As a professional dog and cat sitter, the answer is after EVERY MEAL! 

It is important to clean your dog and cat bowl after every meal to prevent bacteria growth. When I am over at your place to care for your cat and dog, I will make sure to clean their bowls after they finish their meal so that it is ready for the next meal. 

Wet food bowls should be washed immediately after every meal. The moist contents of the food are a breeding ground for bacteria. Wet food can spoil quickly, so it will attract pests such as flies.

Dry food bowls should be cleaned daily. I will clean your pet's dry food bowl after my last visit of the day. Even though it is dry kibble, the food particles, oil, and your dog or cat's saliva will accumulate which will lead to a biofilm buildup, causing bacteria to grow.

Water bowls should be cleaned daily and topped up with fresh water at the beginning of the day. I will ensure I wash your dog or cat's water bowls during the first visit of the day and top them up with fresh water. If water bowls are not washed daily, the water will become a breeding ground for bacteria, mold, and even algae if the sun shines often on it.

Water fountains are becoming common in households with pets nowadays. These water fountains can easily be neglected when it comes to cleaning them, as they usually have filters to catch hair and particles. Water fountains should be cleaned every 3-4 days by dumping the water and scrubbing the entire fountain. This will prevent bacteria from building up.

I stress cleaning your dog and cat bowls daily because a clean bowl will keep your pets healthy.

Dirty bowls that are left unclean for long periods of time can become a breeding ground for dangerous bacteria like salmonella, E Coli, and listeria. These bacteria can cause gastrointestinal issues and other illnesses in your cats and dogs.

Notice the slimy film in your pet's bowl after forgetting to wash it? This slimy film is known as biofilm. Biofilm is a mixture of bacteria, food particles like oil from the food, and saliva.

Cleaning your pets' bowls after every meal will avoid having leftover food sit around for too long. Leftover food can spoil, leading to your pet having an upset stomach or other digestive issues.

A clean bowl will also encourage your pets to eat and drink more, as a fresh bowl is more appealing to them.

Bowls should be washed with pet friendly soap and hot water. I always avoid using plastic bowls, as those are porous and harbor more bacteria. The best pet bowls that I like for my own pets are ceramic bowls, which are nonporous and less likely to harbor bacteria in scratches. Stainless steel is another good option.

Need me to come care for your cat and dog while you're at work or traveling? I am always available for private dog boarding in my home, cat and dog drop-in visits at your home, and dog walking! Feel free to reach out at furvoritepetsitting@gmail.com and have me be your furvorite pet sitter in Leduc, Beaumont, South Edmonton and surrounding areas!