There can be few events as distressing for a cat breeder as watching a litter of kittens fade and die within the first 48 hours of life. Yet this has been the experience of many breeders until it was recognised that the reason was that the queen had a different blood type from her kittens and was killing them, unintentionally, when they suckled her milk. It is particularly a problem in the British Shorthair, Rex, and Turkish Van breeds as almost 60% are blood group B, but it can affect almost any breed of cat, including the dear old domestic moggy.

Knowing your cat’s blood group can save their and their kittens’ lives.

[This page is written for cat lovers, veterinary students, and veterinary nurses. I apologise to veterinarians for the lack of interesting technical detail, and highly recommend the excellent review by Bighignoli et al in John August's textbook Consultations in Feline Internal Medicine, Volume 6.]

What are feline blood groups or blood types?

What is neonatal isoerythrolysis?

 Prevention of neonatal isoerythrolysis

1.

Typing the queen and tom before mating

 

What happens when you mate a blood group B queen to a blood group A  tom?

 

What happens when you mate two blood group B cats together?

 

What happens when you mate two blood group A cats together?

 

The outcome of trial matings to establish whether a blood group A tom carries blood group B genes

 

The outcome of trial matings to establish whether a blood group A queen carries blood group B genes. (What happens when you mate a blood group B tom to a  blood group A queen?)

 

What percentage of my breed is blood group B?

   

2.

Blood group testing the kittens at birth

3.

Prevent at-risk kittens from suckling their queens for 16 hours

       

Register of stud and queen cats of known blood group

To send a sample for blood typing

Blood group tests explained

 

What are feline blood groups or blood types?
Our blood consists of red blood cells, white blood cells and plasma. The red cells carry oxygen and their well-being is essential for life. Red blood cells, like most other components of the body, are made of protein, and proteins can be recognised and destroyed by the body’s immune system. The cat has essentially two blood groups: A and B (although there is a third, very rare, group, AB, which is a combination of the two). The red blood cell proteins are A in one group, B in the other (see figure 1). In fact, the proteins on the surface of type A and B red blood cells are only slightly different, but of course the immune system can detect the difference.  


 

As you know, if you have a blood transfusion, it is essential to get the right type of blood, a transfusion of the wrong blood type could kill you – it is no different for cats. The immune system of the cat or person receiving the blood transfusion reacts to the blood which it sees as alien, and the consequences can be fatal.

    

What is neonatal isoerythrolysis?
A cause of fading kittens in pedigree cats is neonatal isoerythrolysis, where kittens have a different blood type from their queen, and, on suckling her milk, receive antibodies against their own red blood cells. The antibodies cause destruction of the kittens red blood cells which leads to jaundice (see figures 2 and 3), brown urine, and rapid death. In less severe cases, the tail tip drops off.  

Samples of blood from the kittens and queen can be blood typed to confirm the diagnosis.  

 
Figure 2.  A litter of kittens with neonatal isoerythrolysis.  Note the
jaundiced (yellow) noses and bloody tip of the tail of the white kitten. 


Figure 3.The paw of a kitten with neonatal isoerythrolysis – note how jaundiced (yellow) it looks.
(Photography by Allan May)

 

Prevention of neonatal isoerythrolysis

  

1.

Typing the queen and tom before mating

 

What happens when you mate a blood group B queen to a blood group A  tom?

 

What happens when you mate two blood group B cats together?

 

What happens when you mate two blood group A cats together?

 

The outcome of trial matings to establish whether a blood group A tom carries blood group B genes

 

The outcome of trial matings to establish whether a blood group A queen carries blood group B genes. (What happens when you mate a blood group B tom to a  blood group A queen?)

 

What percentage of my breed is blood group B?

2.

Blood group testing the kittens at birth

3.

Prevent at-risk kittens from suckling their queens for 16 hours

 

1. Typing the queen and tom before mating
Prevention involves blood typing the queen and any prospective tom that she may be mated with. Cats get one gene for blood type from their mother (in the egg) and one from their father (in the sperm). The genes for blood type A are dominant to the genes for blood type B, which means that a cat with a mixture of genes – Ab (note that this is different from the third, rare, blood group AB) – will have blood type A  A blood group B queen can give birth to a blood type A kitten if mated to a blood type A tom carrying the genes for blood type B, (as in figure 4 and table 1). This is the situation in which neonatal isoerythrolysis is most likely to occur.

 


Figure 4 - How two type A cats can give birth to a type B kitten

Table 1 - What happens when you mate a blood group B queen to a blood group A tom cat depends on whether his genes are purely A or a mixture of A and B. The kitten’s genes are represented by the shaded boxes. The biggest risk of neonatal isoerythrolysis is when kittens with blood type A are born to blood type B queens.

 

Tom's genes

           Queen's genes

b

b

 A

Ab

Ab

 A

Ab

Ab

 

 

 

Tom's genes

Queen's genes

b

b

 A

Ab

Ab

 b

b

b

In this case all the kittens will be blood group A, but will be carriers of blood group B.

 

In this case, half the kittens will be blood group B (blue shaded boxes) and half will be blood group A, but carriers of blood group B genes.


Cats with blood type B are recessive (i.e. they all have two b genes, genotype bb) and can be safely mated to other blood type B cats - all the kittens will be blood type B (table 2.) and neonatal isoerythrolysis will not occur.

KEY

Gene Type

Blood Group

AA

 A

bb

 B

Ab

 A

 

Table 2. - What happens when you mate two blood group B cats together.

Table 2                   

    Tom's
     genes

       Queen's  genes

        b

    b

        b

        bb

    bb

        b

        bb

    bb

 

All of the kittens will be blood group B (shaded area represents kittens of such a mating) and there will be no risk of neonatal isoerythrolysis.

 

 Table 3. - What happens when you mate two cats with blood type A together.

  

Tom's genes

Queen's genes

A

A

A

AA

AA

A

AA

AA


In the simplest scenario, all the genes of the tom and queen code for blood type A and all the kittens will be blood group A (see table above). However, since blood group A is dominant to blood group B, one or both cats could be carrying the gene for blood group B, as shown below:

 

                                                        

    Tom's
    genes

      Queen's  genes

        A

    b         

        A

        AA

    Ab

        A

        AA

    A

                        Table 3a

    Tom's     genes

      Queen's  genes

        A

    b

       A

        AA

    Ab

        b

        Ab

    bb

 

In the first example above, the tom has both versions of his gene (i.e. the one from his mother and the one from his father) coding for blood group A, therefore all his kittens will be blood type A. Half of his kittens will carry the gene for blood group B, which they have gotten from their queen. None of the kittens will be at risk of neonatal isoerythrolysis as they all have the same blood group as their queen.

In the second table both blood group A cats are carriers of the gene for blood group B. As you can see, one quarter of the kittens born to this pair will be blood group B (shaded box). Queens with blood group A have less anti-type B antibody than blood group B queens have anti-group A antibody, so the type B kittens of this mating might survive. However, if the mating is repeated, the queen will build up anti-B antibody and eventually one fourth of her kittens could die of neonatal isoerythrolysis.

The only way to establish the genotype of a blood type A cat is by trial mating with a type B cat or by submitting a DNA sample to a specialised veterinary laboratory which can genotype cats' blood groups.

 

Table 4.- The outcome of trial matings to establish whether a blood group A tom carries blood group B genes.

What happens when you mate a blood group A tom who is not a type B carrier to a blood group B queen.

  

                              

What happens when you mate a blood group A tom who is a type B carrier to a blood group b queen.
 

    Tom's
    genes

      Queen's  genes

        b

    b         

        A

        Ab

    Ab

        A

        Ab

    Ab

 

    Tom's     genes

      Queen's  genes

       b

    b

       A

        Ab

    Ab

        b

        bb

    bb

All the kittens of this mating will be blood type A and will be at severe risk of neonatal isoerythrolysis.  

 

 

Half of the kittens are blood type A, and half are blood group B. Since the queen is blood type B, the type A kittens are at risk of neonatal isoerythrolysis. The blood group B kittens are safe.

 

 

Table 5. - The outcome of trial matings to establish whether a blood group A queen carries blood group B genes.

What happens when you mate a blood group A queen who is not a type B carrier to a blood group B tom..

  

                              

What happens when you mate a blood group A queen who is a type B carrier to a blood group B tom..
 

    Tom's
    genes

      Queen's  genes

        A

   A         

        b

        Ab

    Ab

        b

        Ab

    Ab

 

    Tom's     genes

      Queen's  genes

      A

    b

       b

        Ab

    bb

        b

        Ab

    bb

All the kittens of this mating will be blood type A and have no risk of neonatal isoerythrolysis, being the same group as their mother. 

 

 

Half of the kittens are blood type A, and half are blood group B. Since the queen is blood type A, the type A kittens are at no risk, but the blood group B kittens are at slight risk. However, queens with blood group A have less anti-type B antibody than blood group B queens have anti-group A antibody, so the type B kittens of a first or even second mating of this pair might survive.   

 

 

 

Does Neonatal Isoerythrolysis occur in my breed?

There have now been many studies looking at the prevalence of blood groups A, B and type AB in various feline populations. These studies have been reviewed by Silvestre-Ferreira & Pastor in 2010, and by Bighignoli et al, also in 2010 (see table 6). There would appear to be some geographic variation, as well as breed variation, but it has to be borne in mind that how the blood group was assessed can affect the results of the study - for example Barrs et al found that 16 of 60 Abysinnian and Somali cats with blood group A seemed to falsely read blood group AB on the card system because their blood formed tiny clots which was easily mistaken for agglutination in the test.
Type AB is very rare.

Remember that some breeds are relatively uncommon and not many cats have yet been tested, so that the figures given in this table are based on a small sample size and may not be wholly accurate. If you have had any kitten deaths which could be due to neonatal isoerythrolysis, have your queen tested no matter what breed she is.

Table 6.  Blood type B frequencies in various feline breeds: breeds without type B cats are safe from developing neonatal isoerythrolysis.  

These figures are mainly based on Bighignoli et al, 2010, and from a study by myself, while at the University of Glasgow Veterinary Diagnostic Laboratory (my own figures are [in square brackets]), that of Knottenbelt et al, 1991 (marked with a K) and that of Callan & Giger (marked CG).

Breed

 Type B %

Type AB %

Total no. of cats tested

Abysinnian

13.5- 20

230, 194

Asian

[0]

 

[1]

Bengal

0

50 K

8 K

Birman

17.6 - [22]

 0

216 [69]

British Shorthair

[53], 59, 59, 46, 29, 33

[0], 1.6, 0, 0, 0

[128], 121, 85, 33, 35, 30

Burmese

[0], 3, 0

[0], 3, 0  

[16], 30, 25

Chartreux (Kartauser) 18.5 3.7 27

Chinchilla

[0]

 

[1]

Cornish Rex

20-30 CG

 

 

Devon Rex

[54], 50, 43, 54

[7], 0, 0, 1.4

[28], 288, 100, 71

Domestic shorthair

8

2

48

Domestic longhair

7 CG

14 K

14 K

Exotic Shorthair

20-30 CG

 

 

Himalayan

20

35 

Japanese Bobtail

10-20% CG

 

 

Maine Coon

4

25

Manx

[0]

 [0]

[3]

Norwegian Forest

<5% CG

 

 

Ocicat

0% CG

 

 

Oriental shorthair

0% CG

 

 

Persian

12 K, 10, 24, 8, 4, 3

0 K, 0, 0, 1, 0, 0  

17 K, 230, 170, 157, 56, 38

Ragdoll [8], 8 [8], 19 [24], 36

Scottish Fold

[0], 15

[0], 0  

[1], 27

Siamese

[0], 0, 0, 4

[0], 0, 0, 0  

[7], 99, 46, 26

Somali

22

0

27

Sphinx

10-20%

 

[3]

Tonkinese

0

0

31

Turkish Angora 46 0 28

Turkish Van

60

85

 
 

2. Blood group testing the kittens at birth
A drop of blood from the umbilicus of the newborn kitten can be used to blood type the kitten to assess whether it is at risk from suckling. Clearly the blood type of the queen must also be determined. It is safe for a kitten to suckle a queen of the same blood group, but if the kitten's and queen's blood types differ, you may want to prevent the kitten from suckling their queen for the first 16 hours of life.

3. Prevent at-risk kittens from suckling their queens for 16 hours
The gut of the newborn kitten only remains permeable to antibodies in colostrum for the first 16 hours of life, after which time it is quite safe for the kitten to suckle its mother, even though she is a different blood type.  

 

To send a sample for blood typing

Blood group tests explained

There are two options when you decide to establish the blood group of a cat:

1. You can test the cat's blood to establish the group (by submitting an EDTA sample to a veterinary laboratory or using a blood typing in-house card test.)

2. You can send a buccal (cheek) swab to the University of California, Davis, USA, or to Langford, Bristol Veterinary School in the UK, for genetic testing.

1. Blood typing card

The advantages of using a blood typing card is that you determine the actual blood group of the cat and it is rapid - can be performed in a matter of minutes. This test is ideal when you are performing a blood transfusion, or typing a newly-born kitten to know whether it's safe to allow him to suckle his queen. The cards tell you whether the cat's blood group is A, B or AB (though a word of caution - Barrs et al found that 16 of 60 cats with blood group A seemed to falsely read blood group AB on the card system because of microscopic rouleaux formation which only disappeared in 4 samples by diluting the sample in saline). The card I use is the RapidVet-H test made by the Italian company Agrolabo. The slight drawback of the card system is that if the cat is blood group A, you cannot determine whether or not he or she is a carrier of the B gene (i.e. Ab). Obviously if the cat is blood group B, you know that genetically he is bb.

You can also send an EDTA sample to Veterinary Diagnostic Services at the University of Glasgow Veterinary School, Scotland, for blood typing.

There is also an immunochromatographic blood typing in-house test called RapidVet-H IC Feline.

2. Genetic testing for blood type

At time of writing, tests have to be sent off to a specialised laboratory to determine the genetic blood type of a cat. The advantages of this test are that no blood sample has to be taken - a cheek swab suffices - and it can be used to determine whether a blood group A cat is a carrier of the b gene (and thus risks producing blood group B kittens). A disadvantage is that this test does not discriminate between a cat with blood group A and those with the rare AB group.

You can send a buccal (cheek) swab to the University of California, Davis, USA, or to Langford, Bristol Veterinary School in the UK, for genetic testing.

This is a film of a buccal swab being taken:

 


Further reading

To me, the review by Bighignoli et al, 2010, is the most comprehensive in the veterinary literature to date:

Bighignoli B, Owen SD, Froenicke L, Lyons LA. 2010  In: Consultations in Feline Internal Medicine  Vol 6.  Editor: August J.  Saunders Elsevier, 3251 Riverport Lane, St. Louis, MO 63043  628-638 (This book is available from Amazon and other booksellers.)

 

Bighignoli B, Niini T, Grahn RA, Pedersen NC, Millon LV, Polli M, Longeri M, Lyons LA. 2007  Cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) mutations associated with the domestic cat AB blood group.  BMC Genet.   6;8:27.

Barrs VR, Giger U, Wilson B, Chan CT, Lingard AE, Tran L, Seng A, Canfield PJ, Beatty JA. 2009 Erythrocytic pyruvate kinase deficiency and AB blood types in Australian Abyssinian and Somali cats.    Aust Vet J.  87(1):39-44.

Callan, MB, Giger U. 1994 Transfusion medicine. Consultations in feline medicine 2.  Ed. August, JR. 525-532

Casal ML, Giger U. 1997 Colostrum: friend or foe? Feline Advisory Bureau Journal 35 70-72

Gurkan M, Arikan S, Ozaytekin E, Dodurka T. 2005 Titres of alloantibodies against A and B blood types in non-pedigree domestic cats in Turkey: assessing the transfusion reaction risk. J Feline Med Surg. 7(5):301-5.

Knottenbelt CM,Addie DD, Jay MJ, Mackin AJ. 1999 Determination of the prevalence of feline blood types in the UK.   Journal of Small Animal Practice 40 115-118

Silvestre-Ferreira AC, Pastor J. 2010 Feline neonatal isoerythrolysis and the importance of feline blood types.  Vet Med Int.  2010:753726

 

 

Updated 13 July 2012

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