Home » Pet Health » Canine Viruses and Infections » Canine Papilloma Virus Overview


Our pets are as vulnerable to illness as we are, and several external factors can contribute to cancer development in our canine friends.

What is CPV?

Canine papilloma virus, or CPV, is a virus that often creates small, non-cancerous (benign) tumors or warts most commonly found around a dog’s mouth and eyes. These warts are called viral papillomas. In humans, warts tend to appear smooth and round. However, papillomas in dogs are often bumpy and irregular, resembling a cauliflower. Although there are seven strains of CPV, the most common is strain 1 (CPV1).

Reports demonstrate that warts associated with CPV may resolve themselves. However, this depends on the age of your dog, where younger dogs are more likely to have warts short-term. Your dog’s immune status will also impact how it handles the infection, with an immunocompromised dog more likely to have a longer-lasting condition and potentially more severe outcomes. CPV cannot transmit across species, so there is no risk to you or your cats.

How does CPV cause papillomas?

Like other viruses, when CPV infects a host cell, it releases its genetic material, causing the cell to produce many copies of the virus. The infected cells release new viral particles that infect surrounding cells. When the host cell becomes infected with CPV, normal cell growth and death processes are disrupted resulting in the uncontrolled division of the host cell. Since CPV primarily infects skin cells, their unchecked growth leads to the formation of papillomas. This process takes some time after infection, which means your dog may have CPV but will remain asymptomatic for some time. It is almost impossible to know when a dog first contracts CPV since symptoms may take years to appear. There are a few stages of papilloma development:

    • Stage 1: A small growth appears near the mouth or lips and continues to grow. Anytime you notice a suspicious lump or bump on your pet, bring them to your vet.
    • Stage 2: The surface of the growth becomes fibrous and texturized.
    • Stage 3: If the wart becomes infected or too large, it might interfere with your dog’s eating and drinking habits. Speak to your vet immediately if you notice this behavior.

Other symptoms

In addition to external warts, your CPV-infected dog might also develop inverted warts (growing into the skin instead of outward) or 1 mm to 1 cm-sized dark-colored lesions. Both may occur in areas apart from the mouth, such as the abdomen or on the legs. These symptoms are more frequently associated with strains of CPV other than CPV1.

Diagnosis and prognosis

Your vet will likely diagnose your dog with CPV upon external examination only, especially if your dog is young. However, they may proceed with microscopic examination of the tissue and molecular lab tests if there is any uncertainty.

If you receive a CPV diagnosis for your dog, the outlook is very bright. As previously mentioned, the characteristic papillomas will probably resolve on their own. If the infection is advanced, your vet may recommend surgery, which has proven effective.

The Pet Cancer Foundation’s Website Editorial team is comprised of veterinarians, veterinary oncologists, and veterinary technicians, as well as scientific writers and editors who have attained their PhD’s in the life sciences, along with general editors and research assistants. All content found in this section goes through an extensive process with multiple review stages, to ensure this extended resource provides pet families with the most up-to-date information publicly available.

The team listing of those contributing to the information on this page is here:

Keep Your Pets Healthy Editorial Team

Last Updated: September 15, 2022

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.


The Pet Cancer Foundation’s Medical Illustration team is comprised of medical illustration specialists and graphic designers that work in consultation with our team of experts to create the medical art found throughout our website. Though not all medical concepts require the assistance of imagery, when a page does contain a medical illustration, credit to the artist and our medical art director will be noted here.

The Pet Cancer Foundation’s medical imagery is protected by copyright and cannot be used without prior approval that includes a mutually signed licensing agreement. Please review our Content Usage Policy.

The following sources were referenced to write the content on this page:

Araldi, RP, Assaf, SMR, de Carvalho, RF, de Carvalho, MACR, de Souza, JM, Magnelli, RF, Módolo, DG, Roperto, FP, de Cassia Stocco, R & Beçak, W 2017, ‘Papillomaviruses: a systematic review’, Genet Mol Biol, vol. 40, no. 1, pp. 1-21.

Bredal, WP, Thoresen, SI, Rimstad E, Aleksandersen, M & Nafstad, PH 1996, ‘Diagnosis and clinical course of canine oral papillomavirus infection’, J Small Anim Pract, vol.37, no. 3, pp. 138–142.

Collier, LL & Collins BK 1994, ‘Excision and cryosurgical ablation of severe periocular papillomatosis in a dog’, J Am Vet Med Assoc, vol. 204, no. 6, pp. 881–883.

Ghim, S, Newsome, J, Bell, J, Sundberg, JP, Schlegel, R & Jenson, AB 2000, ‘Spontaneously regressing oral papillomas induce systemic antibodies that neutralize canine oral papillomavirus’, Exp Mol Pathol, vol. 68, no. 3, pp. 147-151.

Goldschmidt, MH, Kennedy, JS, Kennedy, DR, Yuan, H, Holt DE, Casal, ML, TRaas, AM, Mauldin EA, Moore, PF, Henthorn, PS, Hartnett, BJ, Weinberg, KI, Schlegel, R & Felsburg, PJ 2006, ‘Severe papillomavirus infection progressing to metastatic squamous cell carcinoma in bone marrow-transplanted X-linked SCID dogs’, J Virol, vol. 80, no. pp. 6621-6628.

Lange, CE & Favrot C 2011, ‘Canine papillomaviruses’, Vet Clin North Am Small Anim Pract, vol. 41, no. 6, pp.1183-1195.

Meuten, DJ 2002, Tumors in Domestic Animals, 4 edn, Blackwell Publishing, Ames, Iowa.

Munday, JS, Thomson, NA & Luff JA 2017, ‘Papillomaviruses in dogs and cats’, Vet J, vol. 225, pp. 23-31.

Munday, JS, Tucker, RS, Kiupel, M & Harvey, CJ 2015, ‘Multiple oral carcinomas associated with a novel papillomavirus in a dog’, J Vet Diagn Invest, vol. 27, no. 2, pp. 221-225.

Nicholls, PK & Stanley, MA 2000, ‘The immunology of animal papillomaviruses’, Vet Immunol Immunopathol, vol. 73, no. 2, pp. 101-127.

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.