Oral papilloma

Like many other mammals, rabbits can suffer from papilloma viruses that cause rough, reddened, wart-like skin lesions. Benign oral papilloma are most common in domestic rabbits but in some regions of the world, a more serious form of the virus can affect other areas of the skin and can develop into a more serious form of cancer.

Oral papilloma occurs in rabbits 2-18 months of age, with British and New Zealand White rabbits more commonly affected. Both male and females can be affected.

The condition presents with small (around 1-2 mm in size), reddened, or whitish wart-like lesions found inside the mouth most commonly under the tongue, and sometimes on the gums or floor of the mouth. The most common presentation is with multiple lesions that may appear lumpy like cauliflower. In rare cases, the lesions can grow up to 4-5 mm. Rabbits may have the virus, and not show any physical signs.

Oral papillomas are not highly contagious and rarely progresses to serious disease.

If your rabbit has oral papilloma, it may show signs of salivation/drooling, reduced appetite (due to pain), difficulty eating (if the lesions are large enough to prevent chewing), bleeding from the mouth, or inactivity.

Diagnosis of oral papilloma is made from a clinical examination of the lesion.

Many oral papillomas will resolve on their own within a few weeks. Others may not cause the rabbit any discomfort, so treatment is not required. If the rabbit is uncomfortable, the lesion is bleeding excessively, or if the size of the lesions is affecting normal eating habits, your vet can anaesthetise your rabbit and surgically remove the lesion. They may then send the lesion to a laboratory to gain a definitive diagnosis. Laser removal of the lesions may also be possible in some cases.

Recovery after surgery may include rest, pain medications, and antibiotics if there is concern about secondary infection.

It may be that some rabbits are more prone than others to the infection, and therefore may develop further lesions again at some point, but equally they may resist further infection.

Skin papilloma is caused by a DNA virus known as Shope papilloma virus, or Cottontail rabbit papilloma virus (CRPV). This virus infects the skin on the head and neck, commonly in hairless areas like the eyelids and ears. The lesions are easily traumatised with grooming, scratching, or grooming from a companion rabbit, and therefore may bleed.

Skin papilloma is most commonly seen in wild Cottontail rabbits in the Midwest and the Great Plains of the United States. Natural disease in domestic rabbits has been reported only from Southern California.

Skin papilloma can become malignant, developing into a more serious type of cancer called squamous cell carcinoma. These lesions can invade surrounding tissue. This is one reason why surgical removal may be advised by your vet if a skin lesion is detected.