Thoroughly rinse the cockles and make sure there is no sand or dirt remaining in them. Also, remove any cockles that seem open or damaged.
Use a large bowl and add the cockles to the boiled water.
Cover the bowl and roughly cook for 10 minutes or until you see the shells open. Take out the cockles and put them aside, and allow them to cool down. Reserve the cooking water.
Take another bowl and add some rice to it. Add the reserved cooking water and allow the mixture to get boiled.
Using less heat, steam the mixture for roughly 15 minutes or til the rice gets fluffy and tender. Fluff using a fork and set it aside.
With the help of the remaining water, mix the carrots and celery and boil them for roughly 10 minutes in a saucepan. You can also boil the mix until the vegetables become soft.
Take the meat from the cockle shells and chop them. Make sure that you chop them into small pieces. Get rid of the shells.
Take a large bowl and mix the vegetables, rice, and chopped meat pieces together. Add a pinch of salt for a better taste.
Serve the fresh dish to your dog. You can also store the remaining food treat in an airtight container for serving again.