Colorado wildlife officials are monitoring an abnormal rise in cases of Shouppapillomavirus, a disease that affects wild and domestic rabbits, due to the high number of sightings this summer..
Shope Papillomavirus, also known as Cottontail Rabbit Papillomavirus (CRPV), is a DNA virus that was first identified in the 1930s by Dr. Richard E. Shop. The virus mainly infects wild coton tail rabbits, but can spread to domestic species. It causes horn-like growth, benign papillomas, which usually appear in the head, neck and genital areas. These lesions are not fatal in nature, but can grow large enough to interfere with diet, vision, or movement, making rabbits vulnerable to starvation, injury, or predation.
There are two known types of CRPV: CRPV-1, Progressor typethe lesions continue to grow, leading to further health complications, and CRPV-2. Regreser typethe lesion may eventually shrink and disappear without intervention. Types present in individual rabbits affect the course of the disease and its effects on survival.
Colorado Parks and Wildlife (CPW) reports a significant rise in sightings of infected rabbits in both rural and suburban areas. Wildlife health officers say most cases are visually identified due to their distinctive wart-like growth. Veterinarian sources say the virus is transmitted primarily through direct contact between rabbits or through insect vectors such as mosquitoes, fleas and mites. In warmer months when insect activity is at its peak, the risk of infection is high. Although CRPV is not known to infect humans, it can spread rapidly through rabbit populations.
The state veterinary lab analyzes tissue samples from affected animals to confirm the diagnosis and assess the prevalence of the disease. These findings help wildlife managers monitor spreads and compare them with historical data.
Pet rabbit owners are advised to minimize contact between animals and wild rabbits. CPW recommends that household rabbits be maintained in safe outdoor hatches indoors or insect-protected areas and avoid free roaming in areas frequently visited by wildlife. Handling wild rabbits is discouraged to prevent stress on the animals and the possibility of virus transfer to the pet. The public is encouraged to report rabbit sightings with apparent growth through the CPW wildlife observation channel. These reports help biologists geographically track diseases and identify local clusters. There is no specific treatment for the shuppapillomavirus in wild rabbits, but lesions in household rabbits can sometimes regress on their own. In severe cases, surgical removal is possible under veterinary care. For wild populations, management focuses on monitoring and reducing environmental stressors that can exacerbate spread.
