Papillomatosis in dogs: causes and treatment

Papillomatosis in dogs is caused by canine papillomaviruses, which infect the skin and mucous membranes and form wart-like growths. The mouth and lips are most often affected in young animals, and the skin and conjunctiva are less commonly affected. Most lesions are benign and appear as cauliflower-like growths or thin, thread-like appendages on a stalk. [1]

Infection occurs through direct contact with an infected dog or through grooming items. The incubation period is usually several weeks, after which the number of papillomas increases. The viruses are highly contagious to dogs, but are species-specific, meaning they are not dangerous to humans. [2]

In puppies and young dogs, the disease is often self-limited due to the maturation of cellular immunity. Papillomas can regress within two months, sometimes longer, especially with multiple lesions or secondary inflammation. Bacterial complications often occur when the nodules are traumatized. [3]

In adult animals, other clinical variants are observed, including solitary cutaneous papillomas, inverted papillomas, and pigmented plaques. These are less likely to regress spontaneously and more often require targeted treatment. Different variants are associated with different types of canine papillomaviruses. [4]

Malignant transformation in typical oral papillomas of young animals is described as casuistry, while certain cutaneous forms, such as pigmented plaques, are rarely associated with precancerous and cancerous changes. This emphasizes the importance of accurate diagnosis of the disease form. [5]

Table 1. Key facts about papillomatosis in dogs

Fact	Practical significance
The causative agent is canine papillomavirus.	Infection occurs only between dogs.
The most common localization is the oral cavity in young people	Often self-limiting as immunity matures
Transmission route - contact and care items	Hygiene and isolation are necessary during illness.
Species specificity	Not dangerous to humans
Rare malignant transformation	Requires attention to cutaneous atypical forms

Clinical forms: from "puppy warts" to pigmented plaques

The classic form in young people is multiple oral papillomas. The nodules appear on the lips, buccal mucosa, tongue, and sometimes in the transition zones of the skin and mucosa. They interfere with chewing and may bleed and become inflamed, but most often disappear as the immune response develops. [6]

In adult dogs, solitary skin papillomas are common on the limbs, head, and other areas of the skin. These dome-shaped or cauliflower-shaped growths are often traumatized and infected, requiring removal. Inverted papillomas grow deeper into the epidermis and may appear as crater-like nodules. [7]

Pigmented plaques appear as flat, dark lesions, often multiple, and sometimes breed predispositions are observed, for example in pugs. In some of these cases, a link has been described with virus types that may be involved in the formation of precancerous changes. Caution and biopsy are necessary in atypical cases. [8]

Rare localizations include the conjunctiva, eyelids, nasal labium, and pharynx. With extensive lesions, discomfort, bad breath, loss of appetite, and weight loss are possible. Skin complications are most often associated with trauma and secondary pyoderma. [9]

The risk of malignant transformation depends on the clinical and virological variant. For typical oral papillomas in young individuals, this risk is minimal, but for some cutaneous variants and pigmented plaques, it is described as a rare possibility requiring observation and morphological verification. [10]

Table 2. Main clinical variants

Option	Age more often	Localization	Forecast
Oral papillomas	Young people	Lips and oral mucosa	Often spontaneous regression
Solitary skin papillomas	Adults	Limbs, head, skin	Often require removal
Inverted papillomas	Adults	Skin, less often mucous membranes	A biopsy is needed for confirmation.
Pigmented plaques	Adults	Flat dark spots on the skin	Precancer is possible in some types

Symptoms and Red Flags: When to See a Vet

Typical symptoms of the oral form include cauliflower-shaped nodules, salivation, difficulty chewing, and a foul odor. Warty or dome-shaped nodules, sometimes pedunculated, are visible on the skin. Inflammation and ulceration increase pain and the risk of secondary infections. [11]

Red flags include rapid growth, bleeding, ulcers, severe pain, refusal to feed, weight loss, and a persistent course without signs of regression. These signs require in-person evaluation and, most often, histological confirmation. [12]

Papillomatosis is contagious to other dogs, especially young and immunocompromised dogs. During active infections, temporary separation, individual bowls and toys, and hand hygiene after contact are recommended. Canine papillomaviruses pose no threat to humans. [13]

Some dogs traumatize papillomas with their paws or teeth, which leads to chronic inflammation and bleeding. In such cases, the veterinarian expedites treatment decisions to prevent further trauma and reduce the risk of bacterial complications. [14]

If the nodes are located in the pharynx or at the base of the tongue, coughing, grunting, choking, and decreased exercise tolerance may occur. These are reasons for urgent examination, as large lesions may partially block the lumen and require prompt intervention. [15]

Table 3. When a visit to the doctor is necessary

Situation	Why is it important?
Rapid growth or ulcers	Risk of atypia and secondary infection
Pain, refusal to eat	Risk of dehydration and weight loss
Bleeding and trauma	Risk of anemia and infection
Long-term absence of regression	Morphological verification required
Lesions of the pharynx and tongue	Risk of obstruction and breathing problems

Diagnostics: from clinical examination to histology and PCR

An experienced physician often recognizes papillomatosis by its appearance and location. If in doubt, cytology or, more commonly, histological examination is performed after excision or biopsy. Histology confirms the wart-like architecture and characteristic virus-associated cellular changes. [16]

Polymerase chain reaction (PCR) is useful for determining the virus type and for clinical case clarification. Typing is helpful in complex or recurrent situations, as well as when a connection with precancerous processes is suspected in certain skin variants. [17]

Differential diagnosis includes histiocytoma, mast cell carcinoma, squamous cell carcinoma, epulis, and other oral and skin tumors. This is another reason not to delay biopsy in cases of atypical presentation, rapid growth, or persistent progression without regression. [18]

In cases of multiple oral papillomas in young animals, invasive methods are often not required if the signs are typical and there are no complications. In such cases, observation and oral care are recommended until natural regression occurs. If the condition worsens, the strategy is reconsidered. [19]

Laboratory tests for secondary infection and general assessment help plan treatment and anesthetic risk if surgery is required. The attending physician determines the specific tests based on the patient's clinical presentation. [20]

Table 4. Diagnostic methods and their objectives

Method	What does it give?	When needed
Examination and dermatoscopy	Preliminary verification	A typical picture without any red flags
Cytology	Rapid cell assessment	For inflammation and ulceration
Histology	Final confirmation	Rapid growth, atypical form, adults
PCR typing	Clarification of the virus type	Relapses, atypical and multiple lesions
General clinical tests	Preparing for treatment	Before removal or anesthesia

Treatment: when to wait, when to act and what exactly to do

For typical oral papillomas in young animals, an observational strategy with oral care is warranted, as most cases regress. Active treatment is indicated for pain, bleeding, feeding and breathing difficulties, and persistent cases without improvement. [21]

Surgical methods include excision, cryodestruction, and laser removal. They quickly eliminate problematic nodes, especially those prone to trauma and pain. The method is selected based on the location, number of lesions, and equipment availability, followed by histological confirmation. [22]

Among the drug approaches, options involving azithromycin have been described. In a randomized, double-blind study, treatment was associated with faster lesion resolution compared to placebo, making this option feasible for severe cases and multiple lesions. The decision is made by the physician, taking into account associated factors. [23]

For skin lesions in adult dogs, topical imiquimod is sometimes used, using regimens adapted for veterinary practice. In some patients, it helps achieve regression, but skin irritation monitoring and safety precautions are required. The data are of a practical nature and depend on the type of lesion. [24]

Autovaccines and other immunobiological methods have been described in observational studies, but their effectiveness is difficult to separate from natural regression, and isolated reports indicate possible adverse effects. Therefore, such decisions require careful assessment and discussion of risks and benefits. [25]

Table 5. Treatment options and indications

Approach	When appropriate	Pros	Restrictions
Wait-and-see tactics	Typical oral papillomas in young people	Often enough	Risk of injury and infection in the long term
Surgery and cryo	Pain, bleeding, trauma, no regression	Quick elimination of the outbreak	Anesthesia, risk of recurrence in multiple lesions
Azithromycin	Severe and multiple cases	RCT data on the benefits	The solution is individual, monitoring of side effects
Imiquimod topical	Skin nodules in adults	Alternative to deletion	Irritation, requires control
Immunotherapy and autovaccines	Individual complex cases	Possible effect	Limited evidence base

Prevention and home care: Reduce spread and speed recovery

During periods of active papilloma, it's best to separate your dog from unfamiliar animals, especially young ones. Bowls, toys, brushes, and pillows should be kept separate and cleaned regularly. Hand hygiene reduces the risk of virus transmission between pets. [26]

Daily oral hygiene reduces inflammation and odor, especially if the lesions are traumatized during eating. Choosing gentle, soft foods and avoiding coarse treats helps reduce mechanical irritation. If pain occurs, the doctor may prescribe pain medication. [27]

Keeping the nails short is important for the skin to reduce scratching and the risk of secondary infections. If signs of pyoderma or weeping lesions appear, consult a doctor for treatment. Self-medication with aggressive human wart treatments is unacceptable due to the risk of burns and intoxication. [28]

Prevention includes contact monitoring at sites, caution during group training, and isolation of animals with obvious warts. Returning to normal activity is considered after the lesions have stabilized or been removed to prevent continued virus circulation. [29]

Overall immune health influences the course of the illness. A balanced diet, routine vaccinations according to current guidelines, and treatment of concomitant illnesses help reduce the duration of the episode. If immunodeficiency is suspected, the doctor will conduct a more comprehensive examination. [30]

Table 6. Home checklist for the treatment period

Paragraph	How to do it
Disunity	Individual bowls and toys, separate rest
Oral care	Soft food, gentle hygiene as recommended by a doctor
Claws and skin	Trimming claws, protection from scratching
Prohibition of "self-medication"	Do not use human cauterizing agents
Contact control	Limit play with unfamiliar dogs until recovery

Prognosis, relapses, and association with cancer risk

For the oral form, the prognosis in young dogs is usually favorable. Most cases resolve spontaneously within a few weeks, although with multiple lesions the process may be prolonged. In cases of severe pain and feeding difficulties, more active intervention is required. [31]

Cutaneous forms in adults are more variable. Solitary papillomas rarely recur after removal, but with multiple lesions, new lesions are possible. Monitoring and early treatment of traumatized nodes reduce complications. [32]

Malignant transformation of typical oral papillomas in young animals is extremely rare, whereas precancerous changes have been described in certain cutaneous variants associated with certain viral types. Therefore, morphological confirmation and consistent monitoring are indicated in cases of atypical progression. [33]

Local antitumor ablation methods, including electrochemotherapy, are used for malignant oral tumors in dogs, but are not considered routine therapy for benign papillomas and are mentioned here only to differentiate tactics. The choice of strategy is always made by the veterinarian. [34]

In the long term, the risk of recurrence is reduced by hygiene, contact monitoring, and prompt removal of affected areas. In the case of recurrent episodes, the physician may discuss advanced diagnostics and the selection of additional methods. [35]

Table 7. Prognostic benchmarks

Situation	Forecast	Tactics
Oral papillomas in young people	Favorable	Waiting or targeted treatment for complications
Solitary skin papillomas	Favorable after removal	Histology of the removed node
Pigmented plaques and atypical lesions	Careful	Biopsy, personalized tactics
Multiple and persistent forms	Variable	A combination of local and medicinal methods

Frequently asked questions from owners

Is it dangerous for humans and other animals? Canine papillomaviruses are species-specific and pose no threat to humans. The disease is contagious to other dogs during active lesions, so hygiene and isolation are necessary during this period. [36]

How long to wait for spontaneous regression? With the typical oral form in young children, regression often occurs within two months, sometimes longer. If the course is persistent, with pain, bleeding, or feeding difficulties, active management is needed. [37]

Are there tablets or ointments? In some cases, a doctor may prescribe azithromycin for severe cases; imiquimod is sometimes used for skin lesions in adults. The decision is individual, based on the clinical picture and the risk of side effects. Self-medication is unacceptable. [38]

Do "wart vaccinations" help? Observational studies and case studies have been described, but high-quality evidence is limited and side effects are possible. Such methods are considered only after discussing the risks and alternatives. [39]

When to remove. Indications include pain, bleeding, trauma, feeding problems, lack of regression, atypical appearance, or rapid growth. The removed material is sent for histology to confirm the diagnosis. [40]

Table 8. Brief algorithm of the owner’s actions

Step	Action
Grade	Veterinary examination and monitoring plan
Hygiene	Individual items, minimizing contact
Care	Gentle feeding, scratching control
Therapy decision	Depending on the indications - removal or medical methods
Control	Histology upon removal, re-examination in case of relapse