Vitamin B for Cats Functions, Deficiency and Dosages

The B complex vitamins refer to a group of eight water-soluble vitamins which have various functions especially in cell metabolism and other essential functions as we are going to see.

Whereas they exist in some foods, some are available as dietary supplements and others are meant for medicinal purposes. Any dietary supplement that has all the eight is known as vitamin B complex.

Let us look at each of the vitamin B-complex for cats individually where we will consider their functions, required dosages, their sources, the various deficiency symptoms in cats, and supplementation where necessary.

In this post, we will look at each of the B complex vitamins briefly. However, if you want details, go to | Thiamine | Riboflavin | Niacin | Pantothenic acid | Vitamin B6 | Biotin | Folic Acid | Cobalamin |

Do cats need vitamin B complex
Do cats need vitamin B complex?

1. B1 or thiamine for cats

Vitamin B1 or thiamine plays several roles in a cat’s body including working as a cofactor in the metabolism of carbs as well as in nucleotides and nicotinamide adenine dinucleotide production and in nerve functioning.

Cats cannot make thiamine on their own and they will depend on the amount that occurs naturally in some of their diet (such as meat, pork, eggs, poultry, sea fish, etc.), that added to their commercial foods or it can be supplemented.

However, you should reduce some fish diets since some have an enzyme known as thiaminase that can degrade or destroy this vitamin.

Thiamine deficiency in cats can arise from the use of some preservative such as sulfur dioxide especially in commercial fresh meat foods which will hamper its absorption, degradation during food cooking or processing, diuresis, diseases that affect its absorption and assimilation, among others.

Deficiency signs include vomiting, GI problems, excessive drooling, reduced appetite, vestibular and neurological problems, and ventriflexion.

After a positive diagnosis, supplementation of dosages of 10-25mg given between 12-24 hours can be recommended until symptoms subside. To prevent deficiencies, their foods should have 5mg/kg (AAFCO).

This is only a summary, we have more on the uses of thiamine, deficiency symptoms, possible side effects and so on you should know.

2. Vitamin B2 or Riboflavin

Riboflavin or vitamin B2 occurs as flavin adenine dinucleotide, flavin mononucleotide, and as free dinucleotide riboflavin.

Some of the foods that have thiamine include eggs, milk, and dairy products, meat, leafy green vegetables, among others.

In cats, it works as a coenzyme in fats, carbohydrate and protein metabolism. It is also a component of various enzymes such as glutathione reductase and it also helps in ensuring a good coat quality, healthy skin as well as growth and development of muscles.

Vitamin B2 deficiency can be due to its low intake in diets, degradation during food cooking or processing. Also, conditions such as diabetes, renal disease or the use of IV fluids that often results in diuresis or those that affect its absorption and utilization may cause a deficiency.

A deficiency will be signaled by anorexia, weight loss, fatty liver, alopecia especially on head and neck, testicular atrophy, and so on and supplementation may be necessary.

Cat foods should have 4mg/kg NRC (2006) for growth while AAFCO allows the same amounts for all cat classes.

We have in-depth coverage on riboflavin in cats that will elaborate on the functions, deficiency symptoms and much more.

3. Niacin or vitamin B3

Vitamin B3 comes in niacin (or nicotinic acid – the most common), nicotinamide riboside, and nicotinamide forms. All these forms must be converted to adenine dinucleotide and nicotinamide-adenine dinucleotide phosphate forms before their utilization inside the cat’s body.

Fish, leafy greens, tea, coffee, eggs, milk, meat, poultry, beans, etc., are some of its common sources and cats can get niacin from those foods they can eat or it can be added to some commercial foods. Also, supplementation or use medicinal may be necessary.

Unlike dogs, cats cannot make enough amounts of vitamin B3 due to their overly active picolinic carboxylase enzyme that converts tryptophan amino acids to acetyl-CoA and carbon dioxide. Therefore it must be provided in diets or supplemented.

Some of its functions include metabolism of amino acids, ketone bodies and carbohydrates (like riboflavin), synthesis of lipids and cholesterol), and is necessary for skin, joints, bone, digestive system, and central nervous system health, among other function.

Deficiencies may be due to depletion during cooking or manufacturing, unbalanced diets, manufactured foods that contain leucine since it affects the conversion of tryptophan to niacin, or conditions that result in diuresis, among others.

Symptoms of vitamin B3 deficiency in cats include anorexia, poor coat quality, weight loss, retarded growth, digestive disorders, sore mouth disease, or even death if it is not supplemented in time.

To avoid deficiencies, your feline friend’s foods should have 40mg/kg (according to NRC 2006)). On the other hand, AAFCO (2007) recommends 60mg/kg of their food.

4. B5 or Pantothenic acid

Pantothenic acid or vitamin B5 is an essential B complex vitamin in cats whose sources include mushrooms, avocados, milk, liver, kidney, yeast, sweet potatoes, lentils among others where it is found as part of CoA (coenzyme A), acyl-CoA or acyl carrier proteins.

Being part of coenzyme A, it is involved in the oxidation of glucose and fatty acids to yield energy and in the synthesis of hemoglobin, cholesterol, fatty acids, vitamin D, acetylcholine, and ketone bodies.

Deficiency symptoms have been noted in kittens and they mainly affect the liver and intestinal tract. A deficiency can be due to conditions that cause diuresis, diets lacking pantothenic acid or depletion during food processing or cooking.

After a diagnosis, your vet may recommend supplementation. On amounts in diets, NRC (2006) recommends 4.75mg/kg of cat food for all cat classes and 5.7mg/kg for kittens. On the other hand, the AAFFO puts the amounts at 5mg/kg of food.

We will not delve more into details including its functions, deficiency symptoms, and supplementation as we already covered all that separately. See pantothenic acid for cats

5. Vitamin B6

Vitamin B6 comes in various forms with the pyridoxal 5’-phosphate being the most active and pyridoxine (pyridoxine hydrochloride) is common synthetic form. It can obtain from foods such as liver, kidney, fish, and so on, can be supplemented or added in some cat foods.

Some of the vitamin B6 roles include taking part in fatty acids, amino acid, and carbohydrate metabolism, it helps in the synthesis of amino acid, niacin, and it inhibits mammary tumor cells growth if supplemented, among many others. We have covered them in details under vitamin B6 functions and deficiency signs.

Vitamin B6 deficiency in cats can be caused by several reasons and you expect symptoms such as anorexia, stunted growth, calcium oxalate deposits in kidney and consequently renal damage, neurological disorders among others.

In case of neurological symptoms such as convulsive seizures due to a deficiency, your vet may recommend an injection of 25mg of pyridoxine.

Finally, cat food should have 2.5mg of this vitamin per kilogram or 2.4mg/kg for all cats classes according to the NRC and AAFCO respectively.

6. B7 or Biotin for cats

Biotin or vitamin B7 can be obtained from egg yolk, meats, yeast, salmon, dairy foods among others. Go for animal sources since cats are true carnivores.

Its roles include working as a coenzyme for protein, fats and carbohydrate metabolism and it supports adrenal gland, thyroid, nervous, and reproductive systems.

Furthermore, it ensures healthy skin, nails, fur as well as helps in maintaining right blood sugar levels in case of low carb consumption as we have explained while looking at vitamin B7 or biotic for cats necessity.

Biotin deficiency symptoms in these pets that are mainly reported in kittens include scaly dermatitis, dry secretions on eye and mouth corners and around the nose, facial alopecia, loss of appetite, bloody diarrhea, among others.

For instance, dependency on egg whites which has avidin can result in a deficiency as it affects biotin’s absorption.

Biotin should not be supplemented in cat food unless there are antimicrobials or antivitamins that can deplete it. The NRC (2006) recommends 75 µg of biotin per kg of cat food while AAFCO recommends 70µg/kg.

7. B9 or folic acid for cats and vitamin B10 or PABA

Folate (folic acid if manmade) or vitamin B9 can be obtained from poultry, eggs, meat, milk of a nursing cat, among other sources.

Its functions include repairing and synthesis DNA in rapidly dividing cells especially in growing kittens and fetuses. Also, it helps in the formation of red blood cells and in the synthesis of neurotransmitter and nucleoprotein.

Furthermore, it boosts growth and development since it promotes homocysteine synthesis, among other functions we covered while looking at whether folic acids for cats is necessary or not.

Vitamin B9 deficiency in cats is very rare. However, pregnant queens can lack this vitamin or those with gastrointestinal disorders that affect absorption. Commercial food processing or cooking is known to deplete folate.

Deficiency symptoms include stunted growth, cataract, depression, low cholesterol, anemia, among others.

To manage deficiencies, NRC (2006) recommends that all cat foods have 750 µg/kg of folic acid and AAFFCO (2007) recommends 800 µg per kg of their food.[1]

PABA or vitamin B10 is a part of folic acid

Para-aminobenzoic acid (PABA) once considered as vitamin B10 is now part of folic acid since if the nutritional requirement of folic acid is met, you do not have to add PABA.

Normally, bacteria use PABA to synthesize folic acid and since vertebrates don’t synthesize their own folic acid, PABA is not considered an essential nutrient.

8. Cobalamin or vitamin B12 for cats

Vitamin B12 or cobalamin is naturally available in certain foods (such as liver, kidney, meat, eggs, poultry, milk, fish, etc.), as a supplement or can be added to some cat foods and comes in several forms including the methylcobalamin and adenosylcobalamin that occur naturally.

Cobalamin works together with folic acid as enzyme cofactors for metabolizing carbs, fats, and proteins. Furthermore, it helps in ensuring healthy digestive systems as well as informing and maintaining red blood cells, and ensuring their nervous system is healthy.

Also, cobalamin can help boost cat appetite. Perhaps, it one of the vitamin B for cats appetite you should consider. We have also a discussion on cobalamin for cats with IBD and on managing diabetes neuropathy symptoms with methylcobalamin. Finally, our post on whether cats need vitamin B12 shots will be very enlightening.

Deficiencies can be due to any health condition that affects normal absorption or assimilation of vitamin B12 such as IBD, pancreatitis, intestinal lymphoma, excessive stress or diuresis (causes too much of its excretion).

Also, deficiencies of thyroid, tannic acid, vitamin B6, proteins, and so on may affect its absorption.

After diagnosis, in case of a deficiency, daily oral dosages of 250 µg for about three months, or injections of same amounts for seven days followed by one monthly injection, all subcutaneous or intramuscular may be recommended.

Finally, to prevent deficiencies, NRC recommends that cat diets should have 2.5µg per/kg while AAFFCO puts the amount at 20 µg/kg for all cat classes. See more details on cobalamin functions and deficiency symptoms in cats.


The various vitamin B complex group member can come in various forms including capsules, liquid forms, tablets, solutions, as powders and so on depending on how they are administered. Some may also contain other nutrients especially minerals.

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