Transdermal Medication for Cats: What It Is and How It Works

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If you have a cat in your house, you know the benefits of our adorable, fluffy friends — lots of love, cuddles, purring, and play. As our cats get older, they may develop health issues. Your veterinarian is there to help ensure your cat gets the care and medicine they need. But medicating cats can be a bit stressful, especially if you need to give your cat a pill. Even liquid medication for cats can be tricky, as it often tastes bad. It’s hard to hold on to your cat to give them something they hate!

Luckily for some feline patients, there is a less stressful alternative to oral medication: transdermal medication for cats. 

What Is Transdermal Medication for Cats?

Transdermal medications are drugs that are applied to the skin, cross the skin barrier, and enter the bloodstream. Transdermal medications are not the same as topical medications. Topical medications are used on the skin to treat the area to which it is applied and do not enter the bloodstream. Transdermal medications, on the other hand, affect the whole body. These medications contain a special base, or mix of compounds, mixed with a drug to help the drug absorb through the skin and enter the bloodstream. Transdermal medications typically cost more than the generic drug given by mouth.

There are multiple forms of transdermal medication for cats, including ointments, gels, creams, liquids, or patches. The most commonly used transdermal medication is liquid flea medicine for cats. (This is often referred to as a topical flea treatment for cats, even though it is technically transdermal if it contains ingredients that get absorbed into the bloodstream.) After application, the drug enters the bloodstream and ensures the whole body is protected from parasites. 

With other forms of transdermal medications, you may need to squeeze gels or creams out of a tube or twist a special pen to deliver a specific amount of the drug. 

Cats who may benefit from transdermal medications include:

• Cats who are taking a drug that is commercially available in transdermal form and which offers reliable absorption
• Cats who are very stressed or won’t allow you to give medication in other forms
• Cats with gastrointestinal upset such as vomiting and/or diarrhea when you give them the medication by mouth
• Cats with liver conditions who may benefit from the drug bypassing the liver
• Cats who do not need the medication to work immediately, as it takes several days to weeks for adequate absorption

What Cat Medications Are Available in Transdermal Form?

There are many medications compounded into transdermal medications. A compounding pharmacy alters the form of a medication into a new formulation that suits the needs of an individual patient. While it is tempting to request a transdermal medication for cats as opposed to medication by mouth or injections, know that most compounded transdermal medications lack studies proving that they work or that they work well. Many medication studies have demonstrated poor absorption into the bloodstream through transdermal application.

Besides flea preventatives, there are only four medications for cats shown through studies to be effectively absorbed when used transdermally (1, 2, 3, 4):

• Transdermal buprenorphine for cats: an opioid used to relieve intense pain
• Transdermal fentanyl for cats: an opioid used to relieve intense pain (patches)
• Transdermal methimazole for cats: used to treat hyperthyroidism
• Transdermal mirtazapine for cats: used to stimulate appetite

Some cats respond well to other transdermal medications, even though their absorption into the body is not well proven. If there are no other options working for you, such as giving pills or oral liquid to your cat, you may choose to try transdermal medication for cats. This may include:

• Transdermal amitriptyline for cats or transdermal fluoxetine for cats: anti-anxiety medications (also known as antidepressants)
• Cisapride transdermal for cats: used to stimulate defecation (for constipated cats)
• Transdermal gabapentin for cats: used to treat pain from nerve conditions (neuropathic pain)
• Glipizide for cats: a substitute for insulin injections for diabetic cats
• Transdermal prednisolone for cats: a steroid that reduces inflammation

There are multiple reasons why you should not give certain medications to your cat transdermally. Specifically, antibiotics should not be used in this way. Not only is it unproven that any antibiotics absorb transdermally in cats, but also your cat could develop an antibiotic-resistant infection if antibiotics do not reach high enough levels in the bloodstream. These infections are more dangerous, as most antibiotics won’t get rid of them. These infections can even affect human health. Keep in mind that topical antibiotics are appropriate to treat infections on the skin, and this is different from transdermal antibiotics.

Transdermal Medication for Cats: Pros and Cons

Transdermal meds for cats have many benefits, but there are some downsides as well. Pros of transdermal medication for cats include:

• Easy administration with less stress
• Less gastrointestinal upset, such as vomiting and/or diarrhea as compared to when the medication is given by mouth
• Cats with liver conditions may benefit from the drug skipping the liver as compared to if the medication was given in other ways

Cons for using transdermal medications for your cat may include:

• Side effect of skin irritation at the site where you have applied the medication
• You, your family, or your other pets may be exposed to the drug if they come into contact with the medication on your cat
• The medication may not be absorbed reliably, meaning the medication won’t work or the dose in the body fluctuates day to day
• Transdermal medicine for cats take several days to weeks to reach an effective dose (or the dose that was intended)

How to Apply Transdermal Medication for Cats

Transdermal patches (e.g., fentanyl patch for cats) require your cat to get shaved in a small area. The skin needs to be clean and free of wounds or breaks in the skin. Veterinarians apply these patches to your cat in the clinic.

Liquid transdermal medications for cats are typically labeled for application to the skin on the back. Many pet parents find this application challenging with all that fur in the way. Not to mention, cats are very flexible and can turn and lick their back all the way up between their shoulder blades! As such, it is better to apply this type of medication to the back of a cat’s head. Follow these steps for applying liquid transdermal medication for cats accurately:

1. Choose a time when your cat is generally calm (i.e., not when your cat has the “zoomies” or is playful).
2. Open one dose — each dose should come in a different container.
3. Try distracting your cat with a tasty treat while you apply the medication or have a family member calmly hold your cat so they do not run away.
4. Part the fur on the back of your cat’s head until you can see skin; if the skin is red, irritated, has bumps, or has any kind of break in the skin like a small abrasion, you should not apply the medication there. Part the fur on a different area of skin instead.
5. Squeeze some of the liquid onto the skin and stop once you see that the skin and roots of the fur around it are wet.
6. Repeat parting the fur and applying some of the medication in multiple places until all medication has been applied.
7. Thoroughly wash your hands after application.
8. Ensure no one pets your cat in the area where you applied the medication for at least an hour, but probably longer depending on the medication.

If your veterinarian prescribed a transdermal gel, ointment, or cream for cats, follow these steps to apply the medication accurately to your cat’s ear:

1. Choose a time when your cat is generally calm.
2. Put on protective gloves.
3. Try distracting your cat with a treat or have a family member calmly hold your cat. 
4. If medication still remains on your cat’s ear from the previous dose, gently wipe the area with an ear cleaning solution on a cotton ball or gauze.
5. Follow directions for using the medication carefully. Apply the medication to the inner edge of your cat’s ear flap or pinna (the part of the ear you can see, not inside the ear canal). Rub it gently on the area without fur.
6. Alternate ears for medication so that the next dose is on the opposite ear.

Transdermal Cat Meds: Other Tips and Advice

If your cat experiences skin irritation after applying transdermal medication, speak with your veterinarian for alternatives. There may be another place on your cat’s body to apply the medication, or your veterinarian may wish to discontinue it depending on the level of irritation. 

For homes with small children or other pets — especially other cats — consider separating your cat from everyone else for over an hour. This should allow medication to absorb and decrease risk of exposure to the medication. In some cases, medication may take longer than an hour to absorb. Ask either your veterinarian or the compounding pharmacy for the exact recommendation.

If after applying the medication your cat’s first instinct is to groom themselves, try the following distractions:

• Feed your cat a regular meal right after applying the medication
• Offer food or a few treats in an enriching puzzle toy
• Play with your cat
• Place a soft cat cone collar around their head so that they cannot groom their face and head.

References

1. Zorbium. MyElanco. Accessed online https://my.elanco.com/us/campaign/zorbiumforcats
2. Hofmeister, Erik H, and Christine M Egger. “Transdermal fentanyl patches in small animals.” Journal of the American Animal Hospital Association vol. 40,6 (2004): 468-78. doi:10.5326/0400468
3. Hicks, Elizabeth and Murphy, Pilar Z. “Transdermal Methimazole for Feline Hyperthyroidism.” Open Access Journal of Toxicology. Vol 4 Issue 1. Aug 2019. Accessed online https://juniperpublishers.com/oajt/pdf/OAJT.MS.ID.555630.pdf
4. Poole, Melinda et al. “A double-blind, placebo-controlled, randomized study to evaluate the weight gain drug, mirtazapine transdermal ointment, in cats with unintended weight loss.” Journal of veterinary pharmacology and therapeutics vol. 42,2 (2019): 179-188. doi:10.1111/jvp.12738