Extensive progressive pigmented viral plaques in a Chihuahua dog

Abstract

Extensive exophytic pigmented viral plaques developed on a Chihuahua dog causing pruritus and discomfort. Neither the medical treatments used nor a papillomavirus vaccine resulted in clinical improvement. Laser surgery removed some plaques, yet others developed. This case illustrates the difficulty in treating viral plaques and the progressive nature of this disease.

Clinical, histopathological, and molecular characterization of canine pigmented viral plaques

“…Similarly, azithromycin was found to be uneffective in a single case in this series and it is reasonable that it could be abandoned, although a proper efficacy study in PVPs is lacking. 9,20,35 Imiquimod was uneffective when used by both Hansen et al 9 and Munday et al 20 and lacked a therapeutic benefit in a dog in this case series. All other attempts to use drugs such as retinoids, interferon, and firocoxib, in addition to other drugs, were unsuccessful or with inconsistent results.…”

“…5,19,24 As an alternative to conventional surgery, laser therapy has been successfully used to treat grouped and extensive lesions; however, new lesions can develop elsewhere on the body. 10,20,29 Unfortunately, only one of the cases with a single lesion herein documented was treated with the CO 2 laser. According to Knight et al, 10 the advantage of the laser was that the method only vaporizes tissue within the epidermal basal membrane avoiding scarring and promoting rapid healing, allowing it to be used on large areas.…”

“…All other attempts to use drugs such as retinoids, interferon, and firocoxib, in addition to other drugs, were unsuccessful or with inconsistent results. 9,20,23,29 To date, it appears that no medical therapy is able to cure multiple to generalized viral plaques; laser therapy is the only one that can benefit dogs without the side effects of a more aggressive conventional surgery. 10 Although considered rare, spontaneous regression was observed in 3 cases.…”

“…To date, CPVs identified from pigmented plaques are CPV-3, 4, 5, 8, 9, 10, 11, 12, 14, 16, 18, and 24. 13,20,22,32 The first report investigating a role of papillomavirus (PV) in the genesis of PVPs dates back to 1995. 23 It is noteworthy that similar cases had been published previously, but were considered to be idiopathic and hereditary and were named lentiginosis profusa and referred to as pigmented epidermal nevus.…”

Dermatological Problems of Brachycephalic Dogs

“…This viral skin disease associated with Chipapillomavirus is reported in many brachycephalic breeds, including the Pug, French bulldog, Chihuahua, and Boston Terrier, as well as in non-brachycephalic breeds [65][66][67][68]. The onset of the disease may be related to a genetic immunodeficiency, as reported in pugs, Vizslas, and Chihuahuas, or secondary to immunosuppression [164]. Numerous small, plaque-like, hyperpigmented lesions with an irregular and scaly surface appear on the ventral neck, thorax, abdomen, and ventromedial, proximal limbs (Figure 4).…”