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Dog neck rash after flea treatment: Is it a hot spot or allergy?

Updated On September 23rd, 2025

Pet's info: Dog | Jack Russell Terrier | Female | unspayed

My dog has a rash on her neck, she just got it over last night cause I only saw it in the morning. I use flea treatment advantage on her yesterday because she had fleas. Could this rash be from scratching? What could this rash be from and is it worth me taking her to the vet or does it heal on its own? She’s not itching at it nor does it hurt when I touch it. What could of caused it

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2 Answers

Most Helpful Answer

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Answered By C. Rathjens, DVM

Veterinarian

Published on May 29th, 2019

I can't diagnose it from the picture, but it looks suspiciously like superficial dermatitis (a "hot spot") caused by bacteria on the skin getting out of control and causing a sore. This can be caused by fleas or an allergic reaction (like hay fever in humans), or being wet for a long time if she just had a bath and has a thick undercoat, or even from scratching or licking herself. It could possibly be a reaction to the flea medication, although that is rare and would tend to occur in the location you applied the flea treatment. I would recommend taking her in to the vet to have it looked at. If it really is superficial dermatitis she'll need antibiotics (either a pill or maybe just a medicated bath). If it's not superficial dermatitis, the vet can do some testing to see what else it could be.

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    Answered By Dr. Massimo Orioles, DVM, Cert AVP, MRCVS

    Veterinarian

    Published on May 29th, 2019

    This presentation could be due to a trauma or localized spot of skin infection (likely to be caused by bacteria or fungal). A check up, appropriate disinfection and possibly antibiotics or antifungal meds (oral, topical or in a shampoo formulation) are needed to solve the problem. Disinfection can be possibly started at home with very diluted hibiscrub or betadine or salted water baths. Buster collar may be useful as well to avoid any licking/scratching. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.

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