It had been a difficult mommy morning - missing homework, tangled hair, multiple meltdowns - but I had finally gotten my children off to school when my assistant, Elise, handed me a message. "This client just called. She put her dog's Frontline Plus on her cat, Petunia." I strolled casually to the phone. Frontline Plus, a topical pour-on flea and tick product, has a wide safety margin. The dog and cat versions have the same ingredients, albeit at slightly different concentrations; the main difference is in the volume applied. I would suggest an exam and a thorough bathing. If she ingested a lot while grooming, it might upset her tummy, but I didn't anticipate major problems.
"What size Frontline did you put on her?" I asked Petunia's mom when she answered the phone. "The large dog size," she responded, "but I didn't use the whole tube." It wasn't the first time a client had tried to be economical by dividing a large Frontline into amultiple doses for a smaller animal.
"How long ago?" I asked.
"About nine o'clock last night," she replied. Wondering why she was concerned now, 12 hours after the application, rather than last night, I delved deeper.
"Does she seem sick?"
"Oh, yes," the owner said, clearly upset. "She started acting funny almost right away last night and now she's really bad. We tried to wash it off, but I don't think we did a very good job." With mounting worry, I suggested they come right down, and hung up the phone.
Frontline shouldn't make the cat this sick, I thought as I waited for their arrival, but what if it wasn't Frontline? I had neglected a cardinal rule of toxicity cases. Always have the owner bring the package, pill vial, wrapper, plant, product, in question. It's not uncommon for owners to misidentify things and effective treatment depends on accurate and precise knowledge of ingredients, concentrations, and quantities. When Petunia arrived, I glanced quickly in the carrier. My patient was twitching all over.
"Are you sure it was Frontline?" I demanded.
"I think so," her mother stammered uncertainly. "It was in the Frontline box...I'm not sure...I don't know."
Sending her home to retrieve the package, we whisked Petunia into the bath. Ten minutes later, the owner returned, white plastic applicator in hand. I could tell instantly by the shape and color. This wasn't Frontline. I turned it over. On the back, bold black letters warned, "Do not use on cats." Sigh.
"Did you happen to notice that it says, 'Do not use on cats' right here on the applicator?" I couldn't help but ask. "Or the little icon of the cat in the circle with the slash through it?" Petunia's mother nodded sheepishly. Admitting that she stored several different products together in one box, she commented that she had compared the ingredients and they had looked sufficiently similar. "And isn't that second ingredient the one made from marigolds?" she asked. "I figured that was safe to use." Perusing the package, I could understand her confusion. Frontline Plus contains (S)-methoprene and fipronil. The product she had applied was Zodiac Spot On. It, too, contains (S)-methoprene. So far, so good. But the other ingredient in Zodiac Spot On is permethrin. Here's where vet school comes in handy. Natural pyrethrins are, indeed, derived from flowers, albeit chrysanthemums, not marigolds. That's p-y-r-ethrin, not p-e-r-m-ethrin. Natural pyrethrins are fairly safe to use on cats. Permethrin, although also considered a "pyrethroid," i.e. a pyrethrin-like compound, is a synthetically produced insecticide with a much greater potential for toxicity. Cats, with their unique physiology, lack an enzyme necessary to efficiently eliminate permethrin from their systems. If applied to a cat, permethrin can act like a neurotoxin, causing repeated rapid firing of nerves leading to facial twitching, whole body tremors, and seizures. Other signs may include depression, drooling, agitation, vomiting, diarrhea, incoordination, elevated temperature, weakness, and trouble breathing. Left untreated, permethrin toxicity can be fatal.
Petunia was exhibiting classic twitching and tremors. The constant muscular activity had caused her body temperature to spike at 104.3 degrees. We conferred with the ASPCA Animal Poison Control Hotline. There is no specific antidote, but the tremors could be controlled with the muscle relaxant, Methocarbamol. I had tablets, but Petunia's best chance would be if we used the injectable form intravenously. Luckily, another Island veterinary practice had a bottle on hand. We placed an IV catheter, started fluids, and gave one bolus of Methocarbamol.
The tremors lessened, but did not stop. A second bolus. Waiting. Watching. No further twitching, at least for now. Poison Control said she was unlikely to progress to having seizures at this point, but we should observe her for the day, as the tremors might return. She should be completely out of the woods by 24 hours post-exposure.
Her mom came to pick Petunia up that evening. "Only three hours to go on our 24-hour watch," I told her, walking back to Petunia's cage. I opened the door. Shoot. Darn. Drat. Petunia was twitching again. Two additional doses of intravenous Methocarbamol stopped the symptoms. "You can still take her home," I said, handing her a vial of pills.
"Keep a close eye on her tonight. I think those last injections should be enough, but if she starts to twitch again, these pills should get her through the tail end of all this."
"I feel terrible," Petunia's mom said, as she was leaving. "I just didn't realize using the wrong flea and tick product on a cat could be so serious. You should write an article about this."
So here it is. Never apply any flea or tick product to your kitty that is not specifically labeled for use in cats. Always read labels carefully before using any product and never store different products together in one box. If you make a mistake, call your veterinarian immediately. And if a product says "Do not use on cats," then do not use it on cats. Really.
