Objective To review the published medical literature on dog allergy immunotherapy and discuss prior clinical trials, important allergens, extract specifics, and potential future treatment options for dog allergy relevant to the clinical allergist. Data Sources MEDLINE search was performed using the terms dog, immunotherapy, and allergy limited to human studies from any period. Articles cited in selected studies also were reviewed for appropriateness of inclusion into this review. Study Selections Publications were included that were original research and fit the topic of dog allergen immunotherapy, specifically articles that investigated prior effectiveness and safety of dog allergen immunotherapy, dog extracts, identification of dog allergens, and current prescribing trends among allergists. Results Two hundred fifteen articles were initially identified and 60 were reviewed in complete detail for inclusion in this review. The primary focus was placed on the 17 clinical trials that investigated the safety and efficacy of dog immunotherapy and the 19 studies that explored and defined the complex allergenic profile of dog extracts. Conclusion The medical literature on the use of dog extract immunotherapy in patients with hypersensitivity to dog shows poor and conflicting results of clinical efficacy, which has been attributed to poor-quality extracts and the inherent complex allergenic profile of dogs that remains without a clearly dominant allergen.