Health & Medical

Ask a Vet: Why is My Dog Losing Weight After I Changed Her Food?

Dog losing weight with diet change | Vanillapup

Q. After switching my poodle’s diet to raw commercial food, her weight has been dropping. But when I try to feed her more, she vomits. What is wrong?

If your poodle only started losing weight after the change in diet, malnutrition is a likely cause.

That means that she is either:

  • not getting enough intake of all the nutrients she needs, or
  • not absorbing the nutrients in the diet (malabsorption)

1. Choose food that meets AAFCO standards

First, you will need to ensure that your dog’s diet is formulated to be nutritionally complete and balanced for your dog’s life stage (puppy vs. adult).

Of course, that can be difficult to determine. One way is to examine the packaging. There should be a statement saying that the diet is formulated according to guidelines set by AAFCO (Association of American Association Feed Control Officials) or its equivalent overseas.

But, it is important to note that that does not mean that AAFCO has analysed the diet for nutritional adequacy.

Thus, it is best if there is a statement saying that the diet has passed an AAFCO feeding trial. That means that the diet has been fed to a group of dogs for a period of time and certain health parameters have been monitored during this time for signs of nutritional deficiency or excess.

While the feeding trial is not perfect and not an absolute guarantee of nutritional sufficiency, I believe it is currently the best available standardised method for assessing it.

A diet that does not have an AAFCO (or equivalent) nutritional adequacy statement does not mean that it is not nutritionally adequate. It just means that we cannot make a good assessment based on the packaging.

2. Feed the right amount

If the food packaging states that the diet is complete and balanced, then it is important to ensure that you are feeding the correct amount of food.

Reputable brands will state the recommended feeding amount per day, ideally in grams, if not in cups.

3. Check for gastrointestinal problems

If your poodle is receiving a sufficient intake of all necessary nutrients, then she may not be absorbing the nutrients well.

This could be due to an underlying gastrointestinal disease, such as:

  • an intolerance to one or more ingredients in the diet
  • intestinal parasites
  • inflammatory bowel disease

This is especially likely if your poodle is experiencing soft stools, diarrhea, mucus, or blood in the stools or vomiting. However, a dog with gastrointestinal issues may not show any of these signs.

I recommend having your poodle assessed by a vet to decide whether her case deserves further investigation. Do bring along the food packaging for the assessment.


Photo credit: tanakawho via Foter.com / CC BY-NC

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Dr. Brian Loon
Principal Veterinary Surgeon at Amber Vet
BSc. BVMS (Hons) (Murdoch), Certificate Veterinary Acupuncture (IVAS)

Dr. Brian Loon graduated from Murdoch University, Western Australia in 2007 and has since been practising as a small animal veterinarian in Singapore. His areas of special interest include diagnostic ultrasonography, endoscopy, and minimally invasive (keyhole) surgery (laparoscopy).

He is also certified in Veterinary Acupuncture with the International Veterinary Acupuncture Society (IVAS) and a certified and registered member of PennHIP, an internationally known modality for diagnosing hip dysplasia in cats and dogs.
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