Diseases & Conditions Contributing to Dog Obesity

Over-feeding isn't the only reason for dog obesity.
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Obesity in dogs can be caused by over-feeding, lack of exercise, and the dog's tendency to retain weight. But while these factors often contribute to obesity in dogs, owners shouldn't always assume that conclusion without also looking at the possibility of certain diseases and conditions at work, which can also lead to obesity.

What is Obesity?

Obesity is a nutritional disease defined by an excess of body fat. While common in dogs of all ages, obesity typically occurs in middle-age, and can seriously impact a dog's health and longevity. According a study of approximately 5,500 dogs conducted by the Waltham Centre for Pet Nutrition in collaboration with Banfield Pet Hospital, dogs who are overweight at middle age may have shortened life spans of up to 10 months. Obesity can also contribute to secondary health conditions, such as diabetes, arthritis, and hip dysplasia, as well.


One cause of canine obesity is hypothyroidism, a condition wherein the thyroid gland's release of T3 (liothyronine) and T4 (levothyroxine), which are both required for normal metabolism in the body, is lowered, affecting the dog's metabolism. Doberman pinschers, golden retrievers, Irish setters, Great Danes, old English sheepdogs, miniature schnauzers, dachshunds, boxers, poodles and cocker spaniels are more likely to develop hypothyroidism. Besides weight gain, common symptoms include lethargy, weakness, shedding, hair loss, recurring skin infections, excessive scaling and mental dullness, according to the PetMD website.

Insulinoma, or Pancreatic Cancer

Another cause of canine obesity, though uncommon, is insulinoma, or pancreatic cancer, according to PetMD. Malignant cells in the pancreas secrete insulin and other hormones that affect glucose regulation in the cells. These cancer cells cause the bloodstream to become low in glucose, or hypoglycemia, causing weakness or neurological problems. Physical collapse, loss of consciousness, seizures and extreme weakness are common symptoms, although symptoms may not be consistent due to the unpredictable way in which insulin is released.

Hyperadrenocorticism, or Cushing's Disease

Hyperadrenocorticism is a disorder of the endocrine system that controls hormones. When too much cortisone, a hormone responsible for protein and carbohydrate metabolism, floods the bloodstream, metabolism is affected, causing obesity and gastrointestinal problems and hypertension. If too much cortisone is caused by a benign tumor on the pituitary gland, the disorder is called Cushing's disease. Besides weight gain, symptoms include increased thirst, urination, hunger and panting; a pot-bellied abdomen, and loss of hair, among others.

Neutering & Spaying

The claim that neutering and spaying dogs causes obesity is controversial. While the Hill's Pet Food Company states that neutered and spayed canines are twice as likely to become obese due to a more sedentary lifestyle, other experts might balk at that idea. However, Hills also states there are important health reasons to have your dog neutered or spayed, such as better prostate health for male dogs, and suggests owners simply monitor their dog's weight.