Background Lokivetmab, a caninised monoclonal antibody against interleukin (IL)-31, is an effective treatment for the pruritus associated with canine atopic dermatitis (cAD). Objectives To investigate the efficacy and safety of lokivetmab during long-term treatment defined as at least three consecutive lokivetmab injections in atopic dogs under field conditions. To assess individual factors influencing treatment outcome and adverse events. Animals150 dogs with cAD. Materials and Methods Medical records of dogs treated with lokivetmab were reviewed, and owners and/or veterinarians were contacted as needed for follow-up. A decrease of the pruritus Visual Analog Scale (PVAS) score by >= 2 or a PVAS score <= 2 after treatment was considered as treatment success. Logistic regression was used to investigate the influence of a variety of factors on outcome: type of cAD (food versus environment), age at first lokivetmab administration, disease chronicity, dosage and/or secondary infection. Any adverse event that occurred during the study period was recorded. Results Lokivetmab reduced the PVAS score with long-term use (p < 0.01); the success rate was 53 of 69 total dogs (77%). The probability of treatment failure decreased with increasing treatment duration. None of the factors investigated influenced the treatment outcome. Twelve dogs of 150 (8%) showed adverse events such as gastrointestinal signs or lethargy. Conclusion and Clinical RelevanceLokivetmab appears to be an effective and safe long-term anti-itch therapy for dogs with cAD.