In Beagle dogs, the most common causes of death are similar to those of other dog breeds and include:

1. Cancer: Cancer is a leading cause of death in Beagles, as it is in many other breeds. Beagles are prone to several types of cancer, including lymphoma, leukemia, and mast cell tumors.
2. Cardiac Disease: Heart disease is another common cause of death in Beagles. Heart conditions such as dilated cardiomyopathy, valvular disease, and congenital heart defects can lead to heart failure and death in Beagles.
3. Gastrointestinal Issues: Gastrointestinal problems, such as bloat, are also a common cause of death in Beagles. Bloat is a condition in which the stomach twists on itself, cutting off blood flow and causing the stomach to become distended. If not treated promptly, bloat can be fatal.
4. Respiratory Issues: Respiratory problems, such as chronic bronchitis, can also lead to death in Beagles. Chronic bronchitis is a condition in which the airways become inflamed and narrowed, making it difficult for the Beagle to breathe.
5. Kidney Disease: Kidney disease is another common cause of death in Beagles. Kidney disease can be caused by a number of factors, including genetics, age, and exposure to toxic substances.
6. Liver Disease: Liver disease is also a common cause of death in Beagles. Liver disease can be caused by a variety of factors, including genetics, exposure to toxins, and viral infections.
7. Infections: Infections, such as parvovirus, distemper, and Lyme disease, can also lead to death in Beagles. These diseases can be prevented through proper vaccinations and by avoiding exposure to infected animals.

It’s important to keep in mind that these causes of death can be prevented or managed with proper veterinary care and a healthy lifestyle. Regular check-ups, a balanced diet, and regular exercise can help keep your Beagle healthy and lower their risk of developing these conditions.

In conclusion, while Beagles are generally a healthy breed, they are prone to certain health issues that can lead to death. Regular veterinary care and a healthy lifestyle can help keep your Beagle healthy and lower their risk of developing these conditions.