In total, 2 pet guinea pigs (Cavia porcellus) that were 5 years old were presented with pruritus, erythema, alopecia, and crusting of the ventral abdomen. Skin scrapings revealed multiple nematode larvae, identified as Pelodera strongyloides based on morphologic characteristics. Treatment consisted of systemic ivermectin and fenbendazole in addition to topical benzoyl peroxide application. P. strongyloides is a free-living saprophytic nematode, which is ubiquitously present in any decaying organic material, such as soil or feed. The nematode is capable of invading mammalian skin, resulting in pruritic dermatitis. Diagnosis of the nematode induced skin disease is based on history, including husbandry, presence of a ventrally distributed dermatitis, and demonstration of larvae in skin scrapings. Dermal peloderosis cases have been reported in different animal species, including dogs, cattle, horses, sheep, and a laboratory housed guinea pig. This is the first description of P. strongyloides dermatitis in pet guinea pigs. P. strongyloides dermatitis should be considered as a differential diagnosis for alopecic and crusty skin lesions in guinea pigs.