Dog Mouth Sores (Ulcers): Causes & Treatment

Although ulcers of the mouth appear as a local problem, they may reflect a more serious underlying cause and can have systemic effects on the body.

Unfortunately, oral ulcers in dogs often go unnoticed because of their location. But there are other signs you can watch for that may signal a problem in your dog’s mouth.

A dog’s mouth serves several crucial functions. Primarily, a healthy mouth is necessary for eating and drinking. But dogs also use their mouths for other important purposes including grooming and heat regulation through panting.

In addition to jaws and teeth, the mouth contains important soft tissue structures, such as the gums and tongue. If any of these oral structures are injured or diseased, dogs can develop problems like dehydration or poor nutrition. One category of issues that can affect a dog’s mouth is inflammation and ulcers.

What Are Mouth Ulcers in Dogs?

Oral ulcers are disruptions or breaks in the surface of the skin or mucous membrane of the mouth. An ulcer is a more severe version of erosion and excoriation, which are also types of epithelial defects.

Dogs can have a mouth ulcer that affects the skin of the lips outside the mouth or the mucosa inside the oral cavity. In addition to location, a dog mouth ulcer (aka “dog canker sore”) can vary in depth of the affected tissue.

What Causes Dogs to Get Sores (Ulcers) in and Around Their Mouths?

Any soft tissue structure in and around the mouth can develop ulcers or inflammation. There are different types of mouth ulcers in dogs with various underlying causes.

Potential causes of dog mouth ulcers fall into the following broad categories:

• Inflammation
• Infection
• Immune-mediated disease (e.g. pemphigus vulgaris)
• Metabolic disease (e.g. advanced kidney disease)
• Trauma (e.g. burns, mechanical injury, chemicals)
• Nutrition-related
• Cancer
• Idiopathic (i.e. no specific underlying cause identified)

There are many potential types and causes of canine mouth ulceration and inflammation but we will focus on the most common ones.

Chronic Ulcerative Stomatitis in Dogs

One condition that causes inflammation and ulceration in dogs’ mouths is chronic ulcerative paradental stomatitis (aka CUPS).

As denoted by the name, CUPS is a chronic or persistent condition that can wax and wane. Stomatitis means inflammation of the mouth and paradental means this disease process affects the soft tissue adjacent to the teeth. The classic appearance of this condition is characterized by kissing lesions, which are ulcers affecting the mucosa contacting the teeth.

There seems to be a breed predisposition with Maltese more commonly affected. Cavalier King Charles Spaniels may also have an increased risk of developing this disease.

The oral ulcers associated with CUPS contain a high number of inflammatory cells known as lymphocytes and plasmacytes. Hence, this condition is also referred to as lymphocytic-plasmacytic stomatitis. The high number of inflammatory cells reflects the inappropriately significant inflammatory response to dental plaque and bacteria. In other words, pets with CUPS are essentially allergic to their dental plaque.

Fungal Stomatitis in Dogs

Fungal or mycotic stomatitis in dogs is inflammation of the mouth due to the overgrowth of the yeast known as Candida albicans.

Canines may develop this condition if their immune system is suppressed or may be related to another concurrent oral disease. Additionally, fungal stomatitis can occur following a long course of antibiotics.

Trenchmouth in Dogs

Less commonly, dogs can develop ulcers in their mouth due to necrotizing ulcerative gingivitis (aka “trenchmouth”). In addition to oral ulcers, trenchmouth causes significant gingivitis and tissue death in the mouth. These animals have infections in their mouths that can make their gums bleed or even lead to exposed jaw bone.

Affected dogs seem to be more prone to infection of their oral structures. We do not know the exact cause of trenchmouth but risk factors may include nutritional problems, stress, or steroid medication.

Trauma Causing Mouth Inflammation and Ulcers in Dogs

Any type of trauma can result in inflammation or ulceration in your dog’s mouth. This includes thermal, electrical, and chemical burns. Other common types of oral trauma include cheek biting, insect bites, and foreign bodies like grass awns and string.

Canine Lip Disorders

We must not forget that ulcers and inflammation can also occur outside and around the mouth.

Just as trauma can affect the inside of the mouth, the lips are susceptible to traumatic injury. Like wounds inside of the mouth, lip wounds can also become infected.

Another problem that can affect a dog’s lips is chelitis, or inflammation of the lips. While multiple things can make your dog’s lips inflamed, a common cause is severe inflammation or infection inside the mouth including advanced dental disease.

Inflammation can affect a dog’s lips directly but it can also occur in the skin folds between the lips. Inflammation of the skin between the lip folds is termed lip fold dermatitis. This chronic inflammatory condition is more common in breeds with prominent, droopy lip folds such as Bulldogs, Mastiffs, and Saint Bernards. These breeds can also develop secondary skin infection due to yeast and bacteria.

Symptoms of Chronic Mouth Inflammation and Ulcers in Dogs

Most owners do not regularly examine the inside of their dog’s mouth. So how can you tell if your dog might have a mouth ulcer? While the lesions themselves may not be easily visualized, dog mouth sores and inflammation typically cause other noticeable symptoms.

Symptoms depend on the cause and degree of inflammation or ulceration. As you can imagine, oral ulcers are very painful and symptoms often reflect this discomfort.

In general, the most common symptoms observed with oral inflammation and ulcers include the following clinical signs:

• Decreased appetite
• Difficulty eating and drinking
• Halitosis (aka bad breath)
• Drooling or excess saliva
• Pawing at the mouth
• Sensitivity or resistance to handling of the mouth or face
• Blood-tinged saliva
• Redness or swelling in and around the mouth
• Hesitance or resistance with chewing on toys
• Enlarged lymph nodes of the head and neck region

Additional symptoms can occur depending on the cause of a dog’s mouth ulceration or inflammation.

For example, if a dog has mouth ulcers secondary to a systemic problem such as cancer or kidney disease, he will often also have systemic signs of illness such as lethargy, vomiting, or changes in urination.

If a dog has long-term or recurrent inflammation of the lips or lip folds, he may also have changes consistent with chronicity. For instance, when a dog has chronic inflammation between his lip folds, the affected skin often becomes thickened and darker in color.

Treatment of Dog Mouth Sores and Inflammation

Successful treatment of mouth ulcers requires addressing the primary cause so that the wounds can heal. For example, a dog with fungal stomatitis would be prescribed an anti-fungal medication whereas a dog with a bacterial infection of the mouth would need an appropriate antibiotic.

Treatment and prognosis of dog mouth sores depend on the underlying cause. But there are some treatment strategies that are relevant regardless of the primary cause of mouth ulceration and inflammation.

Medications to Address Pain and Inflammation for Dog Mouth Ulcers

Independent of the primary cause, ulceration and inflammation of the mouth is painful. So your veterinarian will likely prescribe some form of anti-inflammatory and pain relief medication at least temporarily to make your dog more comfortable in the more severe, initial stages of disease. Adequate pain management is critical since it is highly linked to your dog’s ability to eat and drink.

Nutritional Support and Diet Modification for Dogs With Mouth Ulcers

This brings us to the next big aspect of treatment, which is nutritional support. Because mouth ulcers are painful, these animals must be closely monitored for changes in appetite, weight loss, and dehydration.

Pets suffering from oral ulceration may require temporary diet modification. A wet food diet or soft diet will be more gentle on the oral cavity until the affected gums and tissue heals. It is important to work with your veterinarian to ensure your dog still gets enough calories and that his soft food diet is complete and balanced.

In extreme cases, your vet may recommend a temporary feeding tube. While this may seem like a drastic measure, feeding tubes are often well-tolerated with appropriate care and prevent other dangerous issues like weight loss and nutritional deficiencies, which would ultimately delay the healing of your dog’s mouth.

I also recommend avoiding chew toys, dental chews, and hard treats during this time. These can cause mechanical irritation, which can cause further damage and impede the healing process.

Regular Cleaning of the Lips and Skin Outside of Your Dog’s Mouth

In cases where a dog’s lips or lip folds are affected, it is important to keep these areas clean and dry. This is important for managing inflammation and preventing progression to secondary infection. Your vet may also shave the hair around your dog’s mouth and prescribe a topical antiseptic for a thorough dental cleaning of the area.

If a dog has chronic or recurrent lip fold dermatitis, oral surgery may be an option.

Additionally, if your dog is consistently pawing at or rubbing their face, he may need an Elizabethan collar (aka “E-collar”) to prevent him from continuing to traumatize his lips and skin.

The Importance of At-Home Dental Care for Your Dog

Good oral hygiene plays a big role in the healing of dog mouth ulcers.

This is in part because oral bacteria can lead to infection of mouth sores. Additionally, dental disease results in inflammation of the oral tissues, including gingivitis. In cases of CUPS, oral ulceration and inflammation are triggered by dental plaque and bacteria.

Furthermore, infection or inflammation inside of the mouth can extend to the outside of your dog’s mouth. For these reasons, consistent at-home dental care is a crucial part of the treatment plan for canines with mouth ulcers.

Daily tooth brushing is the most effective way to slow the accumulation of dental plaque and tartar. But this option may not be realistic depending on your situation. I always tell owners that the best at-home dental care is whatever regimen they can actually do consistently. Ultimately, success depends on compliance. Fortunately, there are multiple methods that can be combined, including dental chews, dental gels, and prescription dental diets.

Dogs Require Professional Dental Cleaning Under Anesthesia

Like with people, even with the best at-home dental care, dogs require regular professional dental cleaning under anesthesia.

Tooth extractions may also be indicated. For example, in cases of CUPS, owners may choose to have their dog’s teeth extracted to completely remove the source of inflammation. Abnormally positioned teeth (e.g. malocclusion) may also need to be removed to eliminate sources of mechanical trauma and ulceration.

Other Possible Supplemental Therapy for Dog Mouth Ulcers

The following therapeutic methods are usually not sufficient if used as the sole treatment of canine mouth ulcers or periodontal disease. But these therapies may improve treatment success and healing time if used to supplement other treatment strategies.

For instance, topical medication containing zinc ascorbate or zinc gluconate may be prescribed to encourage healing. These ingredients promote collagen formation, which is needed to regenerate epithelium. Dental gels also act as a barrier and may benefit some dogs, like those with CUPS.

Another potential oral ulcer supplemental treatment is CO2 laser. This treatment option has been shown to reduce pain and bacteria in the mouth.