5 mg/kg IM) for moderate-to-severe pain; butorphanol (0.2-0.4 mg/kg IM) for mild pain and sedation synergy.

**Induction**: Propofol (4-6 mg/kg IV to effect — give slowly, watch for apnea; dose reduced 30-50% with effective pre-medication) or alfaxalone (2-3 mg/kg IV). Ketamine (5 mg/kg IV) combined with a benzodiazepine (midazolam 0.2-0.3 mg/kg IV) for cardiovascularly compromised patients — ketamine maintains sympathetic tone.

**Maintenance**: Isoflurane or sevoflurane via endotracheal tube. MAC (minimum alveolar concentration) for isoflurane: dogs 1.3%, cats 1.6%. MAC is reduced by concurrent analgesics — effective multimodal analgesia can reduce inhalant requirements by 30-50%, improving cardiovascular stability.

### Multimodal Analgesia
Pain management uses multiple mechanisms to provide superior analgesia with fewer side effects:

**NSAIDs**: Meloxicam (0.1 mg/kg PO SID for dogs; 0.05 mg/kg PO SID for cats — lower dose, shorter course in cats due to limited glucuronidation). Carprofen (4.4 mg/kg PO SID or 2.2 mg/kg BID for dogs). Contraindicated in dehydrated patients, renal insufficiency, GI ulceration, or concurrent corticosteroid use.

**Local/regional anesthesia**: Lidocaine (max 4 mg/kg dogs, 2 mg/kg cats; onset 5-10 min, duration 1-2 hrs). Bupivacaine (max 2 mg/kg dogs, 1 mg/kg cats; onset 20 min, duration 4-6 hrs). Techniques: incisional line blocks, dental nerve blocks (inferior alveolar, infraorbital, mental — transform dental procedures), epidural (morphine 0.1 mg/kg + bupivacaine 1 mg/kg preservative-free at L7-S1 for hindlimb/abdominal surgery), and ultrasound-guided peripheral nerve blocks (femoral/sciatic for hindlimb, brachial plexus for forelimb).

**Constant rate infusions (CRI)**: Fentanyl (2-5 mcg/kg/hr IV), ketamine (0.5 mg/kg loading then 10 mcg/kg/min — NMDA antagonist, prevents wind-up), and lidocaine (1-2 mg/kg loading then 25-50 mcg/kg/min IV — analgesic, anti-inflammatory, prokinetic; DO NOT use lidocaine CRI in cats — fatal CNS toxicity at therapeutic dog doses). MLK (morphine-lidocaine-ketamine) CRI is a common multimodal protocol for dogs undergoing major surgery.

## Diagnostic Imaging

### Radiography
Systematic ABCDE approach for abdominal radiographs: A (abdomen — serosal detail, peritoneal fluid, free gas), B (bowel — gas pattern, diameter [small intestine >2x width of a rib or >3x height of L5 endplate suggests obstruction in dogs], foreign material), C (colon/cecum), D (density — masses, calcifications, uroliths), E (edges — liver size, kidney size/shape, spleen, bladder, sublumbar space).

Three-view thoracic radiographs (right lateral, left lateral, VD/DV) are standard. Heart size assessed by vertebral heart score (VHS): measure long and short axes of cardiac silhouette, sum in vertebral bodies starting at T4. Normal canine VHS 9.7±0.5, normal feline VHS 7.5±0.3. VHS >10.5 (dogs) or >8.1 (cats) suggests cardiomegaly.

### Ultrasound
Abdominal ultrasound is the first-line imaging for parenchymal organ evaluation. Liver: assess echogenicity relative to falciform fat (hyperechoic liver suggests hepatic lipidosis in cats, steroid hepatopathy in dogs), portal vasculature, gallbladder (mucocele = stellate/kiwi-fruit pattern — consider surgery before rupture). Spleen: focal masses have 50-70% malignancy rate in dogs (hemangiosarcoma most common). Kidneys: cortical-medullary distinction, pelvic dilation, calculi, infarcts. FAST scan protocol (AFAST/TFAST) takes <5 minutes and detects free fluid — invaluable in emergency triage.