Papillomavirus is a small DNA virus that causes wart-like benign tumors in all domestic animals. The virus is specific to each species, meaning that a specific strain can only be spread to another animal of the same species. The three known strains of canine papilloma viruses are:
- Canine mucous membrane papillomatosis
- Cutaneous papillomas
- Cutaneous inverted papillomas
Each of the three strains causes symptoms in different regions of the dog's body.
Symptoms of Canine Papillomavirus Strains
The incubation period and duration of infection varies between dogs. The primary symptom of any papillomavirus is the appearance of it's characteristic papillomas, or lesions. The papillomas start out as very small and pink or flesh toned. Over the course of approximately 4 to 6 weeks, the papillomas change in both size and appearance. They eventually become large, rough warts that appear gray or white in color. The papillomas can occur in large quantities of 50 to 100 and they arise on different parts of the body. The region of the body affected by the papillomas is usually dependent on what strain of the virus has infected the dog.
Canine mucous membrane papillomatosis mainly affects dogs under two years of age. Multiple warts will occur on the oral and conjunctival mucous membranes including regions such as:
- Lips
- Inside mouth
- Esophagus
- Eyelids
- Hair around eyes
In severe cases of mucous membrane papillomatosisoral, the papillomas may affect or inhibit the dog's ability to chew and swallow food.
Cutaneous papillomas have the same appearance as those caused by mucous membrane papillomatosis. The cutaneous papillomas usually occur singularly or in small quantities. They are more common on older dogs and it is believed that Cocker Spaniels and terriers may be predisposed to the condition. These papillomas resemble common "skin tags" and may be found in regions of the body such as:
- Skin on main body, rarely extremities
- Footpads
- Beneath nails, or glandular ducts.
Cutaneous inverted papillomas affect young, but nearly adult, dogs. The papillomas are raised but appear more internal than those caused by the other strains. Cutaneous inverted papilomas are around the glandular ducts, arising in the dog's abdominal region.
It is possible, but rare, for viral papillomas to develop into cancerous cells.
Diagnosis of Canine Papillomavirus
In many cases, the papillomavirus can be visually characterized because of multiple lesions. If the lesions are few in number they may be a similar variation of warts that resemble papillomas. Single skin papillomas are common in older dogs but may not be caused by the virus. Definite diagnosis requires laboratory testing for identification of the virus or it's recognized effect on the body's cells.
Treatment of Canine Papillomavirus
The papillomavirus is self-limiting and most cases will disappear spontaneously within 6 to 12 weeks of maximum growth. If the lesions are in any way disruptive to the dog's health or well being, they may be removed by means of surgry, freezing, or electrocautery. If the warts are to be surgically removed, the procedure will need to be done when they are at or near maximum growth. Warts that are removed while they are still growing may cause regrowth or stimulation of growth. After exposure and recovery, the dog's immune system manufactures antibodies that prevent reinfection of the papillomavirus.