רבי אלעזר אומר בזמן שהן בני תרבות אינן מועדים – Rabbi אלעזר states when they are domesticated they are not מועדים
There is a dispute between ר' אלעזר of our משנה who maintains that wild animals can be domesticated and ר' אליעזר in מס' סנהדרין who maintains that wild animals cannot be domesticated and may therefore be killed even before they killed others. ר' אליעזר, the רבי of ר"ע preceded ר' אלעזר who lived after ר"מ. Concerning ר"ל who maintains that even a נחש can be domesticated (seemingly contradicting the משנה here), we can either say that ר"ל is referring to a situation where they are chained; or that ר"ל is merely restricting the right to kill them, however they may still be obligated to pay as a מועד.
והוא דלא כרע במודים – Provided he did not kneel by מודים
After one kneels by מודים, he should rise like a snake; therefore one who disregarded and did not kneel by מודים, his spine will be tuned into a snake which will cause him embarrassment. [However it cannot mean that since his spine [including the עצם לוז] became a snake that he will not merit תחיית המתים (for such a minor transgression), since כל ישראל יש להם חלק לעוה"ב.
כי תניא מתניתא בארי תרבות ואליבא דרבי אלעזר – this ברייתא was taught in a case of a domesticated lion and according to ר"א
The בריייתא may follow the view of ר"א ורבנן and he is חייב a נ"ש since אייעד; or the ברייתא follows only the view of ר"א; however according to the רבנן there is no need for אייעד.
A domesticated זאב who was אייעד לטרוף reverts to his original status, and if he was טרף it is considered שן.