「散歩に出たらひっつき虫っていう草が犬の毛にたくさんついて絡まって取れなくて大変な状況」は英語で「When I went for a walk, a lot of burrs got stuck in my dog's fur and I couldn't get them out and it was an awful situation」という意味があります。
散歩に出たらーWhen I went for a walk
ひっつき虫っていう草ー(The weed called burr）・Burrs
犬の毛にたくさんついて絡まってーA lot got stuck in (my) dog's fur
取れなくてーI couldn't get the off/out・They wouldn't come off
大変な状況ーIt was an awful situation
I took my dog for a walk and he got covered in burrs and they were so hard to get off.
この場合、次のような言い方ができますよ。
ーI took my dog for a walk and he got covered in burrs and they were so hard to get off.
「犬を散歩に連れて行ったら、身体中にひっつき虫がついて取るのが大変だった」
to get covered in burrs で「身体中にひっつき虫がつく」と言えます。
ご参考まで！
アメリカ合衆国 
カナダ 
