diff --git a/backend/src/controllers/authController.js b/backend/src/controllers/authController.js
index 9dd968f..702a205 100644
--- a/backend/src/controllers/authController.js
+++ b/backend/src/controllers/authController.js
@@ -567,12 +567,12 @@ const removeSubUser = async (req, res) => {
 };
 
 /**
- * Update the role of a sub-user
- * @route PUT /api/auth/sub-user/:subUserId/role
+ * Update the role of a sub-user for a specific pet
+ * @route PUT /api/auth/sub-user/:subUserId/pet/:petId/role
  */
 const updateSubUserRole = async (req, res) => {
   try {
-    const { subUserId } = req.params;
+    const { subUserId, petId } = req.params;
     const { role } = req.body;
     const requestingUserId = req.user.userId;
 
@@ -603,8 +603,8 @@ const updateSubUserRole = async (req, res) => {
       });
     }
 
-    // Update the sub-user role
-    const updatedSubUser = await User.updateSubUserRole(subUserId, role);
+    // Update the sub-user role for the specific pet
+    const updatedSubUser = await User.updateSubUserRole(subUserId, parseInt(petId), requestingUserId, role);
 
     if (!updatedSubUser) {
       return res.status(500).json({
diff --git a/backend/src/middleware/validateSubUserRoleUpdate.js b/backend/src/middleware/validateSubUserRoleUpdate.js
index 9ff8738..93ffb45 100644
--- a/backend/src/middleware/validateSubUserRoleUpdate.js
+++ b/backend/src/middleware/validateSubUserRoleUpdate.js
@@ -5,7 +5,7 @@ const validator = require('validator');
  */
 const validateSubUserRoleUpdate = (req, res, next) => {
   const { role } = req.body;
-  const { subUserId } = req.params;
+  const { subUserId, petId } = req.params;
   const errors = [];
 
   // Validate sub-user ID (must be UUID)
@@ -15,6 +15,13 @@ const validateSubUserRoleUpdate = (req, res, next) => {
     errors.push('Invalid sub-user ID format');
   }
 
+  // Validate pet ID (must be a positive integer)
+  if (!petId) {
+    errors.push('Pet ID is required');
+  } else if (!validator.isInt(petId, { min: 1 })) {
+    errors.push('Invalid pet ID format');
+  }
+
   // Validate role (required)
   if (!role) {
     errors.push('Role is required');
diff --git a/backend/src/models/User.js b/backend/src/models/User.js
index dbb8db9..fcd415b 100644
--- a/backend/src/models/User.js
+++ b/backend/src/models/User.js
@@ -255,21 +255,23 @@ class User {
   }
 
   /**
-   * Update the role of a sub-user
+   * Update the role of a sub-user for a specific pet
    * @param {string} subUserId - Sub-user UUID
+   * @param {number} petId - Pet ID
+   * @param {string} ownerId - Owner UUID
    * @param {string} newRole - New role value
    * @returns {Promise<object>} Updated sub-user info
    */
-  static async updateSubUserRole(subUserId, newRole) {
+  static async updateSubUserRole(subUserId, petId, ownerId, newRole) {
     const query = `
       UPDATE pet_users
       SET role = $1
-      WHERE user_id = $2
-      RETURNING owner_id as parent_user_id, user_id as sub_user_id, role
+      WHERE user_id = $2 AND pet_id = $3 AND owner_id = $4
+      RETURNING owner_id as parent_user_id, user_id as sub_user_id, pet_id, role
     `;
     
     try {
-      const result = await pool.query(query, [newRole, subUserId]);
+      const result = await pool.query(query, [newRole, subUserId, petId, ownerId]);
       return result.rows[0] || null;
     } catch (error) {
       throw error;
diff --git a/backend/src/routes/userRoutes.js b/backend/src/routes/userRoutes.js
index 56f94be..808b859 100644
--- a/backend/src/routes/userRoutes.js
+++ b/backend/src/routes/userRoutes.js
@@ -63,10 +63,10 @@ router.get('/sub-users', authenticateToken, getSubUsers);
 router.delete('/sub-user/:subUserId', authenticateToken, removeSubUser);
 
 /**
- * @route   PUT /api/auth/sub-user/:subUserId/role
- * @desc    Update the role of a sub-user
+ * @route   PUT /api/auth/sub-user/:subUserId/pet/:petId/role
+ * @desc    Update the role of a sub-user for a specific pet
  * @access  Private (parent account owner only)
  */
-router.put('/sub-user/:subUserId/role', authenticateToken, validateSubUserRoleUpdate, updateSubUserRole);
+router.put('/sub-user/:subUserId/pet/:petId/role', authenticateToken, validateSubUserRoleUpdate, updateSubUserRole);
 
 module.exports = router;