Simple Summary Elbow arthroscopy is commonly performed in canine's orthopedics. During this procedure, two portals are required: one to insert the arthroscope, and the second one for surgical instruments. Establishment of an instrument portal is challenging due to limited visibility (via the arthroscope), and little free space inside the joint. To make this procedure easier, the goal of this study was to create a 3D-printed prototype of a device aiming the needle preceding the portal, and to check its feasibility on 15 canine cadavers of different sizes and breeds. On each cadaver, the procedure was performed on both elbows-one using the prototype, and the second one with a free hand. The two techniques were compared according to the mean number of attempts needed to achieve an optimal position of the instrument portal. We conclude that the use of the prototype increases the likelihood of the needle guiding the portal into entering the joint properly during the first attempt, making the arthroscopy less traumatic.Abstract While the insertion of the arthroscope into the elbow joint is relatively easy based on anatomical landmarks, obtaining a correctly located instrument portal is often difficult. Therefore, the goal of the study was to create a 3D-printed prototype of an aiming device for the guiding needle, and to check its feasibility. The study included fresh cadavers of 15 dogs, 9 males and 6 females, aged from 1 to 6 years (median 4 years) with body weight from 17 to 57 kg (median 30 kg). On each dog, we compared the number of attempts needed to obtain optimal direction of the guiding needle for the portal, using one elbow the prototype, and performing this as control on the opposite joint without the prototype (with a free hand). The number of attempts needed was significantly lower using the prototype (median 1) than on the control elbows (median 2, p = 0.009). The number of attempts was not correlated with the body weight neither in the case of experimental (Rs = 0.18, p = 0.532) nor control elbows (Rs = 0.13, p = 0.642). We conclude that the used prototype seems to be helpful in elbow joint arthroscopy.