OR Vet Tech cheat sheet

MAC (minimum alveolar concentration) is the alveolar concentration at which 50% of patients do not respond to a noxious stimulus; lower MAC means a more potent inhalant.

Isoflurane MAC in dogs is roughly 1.3-1.5%; sevoflurane roughly 2.1-2.4%; MAC is reduced by hypothermia, hypotension, concurrent injectable anesthetics, and pregnancy.

Anesthetic depth monitoring: jaw tone, palpebral reflex (lost early), corneal reflex (lost late), and eye position (ventromedial rotation indicates surgical plane with ketamine/dissociatives).

Premedication classes: alpha-2 agonists (dexmedetomidine, xylazine) for sedation/analgesia; anticholinergics (glycopyrrolate, atropine) for bradycardia; benzodiazepines (midazolam, diazepam) for muscle relaxation and seizure control.

Pure mu opioids (morphine, hydromorphone, fentanyl, methadone) provide visceral analgesia; buprenorphine is partial mu agonist; butorphanol is mu antagonist/kappa agonist.

Naloxone reverses opioids; atipamezole reverses alpha-2 agonists; flumazenil reverses benzodiazepines; yohimbine and tolazoline also reverse alpha-2 effects.

Local anesthetics: lidocaine max ~4-6 mg/kg (dogs), bupivacaine max ~2 mg/kg; bupivacaine is cardiotoxic and must never be given IV; add epinephrine to prolong duration and reduce systemic absorption.

IPPV (intermittent positive pressure ventilation) is indicated when end-tidal CO2 exceeds ~55-60 mmHg or when the patient cannot maintain oxygenation; peak inspiratory pressure should stay below ~20 cm H2O.

Normal canine temperature 100.5-102.5°F (38.1-39.2°C); feline 100.0-102.5°F (37.8-39.2°C); hypothermia below 99°F warrants active warming.

Normal canine heart rate 60-160 bpm (higher in toy breeds/puppies); feline 140-220 bpm; respiratory rate dog 10-30/min, cat 20-30/min.

Body condition score (BCS) 1-9: 4-5 ideal; 1-3 underweight; 6-9 overweight/obese.

Pain assessment uses the Colorado State University (CSU) Canine/Feline Acute Pain Scale (0-4) or Glasgow Composite Measure Pain Scale; evaluate posture, vocalization, facial expression, and response to palpation.

Fluid therapy maintenance rate approximately 2-3 mL/kg/hr (or 50-60 mL/kg/day); replace deficits using estimated % dehydration × body weight (kg) × 1000 mL.

Nutritional resting energy requirement (RER) = 70 × (body weight in kg)^0.75 kcal/day; illness energy requirement (IER) typically 1.0-1.3 × RER.

Bandage layers: primary (contact), secondary (absorbent padding), tertiary (outer protective); check for swelling, odor, or toe temperature changes every few hours.

Urinary catheter care: closed system, aseptic technique, monitor for gross hematuria or sediment; remove as soon as feasible to reduce infection risk.

PCV (packed cell volume) measured after centrifugation; normal dog 37-55%, cat 30-45%; anemia if below reference, polycythemia if above.

Total protein by refractometry; normal dog 5.5-7.5 g/dL, cat 6.0-8.0 g/dL; hypoproteinemia with anemia suggests blood loss or protein-losing disease.

Blood smear evaluation: assess RBC morphology (target cells, spherocytes, schistocytes), platelet estimate (~1 platelet per 100x field × 15,000-20,000/µL), and WBC differential.

Buffy coat smear can detect microfilaria (Dirofilaria immitis) and some intracellular organisms when other tests are unavailable.

Urinalysis: specific gravity (dog 1.015-1.045, cat 1.035-1.060), pH, protein, glucose, ketones, bilirubin, blood, and sediment exam (RBC, WBC, casts, crystals, bacteria).

CBC parameters: HCT, Hgb, RBC count, MCV, MCHC, WBC with differential, platelet count; reticulocyte count distinguishes regenerative from nonregenerative anemia.

Serum chemistry: BUN and creatinine reflect renal function; ALT and ALKP indicate hepatobiliary injury; glucose, electrolytes, and calcium assess metabolic status.

Fecal flotation (zinc sulfate or sugar solution) detects nematode eggs, Giardia cysts, and coccidia; direct smear detects motile trophozoites and Giardia.

Standard thoracic radiography: right lateral and either VD or DV views; left lateral preferred for cardiac silhouette assessment; inspiratory film at peak inspiration.

Abdominal radiography: right lateral and VD views; look for organ size, position, radiopacity (mineral, metal, fat, gas), and loss of serosal detail (effusion or peritonitis).

Roentgen signs of disease: size, shape, position, margination, number, opacity (mineral, soft tissue, fat, gas) - the mnemonic 'Roentgen signs' guides interpretation.

Ultrasound is superior for fluid-filled and soft-tissue structures (bladder, gallbladder, heart, pregnancy); radiography is superior for bone and lung.

Echocardiography measures chamber size, wall thickness, contractility, and identifies pericardial effusion or valvular insufficiency via Doppler.

CT provides cross-sectional imaging useful for complex fractures, nasal disease, and oncology staging; MRI is preferred for neurologic and soft-tissue detail.

Radiation safety: ALARA (as low as reasonably achievable) principle; wear lead apron, thyroid shield, dosimeter badge; collimate to area of interest.

Contrast studies: barium for GI series, iodine-based (iohexol) for excretory urography; note that barium is contraindicated if GI perforation is suspected.

Triage ABCs: airway, breathing, circulation; life-threatening hemorrhage and tension pneumothorax require immediate intervention.

CPR: chest compressions at 100-120/min, 1/3 to 1/2 chest depth; compression-to-ventilation ratio 30:2 (intubated: continuous compressions with 10 breaths/min); reverse drug of choice is epinephrine 0.01 mg/kg IV.

Shock: hypovolemic, distributive (septic/anaphylactic), cardiogenic, obstructive; treat hypovolemia with crystalloid bolus (dog 20 mL/kg, cat 10 mL/kg) and reassess.

Anaphylaxis: epinephrine 0.01 mg/kg IV or 0.2-0.5 mg/kg IM; fluids, diphenhydramine, and corticosteroids as adjuncts.

Gastric dilatation-volvulus (GDV): rapid decompression via orogastric tube, fluid resuscitation, and emergency surgery (gastropexy); do not delay surgery.

Heat stroke: cool with room-temperature water and fans; avoid ice water (causes vasoconstriction); monitor for DIC and acute kidney injury.

Seizure emergency: diazepam 0.5 mg/kg IV or rectal; if refractory, levetiracetam or phenobarbital; check glucose and electrolytes.

Poisoning: decontaminate (emesis with apomorphine or hydrogen peroxide only if recent ingestion and patient stable); activated charcoal 1-3 g/kg; call poison control.

Drug dose formula: dose (mg) = body weight (kg) × dose rate (mg/kg); volume (mL) = dose (mg) ÷ concentration (mg/mL).

C1V1 = C2V2 for dilutions; percentage solutions: 1% = 10 mg/mL, so 5% = 50 mg/mL.

Constant rate infusion (CRI): mL/hr = (dose µg/kg/min × weight kg × 60) ÷ concentration µg/mL.

Fluid drip rate: drops/min = (volume mL × drop factor gtt/mL) ÷ time (min); common macrodrip 10, 15, or 20 gtt/mL; microdrip 60 gtt/mL.

Unit conversions: 1 kg = 2.2 lb; 1 g = 1000 mg; 1 mg = 1000 µg; 1 L = 1000 mL; 1 tsp = 5 mL; 1 oz = 30 mL.

Drug classes: NSAIDs (carprofen, meloxicam) - COX inhibition, avoid in renal disease/GI ulcer; corticosteroids (prednisone, dexamethasone) - anti-inflammatory/immunosuppressive.

Antibiotics: beta-lactams (amoxicillin, cefazolin) inhibit cell wall; fluoroquinolones (enrofloxacin) inhibit DNA gyrase; avoid enrofloxacin in growing animals (cartilage damage).

Antiparasitics: pyrantel (roundworm/hookworm), praziquantel (tapeworm), ivermectin (heartworm/mites) - avoid high-dose ivermectin in MDR1-affected Collies.

Controlled substances (Schedule II-V) require DEA registration, secure storage, and a perpetual inventory log with running balance.

Prescription label must include: patient name/species, drug name, strength, dose, route, frequency, quantity, refills, and prescriber.

Expired drugs must be removed from inventory and disposed of per federal/state regulations (e.g., reverse distributor); never dispense expired product.

Compounding is regulated under USP <795> (nonsterile) and <797> (sterile); only use FDA-approved products when available.

Chemotherapy handling requires closed-system transfer devices, gloves, gown, and dedicated disposal; pregnant staff should avoid handling.

Drug storage: refrigerate vaccines and insulin (do not freeze); protect from light for drugs like chlorpromazine and doxycycline; keep away from heat.

Withdrawal times: meat/milk withdrawal periods must be observed for food-animal drugs; extra-label use requires a valid veterinarian-client-patient relationship (VCPR).

Medication errors: double-check calculations, use standard units (mg/kg, not 'cc'), and confirm patient identity before administration.

Aseptic technique: surgical scrub (chlorhexidine or povidone-iodine) for 3-5 minutes; sterile gown and gloves; sterile field maintained throughout.

Instrument categories: cutting (scalpel, scissors), grasping (hemostats, tissue forceps), retracting (self-retaining, handheld), and suturing (needle holders).

Suture materials: absorbable (PDS, Vicryl, Monocryl) vs nonabsorbable (nylon, silk, Prolene); monofilament reduces infection risk; size 3-0 to 4-0 common in small animal.

Suture patterns: simple interrupted, simple continuous, cruciate, mattress, and subcuticular; continuous patterns distribute tension but can compromise blood supply if too tight.

Anesthesia machine check: oxygen supply, vaporizer, breathing circuit, scavenging, and leak test before every procedure.

Surgical prep: clip hair, scrub skin in circular motion from incision site outward; do not re-enter clipped area with contaminated gauze.

Postoperative monitoring: temperature, heart rate, respiratory rate, pain score, incision site for swelling or discharge; provide analgesia (NSAIDs, opioids).

Instrument care: clean with enzymatic detergent, lubricate hinges, autoclave at 121°C/15 psi for 15-20 min (or 132°C for 4 min); cold sterilization with glutaraldehyde for heat-sensitive items.

Dental formula: dog permanent 42 teeth (2× [I3/3, C1/1, P4/4, M2/3]); cat permanent 30 teeth (2× [I3/3, C1/1, P3/2, M1/1]).

Periodontal disease staging: gingivitis (reversible) vs periodontitis (attachment loss); stage 1-4 based on probing depth and attachment loss.

Dental radiographs are required before extraction; full-mouth series (6-8 views) or intraoral sensors detect root fractures, resorption, and bone loss.

Dental scaling uses ultrasonic or hand scalers; always follow with polishing to smooth enamel and subgingival lavage.

Extraction technique: elevate, sever periodontal ligament, extract; multi-rooted teeth may require sectioning; close with suture if needed.

Malocclusion: overbite/underbite, base narrow, wry mouth; assess occlusion after deciduous teeth erupt and again after permanent dentition.

Home care: brushing with pet-safe enzymatic toothpaste (never human toothpaste - fluoride/xylitol toxicity); dental chews and water additives as adjuncts.

Anesthesia for dentistry: intubate with cuffed tube to protect airway; place pharyngeal pack; monitor for bradycardia during traction (oculocardiac reflex).

Restraint principles: minimal force, use of towels, muzzles, and chemical restraint when needed; avoid scruffing cats excessively and never lift by limbs.

Feline handling: use a towel or E-collar, minimize time in dorsal recumbency, and provide hiding/escape options to reduce stress.

Canine behavior: fear aggression, resource guarding, and separation anxiety are common; use positive reinforcement and avoid punishment-based training.

Low-stress handling: pheromone products (Adaptil for dogs, Feliway for cats), gentle handling, and pre-visit sedation for anxious patients.

Husbandry: dogs and cats are carnivores; provide species-appropriate diets, fresh water, and enrichment; rabbits and guinea pigs are herbivores requiring hay and vitamin C (guinea pigs).

Zoonotic disease prevention: hand hygiene, PPE, and vaccination of staff (rabies, tetanus); isolate animals with suspected infectious disease.

Behavioral assessment: observe body posture, ear position, tail carriage, and vocalization; a wagging tail does not always indicate a friendly dog.

Restraint devices: Elizabethan collar, basket muzzle, and restraint bags; ensure airway patency and monitor for stress or respiratory compromise.

Veterinarian-client-patient relationship (VCPR) is required to prescribe drugs and provide treatment; established by examination and ongoing care.

Informed consent: explain risks, benefits, alternatives, and costs before procedures; document in the medical record.

Medical record requirements: legible, complete, contemporaneous; include history, exam findings, diagnosis, treatment, and client communication.

Confidentiality: client and patient information is protected; disclose only with consent or as required by law.

OSHA: employers must provide PPE, training, and hepatitis B vaccination; report needlestick injuries and follow post-exposure protocols.

Controlled substance logs: maintain accurate inventory, reconcile counts, and report theft or loss to the DEA.

Euthanasia: use humane methods per AVMA guidelines (e.g., barbiturate overdose IV); confirm death by auscultation and lack of corneal reflex.

Billing and estimates: provide written estimates, obtain approval for changes, and maintain transparent pricing to avoid disputes.

Skeletal anatomy: axial (skull, vertebral column, ribs, sternum) vs appendicular (limbs); long bones have diaphysis, metaphysis, and epiphysis.

Cardiovascular: heart has four chambers; left ventricle pumps systemic circulation; right ventricle pumps pulmonary circulation; normal conduction via SA node, AV node, bundle of His.

Respiratory: gas exchange at alveoli; inspiration driven by diaphragm and intercostal muscles; normal tidal volume ~10-15 mL/kg.

Renal physiology: glomerular filtration, tubular reabsorption, and secretion; kidney regulates fluid, electrolyte, and acid-base balance; erythropoietin production.

Hepatic function: metabolism, detoxification, bile production, and synthesis of albumin and clotting factors; ALT and ALKP are key markers of injury.

Pathology terms: inflammation (-itis), necrosis (cell death), neoplasia (abnormal growth), hypertrophy (increase in cell size), hyperplasia (increase in cell number).

Lymphatic system: lymph nodes, spleen, thymus, and tonsils; lymph node enlargement may indicate infection, inflammation, or neoplasia.

Endocrine: thyroid (T4), pancreas (insulin, glucagon), adrenal (cortisol), and parathyroid (calcium regulation); diabetes mellitus results from insulin deficiency or resistance.