Mometamax for Dogs: Ear Infection Treatment Guide for Dog Owners
Mometamax is a prescription ear suspension that combines three active ingredients to treat bacterial and yeast ear infections in dogs. Understanding what each ingredient does, how to apply it correctly, and what to watch for makes the difference between a fast recovery and a recurring infection.
What Is Mometamax?
Mometamax Otic Suspension is a prescription-only ear medication manufactured by Merck Animal Health. It is approved by the FDA for use in dogs to treat otitis externa – inflammation and infection of the external ear canal. The suspension combines three active ingredients that each address a different component of ear infections: infection, inflammation, and fungal overgrowth.
It comes in a multi-dose bottle with a dropper tip designed for ear canal use. The suspension is white to off-white and must be shaken before each use. It is not safe for use in cats or other species without specific veterinary guidance, and it requires a prescription in all markets.
The Three Active Ingredients
The effectiveness of Mometamax comes from its three-ingredient formula targeting the full picture of a typical ear infection:
An aminoglycoside antibiotic that kills gram-negative bacteria (including Pseudomonas and Staphylococcus) by binding to bacterial ribosomes and disrupting protein synthesis.
An azole antifungal that kills Malassezia yeast by inhibiting ergosterol synthesis in the fungal cell membrane. Malassezia is the most common cause of yeast ear infections in dogs.
A potent synthetic corticosteroid that rapidly reduces inflammation, swelling, redness, and itch in the ear canal. Controlling inflammation allows the other two agents to penetrate and work more effectively.
What Conditions Does Mometamax Treat?
Mometamax is approved specifically for otitis externa caused by susceptible strains of bacteria and yeast. Common organisms it targets include:
- Staphylococcus pseudintermedius: The most common bacterial cause of otitis externa in dogs.
- Pseudomonas aeruginosa: A gram-negative rod that causes more resistant infections, often in chronic or recurrent cases.
- Malassezia pachydermatis: The yeast most commonly responsible for fungal ear infections in dogs. It thrives in warm, moist, humid ear canals.
Because most ear infections are mixed (bacteria plus yeast), a combination product like Mometamax is often prescribed rather than using separate antibiotic and antifungal drops.
Mometamax must NEVER be used in a dog with a ruptured eardrum (perforated tympanic membrane). The gentamicin component is ototoxic – it can cause permanent inner ear damage and hearing loss if it reaches the middle ear through a perforation. Your veterinarian should examine the ear canal and confirm the eardrum is intact before prescribing Mometamax.
How to Apply Mometamax Correctly
Gently clean visible debris from the outer ear canal and ear flap using a veterinarian-recommended ear cleaner. Pat dry. Never use cotton swabs deep in the canal – they push debris further in. A clean canal ensures the medication contacts the infected tissue.
Mometamax is a suspension – the ingredients separate on standing. Shake vigorously for 5 to 10 seconds before each use to ensure even distribution of all three active ingredients in every dose.
Tilt the dog’s head so the affected ear faces upward. Insert the dropper tip gently into the ear canal opening – do not force it deep. Apply the prescribed number of drops (typically 4 drops once daily for dogs under 30 lbs, or as your vet specifies for larger dogs).
Immediately after applying the drops, hold the ear flap down and massage the base of the ear (below the ear canal opening) firmly for 30 to 45 seconds. You should hear a squishing sound – this confirms the medication is distributing down the canal to reach the infection.
Release the dog and let them shake their head – this is normal and helps move the medication into the canal. Wipe any excess medication from the outer ear flap with a clean cloth. Reward the dog. Wash your hands.
Dosing and Treatment Duration
The standard approved dosing for Mometamax is 4 drops into the affected ear(s) once daily for 7 days. For larger breed dogs (over 30 lbs), some veterinarians prescribe higher volumes – follow your vet’s specific instructions, not the general label guidance.
Dogs typically show improvement within 3 to 5 days – itching and head shaking often decrease noticeably. Even so, complete all 7 days of treatment. Stopping early leaves residual bacteria or yeast that can re-establish the infection, sometimes with reduced sensitivity to the antibiotic component.
Mometamax vs. Tresaderm – Key Differences
Both Mometamax and Tresaderm are combination ear medications for dogs, but they have meaningful differences:
| Feature | Mometamax | Tresaderm |
|---|---|---|
| Antibiotic | Gentamicin (gram-negative coverage) | Neomycin (gram-positive and some gram-negative) |
| Antifungal | Clotrimazole | Thiabendazole |
| Corticosteroid | Mometasone furoate (potent) | Dexamethasone (moderate) |
| Dosing frequency | Once daily | Twice daily |
| Treatment duration | 7 days | 7 to 14 days |
| Storage | Room temperature, avoid freezing | Refrigeration required |
Mometamax is often preferred for convenience (once-daily dosing, no refrigeration) and for infections where Pseudomonas coverage is important. Tresaderm may be preferred when neomycin’s spectrum is more appropriate or when the vet prefers dexamethasone.
Side Effects and What to Watch For
Mometamax is generally well-tolerated when used as directed in dogs with intact eardrums. The most common side effects are local:
- Mild ear irritation or temporary increase in discharge in the first 1 to 2 days
- Brief discomfort at application in some dogs
- Occasional head shaking immediately after application
Less common concerns with prolonged use include:
- Steroid effects: The mometasone component can cause increased thirst, urination, and appetite with extended use, since some systemic absorption occurs even with topical application.
- Gentamicin resistance: With repeated or long courses, bacterial populations in the ear can develop resistance, making future infections harder to treat.
Recurring ear infections treated with Mometamax often signal an underlying problem – allergies (food or environmental) are the most common cause of recurrent otitis externa in dogs. Treating the infection clears the acute episode, but if the root cause is not addressed, infections return. Discuss allergy testing or dietary trials with your vet if your dog has repeated ear infections.
When to Call Your Veterinarian
Contact your vet before or during Mometamax treatment if:
- The ear is extremely painful when you try to apply the medication
- There is no improvement after 3 to 4 days of treatment
- The discharge becomes bloody or has a very foul odor
- The dog shows signs of hearing loss, loss of balance, or head tilt (signs of middle or inner ear involvement)
- The ear canal looks severely swollen or closed
- The dog develops increased thirst or urination during treatment
Frequently Asked Questions
Treating Ear Infections Effectively
Mometamax works best when applied correctly and consistently for the full treatment course. Because ear infections in dogs often have underlying causes like allergies, working with your veterinarian beyond just clearing the acute infection gives the best long-term outcome for your dog’s ear health.