As dogs age, they become more prone to certain health problems and conditions. Some of the most common diseases and conditions that affect older dogs include:

1. Arthritis: Arthritis is a degenerative condition that causes joint pain, stiffness, and inflammation. It is common in older dogs and can be caused by a variety of factors, including genetics, obesity, and injury.
2. Dental disease: Dental disease is a common problem in older dogs, as years of wear and tear can lead to tooth decay and gum disease. Symptoms of dental disease can include bad breath, tooth loss, and difficulty eating.
3. Cancer: Cancer is a leading cause of death in dogs, and the risk of developing cancer increases as dogs age. Common types of cancer in dogs include lymphoma, bone cancer, and mammary gland tumors.
4. Cognitive dysfunction: Cognitive dysfunction, also known as canine dementia, is a condition that affects the brain and can cause confusion, disorientation, and changes in behavior. It is common in older dogs and can be caused by a variety of factors, including genetics, brain injury, and age-related changes in the brain.
5. Kidney disease: Kidney disease is a common problem in older dogs and can be caused by a variety of factors, including genetics, infection, and exposure to toxins. Symptoms of kidney disease can include increased thirst and urination, vomiting, and weight loss.
6. Heart disease: Heart disease is a leading cause of death in dogs, and the risk of developing heart disease increases as dogs age. Common types of heart disease in dogs include congestive heart failure, valvular disease, and cardiomyopathy.
7. Hypothyroidism: Hypothyroidism is a condition that occurs when the thyroid gland does not produce enough thyroid hormone. It is common in older dogs and can cause a variety of symptoms, including weight gain, lethargy, and skin problems.

It’s important to note that these are just a few examples of the many health problems that can affect older dogs. Regular veterinary check-ups and early detection of health problems can help ensure that your dog stays healthy and happy as they age.