Blood type in cats

Blood Type in cats

There are three major blood groups in cats: A, B, and AB. Group A is the most common, but group B is quite common in certain pedigree breeds. Group AB appears to be rare in all breeds. Blood groups are essential as they determine the compatibility of blood.

This is why it is important to test your cats with a genetic panel at a veterinary laboratory.

 

How can neonatal isoerythrolysis be prevented?

As treatment is rarely possible, it’s much more important to prevent this condition from happening in the first place.

It’s more common in pedigree cats, especially where there is a high occurrence of both type A and type B cats within the breed. In these cases, the blood type of the cats used for breeding should always be identified in advance. Several methods can then be employed.

  • Only mate group B queens with group B toms, but sometimes it is impossible
  • Prevent type A kittens from suckling colostrum from a group B queen during the first 24 hours of life. Newborn kittens will need to be blood-typed using blood from the umbilical cord, and Type A and AB kittens need to be removed from the queen. These kittens will need to be bottle-fed  for the first 24 hours (or placed with a type A foster queen that is producing milk), after which, it’s safe to put them back with the queen, as they will no longer have the ability to absorb antibodies

How are affected kittens treated? 

Once the kitten has absorbed the antibodies, it’s tough to treat the problem.

  • If noticed in the first few hours of life, the kitten should be removed from the queen for the remainder of the first 24 hours to prevent further absorption of anti-A antibodies from the colostrum
  • It may be possible to transfuse the kitten. Generally, the problem is recognized too late for this to be helpful, and there are very real, practical difficulties in providing a blood transfusion to a newborn kitten

What to look for in affected kittens 

The kittens will be born normal, but soon after they suckle milk, any group A (or AB) kittens in the litter may begin to show signs of illness.

The severity of the signs varies, likely depending mainly on how much anti-A antibodies the kitten has absorbed. Signs include:

  • Sudden death with no warning signs in some kittens.
  • Most affected kittens will appear to ‘fade’ over a few days – they will stop suckling from the queen, become weak, often appear pale and may become jaundiced (yellow)
  • Affected kittens usually pass red-coloured urine, due to the presence of hemoglobin (released from the breakdown of red blood cells) in the urine
  • Mildly affected kittens may show few signs, but the tip of their tail (and sometimes ears) may gradually die off. This is because the antibodies against the red blood cells may prevent normal circulation to the extremities
  • Some kittens are unaffected, showing no signs of disease

 

 

 

Explanation

 

What are the risks to a cat if blood groups are incompatible? 

Blood transfusions are sometimes necessary in cats and can be life-saving. However, transfusion reactions can pose serious issues. Cats with type A or B blood must receive a donation from a cat of the same blood group, or they risk a potentially life-threatening reaction.

Blood group B cats have high levels of anti-A antibodies in their blood. Antibodies are part of the immune system, which means that if a type B cat receives blood from a type A donor, this could trigger a severe (and potentially fatal) reaction because the immune system would recognize the type A blood as ‘foreign’ and attack it.

Some group A cats also have anti-B antibodies, so they may develop severe reactions if given incompatible blood.

Neonatal isoerythrolysis in Kittens

Any antibodies present in a queen’s (female cat) blood will also be passed into her milk and colostrum (the first milk produced) if she feeds a litter of kittens. These antibodies will help protect the kittens against diseases in the early weeks of life.

While this is very beneficial for the kitten, it can sometimes lead to issues with blood group incompatibilities. If the queen has blood group B, she will naturally have anti-A antibodies. If she mates with a type A tomcat, all kittens will be type AB, and when they feed on the queen’s milk in the first 24 hours of life, they will absorb the anti-A antibodies.

 

The anti-A antibodies will then destroy the kitten’s red blood cells just as if there had been an incompatible blood transfusion. This is a condition called neonatal isoerythrolysis and can be a significant cause of death in young kittens of certain breeds.

 

This disease does not occur in type B kittens born to a type A queen, as type A cats have much lower levels of antibodies against type B blood cells and often no antibodies at all.

Most cats naturally produce antibodies against the blood group they do not possess. Generally, cats with blood group B have strong antibodies against blood group A antigens, while cats with blood group A have weaker anti-B antibodies.

 A mating between a female with blood group B (alleles b/b) and a male with blood group A (alleles A/A, A/a, or A/b) is highly likely to cause neonatal isoerythrolysis in any kittens of blood group A.

In fact, with the initial feeding of colostrum (first milk), the mother passes a large amount of antibodies to her kittens, including anti-A antibodies. These anti-A antibodies in blood group A kittens will attack and destroy their red blood cells, leading to a condition called neonatal isoerythrolysis. This phenomenon is similar to our Rh (Rhesus) system, although the antigens and antibodies involved are different.

This isoerythrolysis reaction can be fatal in kittens of blood group A, so it is not advisable to breed females of blood group B (gene alleles b/b) unless they are mated with a male of blood group B. Conversely, there is no risk in mating a female of blood group A with a male of blood group B since, as mentioned above, the antibodies against the antigens of blood group B are present at a low level in the blood.

 

 

 

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