Dog eating from a bowl - signs of nutritional deficiency in dogs
on September 02, 2026

Nutritional Deficiency in Dogs: How to Spot It & What to Do

Short answer: a nutritional deficiency in dogs most often shows up as a dull coat, digestive changes, skin irritation and low energy. Most healthy dogs on a complete diet don't have one. But vet research shows some deficiencies (like vitamin E, zinc or B12) can cause serious illness, and some are linked to certain breeds.

Below, we cover the real signs of nutritional deficiencies in dogs and what causes them. We also look at two breed-specific examples most guides never mention.

We explain when supplements, such as a complete multivitamin, help and when they don't. Wondering whether your dog needs a multivitamin at all, rather than checking for an existing deficiency? Start with our checklist on how to know if your dog needs vitamins.

Written by Jamie Sinclair, who writes about canine health, nutrition, and everyday care for Doggy Dailies. Jamie turns veterinary research and real ingredient science into practical, honest guidance UK dog owners can use.

Table of Contents

Why Nutritional Deficiencies Happen

Most healthy dogs on a complete, AAFCO or FEDIAF-compliant commercial diet get everything they need. Deficiencies are far more likely in three groups:

  • Dogs on poorly formulated home-cooked diets
  • Dogs with malabsorption problems (like exocrine pancreatic insufficiency, where the pancreas doesn't make enough digestive enzymes)
  • Dogs with a genetic trait that affects how they use certain nutrients

A Real Example: Vitamin E Deficiency and Genetics

This case shows that deficiencies aren't always about diet alone. Research has found a genetic deletion in English Cocker Spaniels, in the TTPA gene. It is linked to vitamin E deficiency and retinopathy (a disease of the retina at the back of the eye).

Affected dogs can also show neurological signs, like an abnormal gait and muscle weakness (peer-reviewed genetic study).

This is a breed-specific, genetic nutritional deficiency. Diet alone can't fix it without a vet's diagnosis.

A Second Example: Zinc-Responsive Dermatosis in Northern Breeds

This well-known problem makes the same point from a different angle. A dog can eat a diet with plenty of zinc and still become deficient, because the gut can't absorb the mineral well.

Zinc-responsive dermatosis is a skin condition seen mostly in Siberian Huskies and Alaskan Malamutes. It is sometimes seen in Doberman Pinschers and Great Danes too.

It is caused by a hereditary defect in how the gut absorbs zinc. The dogs eat a well-balanced, adequately supplemented diet, but a genetic quirk means their gut doesn't take up enough zinc (Vet Times; VCA Hospitals).

It typically shows up as crusting, redness and scaling around the eyes, mouth and pressure points. It often flares with stress or a heat cycle. Around 40% of affected dogs develop signs before 2 years old.

A second, unrelated form of the same problem can affect fast-growing large-breed puppies. Their diet, or an added calcium supplement, gets in the way of zinc absorption. That is one more reason not to add extra calcium to a growing puppy's diet without vet guidance.

Treatment is straightforward once the problem is diagnosed. It means zinc supplements, sometimes for life in the hereditary form. But the skin lesions are easy to mistake for a skin allergy or infection if you forget the breed history.

The Homemade Diet Risk — What the Case Reports Show

Home-cooked feeding is where most avoidable deficiencies happen. Vet research shows how serious it can get. Hutchinson and colleagues (2012, JAVMA) reported a puppy fed a homemade diet that developed seizures alongside severe nutrient deficiencies.

Tal and colleagues (2018, Canadian Veterinary Journal) described a large-breed puppy on an imbalanced diet. The puppy developed compression fractures and vitamin D deficiency. It was also suspected to have nutritional secondary hyperparathyroidism.

Neither case means home-cooking is wrong. It means an unbalanced recipe is, especially during growth. If you feed home-prepared food, the most valuable thing you can do is get the recipe checked by a veterinary nutritionist.

When the Diet Is Fine but Absorption Isn't

A dog can eat a complete diet and still end up deficient if the gut can't absorb what's in it. The zinc case above shows this. B vitamin deficiencies, especially cobalamin (B12) and folate, are commonly seen in dogs with exocrine pancreatic insufficiency (EPI) or small intestinal disease.

The signs of malabsorption overlap heavily with the general deficiency signs below:

  • Changes in stool quality (either very loose or constipated)
  • Weight loss despite a normal appetite
  • Poor coat and skin health
  • Reduced energy

Take these signs to a vet rather than treating them at home. The cause needs to be found. Cobalamin deficiency in particular is usually corrected under a vet's care.

Signs to Watch For

  • Coat and skin changes — dull, brittle fur, heavy shedding, or dry, flaky skin. In a Husky or Malamute, crusting around the eyes and mouth could be a zinc issue, so mention it to your vet
  • Digestive changes — persistent loose stools, constipation, or bloating
  • Low energy or lethargy — especially if it's a real change from your dog's normal behaviour
  • Frequent illness — a weaker immune response to common infections
  • Weight loss despite eating normally — often the clearest sign of an absorption problem
  • Poor growth in puppies — or, in breeding dogs, complications during pregnancy
  • Neurological signs — as in the vitamin E case above, an unsteady gait or muscle weakness can occasionally be linked to nutrition

The Other Side: Over-Supplementation Risks

Too much of certain nutrients causes real problems too. Excess vitamin A has been linked to lameness and reproductive issues. Excess calcium in growing puppies, especially large breeds, can cause bone abnormalities. As noted above, it can also trigger zinc-responsive dermatosis by getting in the way of zinc absorption.

This is why guessing at supplements without a real reason isn't a good idea. Targeted, sensible usage matters far more than "more is better."

What to Do If You Suspect a Deficiency

  1. See your vet first — blood tests can find exact deficiencies, so there's no need to guess
  2. Review the current diet — check it's complete and right for your dog's life stage
  3. Rule out absorption issues — signs that continue despite a good diet can point to a gut or genetic problem worth investigating
  4. Supplement with purpose — target the exact gap you've found, rather than adding a general multivitamin and hoping

Our 10-in-1 Multivitamin

Doggy Dailies 10-in-1 Multivitamin Chews jar

Our 10-in-1 Multivitamin Chews give a broad nutritional top-up to dogs whose diet may have gaps. They're useful for picky eaters and dogs on home-prepared diets. But if you suspect a deficiency, a vet visit is always the right first step, rather than self-diagnosing.

FAQ

What are the signs of a nutritional deficiency in dogs?
The most common signs are a dull coat, digestive changes, low energy, frequent illness, weight loss despite normal eating, and poor growth in puppies. Rarely, deficiencies can cause neurological signs.

Can nutritional deficiencies be genetic?
Yes. Research has found a genetic mutation in English Cocker Spaniels that causes vitamin E deficiency. A separate, well-documented hereditary defect in Siberian Huskies and Alaskan Malamutes causes zinc-responsive dermatosis. Both show that some deficiencies aren't purely diet-related.

What is zinc-responsive dermatosis?
It is a skin condition seen mostly in Huskies and Malamutes. It is caused by a hereditary inability to absorb enough zinc from an otherwise adequate diet. It shows as crusting and redness around the eyes and mouth. It usually needs lifelong zinc supplements.

Are homemade diets risky?
They can be if unbalanced. Published vet case reports describe puppies on homemade diets developing seizures, vitamin D deficiency and compression fractures. A veterinary nutritionist can review the recipe to address this.

Can a dog be deficient even on good food?
Yes. Malabsorption conditions such as exocrine pancreatic insufficiency and small intestinal disease can cause B12 (cobalamin) and folate deficiencies, whatever the diet quality. Certain genetic problems also block absorption of some minerals like zinc.

Can too much of a vitamin be harmful?
Yes. Excess vitamin A has been linked to lameness and reproductive issues. Excess calcium in growing puppies can cause bone abnormalities and even interfere with zinc absorption.

Should I give my dog a multivitamin if I suspect a deficiency?
See your vet first. Blood tests can find the exact nutrient involved, so you can target supplements instead of guessing.

References

  • Hutchinson, D., Freeman, L. M., McCarthy, R., Anastasio, J., Shaw, S. P., & Sutherland-Smith, J. (2012). Seizures and severe nutrient deficiencies in a puppy fed a homemade diet. Journal of the American Veterinary Medical Association, 241(4), 477–483.
  • Tal, M., Parr, J. M., MacKenzie, S., & Verbrugghe, A. (2018). Dietary imbalances in a large breed puppy, leading to compression fractures, vitamin D deficiency, and suspected nutritional secondary hyperparathyroidism. Canadian Veterinary Journal, 59(1), 36–42.
  • Larsen, J. (2010). Feeding large-breed puppies. Compendium on Continuing Education for the Practising Veterinarian, 32(5), E1–4.
  • Colombini, S., & Dunstan, R. W. (1997). Zinc-responsive dermatosis in northern-breed dogs: 17 cases. JAVMA, 211, 451.
  • Peer-reviewed genetic study on TTPA-linked vitamin E deficiency in English Cocker Spaniels (linked above).

This article is for general information only and isn't a substitute for veterinary advice. If you suspect a nutritional deficiency, please consult your vet for proper diagnosis.

Looking for daily nutritional support? Shop our 10-in-1 Multivitamin Chews or browse our full range of dog supplements.