diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java
index 9ae162cc..4f2d28be 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java
@@ -1,8 +1,6 @@
 package cat.udl.eps.softarch.demo.domain;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 
@@ -22,4 +20,10 @@ public class Pet extends UriEntity<Long> {
     String age;
     String description;
     String breed;
+
+
+    @ManyToOne
+    public Shelter isIn;
+    @ManyToMany
+    public User[] favouritedBy;
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java
new file mode 100644
index 00000000..12af9121
--- /dev/null
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java
@@ -0,0 +1,15 @@
+package cat.udl.eps.softarch.demo.repository;
+
+import cat.udl.eps.softarch.demo.domain.Pet;
+import cat.udl.eps.softarch.demo.domain.User;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.repository.query.Param;
+
+import java.util.List;
+
+public interface PetRepository extends CrudRepository<Pet, Long>, PagingAndSortingRepository<Pet, Long> {
+    List<User> findBySize(@Param("size") String size);
+    //List<Shelter> findByShelter(@Param("Shelter") Shelter shelter);
+
+}