Kennel Club Advice
The Kennel Club advises heart testing for aortic stenosis as per The Boxer Breed Council.
Breed Club Advice (Boxer Breed Council)
There is also information about other heart diseases that are prevalent in Boxers on the BBC site.
http://www.boxerbreedcouncil.co.uk/as.html
Heart Testing schemes are constantly being reviewed and updated by VCS and The Kennel Club. The information here is correct at the time of writing (June 2024). If the links do not work it is advisable to refer to the Kennel Club website to check for updated health information about your breed and then to check on your breed club website.
https://www.thekennelclub.org.uk/search/breeds-a-to-z/