receives colostrum from the type B queen, the kittens will develop haemolysis as the result of an immune response from consuming incompatible antibodies in the queen ' s colostrum, resulting in anaemia and eventually neonatal death.
Neonatal isoerythrolysis occurs within the first 48 hours of a litter being born and can be a cause of fading kitten syndrome. If neonatal isoerythrolysis is suspected, the kittens should be removed from the queen immediately and will need hand-rearing. In severe cases, kittens that require supportive treatment, but are too small for intravenous access, will require intraosseous blood transfusions from a matched donor, followed by intensive care and monitoring. Umbilical cord blood can be used to determine a kitten ' s blood type at birth, or to perform a cross-match with serum from the queen. Compatible kittens can be immediately placed back with the queen [ 7 ].
Neonatal isoerythrolysis is commonly observed in pedigree breeds but does not seem to affect type B kittens receiving colostrum from a type A queen [ 8 ]. Prevention of this condition is straightforward and can be achieved through blood typing and ensuring that only compatible cats are bred.
If breeders choose to proceed with incompatible blood-group pairings, they should be prepared to hand-rear the neonates or, where possible, arrange fostering with a type A queen to ensure the kittens receive adequate colostrum [ 6 ].
Nursing kittens with neonatal isoerythrolysis is intensive, and success largely depends on the severity of the condition; in most cases these kittens are considered to have a guarded prognosis. If patients survive for 72 hours, they can be reunited with their queen to continue nursing naturally but under continued close observation, and should be weighed regularly so that signs of fading are detected promptly [ 9 ].
There are a number of clinical signs of neonatal isoerythrolysis [ 6, 7 ]. Breeders should be aware of these signs to ensure early intervention:
• Haemoglobinaemia
• Haemoglobinuria
• Anaemia
• Icterus( jaundice)
• Lethargy and weakness
• Respiratory difficulty
• Failure to thrive, inability to nurse
• Tail-tip necrosis
• Sudden death.
Selecting a blood donor
Blood products are widely supplied to veterinary hospitals via Pet Blood Bank UK. However, the pool of feline donors remains considerably smaller than that of canine donors. Furthermore, due to challenges with storing feline blood products, some practices maintain their own feline donor registers, comprising suitable candidates whose owners can be contacted as required when a transfusion is required for a patient [ 10 ].
Frequent blood donation over a short period may predispose donors to complications such as anaemia and cardiovascular instability, and should therefore be avoided to safeguard their health and welfare. It is currently recommended that a minimum inter-donation interval of 3 months is needed for feline donors to allow sufficient time for erythropoiesis [ 7 ].
The amount of blood considered safe to be collected from a donor cat is 20 % of their blood volume every 4 weeks. The circulating blood volume of cats is 50 – 60 ml / kg, so a 5 kg cat has approximately 250 – 300 ml of circulating blood and can donate 50 – 60 ml of blood( 10 – 12 ml / kg) on each occasion [ 11 ].
In the UK, established criteria for prospective donors are used to identify suitable candidates, while minimising potential health risks to the donor [ 5, 7, 10 ]. It should be noted that these criteria may differ in other countries:
• No current or previous medical health conditions
• Between 1 and 9 years old
• > 4 kg bodyweight
• Up to date with vaccines
• Up to date with flea and worm treatments
• Feline leukaemia virus( FeLV) negative
• Feline immunodeficiency virus( FIV) negative
• Has not travelled outside the UK
• No history of receiving transfusions
• No abnormalities on echocardiography
• Ideally has a calm temperament and is used to being handled
• Preferably an indoor cat but not essential.
Types of blood products
There are various blood products that can be used in a variety of scenarios to support cardiovascular function. Feline fresh whole blood( FWB) is the most commonly used product in feline transfusion medicine, due to limited availability and storage of feline blood.
30 Veterinary Nursing Journal