Veterinary Contraindication Checker

Overview

Systematic contraindication checking for veterinary drug therapy. Goes beyond drug-drug interactions (see drug-interaction-checker) to evaluate patient-specific factors that may make a drug unsafe: species, breed genetics, organ dysfunction, pregnancy, age extremes, and concurrent disease states.

When to Use

• Before recommending any drug therapy in a veterinary patient
• When a patient has known organ dysfunction (renal, hepatic, cardiac)
• When a patient is pregnant, lactating, or neonatal
• When breed-specific drug sensitivities may apply
• Keywords: contraindication, safe to use, can I give, renal dose, hepatic dose, pregnant, breeding, puppy, kitten, geriatric

Contraindication Categories

Species Contraindications

See lethal-variance-detection skill. Some drugs are absolutely contraindicated in certain species regardless of patient status.

Breed/Genetic Contraindications

• MDR1 mutation (ABCB1): Ivermectin (high dose), loperamide, acepromazine (use lower dose), vincristine, doxorubicin -- affected breeds: Collie, Australian Shepherd, Shetland Sheepdog, Old English Sheepdog, and crosses
• Greyhounds/Sighthounds: Prolonged thiopental recovery, different propofol pharmacokinetics, lower normal reference ranges for some lab values
• Brachycephalic breeds: Higher anesthesia risk, avoid heavy sedation protocols, caution with opioid-induced respiratory depression

Organ Function Contraindications

• Renal insufficiency: Adjust or avoid nephrotoxic drugs (aminoglycosides, cisplatin, NSAIDs). Reduce doses of renally excreted drugs.
• Hepatic insufficiency: Avoid hepatotoxic drugs (ketoconazole, azathioprine at standard doses). Reduce doses of hepatically metabolized drugs.
• Cardiac disease: Avoid negative inotropes in heart failure patients. Caution with fluid-loading drugs.
• GI disease: Consider route of administration; oral drugs may have unpredictable absorption.

Life Stage Contraindications

• Neonatal/Pediatric: Many drugs lack pediatric dosing data. Immature hepatic and renal function affects clearance. Fluoroquinolones avoid in growing animals (cartilage damage).
• Geriatric: Reduced organ reserve. Start low, go slow. More susceptible to adverse effects.
• Pregnant/Lactating: Many drugs are teratogenic or excreted in milk. Griseofulvin is teratogenic in cats. Methotrexate, retinoids are contraindicated.

Disease State Contraindications

• Seizure history: Avoid drugs that lower seizure threshold (fluoroquinolones, tramadol in some patients)
• Bleeding disorders: Avoid NSAIDs and drugs affecting platelet function
• GDV/GI obstruction: Oral medications may not be absorbed; avoid prokinetics if mechanical obstruction

Workflow

1. List all patient parameters: species, breed, age, weight, reproductive status, known organ dysfunction, concurrent diseases, current medications.
2. For each proposed drug, check against all applicable contraindication categories.
3. If a contraindication is found, classify severity:
   • Absolute: Do not use under any circumstances
   • Relative: Use only if benefit clearly outweighs risk, with monitoring
   • Dose adjustment: Drug may be used at modified dose or frequency
4. Suggest alternatives when a drug is contraindicated.

Limitations

• Contraindication data is most complete for dogs and cats. Exotic species data is limited.
• Clinical judgment may override relative contraindications when no suitable alternative exists.
• New contraindications are discovered through post-market surveillance and case reports.