All About Weight Loss In Older Dogs

Weight loss in older dogs can be slow and subtle, or it can be sudden and noticeable.

Senior Boxer dog

Either way, if you have an old dog who is losing weight it’s important to figure out why it’s happening.

This is because sudden weight loss could be a symptom of an underlying health problem – and sometimes these problems can be serious.

The earlier you find out what’s causing the pounds to drop off, the better your chances of getting the issue under control quickly, and affordably.

You see your dog every day, and are in the best position to notice any changes, even if they’re small or seem insignificant.

It’s especially important to be on top of this when Fido is a senior.

Common Causes Of Weight Loss In Older Dogs

So, what is considered to be ‘significant’ weight loss?

What size drop  is enough that it could be a sign of illness, or at least warrant a trip to your veterinarian?

Veterinary standards suggest that if your dog has lost 10% or more of his normal weight, then it’s something to be concerned about.

Not panicked, but concerned.

Not all weight loss means trouble….

It’s not unusual for even healthy senior dogs to lose weight slowly as they age.

Things which can cause this type of weight loss include:

  • Loss of muscle mass
  • Reduced appetite
  • Poor absorption/digestion of food

It’s obviously important to rule out illness/disease if your Golden Oldie is losing weight, even if it’s slow/subtle.

However, once given a clean bill of health, there are some simple steps you can take to help keep weight on your older dog (as long as he/she isn’t overweight to begin with).

If your older dog has lost 10% or more of his body weight over the past few months (or within a year) then a trip to your veterinarian for a complete check-up would be advisable.

With most health problems, there’s more than one symptom – and as weight loss in older dogs can be a sign of several different conditions or diseases, – it’s the OTHER symptoms that often give your vet the clues he needs.

So if you notice that your senior dog seems to be losing weight, pay close attention to his other bodily functions and behavior and make a note of anything that seems out of the ordinary, or unusual, for him.

This will give your vet more ‘ammunition’ to use when he’s trying to make a diagnosis.


 Weight Loss and….

  • Dry ‘rubbery’ gums
  • Lethargy
  • Sunken eyes
  • Loss of skin elasticity
  • Less urination
  • Dark urine

Possible Causes

  • Dehydration

The aging process causes some overall loss of fluids and some weight loss in older dogs can be caused by this, IF they’re not getting enough water or have an underlying disease.

This is normal, but it means that you need to be extra-careful to make sure that Fido gets plenty of fresh water every day.

You can also increase his fluid intake by adding broth (low sodium) to his kibble.

Canned dog food (wet) contains much more water per cup than dry food does, so mixing some with the dry kibble can also help.

Senior dogs whose senses of smell or taste are fading, who have dental issues,or who have become ‘picky’ eaters, can also often be encouraged to eat more this way too.

Some diseases that affect older dogs can also cause dehydration, so have Fido checked out by your vet to make sure there’s no underlying health problem.


 Weight Loss and….

  • Excessive drooling
  • Difficulty eating/chewing
  • Bad breath
  • Swollen or bleeding gums

Possible Causes

  • Dental problems

Weight loss in older dogs can sometimes be caused by something as simple as broken or infected teeth, gingivitis, or gum disease.

There are more serious oral conditions such as tumors too. Your vet needs to look inside your dog’s mouth as soon as possible.


 Weight Loss and….

  • Excessive thirst
  • Excessive urination
  • Increased appetite
  • Lethargy
  • Repeated urinary tract infections

Possible Causes

  • Diabetes

Diabetes can cause an older dog to lose weight because it stops his body from getting the energy it needs from glucose the way it normally would.

So, his body tries to convert fat, or protein into energy instead.

This doesn’t work very well at all, and Fido will soon use up any reserves he has, and no matter how much he eats his system can’t keep up and he’ll continue to lose weight.


 Weight Loss and….

  • Decreased appetite
  • Excessive
  • Sudden lethargy
  • Unusual bleeding
  • Lumps, bumps or swelling
  • Distended abdomen
  • Limping or lameness
  • Unusual urination – frequency or amount

Possible Causes

  • Cancer

Cancer is one of those diseases that can be very difficult to diagnose through visible symptoms alone.

There are so many different types of cancer in dogs, and some of them have no obvious symptoms until they’ve become advanced and spread.

BUT, you know your senior dog better than anyone else, and are in the best position to notice what might be very subtle changes that could  be warning signs.

Please don’t panic and assume Fido has cancer if he fits one or two of the symptoms above, but definitely have your veterinarian give him a thorough check up and mention ANYTHING you think might be relevant.


 Weight Loss and….

  • Decreased appetite
  • Lethargy
  • Increased thirst
  • Vomiting
  • Diarrhea
  • Fever
  • Pain (panting/pacing/drooling)
  • Pale or yellow gums
  • Yellowing of skin/eyes

Possible Causes

  • Liver Disease
  • Gallbladder Disease

The signs of liver disease in dogs can be very subtle, but sudden (or consistent) weight loss is one of them.

Several of these symptoms could point to other digestive system problems, so again don’t panic and assume that Fido’s liver is at fault. Only your vet can make an accurate diagnosis.

The yellowing of gums or skin (jaundice) often indicates a liver or gallbladder problem.


 Weight Loss and….

  • Increased thirst
  • Excessive urination (may contain blood)
  • Vomiting
  • Loss of appetite
  • Diarrhea or constipation
  • Pale gums
  • Depression or lethargy

Possible Causes

  • Kidney Disease

As dogs get older their major organs stop working as efficiently as they used to.

Kidney ‘insufficiency’ can come on so slowly that you don’t notice it until the kidneys start to fail.

By the time this happens the disease is pretty well advanced.

This is another reason to be very careful about monitoring Fido’s overall health carefully and get help if you notice weight loss in older dogs, especially if it’s accompanied by any other signs of illness.

Early diagnosis of any problem makes the prognosis better!


 Weight Loss and….

  • A chronic cough
  • Tires easily
  • Exercise intolerance
  • Excessive panting
  • Irregular heartbeat
  • Restlessness

Possible Causes

  • Heart Disease

Heart problems in older dogs can show very subtle signs early on, and mistaking these for the normal ‘slowing down’ of old age isn’t unusual.

But, as with most diseases, the earlier a diagnosis is made the better.

Many heart conditions can be managed with a combination of medication and lifestyle changes – if they’re caught early on.

What To Do About Weight Loss In Older Dogs

A premium dog food that is a good fit for your golden oldie’s health and age, along with appropriate exercise, is often enough to keep dogs at an acceptable weight no matter how old they are.

Useful Info.

Lots of dogs gain weight as they get older, and a gradual thickening of the ‘waistline’ is pretty normal.

In an otherwise happy, healthy older dog this isn’t usually cause for concern.

But rapid weight gain in older dogs, just like rapid weight loss, is a different story, and needs to be evaluated by a veterinarian.

If your senior dog seems a little thinner, but it’s a change that has happened gradually, it’s less likely to be caused by a serious health problem….

…. but it’s unusual enough to warrant a visit to the vet.

BUT, if the weight loss is sudden (or slow but obvious), and especially if you notice any other signs that Fido isn’t feeling well or acting normally, then you absolutely need to have him examined by your veterinarian asap.

Treating the weight loss itself can only be done by treating the problem which is causing it to happen, and the only person who can make an accurate diagnosis is your veterinarian.

There’s no need to panic or assume the worst, many times it’s something simple at the root of the problem, and even chronic or serious illnesses can be treated or managed.

So, get Fido that check up and you can get peace of mind!


  1. My 11 year old male boxer is losing weight rapidly. He is on prednisone and high fiber diet. The vet says he has ibs since his X-rays sonogram and blood work showed nothing more. I hope he’s right. The dog is lethargic, has the sunken eyes and overall just doesn’t look well.

    • Why a high fiber diet? Dogs are carnivores and prednisone is toxic. Up the protein and research proper grain free diet preferably homecooked with adequate minerals and digestive enzymes for dogs.

  2. My 13 year old Lab has just gone blind. She is very disoriented. She will only eat small amounts. She also has a large tumor over her eye but the vet says doesn’t seem to be in pain. She has never been affectionate which has never been like any of my dogs. She is also drooling alot. I don’t know what to do. I don’t know if she is just adjusting to blindness or what.

    • Hello Emly: I was touched by your post and wondering if you found out anything about your lab’s situation? We have used Internal Medicine Vet Specialists in the past when the GP’s are stumped. Also the internet may have some things that you can find as points of discussion to run past a good Vet. I’m wondering if one of the Vet schools has a clinic or a consultation service they offer over the phone that could give a second opinion? I know Cornell has had this service to help us with our cats int he past, not sure about dogs. Maybe she is drooling because she can’t see and I would imagine is a bit disoriented, I know I would be. Sure thinking about you and your baby!

  3. Emily: did you find out what is going on with our lab? We have a lab about the same age, she has not gone blind but sh his losing rapid weight but otherwise seems fine so we are going through the trial things of looking at everything. Do you know if a good Internal medicine vet can help your Lab determine what is going on. Sometimes I ask the “what if” questions from vets or even for my own health if they want me to do all sorts of tests but tests if necessary can rule things out. That’s where a good Specialist vs. a GP could help. Also are their vet schools which can give you a second opinion over the phone? I know Cornell has had consult service for a nominal fee for our cats in the past, wondering if there is a thing for dogs? Sure thinking about you through this.

  4. My dog is a terrier mix and is going on 14 years old. She lost the use of her hind legs when she was around 8 yrs untill I started putting her in a pool and made her swim and before you know it she was walking again. Now she’s starting to do it again and shes getting real skinny rapidly it seems to the point where her ribs stick out and I don’t know what to do. She also drinks alot of water and urinates alot uncontrollably

    • oh, that does not sound good that she is drinking a lot, peeing uncontrollably and losing weight. Could be thyroid or renal failure. I would definitely get her to a vet ASAP

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