The Different Types of B Vitamin

Why B Vitamins Are Important for CKD Cats

Which B Vitamins to Give

Vitamin B Complex

B Vitamins with Iron

B Vitamins with Potassium

Methylcobalamin (Vitamin B12)




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General Health Issues in a CKD Cat: Fleas, Arthritis, Dementia, Vaccinations

Tips on Medicating Your Cat

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Nutritional Requirements of CKD Cats

The B Vitamins (Including Methylcobalamin)

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Home > Diet and Nutrition > B Vitamins



  • B vitamins are water-soluble, so are often lacking in CKD cats, who lose much of their vitamin B through urination.

  • Cats who are not eating much will also probably not be taking in enough B vitamins.

  • A lack of vitamin B may cause loss of appetite, or occasionally may cause twitching or itching. Vitamin B deficiencies are also known to cause non-regenerative anaemia.

  • B vitamin supplements are safe and can often help a CKD cat feel better.

  • Vitamin B12 in the form of methylcobalamin may be particularly helpful.

The Different Types of B Vitamin                                                      


Although vitamin B is commonly referred to as if it were a single vitamin, there are actually a number of B vitamins. These are essential vitamins, which means that they cannot be manufactured in the cat's body, so must be obtained from external sources (from food or a supplement).


These are the main B vitamins:

  • Vitamin B1 - thiamine

  • Vitamin B2 - riboflavin

  • Vitamin B3 - niacin or nicotinamide

  • Vitamin B5 - pantothenic acid

  • Vitamin B6 - pyridoxine or pyridoxamine

  • Vitamin B7 - biotin, also known as vitamin H

  • Vitamin B9 - folic acid, also known as vitamin M

  • Vitamin B12 - cyanocobalamin or methylcobalamin

Pet Education explains more about the different B vitamins.

Nutritional management of renal disease (2008) Sturgess K Presentation to the World Small Animal Veterinary Association World Congress has a table showing the recommended intake of the various B vitamins for CKD cats. Remember, this is total intake, i.e. it includes vitamin B in food.



Vitamin B1, or thiamine, is important for proper muscle and nerve function. A mild deficiency can cause loss of appetite and vomiting, while a severe deficiency can cause numerous health problems, including a stiff neck, seizures and even death. Cats who eat fish regularly can develop this problem (see Which Foods to Feed).


A cat needs to obtain thiamine from food because the body stores very little of it, but there have been food recalls in the past of commercial cat foods because they did not contain sufficient thiamine. Analysis of thiamine concentrations in commercial canned foods formulated for cats (2014) Markovich JE, Freeman LM & Heinze CR Journal of the American Veterinary Medical Association 244(2) pp175-179 examined ninety US  canned cat foods and found 13.3% of the foods contained lower thiamine levels than recommended by AAFCO. Pate-style foods and foods from smaller manufacturers were more likely to be affected. The study recommends that vets should consider thiamine deficiency as a possible cause when presented with a cat with ventroflexion.


Thiamine deficiency (2006) Schaer M NAVC Clinician's Brief August 2006 has a short article on thiamine deficiency, including photos of an affected cat.


The Importance of B Vitamins                                                                   


B vitamins are water-soluble, so are often lacking in CKD cats, who lose much of their vitamin B through the increased urination associated with CKD. Cats who are not eating much will also probably not be taking in enough B vitamins. A lack of vitamin B may cause loss of appetite, or occasionally may cause twitching or itching. Vitamin B deficiencies are also known to cause non-regenerative anaemia. A lack of vitamin B1 may cause an inability to lift the head.


Your vet may therefore suggest a supplement in order to avoid or assist with these problems. This is particularly important if your cat is anaemic or at the low end of the laboratory range for PCV or HCT (measures of anaemia), but even non-anaemic cats often seem to feel and act better when given additional B vitamins.


Which B Vitamins to Give                                                                             


Many people use a vitamin B complex supplement for their CKD cats, as described below.


Vitamin B12, in the form of methylcobalamin, can be particularly useful for CKD cats, but there is only a relatively small amount of vitamin B12 in most B complex supplements, so some people give a separate B12 supplement as well. This is particularly important for anaemic cats. There is more about vitamin B12 below.


Because B vitamins are water-soluble, they are generally considered to be a safe supplement because any excess will simply be urinated out, but you should still be careful not to over-supplement B6 and B9 in particular.

Vitamin B Complex                                                                                          


B vitamins need to be in a certain ratio to each other, so many people buy their supplements in the form of a vitamin B complex. These are usually human products and they are supposed to contain the correct balance of B vitamins, though for some strange reason they often do not contain vitamin B9 (folic acid).


B vitamins are sensitive to heat and light so are best kept in a cool dark place.


B vitamins may make urine yellow or orange, so don't panic if you see this.

Vitamin B Complex Formulations

There are three main ways to give vitamin B complex: orally, injected into the cat, or injected into the fluid bag.


There are a wide range of vitamin B complex products available throughout the world. The vast majority are made for humans but these are commonly used for cats in reduced, cat-sized doses. Here are some products which are widely used on Tanya's CKD Support Group, but check with your vet before using.

Oral Vitamin B Complex

B vitamin supplements are sold for humans, and vary in how much of each B vitamin they contain.


Jarrow's B-Right is a popular choice on Tanya's CKD Support Group because it contains all the B vitamins including B9 (folic acid), and some B12 in the favoured methylcobalamin form. It is also widely available. It does contain relatively high amounts of some B vitamins, so ask your vet about it first. Some people think it has little taste, whilst others think it tastes rather bitter.


This product does contain sugar so may not be suitable for diabetic cats. See below for dosage and sources.


If you decide to use a different product, take a look at the Jarrow's B-Right label and try to find a product with no more than the stated amounts for each vitamin. Your vet may wish you to give less of certain B vitamins, if so, you should of course comply.


Oral Vitamin B Complex Dosage

Whichever product you choose, if it is a human product, you need to reduce the amount you give into a cat-sized dose.


The general rule of thumb is to give a 10 lb cat approximately 1/10th of a human dose each day. Thus, if you buy a product where the dose for a human is one capsule a day, one capsule would be enough  to last a cat for ten days.


Ideally, you then want to divide this daily dose further into 2-3 doses each day if you can, but in practice that is not easy, since you are talking tiny amounts.


You can decant the amount you are giving into a gelcap, or you can sprinkle it on food, though some cats find the taste of some of these products a little bitter.


Oral Vitamin B Complex: How to Create Cat-sized Doses

If you buy tablets, you can crush them and divide them (usually into ten) after crushing. If you use capsules, you can open the capsule and divide its contents.


Either way, it can be fiddly obtaining cat-sized doses. I have been asked so often about how to divide the small amount in a capsule into ten. There are a number of ways people on Tanya's CKD Support Group do this:

  • Some people empty the contents of the capsule onto foil and divide it roughly into ten with a knife or razor.

  • Some people pour the capsule contents into a shallow bowl or plate and divide it into ten.

  • Some people use measuring spoons. These are discussed here. Apparently the drop spoon holds about a tenth of a Jarrows B-Right capsule and the smidgen spoon holds about an eighth of a Jarrows B-Right capsule.

Once the original capsule contents have been divided into cat-sized doses, most people find the simplest thing is to decant the portions into empty gelcaps (capsules) and give a capsule once daily. People dividing their capsules on pieces of foil may carefully tear the foil and fold it into a funnel shape, which they then use to pour the powder into an empty gelcap. Other people prefer to buy a little funnel specially for this task. Members have used this Torpac one, or have found them in the USA at Bed, Bath and Beyond for about US$2.


One person actually found that if she emptied out the contents of a Jarrows B-Right capsule, the correct cat-sized dosage filled one half of a size 5 gelcap to the top, so she simply used the empty size 5 gelcap to scoop up the powder. She could then pop other medications in the capsule as well if necessary, by squashing down the powder with the additional medications.


Oral Vitamin B Complex Sources


Amazon sells 100 capsules of Jarrows B-Right for US$11.46 including shipping.


Vitacost sells 100 capsules of Jarrows B-Right  for US$8.16. Shipping is a flat rate US$4.99 per order.


iHerb sells 100 capsules of Jarrows B-Right for US$10.77 plus shipping.



Amazon UK sells 100 Jarrows B-Right capsules (see above) for £11.98.


Provet in the UK sells a phosphorus-free feline vitamin B supplement called Pro-VitB, which costs £8.32 for 30 tablets.



Megavitamins sells Jarrows B-Right in Australia.


Injectable Vitamin B Complex

I think every vet on the planet has this available. My vet often gives my cats a one-off shot if they are off colour, but for CKD cats who are not visiting the vet every week or so, it can be easier to give the shots at home. Injectable B complex (which is yellow) does sting when injected though, so oral dosing may be better; but it might be worth using the injectable form in vomiting cats.


Some vets add vitamin B complex to the sub-Q fluids bag, but this is not a good idea because it can make the fluids sting; it can compromise the sterility of the bag; and giving vitamins in this way (i.e. added by the vet) tends to increase the cost of the fluid bags. In addition, since most people warm their fluids before using them, the B vitamins could well be rendered ineffective through the repeated warming.


Vedco is used by some members of Tanya's CKD Support Group. It requires a prescription.












Injectable Vitamin B Complex Dosages

For humans, the recommended dosage of the Vedco product is 1-5ml per 100 lbs of bodyweight given once or twice a week. For a 10 lb (4.5kg) cat, the equivalent dose would be 0.1 - 1.0 ml once or twice a week, but be guided by your vet. 


The Vedco product contains a relatively high amount of vitamin B1 (thiamine) and Vedco does mention "Parenteral administration of thiamine has resulted in anaphylactic shock. Administer slowly and with caution doses over 1/3 mL (50 mg thiamine)."


Injectable Vitamin B Complex Sources


Thriving Pets sells a 250ml bottle of the Vedco brand for $19.95. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$100. Shipping is free for orders over US$100 after the discount.


UK and Other Countries

I do not know of any stockists but your vet probably can assist.


Thriving Pets will ship to selected clients in selected countries, read here for terms and conditions.


Vitamin B Complex Cautions    

Avoid products containing alpha lipoic acid, which is toxic to cats.


I would avoid using multi-vitamin products, particularly two US products called Hi-Vites and Felovite II, as a source of B vitamins. There is nothing wrong with these products as such, but unfortunately they tend to be too high in vitamins A and D for a CKD cat, and Felovite II also contains phosphorus. Several cats on the support group have not done well on Hi-Vites in particular.


Aventi Kidney Support (formerly Renal Advanced) is a product made by Candioli which is commonly offered to people in Italy and Canada. It contains vitamin B6, vitamin B12 and vitamin B9 (folic acid), plus probiotics. However, it also contains Lespedeza capita, which is a diuretic and therefore contra-indicated in CKD cats, and prebiotics in the form of fructooligosaccharides which may increase calcium levels in some cases. Personally I would just use B vitamins, and a probiotic separately if appropriate.


B Vitamins with Iron: Pet-tinic or NutriVed                                                     


Some cats (typically anaemic ones) may need iron as well as B vitamins. In these cases it is usually easier to use a combined product, but you should never give iron to a cat with an infection. These are the two most popular combined products on Tanya's CKD Support Group.

NutriVed B Complex Plus Iron

NutriVed B Complex Plus Iron Liquid contains B vitamins and iron (click on the link for the precise composition). The usual dose is 0.1ml per lb of cat, twice a day (which equates to 5mg of iron twice a day) so a 10lb (4.5kg) cat would need 1 ml twice a day, but do check with your vet in case your cat needs a different dose. It does contain sugar, so may not be suitable for diabetic cats.


I used NutriVed for my anaemic cat, Ollie, with no problems. I simply mixed his twice daily dose into a small amount of baby food and he gobbled it up.









NutriVed Sources USA

California Veterinary Supply sells NutriVed for US$8.49 for 4 oz.


Thriving Pets sells NutriVed for US$10.95. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$100.


Healthy Pets sells NutriVed at a cost of US$9.99 for 4 oz.


Natural Pets also sell NutriVed for US$9.99. This is essentially the same company as Healthy Pets, but I'm mentioning it here in case it has offers available.


NutriVed Sources UK

Natural Pets sell NutriVed for US$9.99 and will ship to the UK. Shipping via USPS Express Mail for one or two bottles costs around US$29.


Thriving Pets sells NutriVed for US$10.95. It will ship to selected clients in selected countries, read here for terms and conditions.


Pet-tinic (Pet-Tabs Iron-Plus)


Pet-tinic, now also known as Pet Tabs Iron Plus, is both an iron supplement and vitamin B supplement, though for some strange reason it does not contain folic acid. The usual dose for a 10lb (4.5kg) cat is 1 ml twice a day (which equates to 5.4mg of iron a day), but do check with your vet in case your cat needs a different dose. It does contain corn syrup, so may not be suitable for diabetic cats.






Pet-tinic Sources USA

KV Vet Supply sells Pet-Tabs Iron Plus for US$7.95 for 4 oz, with free shipping for orders over US$50. If necessary, search for item 40168.


Thriving Pets sells Pet-tinic for US$14.95 for 4 oz. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$100.


Pet-tinic Sources UK

KV Vet Supply will ship Pet-tabs Iron Plus to the UK or Canada. It costs US$7.95 for 4 oz, but shipping is relatively expensive, so it is usually more cost effective to order more than one bottle at a time. Search for item 40168 if necessary.


Thriving Pets sells Pet-tinic for US$14.95 for 4 oz. It will ship to selected clients in selected countries, read here for terms and conditions.


Vitamin B with Potassium (Kaminox or Renal K+)                                  


Some manufacturers produce vitamin B supplements combined with other products, i.e. potassium and iron. I would not recommend using these products unless your cat has low potassium levels, which not all CKD cats do; giving potassium when it is not needed can be very dangerous.


ACE inhibitors such as benazepril (Fortekor) may make potassium levels rise; so if your vet has prescribed Fortekor, as so many British vets do, it might be wiser to use a different type of B vitamin without the potassium.


Renal K+ and Amino B & K

In the USA there are two products available which contain both B vitamins and potassium, Renal K+ made by Vetoquinol (it contains potassium gluconate, other ingredients unknown), and Amino B & K from Emerson Ecologics.


Renal K+ Sources USA

Thriving Pets sells 100g of Renal K+ in powder form for US$19.95. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$100. Shipping is free for orders over US$100 after the discount.



If you are in the UK, you may be offered a product called Kaminox. This is a combination of B vitamins, iron and potassium. Alfamedic provides a list of the ingredients. You should not use Kaminox if your cat has an infection because of the iron, see Anaemia for more information.


Kaminox Sources UK

Vet UK sells Kaminox for £19.86 for 120ml, with free UK shipping.


Vetscriptions sells Kaminox for £22.99 for 120ml. Search for Kaminox.


Vitamin B12 - Methylcobalamin and Cyanocobalamin                           

What is Vitamin B12?

Vitamin B12 in the form of methylcobalamin is the neurologically active form of vitamin B12, and is used by the body to correct or prevent neurological problems. It may also help with a variety of other problems (see below).


Although vitamin B12 is often included in vitamin B complex formulations, there is usually too little vitamin B12 for it to be of much use. Therefore many people with CKD cats give both a vitamin B complex and a separate vitamin B12 product.


Oregon State University has some information about vitamin B12.

PDR Health has some information about methylcobalamin in humans.

Net Doctor has some information about vitamin B12 deficiency in humans.


Why Vitamin B12 is Important

A lack of vitamin B12 may cause a variety of problems, including cognitive dysfunction.


Vitamin B12 is essential for red blood cell production, so too low a level of vitamin B12 in your cat's body may cause or contribute to anaemia. If severe anaemia is present, vitamin B12 may help improve it. Treatment of confirmed B12 deficiency in hemodialysis patients improves Epogen requirements (2013) Saifan C, Samarneh M, Shtaynberg N, Nasr R, El-Charabaty E & El-Sayegh S International Journal of Nephrology and Renovascular Disease 6 pp9–93 found that giving vitamin B12 supplements to human CKD patients with low levels of vitamin B12 led to a reduced need for ESAs to treat CKD-related anaemia.


Cats with IBD or pancreatitis tend to have low levels of cobalamin so are often given methylcobalamin. It is also often recommended for cats with diabetic neuropathy.


The prevalence of hypocobalaminaemia in cats with spontaneous hyperthyroidism (2011) Cook AK, Suchodolski JS, Steiner JM & Robertson JE Journal of Small Animal Practice 52(2) pp101–106 found that a sizeable percentage of cats with hyperthyroidism have low levels of cobalamin.


Plasma homocysteine, B vitamins, and amino acid concentrations in cats with cardiomyopathy and arterial thromboembolism (2000) McMichael MA, Freeman LM, Selhub J, Rozanski EA, Brown DJ, Nadeau MR, Rush JE Journal of Veterinary Internal Medicine 14(5) pp507-12 found that cats with heart disease who have thromboembolism (thrown a clot or saddle thrombus) have significantly lower levels of vitamin B6, vitamin B12 and arginine, an amino acid. The study concludes "We interpret the results of this study to suggest that vitamin B12 and arginine may play a role in CM and ATE of cats." If your cat has heart disease, therefore, you may wish to discuss using methylcobalamin with your vet.


Vitamin B12 may be a particular concern for older cats. Vitamin B12 deficiency (2003) OH RC & Brown DL American Family Physician 67(5) pp979-86 mentions that one study found that 15% of people over the age of 65 had a vitamin B12 deficiency. Addressing age-related changes in feline digestion (2010) Patil AR & Cupp CJ Nestlé Purina Companion Animal Nutrition Summit 2010 Focus on Gerontology states "if Vitamins E & B12 are at low levels, then processing of fat and protein are likely compromised in older cats."


Vitamin B12 may also be useful for CKD cats. According to Renal and Urology News, B12 supplements help reduce inflammation in CKD. Chronic renal failure promotes severe variant of Vitamin B12 deficiency (2006) Duning T, Nabavi DG, Dziewas R, Kugel H & Schäbitz W-R European Neurology 56 pp62–65 reports on the case of a human CKD patient with vitamin B12 deficiency and concludes that CKD patients "may require earlier and much larger therapeutic cobalamin doses than previously considered."


If you are using famotidine (Pepcid AC), ranitidine (Zantac 75) or omeprazole (Prilosec), it may reduce the absorption of vitamin B12 from food. Proton pump inhibitor and histamine H2 receptor antagonist use and vitamin B12 deficiency (2013) Lam JR, Schneider JL, Zhao W & Corley DA Journal of the American Medical Association 310(22) pp2435-2442 found that in humans "gastric acid inhibitor use was significantly associated with the presence of vitamin B12 deficiency." Therefore if you are using acid blockers, your cat might benefit from a vitamin B12 supplement.


Methylcobalamin has been found by members of Tanya's CKD Support Group to be very helpful for various CKD-related problems, including anaemia, incontinence, appetite loss and constipation. It is safe and easy to obtain and to give, so speak to your vet about supplementing it.


Vitamin B12 Formulations

Vitamin B12 is routinely offered as a supplement in the form of cyanocobalamin rather than methylcobalamin. Cyanocobalamin is an artificial form of vitamin B12, which has to be converted into methylcobalamin before the body can use it. In the process, a tiny amount of cyanide (so small that it is harmless) is produced. Since methylcobalamin is more bioavailable, and therefore more effective because it is absorbed more readily by the body, I would recommend giving it to your cat in the first place if possible.


Vitamin B12 is available in oral or injectable forms, but the injectable form is cyanocobalamin rather than methylcobalamin (I do know of one US compounding pharmacy which provides injectable methylcobalamin, see below).


It used to be thought that only the injectable form  was effective, and indeed some vets still seem to believe this, but Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency (2005) Vidal-Alaball J, Butler CC, Cannings-John R, Goringe A, Hood K, McCaddon A, McDowell I & Papaioannou A Cochrane Database of Systematic Reviews 20(3) found that oral vitamin B12 was as effective as intramuscular vitamin B12 for human patients with vitamin B12 deficiency. The Gastrointestinal Laboratory at Texas A&M University says "Until similar studies evaluating the efficacy of oral cobalamin supplementation in dogs and cats have been published, the parenteral route continues to be the route of choice." However, this article focuses on cats with gastrointestinal disease, who may have problems absorbing oral medications, rather than on CKD cats. Many members of Tanya's CKD Support Group have successfully used orally administered methylcobalamin for their CKD cats. Discuss the best approach for your cat with your vet.


Oral Vitamin B12

The oral form of methylcobalamin does seem to work well for CKD cats, though it may be less effective in cats with IBD (inflammatory bowel disease) or pancreatitis. It is common to give a relatively high dose though, to make sure the cat receives enough (any excess should be peed out).


Oral methylcobalamin is often sold in the form of fruit-flavoured lozenges which some people do use to pill their cats successfully, though plain methylcobalamin tablets and capsules are also available and what I would choose. See below for stockists.


Some methylcobalamin products contain a sweetener called xylitol. Although this is toxic to dogs, there is currently no evidence that it is toxic to cats. However, some people prefer to avoid products containing it.



Unlike vitamin B complex, injectable vitamin B12 (which is a pinky red colour) does not sting, so some people give this to their cats during or immediately after sub-Qs.


The US National Library of Medicine mentions that many injectable forms of vitamin B12 in the form of cyanocobalamin "contain aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired." If you are only using the injectable form occasionally, it is probably safe but discuss this further with your vet. Injectable methylcobalamin apparently does not contain aluminium (the version I know of is preserved with methyl alcohol).


If you do use an injectable form of vitamin B12, the Centers for Disease Control and Prevention recommend discarding multi-dose vials within 28 days of starting them.


Injectable vitamin B12 is only available via prescription in the USA, but is an over the counter product in the UK. See below for stockists, including a US supplier of injectable methylcobalamin.


Vitamin B12 Dosages



A possible starting dose for oral methylcobalamin would be 500mcg (0.5mg) a day, though some people give twice as much. Although this sounds high, only a small percentage of oral B12 is absorbed. The Gastrointestinal Laboratory at Texas A&M University says "Since cobalamin is a water-soluble vitamin, excess cobalamin is excreted through the kidneys and clinical disease due to over-supplementation has not been described."


Most people using capsules simply open a 500mcg capsule and mix the contents with their cat's food. Ideally, I would divide this daily dose between two meals a day, i.e. give 250mcg with breakfast and 250mcg with dinner.



Doses are lower than for oral administration because less is wasted when the injectable form is used.


A commonly used dose for injectable cyanocobalamin is 250-500mcg every week or every two weeks. Drugs recommends 0.25 to 0.5 ml of the 1000mcg/1ml concentration (so 250-500mcg), every 1-2 weeks as required


Although it is more bioavailable than cyanocobalamin, I understand from those who have used injectable methylcobalamin that the dosage is the same, i.e. 0.25ml of the 1000mcg/ml strength (which is 250mcg), but it is normally only given every 2-4 weeks. Be guided by your vet on the best protocol for your cat.


Vitamin B12 Cautions


Side Effects

Drugs mentions that side effects of vitamin B12 supplementation may include itching and diarrhoea. If you see these signs, speak to your vet about reducing the dose.


Vitamin B12 and Cancer

It may be wiser not to give vitamin B12 to a cat with cancer because cancer cells rely on vitamin B12 for growth In Purina Pro Club Update (2013) 12(1) Dr Sysel of the Bauer Research Foundation states "Vitamin B12 is important in DNA synthesis, as cells cannot divide without it. Rapidly growing tumors that are actively dividing have an especially high demand for vitamin B12. Tumor cells produce TCII [transcobalamin, a protein which moves vitamin B12 through the bloodstream] to obtain all the vitamin B12 they can."


However, if you are dealing with lymphoma, the University of Penn School of Veterinary Medicine is researching whether cats with lymphoma have a vitamin B12 deficiency (which is quite possible, because lymphoma may reduce vitamin B12 absorption in the intestines), and if they do, they plan to offer supplemental treatment to address the deficiency.


Researchers are also looking into whether they can use cancer cells' need for vitamin B12 to target cancer. Purina Pro Club Update (2013) 12(1) reports on a "vitamin B12-based anticancer drug, nitrosylcobalamin (NOCbl)", which is being evaluated to determine "whether it can be used to treat a variety of feline and canine tumors." One study, A stability-indicating HPLC method for the determination of nitrosylcobalamin (NO-Cbl), a novel Vitamin B12 analog (2014) Dunphy MJ, Sysel AM, Lupica JA, Griffith K, Sherrod T & Bauer JA Chromatographia 77(7-8) pp 581-589 reports further on the use of nitrosylcobalamin "as a biologic ‘Trojan horse’, utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells."


Vitamin B12 and Diabetes

Cats with diabetes tend to be given relatively high dosages of methylcobalamin. However, Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial (2010) House AA, Eliasziw M, Cattran DC, Churchill DN, Oliver MJ, Fine A, Dresser GK & Spence JD Journal of the American Medical Association 303(16) pp1603-1609 found that humans with diabetes and kidney disease caused by the diabetes who were given three B vitamins, 25mg/d of vitamin B6 (pyridoxine), 2.5mg/d of vitamin B9 (folic acid) and 1mg/d of vitamin B12 had a lower GFR (a measure of kidney function) and an increased incidence of strokes. The study states "Because these vitamins are water-soluble and renally excreted, vitamin toxicity may be more of a concern in patients with impaired renal function."


Cats with diabetes are usually only given methylcobalamin for up to three months, until the diabetes is regulated, but the humans in this study were taking cobalamin for 36 months. It is also not known which form they were taking, but most probably it was cyanocobalamin. These patients had severe diabetes as well as advanced CKD and were receiving multiple treatments apart from B vitamins.


I would not give more than 1 mg a day to your CKD cat, and personally, I would feel more comfortable giving 500mcg (0.5mg) only. Be guided by your vet as to the most appropriate dose for your cat.


Injectable Vitamin B12 Considerations

The US National Library of Medicine mentions that many injectable forms of vitamin B12 in the form of cyanocobalamin "contain aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired." If you are only using the injectable form occasionally, it is probably safe but discuss this further with your vet.


If you do use an injectable form of vitamin B12, the Centers for Disease Control and Prevention recommend discarding multi-dose vials within 28 days of starting them.


Vitamin B12 Sources

Vitamin B12 Sources - USA



Vitacost sells 300 plain methylcobalamin 500mcg (0.5mg) capsules for US$10.68 plus flat rate shipping of US$4.99 per order. I ordered these myself on a Sunday evening, and received them on the following Tuesday. If you are a new Vitacost customer, but know somebody who already uses them, you should be able to use this coupon to get a US$10 discount off your first order.


Amazon sells 60 Superior Source 1000mcg methylcobalamin lozenges for US$9.74.


Drugstore sells 60 Superior Source 1000mcg methylcobalamin lozenges for US$9.74. I've used Drugstore for other items and always had good service.


Vitamin Shoppe sells 60 Superior Source 1000mcg methylcobalamin lozenges for US$9.99 online, and you can often find this product in store too.


The Superior Source product apparently contains lactose, so may not be suitable if your cat is lactose intolerant.


Bayho sells 180 1000mcg (1mg) plain methylcobalamin tablets for US$34.10. Although the site states that it only sells to health professionals, they will normally sell to individuals if you tell them it is for veterinary use.


Some national chains also sell methylcobalamin, but it is often in lozenge form rather than capsules. Check for other ingredients too.


I use Natural Factors chewable 1000mcg methylcobalamin.  Cut tablet with pill cutter into quarters, plop in some water in a small glass, stir, it dissolves, turns red, pour into food.  tasteless.


A prescription is required.


Allivet sells a 100ml bottle of injectable cyanocobalamin 1000mcg/ml strength for US$5.49.


KV Vet Supply sells a 250ml bottle of injectable cyanocobalamin 1000mcg/ml strength for US$10.95.


Thriving Pets sells a 100ml bottle of injectable cyanocobalamin 1000mcg/ml strength for US$14.95. It has a thirty day expiration date.


Diamondback Drugs sell injectable methylcobalamin, which can be very hard to find otherwise. It is not mentioned on their site but members of my support group have obtained it from them with no problems. It costs US$35 for a 5ml vial of 1000mcg/ml strength plus US$10 cold shipping, with a three month expiration date. It must be kept in the fridge.


You can also usually obtain injectable cyanocobalamin from your local Costco pharmacy. You can also search Good RX for cyanocobalamin.


Vitamin B12 Sources - UK



Some health food shops sell the Solgar brand of methylcobalamin, but it is often not easy to find methylcobalamin in UK stores, so you will probably have to shop online.


Amazon UK sells 90 of the Health Leads brand 500mcg capsules for £7.20. Also available directly from Health Leads.


Health Monthly sells 60 Superior Source Methylcobalamin tablets in 1000mcg strength for £9.99.


Amazon UK sells 60 Superior Source Methylcobalamin tablets in 1000mcg strength for £12.99. The Superior Source product apparently contains lactose, so may not be suitable if your cat is lactose intolerant.


Vitacost sells 300 plain methylcobalamin 500mcg (0.5mg) capsules for US$10.68 plus international shipping, which is calculated by weight but which costs roughly USD6.99 for small, lightweight orders and takes 7-14 days. Vitacost have local phone numbers in UK, Australia and Hong Kong. I have not used Vitacost to ship to the UK, but I used them within the USA and they were very efficient and very fast. If you are a new Vitacost customer but know somebody who already uses them, you should be able to use this coupon to get a US$10 discount off your first order.


Vitamin UK sells a number of different types of methylcobalamin, click on Search, then type in methylcobalamin.



Petmeds in the UK sells 50ml of injectable cyanocobalamin 1000 mcg/ml strength for £18.25. A possible dose is 250-500mcg every week or every two weeks, i.e. 0.25 to 0.5 ml, but check with your vet. You should buy a new bottle every month, so you might prefer the weaker strength (250mcg/ml) on the same page.


Vitamin B12 Sources - Other Countries


Methylcobalamin Resources has details of suppliers in USA, UK, and New Zealand, some of whom will ship worldwide. Please note this site is recommending methylcobalamin for cats with diabetes, so the sizes and doses may be too high for a CKD cat; ask your vet.



Natural Vitamin Direct sells 90 1000mcg methylcobalamin tablets for CAN$7.50.



Complementary Compounding Services sell 50 3mg capsules for AUS$65. These are 3 mg capsules so stronger than usually used for CKD cats, but the capsules can be opened and divided into smaller doses. You would normally use one sixth of a capsule but check with your vet..


Custom Medicine also sells 50 3mg capsules.


Complementary Compounding Services also sell injectable methylcobalamin.


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This page last updated: 07 June 2015

Links on this page last checked: 29 April 2015







I have tried very hard to ensure that the information provided in this website is accurate, but I am NOT a vet, just an ordinary person who has lived through CKD with three cats. This website is for educational purposes only, and is not intended to be used to diagnose or treat any cat. Before trying any of the treatments described herein, you MUST consult a qualified veterinarian and obtain professional advice on the correct regimen for your cat and his or her particular requirements; and you should only use any treatments described here with the full knowledge and approval of your vet. No responsibility can be accepted.


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