Can Dogs Get Fever Blisters?

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There are few things as embarrassing as getting a cold sore, also referred to as a fever blister, before a big event, but do our canine companions suffer from fever blisters? Can we pass them onto our pets? Fever blisters in humans are caused by the herpes simplex virus type 1 (HSV-1), which causes blisters on the lip, and can be passed from person to person.

Can Dogs Get Fever Blisters?

NO!

HSV-1 cannot be passed from humans to dogs, so your dog can not get a human fever blister or cold sore. But, dogs can get blisters and sores on their skin, including on and around their mouth, and they do have their own transmissible herpes virus that is specific to dogs. Although, unlike in humans, they do not usually worry about covering it up before a date!

Does My Dog Have Fever Blisters?

A fever blister in humans is caused by a herpesvirus that is specific to humans. When blister-like sores appear on your dog's mouth, there could be a variety of reasons which are not related to the human condition at all.

Dogs have their own version of the herpes virus, which is not transmissible to humans, just as human herpes is not transmissible to dogs. The dog herpes virus does not usually cause mouth blisters on your dog, instead it causes genital sores, and if puppies contract it while passing through the birth canal of an infected dog, they can acquire “Fading Puppy Syndrome”. Read Canine Herpes Virus Infection in Dogs for more on the effects of this virus.


Eosinophilic granulomas, lesions from white blood cell masses, which are more common in cats then dogs, can occur as lesions on your dog's skin around their oral cavity, often as a result of allergic reactions. These may appear to be like fever blisters, although they are not. They appear as benign masses, usually yellow or white around your dog's, face and mouth.

Several other conditions can cause mouth sores in and around your dog's oral cavity including bacterial infections, viral infections, parasitic infections, periodontal disorder, cancers and autoimmune disorders. For more information check out the following guides:

Chronic Mouth Inflammation and Ulcers in Dogs

Skin Blisters and Pustules in Dogs

Cancerous and Noncancerous Mouth Growths in Dogs

Diagnosing the cause of sores in and around your dog's mouth may require blood tests to rule out herpes or other infections, or biopsies to determine the nature of abnormal cell growth and lesions at the mouth and lips of your dog.

How Do I Treat My Dog’s Blisters or Sores?

As stated above, dogs do not get fever blisters, the same as humans, so if your dog presents with sores on their mouth, determining the cause of those sores will be required before successful treatment can be made.

  • Puppies with herpes virus can be very ill and the only treatment available is supportive treatment with fluids, keeping them warm, and possibly anti viral drugs.

  • Eosinophilic granulomas can be treated with corticosteroids

  • Bacterial infections are treated with topical or oral antibiotics

  • Cancerous lesions may be removed surgically

  • Sores caused by allergies can be treated with antihistamines or steroids

Pet owners may be able to ease mouth sores by:

  • Supporting their dog's immune system, including providing a high protein diet

  • Providing soft food that is not too hot or too cold.

  • Applying cold compresses or ice packs to the sore

How are Blisters Similar in Dogs and Humans?

Although not the same condition, oral sores on dogs are unsightly and irritating the same as the blisters and sores we experience. Herpes in dogs, although different than in humans, has no direct treatment, much like the human counterpart treatment is focused around addressing symptoms and controlling them. Both types of herpes are common in their respective species with ⅓ or more of dogs experiencing an infection at some point in their lives.

How are Blisters Different in Dogs and Humans?

In humans, fever blisters are caused by HSV-1. Dogs have their own form of herpes, although it does not usually cause sores on the mouth. In dogs, sores on the mouth can be from a variety of other causes. Bacterial, parasitic, viral, and neoplastic causes can all responsible for sores on your dog's mouth.

In humans, stress and weakened immune system are a factor in cold sore breakouts, with dogs the cause is usually physical although the immune system and allergies can play a role.

Case Study

A female dog gave birth to puppies and, although she showed no signs of illness, she was secretly harboring canine herpes virus. Unlike in humans, no oral sores were present, however, when her puppies were born, some of the contracted the disease while passing through the birth canal. A few of her puppies were weak, listless and had diarrhea and skin sores. The pet owners provided supportive care for the puppies, hand feeding them liquids and providing intravenous fluids to the sick puppies as well as antiviral medications. Sadly, most of the infected puppies passed away, although, one recovered with the supportive care they received.