What Might Be Causing a Senior Dog to Lose Weight Despite No Changes to Diet?

“I took my pitbull (she’s almost 13 years old) to the vet because she’s lost so much weight. They can’t find what’s wrong—no twisting, no bloat, no worms (though she’s been dewormed twice just to be on the safe side). Her stomach looks large, and her ribs and spine show. She eats great and hasn’t had any change in her diet. She also drinks the same and is pottying the same. The only difference is she acts like she gets tired easily, but she’s still so lovable. I am worried about her. I don’t want to give up on her, but I don’t want her to suffer, either. Thank you in advance.”

This is a message from a pet owner named Wendy to PetHelpful’s Ask-A-Vet section. She’s among the many people who seek expert advice from this popular site concerning their pets, be they cats, dogs, birds, or exotic animals.

In this case, Dr. Mark dos Anjos responded with the diseases that may cause senior dogs to lose weight:

• Organ failure. Even mild organ damage causes clinical symptoms, which can worsen as your dog ages. Kidney disease and diabetes are common among senior dogs.
• Respiratory disease. Lung cancer is among the respiratory illnesses that usually afflict older dogs. You will observe how some senior dogs get tired easily with this condition.
• Heart disease. Weight loss and reluctance to engage in exercises are among the symptoms of heart disease in dogs. They may also suffer from persistent coughing.



• Dental disease. Pockets of pus underneath an older dog’s gum line may cause it to stop eating.
• Digestive problems. Dogs, regardless of age, may have food sensitivities and digestive diseases. But there are malabsorption disorders that particularly afflict senior dogs.
• Parasites and chronic infections. As a dog ages, its immune system weakens; that’s why it becomes vulnerable to infections and parasitism.

To determine the cause of a dog’s weight loss, a veterinarian may perform: bloodwork, radiographs, oral x-ray and examination, ultrasound, EKG and echocardiograph, and fecal exam.

But just in case the results remain negative, here are more possibilities, according to Dr. dos Anjos:

• Low-quality diet
• Absorption disorder
• Undiagnosed dental problem
• Undiagnosed organ disorder
• Undiagnosed cancer

Dr. dos Anjos advised Wendy not to give up and to keep on searching for an answer and treatment with the help of other experts.