Leucogen (purified p45 FeLV-envelope antigen) - QI06AA01

Updated on site: 09-Feb-2018

Medication name: Leucogen
Substance: purified p45 FeLV-envelope antigen
Manufacturer: Virbac S.A.

Article Contents


feline leukaemia vaccine (inactivated)

This is a summary of the European public assessment report (EPAR) for Leucogen. It explains how the Agency assessed this veterinary medicine to recommend its authorisation in the European Union (EU) and its conditions of use. It is not intended to provide practical advice on how to use Leucogen.

For practical information about using Leucogen, animal owners or keepers should read the package leaflet or contact their veterinarian or pharmacist.

What is Leucogen and what is it used for?

Leucogen is a veterinary vaccine used in cats from eight weeks of age to protect them against feline leukaemia. Feline leukaemia is an infectious disease of cats caused by the feline leukaemia virus (FeLV). Signs of the disease can include loss of appetite, weight loss, poor fur condition, fever, pale gums and diarrhoea; cats persistently infected with the virus may spread it to other cats.

The medicine contains a protein from the outer layer of FeLV.

How is Leucogen used?

Leucogen is available as a suspension for injection and can only be obtained with a prescription.

The vaccine is given to cats as an injection under the skin. The initial vaccination course is two injections 3 or 4 weeks apart from 8 weeks of age. In cases where the kitten may have antibodies passed from the mother, a third injection can be given from 15 weeks of age. An annual booster vaccination of a single injection is necessary. Protection starts 3 weeks after the primary course of vaccination and lasts one year.

How does Leucogen work?

Leucogen is a vaccine. Vaccines work by ‘teaching’ the immune system (the body’s natural defences) how to defend itself against a disease. Leucogen contains small amounts of a protein from

the outer layer of the virus called ‘envelope p45 protein’. The FeLV protein used in the vaccine is not extracted from viruses but is made in a bacterium using ‘recombinant technology’. When a cat is given the vaccine the cat’s immune system recognises the protein as ‘foreign’ and makes antibodies against it. In the future, the immune system will be able to produce antibodies more quickly when it is exposed to FeLV, which will help to protect against the disease caused by the virus.

Leucogen also contains aluminium hydroxide gel and extract of Quillaja saponaria as adjuvants (ingredients that strengthen the immune response).

What benefits of Leucogen have been shown in studies?

In one field study kittens aged 8 to 9 weeks were given an initial vaccination course of Leucogen with 2 injections 3 weeks apart and an annual booster injection 1 year later. After the first injection 69% of the kittens had antibodies to FeLV and this increased to 100% after the second injection. Some 64% of cats still had FeLV antibodies before the annual booster, and 100% of cats had FeLV antibodies after the booster.

In a second study, kittens aged 8-9 weeks were given an initial vaccination course of a combination vaccine consisting of one dose of Feligen RCP (against feline rhinotracheitis virus, feline calici virus and feline panleucopaenia virus) with one dose of Leucogen. After the second injection, 100% of kittens had antibodies to FeLV.

What are the risks associated with Leucogen?

The most common side effect with Leucogen (which may affect more than 1 in 100 cats) is a moderate and short-lived swelling or lump after the first injection. This usually resolves on its own within three to four weeks. This reaction is reduced after subsequent injections.

Leucogen must not be used in pregnant cats.

For the full list of restrictions and all side effects reported with Leucogen, see the package leaflet.

What are the precautions for the person who gives the medicine or comes into contact with the animal?

In case of accidental self-injection, medical advice should be sought immediately and the package leaflet or label shown to the doctor.

Why is Leucogen approved?

The Agency’s Committee for Medicinal Products for Veterinary Use (CVMP) concluded that Leucogen’s benefits are greater than its risks and recommended that it be approved for use in the EU.

Other information about Leucogen:

The European Commission granted a marketing authorisation valid throughout the EU for Leucogen on 17 June 2009.

The full EPAR for Leucogen can be found on the Agency’s website: ema.europa.eu/Find medicine/Veterinary medicines/European public assessment reports. For more information about treatment with Leucogen, animal owners or keepers should read the package leaflet or contact their

veterinarian or pharmacist.

This summary was last updated in September 2017.