What is Anaemia?

Major Symptoms and Risks

Why Anaemia Occurs in CKD Cats

Other Causes of Anaemia

Diagnosis, Including PCV or HCT, RBCs, Reticulocytes and Iron

Treatments, Including Vitamins, Iron and Blood Transfusions




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The Importance of Phosphorus Control

All About Hypertension

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

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Home > Key Issues > Anaemia



  • Anaemia is a condition in which not enough red blood cells (RBC) exist in the body.

  • Anaemia is relatively common in CKD cats, so it is important to know about it and to be prepared to deal with it promptly.

  • Untreated anaemia can kill a cat far more quickly than the CKD, and a severely anaemic cat may look very ill, but fortunately anaemia is very treatable, so don't give up hope.

What is Anaemia?                                                                                                 Back to Page Index


Anaemia is a condition in which not enough red blood cells (RBC) exist in the body. Red blood cells contain a protein called haemoglobin, which transports oxygen round the body, so if a cat does not have enough red blood cells, oxygen is not reaching the cells where it is needed, and the cat will not be able to function properly.


Anaemia is relatively common in CKD cats, so it is important to know about it and to be prepared to deal with it. Untreated anaemia can kill a cat far more quickly than the CKD, and a severely anaemic cat may look very ill, but fortunately anaemia is very treatable, so don't give up hope. University of Georgia College of Veterinary Medicine states that "anemia is not a poor prognostic indicator in cats as most live for more than 300 days despite presenting with anemia", but many cats live a lot longer.


Treating anaemia is not only about lifespan, but also about quality of life. The difference in a cat's behaviour and wellbeing once severe anaemia is brought under control is often quite astonishing. Anaemia is usually very responsive to treatment, but most treatments take a week or so to take effect (apart from blood transfusions, which kick in immediately). Therefore I would recommend treating anaemia for at least two weeks before contemplating euthanasia.


Major Symptoms and Risks of Anaemia                                                         Back to Page Index


It is very important to treat anaemia because it can have some serious effects on the body, and in the worst case it can even kill. Symptoms you may see include:

Faster Heart Rate

In an anaemic cat the heart rate increases in an attempt to push the reduced amount of haemoglobin around the body. This faster heart rate is called tachycardia. Occasionally anaemia may cause a heart murmur.


High Blood Pressure

The heart tries to provide more blood, and thus oxygen, to the body's cells by increasing the pressure with which it pumps. 



Because there is less oxygen in the body's tissues, the cat breathes more often and more deeply in an attempt to take in more oxygen.



This is also caused by the lack of oxygen in the tissues, which means the cells cannot work as effectively.


Oedema and Heart Failure

The heart can only compensate for the lack of haemoglobin to a certain extent. Eventually, if the problem remains untreated, blood will not circulate properly and will build up, and fluid will leak into body tissues. This causes swelling known as oedema. If oedema occurs in the lungs, it is known as pulmonary oedema, and if it is left untreated this can kill the cat.


The University of North Carolina has some information on the risks of anaemia in connection with heart failure in humans.


Eating Litter or Licking Concrete

One commonly seen symptom which you might not associate with anaemia is eating litter or licking rocks or concrete. Some cats may eat ice or snow. Many vets do not know this type of behaviour can be a symptom of anaemia, but I hear of it so often, and when the cat is tested, anaemia is virtually always present. Very occasionally, eating litter or licking rocks or concrete is a sign of calcium imbalances instead; but either way, if you see this symptom, take your cat to the vet.


The problem should disappear once the anaemia is under control, but in the meantime, switch to a paper- or corn-based litter.


Feline compulsive behavior (2005) Moon-Fanelli A mentions that eating litter may be a sign of anaemia.

Pet Place mentions the case of an anaemic cat who ate litter.

The Mayo Clinic says that eating ice may be a sign of anaemia.


Other Symptoms

Almost all anaemic cats experience loss of appetite, often severe, and extreme lethargy. You may also see pale eyelids or gums. They tend to feel cold, so often seek out warm places.


As you can see, anaemia is potentially very serious, and severely anaemic cats often look and act extremely ill. My Thomas could not even walk downstairs, and just walking to the litter tray was a massive effort for him. Fortunately, anaemia is treatable.


Why Anaemia Occurs in CKD Cats                                                                   Back to Page Index


Healthy kidneys produce a hormone called erythropoietin, which stimulates the bone marrow to make the blood cells. As the kidneys fail in CKD, they cannot produce enough erythropoietin, so the bone marrow is not stimulated, blood cells are not produced, and a particular type of anaemia called non-regenerative anaemia results.


In addition, a uraemic toxin called parathyroid hormone, which is not processed properly by damaged kidneys, may also adversely affect the production of erythropoietin. Role of secondary hyperparathyroidism in erythropoietin resistance of chronic renal failure patients (2002) Drücke TB & Eckardt K-U Nephrology Dialysis Transplantation 17Supp.5 pp17-21 mentions this, but states that it is less of a factor than iron deficiency or inflammation.


And finally, even if a cat is still able to produce red blood cells, these last for around 70-80 days in healthy cats, but only around half that time in CKD cats.


Managing anemia in patients with chronic kidney disease (2011) Chalhoub S, Langston CE Veterinary Medicine May 2011 has a table outlining the causes of anaemia in CKD cats (click on the table to enlarge it).

How Stuff Works has a simple article about how blood cells are made. 

Understanding anaemia is an excerpt from a book by Ed Uthman.

Pet Place has an overview of anaemia in cats (no need to register, just click on Close at the bottom of the pop-up).


Other Causes of Anaemia                                                                                  Back to Page Index


There are quite a few other causes of anaemia, so the following list is not exhaustive:

  • A Vitamin B deficiency can cause anaemia, and is quite common in CKD cats who pee more, and who therefore pee out a lot of Vitamin B because it is a water soluble vitamin.

  • Inflammation or infection may cause anaemia. In Selected diseases of the feline kidney (2001), a presentation to the World Small Animal Veterinary Association World Congress, Dr Stephen DiBartola explains that pyelonephritis (a kidney infection) may cause non-regenerative anaemia in some cats, and this happened to my cat every time he got a bout of pyelonephritis. The reason for this is, if a cat has an infection, the cat's body will sequester iron away (i.e. iron is stored rather than released into the bloodstream), because bacteria thrive on iron. Since iron is necessary for blood cell production, iron deficiency anaemia may result. Iron metabolism in pathogenic bacteria (2000) Ratledge C & Dover LG Annual Review of Microbiology 54 pp881-941 explains more about this. Once the infection or inflammation is under control, the anaemia should gradually improve.

  • Gastro-intestinal bleeding, particularly if the anaemia develops suddenly, may cause anaemia. Most cats with anaemia caused by CKD become anaemic gradually, so if your cat becomes anaemic suddenly, consider this possibililty.

  • Feeding onions to cats causes a specific type of anaemia called Heinz body anaemia, and it is possible that garlic (which belongs to the onion family) may also be a risk.

  • A severe flea infestation may cause anaemia because fleas drink blood. Mar Vista Vet has more information about this.

  • The most common cause of anaemia in otherwise healthy cats is an infective agent called  haemoplasma, one type of which is sometimes known as feline haemobartonellosis or feline infectious anaemia. Pet Place has some information about it. It can be transmitted by fleas, and can usually be treated with an antibiotic called doxycycline and occasionally steroids. Unfortunately it does not always show up in tests, so some vets treat for it even if the tests are negative.

  • Cats with hyperthyroidism who are being treated with methimazole may sometimes develop anaemia. If this is going to occur, it usually does so within the first three months of use. Stopping the medication usually resolves the problem within a couple of weeks.


Feline anaemias: a diagnostic challenge (2002) is a paper on the various causes of anaemia presented to the World Small Animal Veterinary Association World Congress by Urs Giger.

Basic approach to anaemia diagnosis (2005) is a paper on the various causes of anaemia presented to the World Small Animal Veterinary Association World Congress by Harold Tvedten.

Merck Veterinary Manual discusses anaemia in a quite technical but useful manner.

Antech Diagnostics has an article entitled Canine Anaemia (which covers cats as well).


How is Anaemia Diagnosed?                                                                            Back to Page Index

There are two types of anaemia, regenerative and non-regenerative. Regenerative anaemia means that the cat's body may be able to correct the anaemia without any external help, whereas with non-regenerative anaemia, the cat is going to need some help in the form of some kind of treatment.


It is important to know which type of anaemia you are dealing with because the treatments are different. Most (but not all) cats with both CKD and anaemia are suffering from a type of non-regenerative anaemia caused by problems with production of a hormone called erythropoietin (see Why Anaemia Occurs in CKD Cats). Before your vet can advise on the best course of treatment, s/he must decide:

  • Whether your cat has non-regenerative anaemia rather than regenerative anaemia; and

  • If it is non-regenerative, whether it is caused by the CKD or some other condition.


There is a small chance of causing, or more likely, worsening anaemia if a lot of blood is taken too frequently from your cat for blood tests, so bloodtests should ideally not be run too often on CKD cats. If your vet wishes to test only for anaemia, it is not usually necessary to draw a lot of blood - a tiny drop taken from the ear may be sufficient (make sure the ear is warm), so ask your vet if this method could be used, though some machines do need more blood than this. Veterinary Partner has a description of how this is done in diabetic cats, as does Sugar Cats.


A few members of Tanya's CKD Support Group have been using a machine they purchased from Ebay to measure PCV at home in order to spare their cats the stress of vet visits and themselves the cost of frequent tests (see Erythropoiesis Stimulating Agents). They have found the machine to be pretty accurate (it varied by about 2% from vet readings). Personally, if I was dealing with severe anaemia (PCV below 18%), particularly if my cat was on an ESA such as Epogen, I would prefer regular vet visits because when PCV is so low, every percentage point matters, plus vet visits give your vet the opportunity to check your cat over and check blood pressure as well as checking PCV. If you do buy one of these machines, please check its readings against those from your vet's equipment.


One possible compromise would be what one member of Tanya's CKD Support Group used to do. He would obtain the blood from his cat's ear at home as outlined above, but then take the sample to his vet for analysis. This saved his cat the stress of the vet trip, but still gave an accurate result.


Packed Cell Volume (PCV) or Haematocrit (HCT): Determining if Anaemia is Present

Your vet will determine whether your cat has anaemia through a bloodtest called Packed Cell Volume (PCV). PCV measures the ratio of red blood cells to total blood volume. The blood is spun in a centrifugal machine and your vet measures the total number of cells that are left. It does not distinguish old blood cells from new but it is a still a useful and accurate test for anaemia.


Some vets check Haematocrit (HCT) instead, which is very similar to PCV. HCT actually refers to the red cells that are left only; but since the other blood cells (white cells and platelets) usually make up less than 1% of blood volume, the difference between PCV and HCT is too small to be concerned about.


Only a small amount of blood is needed for these tests (although more blood is needed for HCT than for PCV) and many vets have the necessary equipment in their offices so you can get a result in a few minutes.


Technically, a cat is anaemic if the PCV level is below 30% (or with some labs, 25%), but you may not start to see any differences in your cat's behaviour until the level is closer to 20%. Below 20% is generally considered to be severe anaemia, and it really must be treated as a matter of priority. Dehydration will make PCV look higher than it really is, so once the cat is rehydrated, PCV will often fall. In other words, your dehydrated cat may have, say, a PCV of 26% which does not indicate anaemia, but once the dehydration has been corrected, the PCV may have fallen to 20%, indicating anaemia is present.


Cats with hyperthyroidism may have PCV or HCT levels in the high end of the range.


Reticulocytes: Deciding if it is Regenerative or Non-Regenerative Anaemia

The PCV test shows if your cat is anaemic, but it does not show whether the anaemia is regenerative or non-regenerative. Regenerative anaemia means that the cat's body may be able to correct the anaemia without any external help, whereas with non-regenerative anaemia, the cat is going to need some help in the form of some kind of treatment.  Most (but not all) cats with CKD and anaemia are suffering from non-regenerative anaemia caused by problems with production of a hormone called erythropoietin (see Why Anaemia Occurs in CKD Cats). 


The only way to know for certain which type of anaemia you are dealing with is by testing for reticulocytes. Reticulocytes are immature red blood cells produced by the bone marrow. When seen in the blood stream, they are about 5-7 days old. Since anaemia means there is a lack of red blood cells, the body's usual response is to try to generate more red blood cells, so normally you would see reticulocytes if the anaemia is regenerative - this shows that the bone marrow is still making blood cells. However, in non-regenerative anaemia (as often seen in CKD), the lack of the hormone called erythropoietin means the bone marrow is not able to make blood cells, or not enough of them to replace old ones, so there will be few or no reticulocytes present. 


Unfortunately the reticulocyte test (which at most laboratories only measures aggregate reticulocytes) is unlikely to be reliable unless the anaemia is relatively severe. Anaemia needs to be pretty bad before a brisk regenerative response is considered necessary by the cat's body, so there is little point testing for reticulocytes unless the PCV has been below 20% for five days or longer. In addition, most vets cannot test reticulocytes in house, so the test has to be sent out to a lab, which takes more time.


Because of this, some vets simply assume that a CKD cat with anaemia is suffering from non-regenerative anaemia caused by a lack of erythropoietin production and treat accordingly. For cats with milder anaemia (PCV above 20%), they may recommend B vitamins. For cats with PCV below 20%, it is trickier. In these cases, the anaemia is a more urgent problem and you need to act quickly, especially if your cat seems poorly, so your vet may recommend the use of Erythropoiesis Stimulating Agents (ESAs) (Epogen, Aranesp etc.), which are used for non-regenerative anaemia caused by a lack of erythropoietin production. In view of the possible risks associated with this treatment, you might wish to wait five days and have the reticulocyte test done to be sure you really are dealing with non-regenerative anaemia; but on the other hand, ESAs take up to two weeks to start taking effect, so waiting may be risky because your cat will not be feeling well and the anaemia may worsen while you wait.


My vet felt it was more important that we start treating Thomas as quickly as possible. Since Thomas had severe anaemia (his PCV was 18% and he was very weak and breathless), she felt the most likely cause was non-regenerative anaemia caused by the CKD, so we began using an ESA immediately rather than wait several days or more for the results of a reticulocyte test.


Reticulocytes Test

This table shows what differing levels of reticulocytes indicate. Remember, the table is only really of any use for cats with severe anaemia (PCV below 20%).


The usual level of regeneration in a healthy cat who is not anaemic is approximately 1% (around 50,000- 60,000 reticulocytes). In an anaemic cat, you would expect it to be above this level, since you would expect to see a marked response, i.e. the bone marrow should be busily making new red blood cells if it can. It can only do this if there is sufficient erythropoietin available. So if the reticulocyte count is low (below 1%) or even zero despite the PCV being below 20% for five days or longer, this indicates non-regenerative anaemia.


Degree of Regeneration Reticulocytes in % Absolute Reticulocytes
Normal/Negligible Under 1.00 Under 60,000
Mild 1.00 - 2.5 60,000 - 100,000
Moderate 2.5 - 5.00 100,000 - 200,000
Marked Over 5.00 Over 200,000


Even if the level looks acceptable, it may not be sufficient to cope with the demand from the body for red blood cells. In particular, since reticulocytes are commonly expressed in percentage terms, they need to be adjusted to allow for the degree of anaemia, i.e. 1% reticulocytes in a cat with a PCV of 20% is twice as many as 1% reticulocytes in a cat with a PCV of 10%.


Let's assume your cat's PCV is 18% and the measured reticulocyte count is 0.75%. You multiply the PCV by the measured count, then divide the result by the normal PCV level (35%). In this instance, you would get an adjusted result of 0.39%, which indicates non-regeneration.


In contrast, if your cat's PCV was 13% and the measured reticulocyte count was 0.75%, your adjusted result would be 0.28. This also indicates non-regeneration, but it is more severe (i.e. the lower the corrected value, the lower the regenerative response).


I know this is complicated, and you're probably stressed enough about your cat's anaemia. Basically, if your cat's PCV or HCT level has been below 20% for five days or longer, ask your vet to do a reticulocyte test and let your vet tell you if the anaemia is regenerative or not. But if your cat is severely ill, you should definitely start treatment with B vitamins immediately, and you may decide to start treatment with an ESA before you get the results of the reticulocytes test or even dispense with this test altogether in the circumstances.


The differential diagnosis of feline anaemia (2006) is a presentation by Dr S Tasker to the World Small Animal Veterinary Association World Congress 2006 which explains more about reticulocytes and anaemia.

Cornell University College of Veterinary Medicine provides more information on this complex subject: click on the word Feline on the left of the page for further information, including a table of reticulocyte counts.

Understanding reticulocyte counts in cats (2008) Dr JW Harvey DX Consult 2(1) pp16-17, provides a good overview.

Antech Diagnostics has information on how they run this test.


Red Blood Cells (RBC)

If a cat cannot manufacture sufficient red blood cells, s/he will become anaemic. Unfortunately the lifespan of red blood cells in patients with kidney disease is approximately 50% that of healthy cats, so this is another reason why CKD cats become anaemic.


A low red blood cell count is usually indicative of anaemia. The red blood cells are often a paler colour if MCV is also low.


If the RBC count is high, this may be indicative of dehydration.


Measures of Iron Deficiency

Haemoglobin, the main oxygen-carrying protein of red blood cells, needs iron for its production. Therefore a cat with low iron levels may develop a type of anaemia known as iron-deficiency anaemia. Since iron is present in food, particularly meat, iron deficiency anaemia from lack of iron in the diet is rare in cats. However, cats with inflammation or an infection may have an iron deficiency because the body sequesters (hides away) iron if inflammation or infection are present. Iron metabolism in pathogenic bacteria (2000) Ratledge C & Dover LG Annual Review of Microbiology 54 pp881-941 explains more about this.


Cats with sudden blood loss, such as from gastro-intestinal bleeding, may also have an iron deficiency. Cats who are having blood taken frequently (once a week or more) for testing may also be at risk of anaemia if a lot of blood is being taken each time.


Cats with iron deficiency anaemia are usually treated with an iron supplement.


Mean Corpuscular Volume or Mean Cell Volume (MCV)

This is a measure of red blood cell size. If your cat has a low MCV (known as microcytosis), this means the red blood cells are smaller than usual, which may indicate a lack of iron. Possible causes of a lack of iron include gastro-intestinal bleeding or chronic liver disease.


Cornell University College of Veterinary Medicine has more information about MCV.


If your cat's MCV is low, you need to know if the cause is a lack of iron before rushing to give an iron supplement. There are three main tests for iron deficiency, though these can be hard to obtain and are not always reliable.


If your cat's MCV is high, the red blood cells are larger than normal. Newly formed red blood cells are usually larger than normal, so this might be a sign that your cat's anaemia is regenerative. High MCV may occasionally may be seen in cats with hyperthyroidism. High MCV levels may also indicate a lack of Vitamin B12 and folic acid (Vitamin B9) - in these cases, the anaemia is most probably non-regenerative.



  • This measures the amount of iron circulating in the blood.

  • This test should be a fasting test, and iron supplements should not be given for 24 hours before the test.

  • If serum iron is low but ferritin (see below) is normal, the cat may have an infection.

  • Serum iron is normally high if a cat has had a number of blood transfusions. These cats should not be given iron supplements.

  • Cornell University College of Veterinary Medicine has some information about iron.


  • This is a measurement of how much iron is stored in the body in soluble form.

  • Low levels can indicate iron deficiency or chronic inflammation.

  • High levels can indicate iron overload.

  • Cornell University College of Veterinary Medicine has some information about ferritin.

TIBC (Total Iron Binding Capacity)

  • This measures the capacity of the blood to transfer iron to the cells where it is needed.

  • If a cat has an iron deficiency, serum iron will be low, but TIBC will be elevated.

  • If a cat is suffering from an iron overload, iron levels will be high and TIBC will be low or normal.

  • Cornell University College of Veterinary Medicine has some information about TIBC.

If a cat has anaemia of chronic disease (e.g. caused by Inflammatory Bowel Disease), the serum iron will be low, TIBC will tend to be low, but ferritin will be high.


MCHC (Mean Cell Haemoglobin Concentration)

If your vet cannot check ferritin or TIBC, you can be guided by the MCHC instead. As the name suggests, this measures the concentration of haemoglobin in a red blood cell. You can calculate MCHC as long as you have a measurement for haemoglobin (Hb):


MCHC = (Hb divided by PCV or HCT) x 100


If this is normal (around 33%), you probably do not need to worry. If MCHC and MCV are both low, this may indicate iron deficiency anaemia.


Cornell University College of Veterinary Medicine has some information about MCHC.


Treatments                                                                                                            Back to Page Index

There are various treatments for anaemia, and which one you should use depends upon the cause and the severity of the anaemia. Your vet can advise you which is the most appropriate treatment, though you need to be aware that not all vets have used ESAs such as Procrit or Aranesp or know much about them.


If you know the cause of your cat's anaemia, getting that under control should resolve the problem e.g. if your cat has an infection, once it has gone your cat's anaemia should gradually improve.


Even if you don't know the precise cause, mild anaemia can often be improved with simple treatments such as Vitamin B and sometimes iron (iron is not always appropriate, see below). I recommend giving every CKD cat a Vitamin B supplement, because it can be very helpful and is not toxic since any excess is simply peed out.


Correcting Vitamin B Deficiencies 

A lack of certain B Vitamins, such as Vitamin B12 or Folic Acid (Vitamin B9), can cause non-regenerative anaemia. Generally speaking, all CKD cats with mild to moderate anaemia (PCV or HCT below 30% but above 20%) would probably benefit from a vitamin B supplement. 


I would also give a supplement to a cat with more severe anaemia. You will probably still have to consider other treatments such as an ESA, but in some cases a B vitamin supplement may be sufficient to help your cat.


Your vet can prescribe a suitable Vitamin B supplement, or give your cat Vitamin B injections. Be careful about using multivitamin supplements because they may contain other vitamins such as A and D which are not usually suitable for CKD cats. 


Because B vitamin supplementation is so important for CKD cats, it has its own page here.


Vitamin E

The Winn Feline Foundation gave a grant to Colorado State University in 2010 for a study into "Vitamin E as a Novel Treatment for the Anemia of Feline Chronic Renal Failure." Vitamin E was selected for its antioxidant properties. As at October 2011 the study is still ongoing, but I will report on its findings once it is completed. In the meantime, please do not supplement Vitamin E without your vet's approval.


It is possible to participate in this study if you meet certain criteria, see Research Participation Opportunities.


Iron Supplements: Overview

As explained above, you should only use iron supplements when tests indicate that they are required, so be guided by your vet regarding when and if to start one. Pet Education discusses iron requirements in cats.


Iron supplements can be given orally (usually daily) or a monthly injection can be given, though the injection is into muscle so it can be painful. Iron supplements may cause constipation or stomach upsets. In theory iron should be taken on an empty stomach, but taking it with food may reduce the risk of stomach upsets.


Phosphorus binders containing aluminium hydroxide should ideally be given separately from iron, because the binders may reduce the absorption of the iron. Drugstore has some information about this interaction.


Bacteria thrive on iron. Therefore if a cat has an infection or inflammation, the cat's body will sequester iron (i.e. iron is stored away rather than released into the bloodstream) so as not to feed the bacteria. This means that the cat's body will be unable to use any iron you give. In most cases, the infection or inflammation will only be short-term, and the cat will be able to manage without a supplement. Sequestering does not happen with heme iron (iron from meat), so if your cat definitely needs iron, you could ask your vet about feeding a small amount of chicken liver (one or two tablespoons, once or twice a week). Most cats seem to like liver, and although you should not give liver too often or in large quantities because it contains very high levels of Vitamin A and is also high in phosphorus, the above dosage should be safe, but do discuss with your vet.


Cats who begin treatment with an ESA such as Epogen or Aranesp are usually given iron supplements because the cat's body is busily making new red blood cells, so there is an increased demand for iron to assist with this process. If your cat does not respond to an ESA and you are giving the ESA in sufficient quantities and frequently enough (see Erythropoiesis Stimulating Agents), consider the possibility of low iron levels and check for iron deficiency as explained above


Pet Place has some information about iron toxicity.

Managing anemia in patients with chronic kidney disease (2011) Chalhoub S, Langston CE Veterinary Medicine May 2011 has information about when and how to supplement iron when using ESAs.

Use of erythropoietin and calcitriol for chronic renal failure in dogs and cats (2005) Sanderson S Presentation to the World Small Animal Veterinary Association World Congress 2005 explains more about when and how to supplement iron when using ESAs.


Iron Supplements: Your Choices


Injectible: Iron Dextran

Iron dextran is an injectible form of iron. It may be prescribed by your vet because it works quickly and does not cause gastro-intestinal upsets, whereas oral iron may cause an upset stomach and absorption can be a bit hit and miss. Iron dextran also lasts about a month, so there is no need to medicate your cat each day.


The downsides are that it may cause a severe allergic reaction in a small number of cats, and the fact that it lasts about a month can be a negative if the cat does not really need supplemental iron.


If you do use iron dextran, your vet will usually give the shot. You should not use oral iron supplements if a shot has been given.


Drugs has some information about iron dextran.


Oral Iron Supplements



Fer-In-Sol is an infant iron supplement containing ferrous sulphate which may be suitable for some cats. The formulation changed recently so the dropper is marked 0.5ml to provide 7.5mg of iron. A 10lb (4.5kg) cat might receive 5mg of iron a day, so the dosage appears to be 0.33 ml once a day; but do check with your vet about dosage, since this is not a veterinary product. Please note this is only iron, so you may need to supplement B Vitamins separately.



We used an iron supplement from Boots the Chemist called Sytron, which contained 27.5mg of iron per 5ml. Your vet can suggest an alternative brand and give advice on dosage.


Spatone is an interesting possibility. This is a spa water which contains naturally occurring iron. The manufacturers claim that using iron in this way makes it more easily absorbed into the body. The manufacturers know of several dogs taking the product without problems, and one Tanya's CKD Support Group member is now using this product on her cat with her vet's approval.


Spatone is sold in sachets, and a box of 28 sachets costs £6.90, though discounts may be available for four boxes of 28 sachets or more. It is available in Boots. The product does taste of iron, so the manufacturers recommend giving the product in additional water. They suggest using 0.5-1.5 sachets per day in cats, which would be the equivalent of 100mg of ferrous sulphate.


Apparently Spatone is also available in Canada.


Combined Supplements Containing Iron

It can be easier to use a combined product. There are two popular combined iron and vitamin B products on Tanya's Support Group:

There are also combined iron, vitamin B and potassium supplements available:


NutriVed B Complex Plus Iron

NutriVed B Complex Plus Iron contains B vitamins and iron. 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

  • Thriving Pets sells NutriVed for US$9.95. Handling costs US$2, shipping charges are determined by weight. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$55.

  • 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 giving 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$9.95. Handling costs US$2, shipping charges are determined by weight. It will ship to selected clients in selected countries. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$55.

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-tinic at US$6.85 for 4 oz, with free shipping for orders over US$50. Search for item 40168.

  • Thriving Pets sells Pet-tinic for US$12.95 for 4 oz. Handling costs US$2, shipping charges are determined by weight. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$55.

Pet-tinic Sources: UK

  • KV Vet Supply will ship Pet-tinic to the UK or Canada. It costs US$6.85 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.

  • Thriving Pets sells Pet-tinic for US$12.95 for 4 oz. Handling costs US$2, shipping charges are determined by weight. It will ship to selected clients in selected countries. If you enter the word "tanya" (without the ") in the promotional code box, you will receive a 10% discount on orders over US$55.

Iron and Vitamin B with Potassium (Kaminox or Amino B & K)                                           

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. 


In the USA there are two products available containing potassium and B vitamins, Renal K+ made by Vetoquinol, and Amino B & K from Emerson Ecologics. Amino B & K also contains some iron but Renal K+ does not appear to.


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.


Iron and Vitamin B with Potassium: UK

  • Vet UK sells Kaminox for £29.49 for 120ml, with free UK shipping.


Anabolic Steroids

If anaemia is not too severe, anabolic steroids may help improve anaemia or at least slow down its progression. They may also be beneficial for CKD cats with muscle wasting and as an appetite stimulant. Steroids may damage the liver so your vet will need to monitor your cat's liver values. 


There is more information about steroids on the Treatments page.


Erythropoiesis Stimulating Agents (ESAs)                                               

Another possible treatment for anaemia is an erythropoiesis stimulating agent. These treatments are sold under the trade names of Epogen, Eprex, Procrit, Aranesp or NeoRecormon.  This is quite a complex subject, so it has its own page here.


Blood Transfusions                                                                                             Back to Page Index



Cats can receive blood transfusions just like humans. They are sometimes used in severely anaemic CKD cats who need support whilst waiting for an ESA such as Epogen to take effect, or in cats who have lost a lot of blood suddenly (e.g. a road accident or severe gastro-intestinal bleeding) or who have developed the antibody reaction to ESAs. As a rough guide, it is worth considering a transfusion for a cat with a PCV or HCT below 13%, especially if the cat seems to be struggling to cope with the anaemia, or if the PCV or HCT has fallen very suddenly, which gives the cat's body less time to adapt to the anaemia.


A blood transfusion is not a major procedure, and normally the cat only needs to stay at the vet's for 3-4 hours; just long enough to receive the blood (which is given slowly) and to be monitored for a possible reaction (occasionally diarrhoea and nausea are seen with a poorly matched transfusion). Ideally the cat's PCV or HCT will double, though this does not always happen. Nevertheless, most cats feel and act much better immediately following their transfusion, and with a well-matched donor (see below), the effects may last for 4-5 weeks, although it will be less if the cat is experiencing ongoing blood loss (e.g. gastro-intestinal bleeding).


If your cat has a blood transfusion, you should not give him/her any supplements containing iron because there is a risk of iron toxicity.


The Merck Veterinary Manual has an overview of blood transfusions. It explains how to calculate what level of PCV or HCT you can expect to see after a well-matched transfusion.

Transfusion medicine -do's and don'ts (2010) is a presentation by Dr U Giger to the 35th World Small Animal Veterinary Association 2010 World Congress.


Feline Blood Groups

Cats have fewer known blood groups than humans:

  • A (the most common, particularly in non-pedigrees)

  • B (relatively common in pedigree cats); and

  • AB (rare)

However, unlike humans, cats do not have a universal donor (in humans, if blood type is not yet known, the person can be given the universal blood type, O negative, to tide them over with no adverse effects), although type AB cats can receive blood from either type A or B donors.


In an emergency case such as a cat who is going to die anyway without the transfusion (e.g. after a traffic accident), a vet may do a transfusion without checking the blood types, and in the case of the average cat, this will often not result in disaster the first time it is done, though it is far riskier for pedigree cats who tend to have the rarer blood groups.  If time permits (as it usually does for CKD cats), it is far safer to type or cross-match a  cat's blood type before a transfusion. Unfortunately, blood typing may not be accurate in cats with a PCV or HCT below 10%.


Whole blood transfusions in 91 cats: a clinical evaluation (2004) Weingart C, Giger U, Kohn B Journal of Feline Medicine and Surgery 6 (3) pp139-148 concludes that "with proper donor selection and appropriate compatibility screening, blood transfusions are well tolerated, appear effective, and may increase chances of survival."

Feline blood typing and transfusion - a practical approach (2006) Kohn B & Weingart C Presentation to the 31st World Small Animal Veterinary Association World Congress has a good overview of blood transfusions.

University of Illinois has general information about feline blood transfusions.

Cornell University College of Veterinary Medicine has information on feline blood groups and transfusions generally: use the links at top left.

Idiosyncrasies in feline blood transfusions (2012) Schumacher D Veterinary Technician May 2012 ppE1-5 has an overview of blood transfusions and possible problems.

International Cat Care has a table showing the frequency of the different blood groups in various breeds.

Feline anaemias - therapeutic options and transfusion therapy (2002) is a paper presented by Urs Giger to the World Small Animal Veterinary Association World Congress.


Typing and Cross-Matching

Typing means that you find a cat with the same blood group as your cat, and obtain blood from that cat. For example, if your cat has type B blood, then you find another cat with type B blood to act as the donor.


Cross-matching means that further tests are done to check whether the typed donor cat's blood is compatible with the recipient's blood. This is important because there are further factors within cats' blood, so even if typing has been done, there is still a risk of a reaction if the blood has not been cross-matched, which in severe cases may cause shock and even death. Even if a donor cat's blood has been successfully cross-matched once, it is safest to cross-match it again before using that cat as a donor once again, because the recipient cat may have built up antibodies to the donor cat's blood. 


DMS Laboratories sells kits for vets to type and cross match feline blood themselves.

Colorado State University Diagnostic Laboratory will type feline blood in the USA for US$38.25, and cross-match it for local clients for US$32 (click on Test Schedule, then on Clinical Pathology), though your vet may know of a local laboratory which can do this. If you cross-match, you do not need to type the blood as well, that will be done as part of the cross-matching.

NationWide Laboratories (UK) has an interesting article about feline blood typing, and can type blood for you with results available the same day.

The University of Bristol offers feline blood typing for £23 and cross matching for £27, with both tests being turned around on the day of receipt. Click on Submission Forms, Immunology for the application form and on Information and Services, Pathology Charges for current prices.


Obtaining Blood

The main problem with blood transfusions tends to be finding a donor cat at all, particularly at short notice. You may be able to use another cat in your family as the donor, or your vet may be able to find a cat (many vets occasionally offer their own cats as donors). 


When choosing a donor, naturally you want one who has been tested and found to be free of infectious diseases such as feline leukaemia. The donor also has to be healthy and big enough to give blood without any adverse effects for himself/herself - usually a donor must be at least 9-10 lb in weight. In addition, a donor usually cannot give blood more often than every two months. If the donor cat meets these criteria, there are no side effects for him/her, and it does not appear to be any more stressful than a standard vet visit for either the donor or the recipient.


Alternatively, there are a limited number of feline blood banks which may be able to help, including: 



Animal Blood Resources International also stocks feline blood.

The Veterinarians' Blood Bank stocks feline blood.

Blue Ridge Veterinary Blood Bank is located in Virginia. It does not stock feline blood but can provide it upon request.



Cat Blood Donors in the UK does not stock blood itself, but maintains a database of donor cats which British vets can access free of charge.



The Canadian Animal Blood Bank does not stock feline blood, but will provide advice and certain supplies on obtaining blood safely. The US blood banks mentioned above may be able to ship feline blood to Canada if required.


Canine Blood

If you are unable to obtain feline blood, and it is an emergency, Xenotransfusion with canine blood in the feline species: review of the literature (2013) Bovens C & Gruffydd-Jones T Journal of Feline Medicine and Surgery 15(2) pp62-7 found that using canine blood may buy you up to four days, but it can only be used once because subsequent use will cause anaphylactic shock, which often kills the cat.


Oxyglobin (Synthetic Blood)

Oxyglobin is a synthetic blood product containing haemoglobin, which is approved for use in dogs as a single treatment only. It does not contain red blood cells, so its effects are short-lived (a couple of days). Since it is designed for dogs rather than cats, there is a risk of volume overload when using Oxyglobin (only 4% of a cat's body weight is accounted for by blood volume, whereas in dogs the level is 7%). It is therefore better to use feline blood for a transfusion, but in case of urgent need, a one-off use of Oxyglobin might help buy you some time while you search for a suitable blood donor.


OPK Biotech - the manufacturer's website.

Veterinary Practice News explains how Oxyglobin can buy time while you are waiting for a delivery of fresh blood.

Clinical use of a haemoglobin-based oxygen carrying solution (Oxyglobin) in 48 cats (2002-2006) (2008) Weingart C, Kohn B Journal of Feline Medicine & Surgery 10(5) pp431-8 found that Oxyglobin worked well at improving anaemia in anaemic cats but was risky for cats suffering from heart disease.


Antibody Formation to Blood Transfusions

Unfortunately, as with ESAs, a cat may eventually develop a reaction to blood transfusions, and the odds seem to increase with each transfusion. The limit is thought to be roughly five transfusions per cat. At the beginning, each transfusion lasts around five weeks, but this time tends to reduce with each transfusion until eventually a transfusion may only buy the cat a few days. However, there have been a few members of Tanya's CKD Support Group whose cats have lived for much longer because of transfusions. One cat managed nine months on transfusions after developing the antibody reaction to Epogen, and he eventually only needed transfusions about once a month. Another cat had forty transfusions over a period of more than two years with no problems (the exact cause of this cat's anaemia is unknown). He was given an antihistamine before each transfusion to minimise the risk.


If your cat has severe non-regenerative anaemia because of CKD but is not yet critical (in which case your cat might need a transfusion to tide him/her over until the ESA kicks in), I would recommend using ESAs instead of transfusions, keeping transfusions in reserve in case your cat does develop a reaction to ESAs, at which time you could probably buy your cat some more time by using transfusions. This should be safe because developing a reaction to an ESA such as Epogen does not increase the chances of your cat developing a reaction to donated blood. Cats with the antibody reaction to ESAs may need transfusions fairly frequently to start with while the body is dealing with the ESA antibodies, but the period between transfusions may lengthen over time as the antibodies go away (this takes approximately 4-8 weeks, though may take longer in some cats).


Making your Cat Comfortable                                                                           Back to Page Index


Minimising Effort

It is a real effort for anaemic cats to do simple things like jumping onto beds or climbing stairs; Thomas did not use the stairs for three weeks and simply stayed upstairs until he became stronger. It is a kindness to your cat if you can minimise the effort required to do simple tasks like visiting the litter tray. If you have a litter tray downstairs but your cat prefers to stay upstairs, place an extra litter tray upstairs not too far from your cat's favourite spot (but away from food and water). If the litter tray has a high edge which is hard for your cat to climb over, you may need to provide a litter tray with a lower edge until your cat has regained some strength.  


Similarly, provide food and water near to your cat's favourite place - he or she will be more inclined to eat if it doesn't involve an epic trek to the food bowl. 


Also try to reduce the amount of climbing your cat has to do: Thomas decided his favourite place was the bed, so we arranged a series of footstools, piano stools and so on in order to create a kind of stairway up to the bed.  We also placed Thomas's food bowls on the bed and his water bowl on the bedside table so he only had to get down in order to use the litter tray. But do be aware that occasionally a cat may no longer jump and climb because of blindness caused by hypertension.


Pet Planet in the UK sells a number of different ramps and steps.

Drs Foster and Smith sell a number of ramps and steps in the USA.

Cozy Cat Furniture sell a selection of steps in the USA.


Heat Pad

Anaemic cats feel very cold, even in summer. The best treatment we could find, apart from treating the anaemia of course, was a heat pad. This is a small flat heated pad with a fleecy cover - it looks like a little flat cat-sized bed. Thomas had long legs but we found the 12 inches square bed was fine for him because anaemic cats tend to hunch up because they are cold.


Heat pads are designed for people with problems such as arthritis, but are excellent as electric blankets for anaemic cats because you just plug the heat pad into the mains, choose from three temperatures and then the pad stays at the chosen temperature constantly, unlike a hot water bottle. You must of course keep an eye on your cat while he or she is using this since it is electrical equipment, and I would not use one for a cat who is incapable of moving if s/he gets too hot. We never had any problems with overheating, and Thomas found it very comforting when his anaemia was bad, whilst Harpsie loved his when he developed arthritis.


Drs Foster and Smith sell a number of heated beds in the USA.

Litterboy sells a variety of heated beds in the USA - click on Shop by Sub-category and choose Heated Mats, Beds, Sills.

Boots the Chemist in UK sells a heatpad for £20.95 which is similar to the one we used for Thomas when he had anaemia.

Pets at Home sells a non-electric thermal bed for £32.99.




I know this can all seem overwhelming, so here's a short summary:

  • If your cat is anaemic, however severely and whatever the cause, start giving B vitamins immediately. Vitamin 12 in the form of methylcobalamin may be particularly helpful. See Vitamin B for more information.

  • If you can ascertain a cause other than the CKD, treat it - this may be sufficient to get the anaemia under control. For example, anaemic cats with infections should improve a lot once the infection is brought under control. Cats with gastro-intestinal bleeding may need a treatment such as sucralfate. In some cases, treating these other problems may improve the anaemia to such an extent that you will not need to start an ESA just yet.

  • If your cat has an iron deficiency or is about to start an ESA such as Epogen or Aranesp, ask your vet about an iron supplement. Otherwise it is usually better not to use iron supplements, especially not in cats with infections.

  • In cases of mild anaemia (PCV or HCT above 19%), anabolic steroids may help to some degree, though they are not commonly used these days.

  • For severe non-regenerative anaemia (PCV or HCT below 20%) caused by the CKD (because of a lack of the hormone, erythropoietin, which the damaged kidneys can no longer properly produce), you will need to consider the use of a synthetic version of the hormone such as Epogen or Aranesp, especially if your cat is showing symptoms of anaemia. The Erythropoiesis Stimulating Agents page explains more about these treatments in great detail.

  • If your cat's anaemia is extremely severe (PCV or HCT below 13%), then whatever the cause you may need to provide a blood transfusion to keep your cat going and buy you the time to get to the bottom of the problem and start other treatments as appropriate.

Remember: anaemia is almost always treatable, so don't give up hope! Thomas went from being unable to walk downstairs to going outside hunting (yes, I know, not his best characteristic but he had been a stray for years and old habits died hard) once his anaemia was under control. 


Harpsie doing his bit to keep Thomas warm when he had anaemia.



Back to Page Index

This page last updated: 30 November 2013


Links on this page last checked: 20 April 2012






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.


If your cat appears to be in pain or distress, do not waste time on the internet, contact your vet immediately.



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