Intralymphatic Immunotherapy with Ultrasound Guidance Seems to Be Associated with Improved Clinical Effect in Canine Atopic Dermatitis—A Retrospective Study of 109 Cases

<b>Background:</b> Intralymphatic immunotherapy (ILIT) has been used successfully in both human and veterinary medicine as a safe and effective treatment for allergic diseases. Initially, ILIT was administered by ultrasound guidance, but palpation-based injections have become more popular among veterinary dermatologists. Data from human medicine, however, show that precise injection into the lymph node is mandatory, and injection quality clearly correlates with clinical response. <b>Hypothesis:</b> Our aim was to assess the impact of the injection method (ultrasound guidance versus palpation-based guidance) on clinical response in dogs with atopic dermatitis. <b>Methods:</b> A total of 129 canine atopic dermatitis (CAD) cases treated with ILIT between 2014 and 2022 were retrieved from the hospital clinical database. The included dogs had to receive at least three intralymphatic injections administered either by palpation or ultrasound guidance. Those cases were retrospectively assessed and compared regarding clinical response to ILIT. <b>Results:</b> In total, 84 dogs received ILIT by ultrasound guidance, and in 25 dogs, ILIT was injected based on palpation. The success rate of ILIT was significantly higher in the ultrasound guidance group when compared to palpation-based injections. <b>Conclusions:</b> Low-quality injections must be considered as a possible reason for ILIT failure in dogs. Further prospective and controlled studies are necessary to confirm these results.