Here's an ideal itinerary for 3 days in London that is pet-friendly:

Day 1:

• Start your day with a visit to Hyde Park, one of the largest parks in London. It's a great place to take your furry friend for a walk and enjoy the beautiful scenery.
• Afterward, head to the British Museum, which is free to enter and has a vast collection of artifacts from around the world. You can explore the museum with your pet as long as they are on a leash or in a carrier.
• In the afternoon, take a stroll through Covent Garden, a bustling area filled with street performers, shops, and restaurants. Many of the outdoor cafes allow pets, so you can grab a bite to eat while your furry friend relaxes by your side.

Day 2:

• Start your day with a visit to the Tower of London, a historic castle that has served as a royal palace, prison, and armory over the centuries. Pets are not allowed inside the buildings, but you can still explore the grounds with your furry friend.
• Afterward, head to the nearby St. Katharine Docks, a picturesque marina filled with boats and surrounded by restaurants and cafes. Many of the outdoor seating areas are pet-friendly, so you can enjoy a meal or a drink while your furry friend takes in the sights and smells.
• In the evening, catch a show at Shakespeare's Globe Theatre, a replica of the original theater where many of Shakespeare's plays were first performed. Pets are not allowed inside the theater, but you can still enjoy the atmosphere and take a walk along the nearby River Thames.

Day 3:

• Start your day with a visit to the iconic Tower Bridge, which offers stunning views of the city. Pets are not allowed inside the bridge, but you can still walk across it and take in the sights.
• Afterward, head to the nearby Borough Market, a bustling food market filled with stalls selling everything from fresh produce to artisanal cheeses. Many of the outdoor seating areas are pet-friendly, so you can grab a bite to eat while your furry friend relaxes by your side.
• In the afternoon, take a stroll through the nearby Southwark Park, a beautiful green space that offers plenty of room for your pet to run around and play. You can also visit the nearby Canada Water Cafe, which has an outdoor seating area that is pet-friendly.

I hope this itinerary helps you plan your trip to London with your furry friend!