Nitroglycerin (topical)

What is this medication for?

• Adjunctive preload reduction in CHF/cardiogenic pulmonary edema (front-line furosemide + oxygen ± nitroprusside era adjunct); questionable efficacy as outpatient

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Gloves for staff: a dog's ear-pinna dose is a nurse's headache — the most-mentioned human-safety note of topical NTG.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Hypotension (overdose) (Dose-related)
• Application-site rash (Rotate sites)
• Headache (human) — presumed possible (Transdermal systemic)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Anemia, nitrate hypersensitivity; severe low blood pressure/hypovolemia
• has or has had: Head trauma/cerebral bleeding (vasodilation worsens ICP), diuretic-depleted patients

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • PDE5 inhibitors (sildenafil class — human rule)
  • Other hypotensives (nitroprusside, hydralazine)
  • Aspirin (human)

Storage and handling

Gloves for application — human absorption is real (headache/low blood pressure in the applier); rotate sites; paste tubes/patches.

Good to know

• The 12-on/12-off patch clock: nitrate tolerance in 48–72 h makes continuous wear pointless — the dosing schedule IS the pharmacology.
• Gloves for staff: a dog's ear-pinna dose is a nurse's headache — the most-mentioned human-safety note of topical NTG.
• Modern niche: largely historical in dogs/cats (variable fur-patient absorption + better agents) — but still appears in pulmonary-edema crisis cocktails.