Show all objects, except those belonging to the logged in user

Good afternoon, I'm doing a web system where the user can register several dogs, my question is how do I show all dogs in the system, except what is registered by the logged in user?

class PetsController < ApplicationController
  before_action :set_pet, only: [:show, :edit, :update, :destroy]
  before_action :authenticate_user!

  # GET /pets
  # GET /pets.json
  def index
    @pets = Pet.all
  end

  # GET /pets/1
  # GET /pets/1.json
  def show
  end

  # GET /pets/new
  def new
    @pet = Pet.new
  end

  # GET /pets/1/edit
  def edit
  end

  # POST /pets
  # POST /pets.json
  def create
    @pet = Pet.new(pet_params)
    @pet.user = current_user


      if @pet.save
        redirect_to root_path
      else
        render :new
      end
    end


  # PATCH/PUT /pets/1
  # PATCH/PUT /pets/1.json
  def update
    respond_to do |format|
      if @pet.update(pet_params)
        format.html { redirect_to @pet, notice: 'Pet was successfully updated.' }
        format.json { render :show, status: :ok, location: @pet }
      else
        format.html { render :edit }
        format.json { render json: @pet.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /pets/1
  # DELETE /pets/1.json
  def destroy
    @pet.destroy
    respond_to do |format|
      format.html { redirect_to pets_url, notice: 'Pet was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_pet
      @pet = Pet.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def pet_params
      params.require(:pet).permit(:name, :breed, :breed, :age, :genre, :vacina, :pedigree, :name_mon, :name_dad, :temperament, :user_id)
    end
end