Home Doggy Blog Dog Health Sudden Weight Loss in Dogs – Causes & what to do about it

Sudden Weight Loss in Dogs – Causes & what to do about it

Sudden Weight Loss in Dogs – Causes & what to do about it

Is it just you, or does your pup seem thinner lately? This is a question that many dog parents may wonder in the course of their dog’s life and with good reason. The list of causes of sudden weight loss in dogs is a long one with many contributing factors. Let us help you determine what may be causing your pup’s drop in weight and how you may be able to fix it.

In This Article

Is Your Dog Losing Weight?

First, it’s important to determine if your dog is actually losing weight. A dog’s haircoat can make it difficult to notice minor changes in weight, so getting your hands on them is important. The easiest way, of course, is getting regular body weights using a scale. If you don’t have one at home, consider taking them to your vet for quick weigh-ins where you can monitor their body weight and make a trip to the veterinarian seem fun at the same time.

If access to a scale is not in the cards, take note of your dog’s body condition score to monitor for weight loss and weight gain.

What Causes Sudden Weight Loss in Dogs?

Sudden weight loss in dogs can be broken down into five categories. Within those five categories, there are a number of different causes. We’ll look at those in more detail.

  • High energy demand: A dog may lose weight simply because they are burning an excessive number of calories. This most commonly happens in those dogs that answer, “how far?” when you say, “run”. It can also happen in an outside dog during cold temperatures. Don’t underestimate the number of calories that it takes to keep a body temperature in the ‘liveable’ range.
  • Excessive nutrient loss: This just means that weight loss can occur if nutrients are being lost somewhere before they get a chance to be utilized by the body. Severe or chronic vomiting and diarrhea may be culprits, as well as increased urination.

Severe gastritis, a foreign body in the digestive tract, or kidney disease all fall into this category. Also, extreme burdens of intestinal worms can create weight loss.

  • The diet: If only you could trust every commercial dog food out there. Fortunately, there are many high-quality dog foods. Unfortunately, there are many that are lacking. Poor quality food might not supply the number of calories that a dog needs to maintain their weight. This can due to a low digestibility of nutrients and a high amount of fillers.

Quality of the dog food aside, your dog might not be eating enough, either because it’s not offered to them or they don’t like it. Contrary to popular belief, dogs don’t always eat everything and a picky one might choose to starve rather than eat the kibble placed before them.

A dog might also choose not to eat because they are nauseous, are in pain, stressed, or have difficulty swallowing.

  • Metabolism: A dog’s metabolism determines how many calories their body burns. A higher metabolism means more calories are required and vice versa. Some disorders can change a dog’s metabolism and lead to weight loss or weight gain. Hyperthyroidism, diabetes, and some types of cancer can all lead to weight loss. With these diseases, you may also notice a change in appetite, an increase in water consumption and urination, and a decrease in activity levels. Cancer may show up as various lumps, bumps, or swellings as well.
  • Malabsorption/maldigestion: In order for your dog to get the nutrients and calories that they need, they have to be able to digest and absorb food. Maldigestion is usually related to pancreatic insufficiency where the pancreas isn’t producing the required digestive enzymes. Food isn’t broken down as it should be and instead moves through the digestive tract relatively untouched.

Malabsorption disorders relate to the intestine. Damage to the intestinal lining from bacterial, viruses, or parasites can affect their absorptive capabilities. Inflammation from allergies, inflammatory bowel disease, or cancer can do the same.

These diseases will often also cause diarrhea, maybe vomiting, an increased appetite, and even abdominal pain.

What To Do If Your Dog is Losing Weight

First thing’s first, if your dog is losing weight, get them to your veterinarian. Whether the cause is as simple as a tastier diet or as complex as diabetes, they will help you figure it out and make a plan.

Expect your veterinarian to take a history complete with diet and feeding amount information, perform an examination, run blood work to check organ function, take a fecal sample, and maybe take some x-rays or ultrasounds to get a look at the digestive tract.


Treatment of sudden weight loss will depend on the cause. Changing your dog’s diet to a high quality one or increasing the amount that you feed may be all that’s needed. Other treatments may include pancreatic enzyme supplementation, insulin, anti-inflammatories, antibiotics, and even fluids.

What Can You Do At Home If Your Dog is Losing Weight

If your dog doesn’t appear sick and isn’t showing any other symptoms, start by monitoring their food intake. Are they eating? Are they voraciously cleaning it up or leaving half for later? Do they retch after eating? Are they pooping normal amounts 3-4 times a day? If all appears normal, start by increasing their meal sizes, especially if your dog is an Energizer Bunny type.

Switch to a higher protein, higher fat diet. These tend to be tastier and pack more of a punch for high energy or sporting dogs. Consider softening the kibble with water or feeding canned food if you suspect a texture issue.

If you don’t notice an increase in your dog’s weight within a couple of weeks, or if other symptoms present themselves, see your veterinarian.

Final Thoughts

Sudden weight loss in dogs isn’t uncommon, perhaps because it can come about due to many different reasons. Keeping tabs on your dog’s eating and exercise habits will help you to rule out some of the causes, and recognizing abnormal symptoms, such as vomiting, diarrhea and lethargy, will help as well. Always see your veterinarian any time you are worried about your dog’s weight.