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Gnat Bites on Dogs: What They Look Like & How to Treat

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closeup picture of a gnat on grass

Gnats are small flies that tend to fly in swarms. Some are non-biting, but it is the biting ones that cause our dogs problems. They are most prevalent in the Spring months and like to live near long grass and bodies of water.

The bites they inflict can look quite nasty and many owners come to my clinic worried that their dog has a serious skin issue. Thankfully, for most they cause little irritation and resolve quickly. Let’s take a closer look at gnat bites on pet dogs.

Gnats & how they impact dogs

Gnats are more of a nuisance than anything else and dogs dislike when they fly too close to them. When dogs are bitten a number of times, they may become quite itchy and this can lead to secondary skin infections. This can become uncomfortable and, if not treated promptly, could lead to a skin infection that becomes difficult to manage.

What are gnat bites? What do they look like?

The classic gnat bite causes red, circular lesions which are sometimes mistaken for ringworm. Initially they are a bright or dark red but soon fade to a paler color. They can get quite large, especially if the dog has been licking, chewing or scratching at them.

red, circular lesions due to gnat bites

If you know your dog has been near gnats, you can be quite confident that lesions which look like this are gnat bites.

lesions on a dog's belly as a result of gnat bites

However, red circular lesions like this can also be seen with infections like Ringworm or Staphylococcus bacteria infections, so always have a veterinarian confirm the diagnosis if you’re unsure.

My dog has gnat bites all over its body – is this an emergency? 

No, most dogs cope well with gnat bites and they just cause mild discomfort. For those who are very itchy or seem to have secondary skin infections, a routine vet appointment should be scheduled.

Uncommonly, a dog may have an immediate allergic reaction to a gnat bite. Signs could include facial swelling, trouble breathing, widespread hives and weakness. In this instance, you would need to seek immediate vet care.

Top symptoms of gnat bites in dogs 

After a gnat bite, your dog may develop the following signs:

  • Red lesions that form a ring (like a ‘bullseye’)
  • Mild itching
  • Slight crusting

Bites often occur in clusters and we tend to see them on the furless areas of skin.

If there is a secondary infection, we may also notice ooze, a bad smell and redness which is spreading.

What to do to help a dog suffering from gnat bites

We can gently bathe the skin in an oatmeal wash, medicated wash or salt water and distract our pets from any itching with e.g. food puzzles, chews and lick mats.

dog taking bath
A dog taking a shower with soap and water

Your vet may also discuss the use of an antihistamine from home. These are sometimes continued for several days.

To protect the skin, use a buster collar or loose pet t-shirt, as excess licking and chewing will introduce infection.

If your dog seems uncomfortable or the gnat bites are not improving, it is a good idea to schedule a vet visit.

Best products to help at home

Itch Relief Shampoo

A shampoo like this is a good idea, to soothe the skin and remove surface yeast and bacteria. This makes infections less likely to set in. The oatmeal in this shampoo helps to calm any itchy or inflamed skin.

Vet's Best Allergy Itch Relief Dog Shampoo |...
  • RELIEF FOR ITCHY SKIN - Vet’s Best Allergy Itch Relief Dog Shampoo is a soothing, natural remedy for dogs with itchy skin due to allergies or sensitivity.


Lick Mats and Kongs help your dog to stay calm while itchy and they will appreciate a distraction from the itch, making it less likely for them to lick their own skin.

I’m a big fan of food puzzles as they are easy for dogs to use, even when wearing a buster collar.

Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.

Always monitor your pooch when using these products, to ensure they are not chewed apart or ingested.

MateeyLife Set of 3 Lick Mat for Dogs and...
  • REDUCES ANXIETY & DESTRUCTIVE BEHAVIOR: These lick mats for dogs and dog lick mat with suction cups help release your puppy's endorphins through the promotion of licking, which can calm and soothe your puppy. Our cat lick mat is a safe alternative for your dog to lick which is excellent for stressful times such as grooming, bathing, nail trimming, injury recovery, and fireworks. Moreover, a dog licking mat as a boredom buster can keep your pets busy and reduce separation anxiety.
KONG - Classic Dog Toy, Durable Natural...
  • Large Dogs (Up to 65 lbs): The KONG Classic red rubber toy is 2.75" by 4"; it helps satisfy dogs' instinctual needs while providing mental stimulation and encouraging healthy play

Are gnat bites painful?

Thankfully, gnat bites are not known for causing pain and the itch tends to be mild. However, if your dog has many gnat bites or their skin is infected, they are likely to have some discomfort.

Is it a gnat bite or it is something else?

I always want my owners to be aware that several issues can mimic gnat bites. The most common would include fungal infections, bacterial infections and lesions that occur with flea allergy dermatitis.

ringworm on dog with closeup view

Your vet can often determine if a lesion is a gnat bite by simply looking at it, given their experience. If unsure, they may discuss some tests such as a skin swab, flea comb and skin scrape.

If you’ve not seen gnats near your dog and it is the wrong time of the year, we should question if there could be more going on than gnat bites.

Should I email pictures to my veterinarian?

It is always a great idea to email photos to your vet (or to an online vet service), so they can let you know if they agree that we are dealing with gnat bites. The vet will also be able to spot signs of a secondary infection and can advise on the best treatment plan going forward.

Signs that you need to call the veterinarian

Never hesitate to contact your vet if concerned. It may be that your dog is very unsettled by the bites, they are not healing quickly or that your dog is showing signs of illness (for example as a result of an allergic reaction).

Your vet will be happy to advise and may suggest you bring your dog in for an assessment if they are concerned.

WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]


  • Dr. Linda Simon, Veterinarian

    Dr Linda Simon (MVB MRCVS) has 10 years of experience as a veterinarian. She is a veterinary surgeon with a special interest in geriatric patient care, dermatology and endocrinology. She is a member of the British Royal College of Veterinary Surgeons. She graduated top of her class from UCD School of Veterinary Medicine in Dublin in 2013. Linda has also worked as a locum vet in a range of clinics, including 24 hour emergency clinics and busy charity clinics.

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