There may be diseases caused by obesity in dogs and cats but what we see more often are ordinary medical problems made worse by obesity, explains Dr. Brinson. For example, pets of any body condition can get diabetes, but the disease is more difficult to manage in obese pets because the additional body fat interferes with insulin effectiveness. Problems such as torn ligaments are more common in obese pets both because of their disproportionate size and because they often do not have the muscle tone to balance and support the extra weight. Arthritis is not caused by obesity but may be worsened by the extra load on the arthritic joints. Just about every organ in the body may be affected by obesity, but most at risk are the musculoskeletal, cardiovascular, and respiratory systems.
Obesity also compromises the effectiveness of a proper physical exam.
Body fat can mask heart and lung sounds. The consistency and size of abdominal organs are difficult to feel through intervening fat, says Dr. Brinson. This may prevent the veterinarian from finding early indicators of disease and delay diagnosis until a disease has reached advanced stages. There are diseases, such as hypothyroidism and Cushing's disease, that are associated with weight gain. Owners do not realize that they are killing pets with kindness, says Dr. Brinson.