Old Dog Products

Appetite & eating

Senior Dog Losing Weight? Weight Loss in Older Dogs, Causes Vets Check and When to See the Vet

By The Old Dog Products team · Published

Not veterinary advice. This article is general information to help you care for your dog at home. It isn’t veterinary advice and can’t replace an exam. If you’re worried about your dog, call your vet.

You give your old dog a hug and feel more spine and hip bones than you used to. Weight loss in a senior dog can creep up slowly, and it’s worth taking seriously. The good news: you’ve noticed, and that’s the first step.

If you only have a minute

  • Weight loss in older dogs is a symptom, not a diagnosis. Book an appointment with your vet.
  • That’s true even if your dog is still eating well.
  • Weigh your dog weekly and take notes to bring along.
  • Don’t change their diet or add supplements until your vet has looked for the cause.

When to book an appointment with your vet

If your dog is losing weight, book an appointment with your vet. Call soon if…

  • Your dog is losing weight without you trying. AVMA says sudden weight loss in a senior pet often means something is wrong, and to contact your vet (AVMA)
  • Weight loss comes with appetite changes, vomiting, diarrhea, more drinking or peeing, or low energy (VCA)
  • Your dog can’t chew dry food (VCA)

Emergency: not eating plus repeated vomiting, a swollen belly, collapse, or trouble breathing → call now (PetMD).

Why is my older dog losing weight?

Dogs lose weight for lots of reasons, and only your veterinarian can find the underlying cause. Sources describe:

  • Illness. AVMA names cancer, diabetes, and kidney disease among common causes of sudden weight loss in senior pets (AVMA)
  • Mouth pain that makes eating hard (VCA)
  • Muscle loss with age. AAHA notes dogs tend to lose lean body mass as seniors, with overall weight loss at advanced ages. It also notes that weight and muscle loss can come from disease (AAHA guidelines PDF)

Weight loss in older dogs vs muscle loss

Vets also look at muscle, not just weight. A dog can carry fat but still be losing muscle, and muscle loss in the back legs often shows up as weakness or wobbling (see back legs giving out). WSAVA’s guidelines make nutritional assessment, including body condition and muscle loss, part of every exam (WSAVA Nutritional Assessment Guidelines).

When is a dog a “senior”?

There’s no single age. VCA describes dogs as senior at roughly 75% of their expected lifespan, which can be five or six for a giant breed and 10 to 12 for a small one (VCA). So a Great Dane and a Chihuahua of the same age may be at very different stages, and what counts as normal weight change differs too.

Is some weight change normal with age?

Some change in body shape is common with age, and AAHA notes that older dogs tend to lose lean muscle (AAHA guidelines PDF). VCA notes that older dogs’ calorie needs drop, which can lead to weight gain (VCA). That’s why an old dog that is losing weight without a diet change stands out. VCA lists weight loss among the signs that mean you shouldn’t wait for the next routine checkup (VCA).

Dogs lose weight for many reasons, and some of the conditions VCA lists as common in older dogs, such as kidney disease, liver disease, heart disease, diabetes, hormonal disorders, dental disease and cancer, can all show up as changes in weight or appetite (VCA). You can’t tell these apart at home, and you don’t need to. Your job is to notice and write it down.

Old dog losing weight but still eating

It’s still worth a vet visit. A good appetite is reassuring, but it doesn’t rule out a problem. AVMA’s advice is simply to contact your vet about sudden weight loss in a senior pet (AVMA). Tell your vet your dog’s current diet and the amount they eat, so they can compare it with the weight they’re losing. Your vet may also review the protein and fibre in that diet as part of looking for the cause.

How to track your dog’s weight at home

  • Weigh weekly on the same scale at the same time. A common way to weigh a small dog at home: weigh yourself, then yourself holding your dog, and subtract.
  • Feel for change. WSAVA’s body condition chart describes how ribs, waist, and tummy tuck look and feel at each score (WSAVA BCS chart). AAHA cites an ideal score of 4.5–5 out of 9 for dogs (AAHA). Your vet can show you how to score your own dog.
  • Take a monthly photo from above and the side.
  • Log what they eat (see the food log in Senior dog won’t eat).

What happens at the vet appointment?

Whether it’s a routine exam or a visit booked because of the weight change, the basics are similar. Every clinic works differently, so think of this as a rough idea rather than a script. VCA suggests talking with your vet about wellness testing for older dogs, which can include blood and urine tests and imaging (VCA). Your vet will usually weigh your dog, check body condition and muscle, look in the mouth, and ask about eating, drinking, toilet habits and energy. Your notes make that conversation much easier.

Things worth bringing:

  • Your weekly weights, with dates
  • What your dog eats in a day, including chews and table scraps
  • Any changes in drinking, peeing, stools or sleep
  • Photos from a few months ago, if you have them

How often should an older dog see the vet?

VCA recommends a vet exam for senior dogs at least twice a year, and suggests weighing your dog every couple of months on the same scale, since a change in weight can be an early clue to illness (VCA). Weekly weigh-ins at home sit comfortably on top of that.

Helping your dog at mealtimes (with your vet’s plan)

Once your vet has a plan, small practical changes at home can make it easier to follow:

  • Give them space. VCA suggests making sure other pets aren’t keeping your senior dog from their food or water (VCA).
  • Keep water easy to reach. VCA suggests a water bowl on every floor of the house (VCA).
  • Mention chewing trouble. If your dog struggles with dry food, tell your vet. It’s on VCA’s list of reasons to book a visit (VCA).

Do dogs lose weight when they are sick?

Often, yes. Many illnesses make dogs lose weight, sometimes before you notice anything else. That’s why weight loss is best seen as a symptom of a larger issue: if your senior dog is losing a significant amount of weight, it needs to be diagnosed and addressed by your vet rather than fixed with extra food.

My dog needs to gain weight. What can I do to help?

Start with your vet. Until they’ve found out why your dog is getting thinner, adding extra food can hide the problem or upset a sensitive stomach. Once your vet has a plan, follow their advice on what and how much to feed, and keep weighing weekly so you can both see whether it’s working. Raised bowls can make mealtimes easier for some dogs who find bending hard; see raised dog bowls for senior dogs.

My 15-year-old dog has stopped eating but is still drinking water

Call your vet today. A senior dog that stops eating needs prompt attention even if they’re still drinking, and changes in thirst are worth mentioning too (VCA). Our guide to a senior dog that won’t eat covers what to note before the call.

What not to do

  • Don’t just add more food or change your dog’s diet before seeing your vet. Weight loss is a symptom, and some illnesses need specific diets.
  • Don’t start supplements or appetite products without your vet’s OK. If your dog needs a different balance in their diet as they age, your vet will tell you.

What to write down before the appointment

A short record makes the visit more useful. Note what your dog eats each day and how much, any change in thirst or toilet habits, and the dates and numbers from your home weigh-ins. Inform the vet about any food change you’ve already tried. These notes help your vet look for an underlying condition and decide whether the food itself, such as the amount of protein, needs a rethink.

Questions to ask your vet

  • What do you think is causing the weight loss? What tests do you recommend?
  • Is my dog losing muscle as well as fat?
  • What’s my dog’s ideal weight and body condition score?
  • Should I change their food, and how?
  • How often should I weigh them, and what change should make me call?

Sources

Products mentioned

Products don’t treat any condition. They can make the home safer or easier. Ask your vet what suits your dog.

Large or giant breed? Ask your vet before using a raised bowl. Our raised-bowls article explains the bloat caution.

More picks in our product guide: Food & water.