1. Dull Coat or Itchy Skin
Your dog’s dull coat or excessive scratching isn’t just about looks. Their skin and fur tell a story about their overall health. These signs often reveal nutritional deficiencies or health problems before other symptoms show up.
Why skin and fur reflect internal health
The skin is your dog’s largest organ that makes up 10-15% of their body weight and is a vital barrier between internal systems and the environment. Your dog’s coat acts like an early warning system about their nutritional status and general health.
Research shows that 25-30% of your dog’s protein intake goes straight to their skin and fur [1]. This high resource allocation shows how much your dog’s body values skin and coat health. Your dog’s fur is made up of about 95% protein, which makes protein intake vital to keeping a healthy coat [1].
Dogs prioritise essential body functions over coat appearance when they lack proper nutrition. A poor-quality coat often appears as the first visible sign of nutritional deficiency. Your dog can survive looking untidy but needs functioning muscles and immune system to live.
These signs point to nutritional deficiencies:
- Dull, dry, and rough fur
- Thinning coat or brittle fur that breaks easily
- Abnormal shedding or slow hair regrowth
- Scaly, crusty, or thickened skin
- Poor wound healing
Key vitamins involved: A, E, and essential fatty acids
Your dog’s skin and coat health depends on several vital nutrients:
Vitamin A helps normal cell growth and differentiation. It aids in the keratinization (hardening and thickening) of skin cells, which maintains the skin’s barrier function [1]. Dogs with vitamin A deficiency often develop dry, scaly skin and a dull coat.
Vitamin E works as a powerful antioxidant that shields skin cells from oxidative damage and controls inflammation [1]. It keeps skin elastic and promotes healing. Dogs getting vitamin E supplements showed better results with canine atopic dermatitis, highlighting its benefits for skin problems [2].
Essential Fatty Acids (EFAs) are the foundations of coat health. These include:
- Omega-6 fatty acids from chicken fat, corn, and soybean oils help skin retain moisture [3]. Linoleic acid, a vital omega-6 fatty acid, becomes part of cell membranes and maintains the skin’s barrier [2].
- Omega-3 fatty acids from fish oils reduce inflammation and give your dog’s coat its shine [3]. They work against arachidonic acid and help control inflammatory responses [2].
A ratio of 5:1 omega-6 to omega-3 fatty acids benefits dogs the most [1].
How to improve coat health through diet
Your dog’s coat needs attention especially when it loses its shine. Here’s what you can do:
- Ensure adequate protein intake: Choose high-quality dog food with 25-30% protein (dry matter basis) for adult dogs, or 30-35% for puppies [4]. Real meat should top the ingredient list to provide needed amino acids for coat health.
- Add omega-rich foods: Include omega-3 sources like salmon, trout, and other cold-water fish [1]. Chicken fat or plant oils like sunflower oil provide omega-6 fatty acids.
- Consider supplements when necessary: Essential fatty acid supplements might help dogs with ongoing skin issues. Talk to your vet first since too many supplements can cause problems like blood clotting issues [5].
- Ensure adequate vitamins and minerals: Zinc matters greatly for skin health. Siberian Huskies and Alaskan Malamutes need extra attention due to their higher risk of zinc deficiencies [4]. Selenium, copper, and manganese also play key roles [1].
Most complete commercial dog foods contain enough of these nutrients. Major changes in your dog’s coat might signal serious issues. See your vet if dietary changes don’t help within a month.
2. Low Energy or Lethargy
Your once bouncy dog spends more time lounging around lately? A sudden drop in your dog’s energy levels might worry you. While it could be from a long day at the dog park, ongoing tiredness might signal that your furry friend lacks essential vitamins.
The role of B vitamins and carbohydrates
B vitamins work as the unsung heroes of your dog’s energy production. These vitamins act like spark plugs in your dog’s metabolic engine that turn food into usable energy. Thiamine (B1) helps regulate energy and carbohydrate metabolism [6]. Riboflavin (B2), B12, and niacin make enzyme function easier that powers your pet’s daily activities.
B6 plays a crucial role because it generates glucose, supports red blood cell function, and maintains nervous system health [6]. Your dog might feel extremely tired without enough B6, as their cells can’t produce energy needed for normal activities.
Pantothenic acid (B5) supports energy metabolism directly [6], which your dog needs to maintain natural vigour. Dogs that don’t get enough B vitamins might look tired because their bodies can’t turn food into energy quickly.
Carbohydrates serve as your dog’s main fuel source. Your dog’s body turns carbohydrates into glucose, providing that excited let’s-play-fetch-today kind of energy [7]. Your dog’s body will use protein as its main energy source without enough carbohydrates [8]. This less efficient process takes protein away from its job of maintaining and repairing your dog’s body.
Dogs don’t have specific carbohydrate requirements in their diet [9], but they just need glucose for brain function and red blood cells [10]. The body produces glucose through gluconeogenesis when carbohydrate intake stays low. This demanding process often leads to tiredness.
How to tell if your dog is just tired or deficient
You need to watch carefully to tell normal tiredness from a vitamin deficiency. A tired dog might stay inactive for a day but recovers after rest. A dog lacking nutrients shows ongoing tiredness that rest alone won’t fix.
These signs suggest your dog’s tiredness might link to vitamin deficiencies:
B12 deficiency shows up as tiredness, lost interest in life, and poor appetite [11]. Your dog might lose weight and in serious cases, even have seizures.
Tiredness from nutrient deficiencies usually comes with other symptoms. Veterinary experts note that dogs lacking nutrients will “sleep more, lose interest in daily life, and become less active than usual” [12]. They might not come when called or ignore commands they usually follow.
Physical signs offer more clues. Your dog’s coat quality might change along with energy issues if they lack B-vitamins [6]. Pale gums, trouble getting up, or changes in eating habits point to something more serious than regular fatigue.
When to think about a supplement
You should think about supplements when your dog’s food doesn’t provide enough vitamins. Note that you should talk to your vet before starting any supplements.
B-complex supplements help dogs that feel tired and have digestive problems, since gut issues can block proper nutrient absorption [11]. Antibiotics can disrupt gut flora that makes certain B vitamins, so your dog might need supplements [13].
Some breeds, like Border Collies, have genetic issues that affect B12 absorption [11], making supplements more helpful. Dogs with pancreatic conditions often can’t get B12 from food, so they need supplements [11].
The type of supplement matters by a lot. Oral B12 supplements don’t work well for dogs with digestive problems. These dogs might need injectable cyanocobalamin [11]. B-complex supplements with multiple B vitamins work better than single-vitamin products for general energy support.
Look for products with the National Animal Supplement Council (NASC) seal to ensure quality and safety [13]. Note that vitamin supplements can improve energy levels in dogs that lack nutrients, but they won’t fix all cases of tiredness. Take your dog to the vet if their energy doesn’t improve after a few weeks of better diet.
3. Digestive Issues Like Diarrhoea or Constipation
Your dog’s digestive health is the life-blood of their overall wellbeing. Problems with their stomach and intestines can make them uncomfortable and affect how they process the nutrients they need.
How gut health affects nutrient absorption
A balanced gut microbiota—the community of bacteria living in your dog’s intestines—plays a huge role in nutrient absorption. These tiny organisms protect barriers, help with nutrition, and handle metabolic functions that your pet needs to stay healthy [14].
The gut microbiota helps maintain intestinal balance by fighting off harmful organisms, helping digestion, and supporting the immune system. Any disruption to this delicate ecosystem, called dysbiosis, means your dog won’t get enough nutrients from their food.
A healthy dog’s gut contains good bacteria that produce short-chain fatty acids (SCFAs) like butyrate. These acids fuel colonic epithelial cells and keep the gut barrier strong [14]. Your dog won’t absorb nutrients well if these helpful bacteria decrease, even if you feed them premium food.
Vitamins B12 and D: common culprits
B12 (cobalamin) and D top the list of nutrients that digestive problems affect most.
Your dog needs vitamin B12 for cell metabolism, DNA synthesis, nerve myelination, and blood cell formation [15]. Dogs can’t make B12 on their own, which makes their diet vital. They need specific proteins in their saliva and stomach fluid, pancreatic proteases, and intrinsic factor from their pancreas to absorb it properly [15].
Dogs with exocrine pancreatic insufficiency (EPI) or small intestinal diseases often lack B12. Up to 82% of dogs with EPI have low serum cobalamin levels [15]. These levels stay low unless specifically treated, even after addressing other health issues.
Vitamin D helps with calcium absorption and gut health too. Unlike B12, dogs usually lack vitamin D because their diet doesn’t contain enough, rather than absorption problems [16].
Signs your dog isn’t absorbing nutrients properly
Look out for these signs that might indicate malabsorption:
- Persistent diarrhoea or large amounts of oily-looking stool
- Weight loss even though they eat normally or more than usual
- Lethargy and weakness from not getting enough nutrients
- Coat changes including dull, brittle fur, or unusual shedding
- Excessive gas and stomach rumbling (borborygmi)
Take your dog to the vet if these symptoms last more than a couple of days. Yes, it is important because malabsorption syndromes need professional diagnosis through blood tests that measure serum vitamins, especially B12 and folate [15].
Your dog might need supplements. Recent studies show that daily oral B12 supplements can restore normal serum levels in dogs with deficiencies by skipping the usual absorption process [17]. Probiotics might also help improve gut health by changing microbiota composition and making digestion better [18].
4. Behavioural Changes or Anxiety
Your usually happy dog seems anxious, irritable, or moody lately? The biochemistry of their brain significantly affects these behavioural changes, and their diet might be the unexpected cause.
How vitamin deficiencies affect mood
Your dog’s brain needs a complex balance of chemicals to work properly. The “happy hormones” – serotonin and dopamine – directly affect your dog’s mood. Their diet provides the nutrients needed to combine these chemicals [19]. A lack of vital vitamins can deplete these chemical messengers and lead to depression, anxiety, or irritability [4].
Scientists have found that there was an intriguing link between your dog’s digestive system and mental state – the “gut-brain axis”. Studies show that dogs with less diverse gut bacteria tend to be more aggressive [20]. A healthy gut makes chemicals needed for balanced mood, including serotonin that controls emotional wellbeing [20].
Magnesium and B-complex vitamins for brain health
Many call magnesium the “ultimate chill pill” because it plays a crucial role in how the brain works. It blocks excitatory neurotransmitters that can kill brain cells and damage brain structure when present in high amounts [4]. Low magnesium levels relate to less serotonin production, which might trigger anxiety symptoms [21].
B-complex vitamins support brain function in several ways. Vitamin B6 helps control hormones and creates neurotransmitters like serotonin and norepinephrine that regulate mood and behaviour [22]. Dogs that received extra B vitamins performed better in cognitive tests [23].
These vital nutrients can be found in:
- Magnesium: spinach, pumpkin seeds, and leafy greens [4]
- B vitamins: eggs, liver, chicken, fish, and dark vegetables [4]
When to talk to your vet about behaviour shifts
Your dog’s sudden or unexplained behavioural changes often point to medical issues rather than training problems [1]. You should talk to your vet right away if you notice these changes. Even small changes like increased irritability, excessive barking, or restlessness need professional attention [5].
Your vet must approve any supplements first because too much can cause serious problems like copper and zinc toxicity [4]. They might test for vitamin deficiencies and check other possible medical causes before blaming diet alone [1].
5. Slow Healing or Frequent Illness
Dogs with slow-healing wounds or persistent health issues might have immune system problems. Their bodies need specific nutrients that are vital for wound repair and immune function.
The immune system’s link to nutrition
Nutrition is the life-blood of your dog’s immune system. The gut houses 70-90% of the immune system [24], which makes proper nutrition vital for optimal immune function. Dogs, like humans, need proteins, fats, and various vitamins and minerals so their immune cells can function properly [25].
Your dog’s body needs enough energy from fats and carbohydrates to rebuild tissue after an injury. The body breaks down its own protein to meet these needs when resources are scarce [2]. This process can delay wound healing or prevent complete recovery.
Studies show that healing slows down when plasma protein levels fall below 6.0 g/dL. The risk of healing failure increases by 70% with levels under 5.5 g/dL [2]. Protein also helps prevent oedema that can complicate healing.
Vitamins C, D, and Zinc in immune support
These nutrients are significant for immune health:
Vitamin C works as a powerful antioxidant that neutralises free radicals and reduces inflammation. Dogs produce vitamin C in their liver [26], but this natural production might not be enough during illness or stress. White blood cells function better with vitamin C support [26].
Vitamin D controls both innate and adaptive immune responses. Your dog’s defence system relies on T- and B-lymphocytes, which vitamin D regulates [27]. Dogs with vitamin D deficiency often get more infections.
Zinc stands out as the most significant mineral for immune function. It affects how immune cells develop and work, including B and T cells, natural killer cells, and macrophages [25]. Dogs with zinc-responsive dermatosis often develop bacterial or yeast infections, which shows zinc’s role in infection prevention [28].
How to boost your dog’s defences naturally
Your dog’s immune system becomes stronger with these approaches:
A balanced, complete diet with adequate protein (4-6g per 100 kcal for dogs) serves as the foundation [2]. Dogs need more protein when recovering from illness or injury.
Probiotics support immune function by increasing beneficial gut bacteria [29]. The gut provides 90% of your dog’s immune system, which makes probiotics essential [29].
Dogs with stressed immune systems benefit from omega-3 fatty acids [24]. Fish oils provide these nutrients, but make sure to check for heavy metal contamination.
Medicinal mushrooms like reishi, maitake, and turkey tail contain beta-glucans and polysaccharides that help cellular health and normal immune function [29].
Your veterinarian should approve any new supplements. Keep in mind that healthy dogs eating complete commercial diets usually get all their needed vitamins [24].
Conclusion
Your dog’s health signals can mean the difference between a thriving pet and one that struggles with nutritional gaps. A dull coat, lethargy, digestive troubles, behavioural changes, and slow healing are great ways to get insights into your dog’s nutritional status. Commercial dog foods provide essential vitamins and minerals, but some dogs need extra support because of their age, breed-specific needs, or health conditions.
Prevention works better than cure. Don’t wait for obvious signs of deficiency – schedule regular vet check-ups to spot potential issues early. On top of that, knowing your dog’s dietary needs based on size, breed, and activity level helps you provide the right nutrition throughout their life.
Supplements might look like a quick fix, but they should enhance—never replace—a balanced diet. Your vet’s approval is crucial before adding any supplements to your dog’s diet. Over-supplementation can harm your pet just as much as deficiency, especially when you have fat-soluble vitamins that build up in the body.
Your dog depends on you completely for their nutritional needs. Taking time to learn about canine nutrition and spotting these subtle warning signs shows the care that makes you more than just an owner – you become a true companion to your four-legged friend. Regular vet care, proper nutrition, and your watchful eye will help your dog live a healthy, vibrant life for years to come.
References
[1] – https://www.whole-dog-journal.com/behaviour/when-to-see-a-vet-and-when-to-see-a-trainer/
[2] – https://todaysveterinarypractice.com/nutrition/nutrition-and-wound-healing/
[3] – https://www.iams.com/dog/dog-articles/what-nutrients-does-your-dog-need-their-skin-and-coat-health
[4] – https://mypetnutritionist.com/post/6-nutritional-tips-for-your-anxious-dog/
[5] – https://www.animalhumanesociety.org/resource/monitoring-behaviour-changes-your-dog-and-knowing-when-seek-help
[6] – https://wagwalking.com/treatment/b-complex-vitamins-for-dogs-1
[7] – https://vetericyn.com/blog/signs-and-symptoms-of-dog-nutritional-deficiencies/?srsltid=AfmBOopvGB8V9iP27VlFyNm3WwROEvci-eTNAMdxQ7_oT82z2tKRbxro
[8] – https://www.caninenutritionist.co.uk/dog-nutrition/carbohydrates-in-dog-food/
[9] – https://ovcpetnutrition.uoguelph.ca/2022/11/17/carbs-dogs/
[10] – https://www.petmd.com/dog/nutrition/evr_dg_carbohydrates_key_to_balanced_dog_food
[11] – https://total.vet/vitamin-b12-for-dogs/?srsltid=AfmBOoqj6JVTCXKReXX35rekq5Vh5ewR1dEbmfgtu0DiJJuTDIMf2eFx
[12] – https://veteris.co.uk/petcare-advice/lethargy-in-dogs-causes-and-treatments
[13] – https://www.petmd.com/dog/nutrition/what-are-dog-supplements-how-do-they-work
[14] – https://pmc.ncbi.nlm.nih.gov/articles/PMC10609632/
[15] – https://www.veterinary-practise.com/article/diagnosing-managing-cobalamin-deficiency-companion-animals
[16] – https://wagwalking.com/wellness/vitamin-d-for-dogs
[17] – https://www.msdvetmanual.com/digestive-system/diseases-of-the-stomach-and-intestines-in-small-animals/malabsorption-syndromes-in-small-animals
[18] – https://www.mdpi.com/2813-9372/1/2/11
[19] – https://www.petmd.com/dog/centres/nutrition/evr_multi_how_your_dogs_food_affects_his_mood
[20] – https://www.naturesmenu.co.uk/blog-can-diet-affect-dog-behaviour.html
[21] – https://mypetnutritionist.com/post/why-is-magnesium-so-important-to-your-pet/
[22] – https://www.avantispet.com/en-in/blog/vitamin-b-complex-benefits-of-vitamin-b-for-dogs
[23] – https://www.ardengrange.com/nutrition-and-advice/fact-sheets/canine-fact-sheets/fact-sheet-behaviour-section/fact-sheet-diet-and-behaviour/
[24] – https://www.vet.cornell.edu/departments-centres-and-institutes/riney-canine-health-centre/canine-health-information/diets-boost-immunity
[25] – https://pmc.ncbi.nlm.nih.gov/articles/PMC11680413/
[26] – https://wagwalking.com/wellness/vitamin-c-for-dogs
[27] – https://feedcompounder.co.uk/the-role-of-vitaminsin-the-immune-system-of-cats-and-dogs/
[28] – https://www.purinainstitute.com/centresquare/therapeutic-nutrition/zinc-responsive-dermatosis-in-dogs
[29] – https://www.dogsnaturallymagazine.com/boosting-your-dogs-immune-system/