Blood group incompatibility

Overview:

Neonatal Isoerythrolysis (NI) is the result of incompatible blood groups between the mother & her kittens &  is a cause of 'fading kitten syndrome'.

Cats have one of three blood groups, A, B & AB (AB is very uncommon). A being dominant & B recessive. Genes come in pairs (one from the mother, one from the father) & their blood group may be A/A (homozygous), A/b (heterozygous) or b/b (homozygous). Note: Ab (heterozygous) is completely different to the AB blood group. We won't go any further into genetics & inheritance in this article.

Neonatal isoerythrolysis occurs when a kitten is born with type A blood to a queen with type B blood. Unlike other animals, who develop antibodies as a result of previous pregnancies to offspring with the A blood group,  cats have naturally occurring anti-A antibodies, and do not need to have had a prior exposure.

The queens first milk is known as colostrum. Colostrum is produced in the first 48 - 72 hours after birth & provides newborns with essential nutrients & antibodies which protect the kitten from infection. However, in this case the antibodies attach to the kitten's red blood cells, causing their destruction.

What are the signs of neonatal isoerythrolysis?

• Kittens are healthy at birth  but one to two days later their health deteriorates rapidly. Symptoms include;
• Jaundice (yellowing of the mucous membranes)
• Brownish-red urine
• Tail tip necrosis
• Respiratory difficulty
• Cease nursing
• Fail to thrive

How is it diagnosed?

Blood testing of the queen & kitten(s).

How is it treated?

Your veterinarian may perform blood transfusions & provide supportive care. Even with treatment, prognosis is guarded.

Prevention is the best way to address blood type incompatibilities. Avoiding mating a queen with a B blood type with a tom who has an A blood type.

If such a mating does occur, preventing the kittens drinking the colostrum is required. It is always important to know the blood group of the queen prior to mating. With this knowledge, if you know the queen has a type B blood group, and are able to determine the blood type of the kitten(s) prior to it suckling, any kittens with the same blood type as the queen (ie: B type), are  fine to nurse. Any kittens which have type A blood with a type B queen must avoid nursing for the first 3 days. They can either be fostered to a queen who has A blood type, or given kitten milk replacer (KMR) for the first three days. After this, they can be returned to their mother.