1. A composition comprising a gel of at least one first biodegradable polymer, forming the first agent for filling the soft tissues of an animal, and a suspension of microspheres in this gel with an average diameter of from 5 to 50 micrometers, wherein said microspheres include from 50 up to 90 wt.% at least one biodegradable polysaccharide relative to the total weight of the microspheres, these microspheres contain at least one second biodegradable polymer, forming a second agent for filling the soft tissues of animals. 2. The composition according to claim 1, characterized in that the microspheres have an average diameter of from 5 to 40 microns, and preferably from 10 to 40 microns, and more preferably from 20 to 40 microns. A composition according to claim 1 or 2, characterized in that said first and second agents for filling the soft tissues of an animal are the same or different glycosaminoglycans. A composition according to claim 3, characterized in that said glycosaminoglycan is hyaluronic acid or hyaluronate or a salt thereof. A composition according to claim 1 or 4, characterized in that the polysaccharide is selected from the group consisting of cellulose derivative, cellulose ether, for example, carboxyalkyl cellulose, and preferably carboxymethyl cellulose, and alkyl hydroxy cellulose, preferably ethyl hydroxymethyl cellulose hydroxy cellulose hydroxy cellulose hydroxy cellulose hydroxy cellulose hydroxy cellulose hydroxy cell ethyl cellulose or methyl cellulose； cellulose ester, for example, cellulose acetate, cellulose propionate； cellulose nitrate； resin such as gum arabic, maltodextrin, k�1. Композиция, включающая в себя гель из по меньшей мере одного первого биоразлагаемого полимера, образующего первый агент для заполнения мягких тканей животного, и суспензию в этом геле микросфер со средним диаметром от 5 до 50 микрометров, при этом указанные микросферы включают в себя от 50 до 90 масс.% по меньшей мере одного биоразлагаемого полисахарида относите
