Neomycin is an antibiotic most commonly used in veterinary medicine as part of a triple topical regimen for the treatment of eye conditions. In this article, you’ll learn about how neomycin fights bacteria, what it’s formulated for, side effects and precautions to watch out for, and some common problems.
Overview of Neomycin for Felines
Oral tablet, topical or ophthalmic combination preparation
Do I need a prescription? :
Yes, for the oral form and most topical medications. Some OTC topical forms are available.
Oral form is not. Some topical combination preparations, such as Tresaderm, are FDA-approved for use in cats.
Oral: Biosol, Neomix; many prescription and over-the-counter topical combination formulations contain neomycin (Tresaderm, Vetropolycin, Enterederm, Animax, Quadritop, Neosporin)
Oral neomycin sulfate tablet: 500mg
Valid period range:
In a dry state, neomycin is stable for at least 2 years when stored at room temperature. For topical combination products, always use the product before the expiry date on the package.
About Feline Neomycin
Neomycin is an aminoglycoside antibiotic. These antibiotics work on bacteria by interfering with their ability to synthesize certain proteins they need to grow and reproduce.
Aminoglycosides, which also include antibiotics such as amikacin and gentamicin, are mainly active against aerobic or oxygen-dependent Gram-negative staining bacteria such as Pseudomonas and Enterobacter. They also have some effect on Gram-positive staining bacteria.
Neomycin is available in both oral and topical forms. The oral form is rarely used in veterinary medicine, but may be rarely considered in cases of reducing bacterial growth in the digestive tract. This may be in preparation for a procedure such as colon surgery, or to reduce ammonia-producing bacteria that can cause signs of a liver disease called hepatic encephalopathy.
Oral neomycin is poorly absorbed, so its general use as an oral antibiotic is very limited. The injectable form comes with significant concerns about nephrotoxicity, making its other injectable antibiotic cousins a more likely choice if need be.
Neomycin is most commonly used as a topical formulation for the skin and eyes. Often, it is combined with two or more other ingredients to make a “triple” antibiotic ointment. Examples include neomycin with polymyxin B and gramicidin or bacitracin, and neomycin with polymyxin B and dexamethasone.
Tresaderm is labeled for topical treatment of skin and ear infections in cats and contains neomycin along with the corticosteroids dexamethasone and the antifungal thiabendazole.
What does neomycin do to cats?
Most commonly, neomycin is used topically in cats for small skin wounds, localized areas of bacterial infection, and ear infections caused by bacteria.
It is also common to use neomycin ophthalmic ointment preparations for eye conditions thought to involve bacterial infection, such as corneal scratches, corneal ulcers, conjunctivitis (infection of the eye under the eyelid), or blepharitis (infection of the eyelid itself).
Neomycin Side Effects in Cats
Some cats may have localized hypersensitivity or reactions to neomycin, polymyxin B (often paired with it), or both.
On the low end, this may be seen as itching, scratching, or irritation at the application site. Worse, a severe allergic reaction may occur.
Fortunately, such reactions have not been associated with products containing steroids such as dexamethasone, hydrocortisone, betamethasone, or triamcinolone.
Since most neomycin products used in veterinary medicine do contain a steroid to address skin or eye inflammation, severe reactions to most veterinary medicine products do not appear to be common.
But since neomycin is a common ingredient in many over-the-counter triple antibiotic ointment products that don’t contain steroids (Neosporin, etc.), it’s important to always check the ingredients of any OTC product you plan to use on your pet, and consult your veterinarian before using .
If corneal ulcers are present, any eye drops containing steroids have the potential to worsen the disease. A corneal ulcer is where a scratch or abrasion on the eye becomes infected and begins to erode the surface of the cornea.
This is why it is very important not to use steroid-containing medications in the eyes unless your veterinarian directs you to do so. When checking for eye problems, veterinarians will often apply a stain called fluorescein to the eyes to check for ulcers and to make sure it’s safe to use products that contain steroids.
It is also very important to know what form or type of neomycin topical preparation you have. There are branded and generic products for skin, ear and eye products, it is very important not to use skin/ear products on the eyes.
Neomycin Dosage for Cats
For most topical eye preparations, use one drop or approximately 1/4-inch strip of ointment two to three to four times daily in the affected eye.
For other topical preparations for skin and ears, it is usually applied every 12 hours. But it is important to follow your veterinarian’s directions, as the amount and frequency of application may vary depending on the subject being treated.
For the oral form of neomycin, no dosage is given here because it is an uncommonly used form except in very specific circumstances, in which case the veterinarian’s instructions should be strictly followed.
Although the oral form is rarely used in veterinary medicine, neomycin is a very common ingredient in topical formulations for the eyes, ears, and skin.
Some cats may be allergic to neomycin, which is less common with combination products containing steroids.
Always consult your veterinarian before using over-the-counter products containing neomycin, or prescription products that previously contained neomycin that you may still be using at home.
frequently asked questions
What is Neomycin and Polymyxin B Sulfate for Cats?
Most commonly, neomycin and polymyxin B are found in topical combination products used in cats to treat eye infections such as conjunctivitis. It is often found that they are also paired with a third ingredient, such as a steroid such as dexamethasone.
Is Neomycin Ointment Safe for Cats?
Some cats may have mild to severe allergic sensitivities to neomycin. This may manifest as some minor scratching or irritation at the application site, or it may manifest as an allergic reaction. Fortunately, this reaction appears to be rarely recognized in neomycin-containing products, and most veterinary medicines containing neomycin (Animax, Enterederm, Tresaderm) contain steroids.
Can neomycin and polymyxin B sulfate and hydrocortisone be used on cat ears?
It is important never to use ear medicines on cats without first consulting your veterinarian. This is especially true for any pharmaceutical preparation for human use. The only product currently labeled for ear infections in cats is Tresaderm, although veterinarians may use some products approved for dogs on cats off-label.
What is the use of neomycin in animals?
Neomycin is an antibiotic that has a range of effects against certain bacteria. The oral form is rarely used in animals as a way to “sterilize” the intestines to reduce ammonia-producing bacteria or to prepare for colon surgery. More commonly, neomycin is used as part of a combination product, or “triple” antibiotic ointment, to treat eye, ear, and skin infections in pets.
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