Vaccine Associated Sarcomas
The feline leukemia virus was until recently the most common fatal
disease for cats.
The virus manifests itself in both cancerous and non-cancerous ways:
However, it is a little-publicised fact that the vaccine itself can cause cancer.
The virus manifests itself in both cancerous and non-cancerous ways:
- Leukemia
- cancer of the white blood cells. (This was the
first disease associated with the virus, hence the name Feline
Leukemia)
- Lymphosarcomas
- cancer which begins in lymphoid tissue,
such as lymph nodes, but includes intestines, kidneys, spinal cord,
bone marrow etc.
- Non-cancerous diseases - anemia, arthritis and immune suppression for example. If the immune system is suppressed, the cat is often unable to resist even mild diseases and some may become fatal.
The
virus can be passed from one cat
to another in many ways including via saliva exchange during a fight,
from mother to kitten or, less commonly, through sharing
food bowls.
There is no doubt that the feline leukemia vaccine has helped to keep our cats safe from this disease and its many fatal side effects.
There is no doubt that the feline leukemia vaccine has helped to keep our cats safe from this disease and its many fatal side effects.
However, it is a little-publicised fact that the vaccine itself can cause cancer.
The original feline leukemia vaccine used a
live virus, but it was noted
that a number of cats developed the disease from the vaccine. In
response to this problem killed virus vaccines were developed. But they
didn't produce a strong enough inflammatory response to work very well,
so products known as adjuvants were added to the virus to enhance the
immune response. Aluminum Salt is a common adjuvant.
In the late 1980s the veterinary world became aware that an increasing number of cats were developing sarcomas (a cancerous tumour) at vaccine sites. Much research has been carried out since and although initial findings pointed to these cancers being caused by a reaction to the adjuvants, as aluminum deposits were sometimes found in the analysis of removed tumours, more recent research points to it possibly having more to do with inflammation than the presence of adjuvants. Other recent research suggests that administering vaccines cold from the fridge, rather than warmed to room temperature, might be identified as a possible risk factor for VAS.
But no-one has a definitive answer, it may be a combination of multiple factors – including a predisposition within individual cats. It could be many years before the veterinary world can say for sure they understand VAS and develop a feline leukemia vaccine which is completely VAS safe.
Estimates vary as to the possibility of developing VAS. Some put it as low as 1:500 vaccines, but others put it nearer 1:5,000. Either way, owners should be aware of the risks in order to make an informed choice about whether to vaccinate or not.
To vaccinate or not to vaccinate?
In the late 1980s the veterinary world became aware that an increasing number of cats were developing sarcomas (a cancerous tumour) at vaccine sites. Much research has been carried out since and although initial findings pointed to these cancers being caused by a reaction to the adjuvants, as aluminum deposits were sometimes found in the analysis of removed tumours, more recent research points to it possibly having more to do with inflammation than the presence of adjuvants. Other recent research suggests that administering vaccines cold from the fridge, rather than warmed to room temperature, might be identified as a possible risk factor for VAS.
But no-one has a definitive answer, it may be a combination of multiple factors – including a predisposition within individual cats. It could be many years before the veterinary world can say for sure they understand VAS and develop a feline leukemia vaccine which is completely VAS safe.
Estimates vary as to the possibility of developing VAS. Some put it as low as 1:500 vaccines, but others put it nearer 1:5,000. Either way, owners should be aware of the risks in order to make an informed choice about whether to vaccinate or not.
To vaccinate or not to vaccinate?
This is a
tricky question as no-one wants to put a cat at risk of succumbing to
the virus itself by not vaccinating.
If your cat goes outside, unattended, and comes into contact with other cats then it makes sense to continue to vaccinate your cat as the risk of them catching the feline leukemia virus will be far higher than developing VAS. Having said that, some studies have shown that cats can develop a natural immunity to Feline Leukemia, regardless of whether they are continually vaccinated. And some cats may still unfortunately fall prey to this terrible disease even though vaccination has occurred.
However, if your cat is one of the increasing number of indoor cats who do not go out and will not come into contact with another cat carrying the virus, then vaccination may not be necessary. If you have more than one indoor cat, a simple blood test for each cat will determine whether any of your cats are carrying the virus.
Unnecessary vaccination increases the chance of your cat developing a fatal disease.
If your cat goes outside, unattended, and comes into contact with other cats then it makes sense to continue to vaccinate your cat as the risk of them catching the feline leukemia virus will be far higher than developing VAS. Having said that, some studies have shown that cats can develop a natural immunity to Feline Leukemia, regardless of whether they are continually vaccinated. And some cats may still unfortunately fall prey to this terrible disease even though vaccination has occurred.
However, if your cat is one of the increasing number of indoor cats who do not go out and will not come into contact with another cat carrying the virus, then vaccination may not be necessary. If you have more than one indoor cat, a simple blood test for each cat will determine whether any of your cats are carrying the virus.
Unnecessary vaccination increases the chance of your cat developing a fatal disease.
Talk
to your vet and get their advice. Please don’t stop
vaccinating unless you are sure your cat is in no
danger of catching the feline leukemia virus.
Where to vaccinate and why?
Where to vaccinate and why?
In
the UK it is
common for vets to administer vaccinations in the scruff/shoulder area.
It is understandable for them to do this as it means their hands are
well away from sharp claws and teeth of a cross cat. But if your cat is
unfortunate enough to develop VAS in the shoulder/scruff area then the
odds are against a successful removal. Some types of sarcoma (known as
fibrosarcomas) require wide margins of tissue to be taken from around
the tumor for successful removal, which is very difficult - and may
often be impossible to achieve in the scruff area.
In the US it is increasingly common for the leukemia vaccine to be administered in the rear left leg. (Rabies injections are compulsory in many parts of the US and they have the same VAS issues, so these are administered in the rear right leg). Vaccination in the rear left leg will not diminish your cat’s chances of developing VAS but it does offer one alternative surgery – amputation. Amputation of the whole leg will help towards the complete removal of VAS, and help to prevent it returning or spreading.
Amputation sounds terrible when thought about in the context of a healthy cat – but in the context of a cat with VAS, it could be their best lifeline.
Cats do respond well to the amputation of a rear leg and once they have sorted out their centre of balance, will be able to run, jump, climb stairs etc., and lead a happy life.
Even with surgery as drastic as amputation, complete remission is unfortunately not guaranteed, but it’s their best chance of overcoming VAS.
In the US it is increasingly common for the leukemia vaccine to be administered in the rear left leg. (Rabies injections are compulsory in many parts of the US and they have the same VAS issues, so these are administered in the rear right leg). Vaccination in the rear left leg will not diminish your cat’s chances of developing VAS but it does offer one alternative surgery – amputation. Amputation of the whole leg will help towards the complete removal of VAS, and help to prevent it returning or spreading.
Amputation sounds terrible when thought about in the context of a healthy cat – but in the context of a cat with VAS, it could be their best lifeline.
Cats do respond well to the amputation of a rear leg and once they have sorted out their centre of balance, will be able to run, jump, climb stairs etc., and lead a happy life.
Even with surgery as drastic as amputation, complete remission is unfortunately not guaranteed, but it’s their best chance of overcoming VAS.
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It is not intended to deter owners from vaccinating cats against feline leukemia, but to provoke consideration of whether vaccination is necessary, the associated risks and where best to administer the vaccine.
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It is not intended to deter owners from vaccinating cats against feline leukemia, but to provoke consideration of whether vaccination is necessary, the associated risks and where best to administer the vaccine.
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Designed by Ben Meadowcroft
This
work is licensed under a Creative
Commons License.