A vitamin is defined “organic” substance that the body needs in small amounts to function normally. To count as a vitamin, a substance must be a component of our diet that the body doesn’t produce enough of to meet its needs. A lack of them must result in a “deficiency syndrome” – a health problem resulting from their absence. They tend to be classified as “water-soluble” or “fat-soluble”, although some do not exactly fit into these categories.
Vitamin A is needed for normal eye-sight, healthy coat, skin, and teeth. It plays a role in reproductive health too. Too much can lead to severe problems with excessive bone growth amongst other conditions and is seen in animals fed an excess of liver or liver oil in their diet.
Vitamin D is vital for the body’s absorption and use of the essential minerals calcium and phosphorus. It is especially important in growing puppies that can develop rickets if too low. However, too much vitamin D can be fatal, so never administer human supplements to your pet.
Vitamin E exists in several different forms which serve different roles. The most active form (Alpha-tocopherol) is an “antioxidant”. Antioxidants work to combat “free radicals”. Free radicals are a normal by-product of our body’s day-to-day functions. They damage cells, impacting our immune-system function and contributing to many disease processes.
Vitamin K is essential in forming several vital components of the blood clotting pathways. A deficiency can lead to severe, uncontrollable bleeding – this is how several types of rat bait work.
There are many different types of B vitamins, their roles are complex and diverse, but overall, they are essential for the function of enzymes that work to convert food to fuel. A few specific examples that are more common – although still rare – as deficiencies include:
Thiamine plays a vital role in the body’s use of carbohydrates; this is especially important for brain function. Deficiency can lead to weakness, seizures, tummy upset, and heart problems. Deficiency is rare in dogs and more frequently reported in cats.
Biotin has an essential role in various enzymes in the body that break down fats, carbohydrates, and proteins. It is in many different foodstuffs, so severe deficiency is rare but mild deficiencies can manifest as fur, skin, or nail problems in dogs.
Folate is crucial in forming DNA), producing our pets’ red blood cells, and the body’s utilisation of proteins. It is also essential in pregnancy. Deficiencies can be seen in pregnancy or with small intestinal or pancreatic disease. Deficiencies can cause anaemia (low red blood cell levels) and problems with puppy development.
Cobalamin has essential functions in intestinal health, nutrient absorption, DNA formation, nerve function, and red blood cell development. Primary deficiencies are rare but reported in several breeds (including Border Collies, Beagles, and Australian Shepherds). Deficiency is common in dogs with gut or pancreatic diseases.
Other B vitamins not covered here include Riboflavin (B2), Niacin (B3), Pantothenic acid (B5), and Pyridoxine (B6),
Healthy dogs can make their own vitamin C from glucose, so it isn’t an essential dietary component. However, evidence suggests that it may help treat and prevent disease due to its antioxidant benefits.
Choline plays an important role in the pathways used by the liver to remove toxins and in the formation of essential chemicals used by the brain. It may be prescribed as a supplement in dogs with brain diseases.
L-carnitine is naturally only found in animal protein sources. It plays a role in transporting fats into parts of our cells called “mitochondria” that produce energy for our body tissues. Deficiency has been documented in some types of heart disease in dogs.
Carotenoids are pigments found in plants. There are over 600 different types. Currently, four are suggested to contain potential health benefits; beta-carotene, lycopene, lutein, and astaxanthin. They may function as antioxidants and support immune function, although there is not strong scientific evidence to support this. Dogs can convert beta-carotene — which is what makes carrots orange – into vitamin A (cats cannot).
Flavonoids are another group of plant pigments found in peels or skins of coloured fruits and vegetables. They may also have an antioxidant function.
There are at least 18 minerals known to be essential for all mammals, dogs included. Minerals are “inorganic” and cannot be produced by living organisms but are necessary for body function. Plants get their minerals from the soil, and these minerals then pass through the food chain. Minerals are subcategorised as macrominerals (those we need larger amounts of) and micro – or trace – minerals, of which we need smaller quantities. Several minerals play an essential role as “electrolytes”. Tiny changes in the levels of electrolytes can lead to severe consequences.
Calcium is an electrolyte that plays many vital roles in our dog’s body functions, including but not limited to bone growth and health, blood clotting, nerve function, and muscle contraction. Too much or too little calcium can have severe consequences for your dog. As a result, the body has many complex systems to prevent this from happening. However, a diet too low in calcium (often associated with excess phosphate – see below) can disrupt this balance and the development of bone diseases, especially when calcium demands are high such as in growth or lactation. Conversely, excessive calcium supplementation, especially in rapidly growing, large breed dogs, can lead to the development of joint disease.
Phosphate is an electrolyte that has a critical role in many different cell functions. It has a key role in forming the membranes that make up our cell structure and is crucial in the body’s formation of fuel. It is also vital for the formation of bones, teeth, and DNA. If a diet contains too much phosphate, this can bind to calcium in your pet’s gut and prevent it from being available for use.
Sodium, found in salt, is an electrolyte crucial for maintaining cell structure, nerve and muscle cell function, and for maintaining blood pressure. Rapid changes in sodium levels can cause severe brain problems, so levels are tightly controlled. Disorders with sodium levels in your pet’s body are almost always associated with water intake disorders or water loss by the kidneys or via the intestines. Dogs that have drunk significant amounts of seawater can develop salt poisoning.
Chloride is another electrolyte that plays an essential role in maintaining the balance of fluids in your body in addition to the specific acidity levels within those fluids, the “pH”. All cellular reactions in the body are affected by pH, and slight shifts in this level can impair or even halt vital chemical reactions, which can be fatal. In the absence of diseases such as kidney or gut disease, derangements of chloride are very rare.
Potassium is an electrolyte that serves a vital role in muscle and nerve function. Altered potassium levels in dogs are associated with several disorders, including malnutrition, hormone imbalances, and kidney disease. Severe increases in potassium levels can lead to fatal heart disorders.
Magnesium is an electrolyte used in many different fuel production pathways in the body. Deficiency is rare but can be associated with excessive calcium and phosphorus supplementation.
Iron plays a vital role in many proteins, but most notably in the mechanism by which our bodies transport oxygen around the body on our red blood cells (a protein called “haemoglobin”). An iron deficiency can lead to anaemia.
Zinc plays many roles, including enzyme, protein, immune system, and thyroid gland function. Deficiencies can cause problems with skin, fur, and nails as well as interfere with normal sexual function. There is a group of specific skin disorders linked to zinc deficiency, termed “zinc-responsive dermatosis”, some of which can be hereditary (passed down from a puppy’s parents).
Copper is involved in the production of red blood cells. Deficiency can result in anaemia. Some dogs may have hereditary problems when storing copper, leading to liver disease. Commonly affected breeds include Bedlington Terriers, Labrador Retrievers, and Dalmatians.
Iodine is essential for the production of thyroid hormones within the thyroid gland. This hormone plays a crucial role in doggy metabolism.
Other microminerals not discussed include Selenium, Chromium, Fluorine, Cobalt, Molybdenum, Boron, and Maganese.
Many different vitamins and minerals are needed to keep our dogs healthy. If you prefer to feed your furry companion a homemade diet, it is essential to discuss this with your veterinarian. They will recommend a licensed nutritionist who can help ensure that the diet you prepare contains everything needed to keep your dog happy and healthy. You must also stick religiously to the recommended diet — substituting ingredients is one of the ways that diets become unbalanced.