Sudden Dog Weight Gain: 7 Possible Causes


Hypothyroidism is a hormonal condition that decreases your dog’s metabolic rate. As a result, you may notice your dog gaining weight despite no changes in their eating habits.

Cushing’s Disease

Hyperadrenocorticism, which is also called Cushing's disease, is a chemical disorder that makes your dog eat more. 

Orthopedic Conditions

Conditions like arthritis or a healing bone fracture may make it difficult for your dog to get around. As a result of decreased activity levels, your dog may gain weight.

Medication Use

Long-term use of steroids like prednisone can increase your dog’s appetite, leading to weight gain.

Getting Spayed or Neutered

The surgery itself does not cause your dog to gain weight. However, your pet’s energy requirements decrease after they’re altered.


Pregnant dogs should have a weight increase of 15-25 percent in the last month of pregnancy.


Sudden weight gain in older dogs may occur due to a decreased metabolic rate. Senior dogs generally have a lower energy requirement than their younger counterparts.