You want to keep your cat safe, of course you do. But the world is a dangerous place – worms, parasites, dogs, cars, the list goes on and on…
However, many of the infectious diseases of cats can be prevented – with vaccination. In this blog, we’ll briefly review the diseases which vaccines can protect against, and then look at what vaccines are, how they work, and how safe they are (because this is a really important issue). We will finish with a few thoughts on vaccinating cats.
This is not usually a killer disease, although occasionally lethal strains of Calicivirus turn up. It’s caused by several different bugs, and we routinely vaccinate against Calicivirus and Herpesvirus. Symptoms include sneezing, runny noses, sore eyes, and lesions on the gums; complications may include pneumonia. Unfortunately, many cats infected with Herpesvirus will remain infected for life, with the virus reactivating at times of stress or other illness.
This really is a killer – the virus can stay dormant in the environment for many months. It attacks a cat’s immune system and gut, usually causing severe vomiting and diarrhoea as well as weakening the immune system’s ability to fight off other infections.
Feline Leukaemia Virus
This is the nastiest of all – it is incurable and 80-90% of infected cats will be dead within 3 years. The virus can be spread by sharing saliva (e.g. grooming or fighting), and causes the immune system to collapse; it also triggers tumours to grow, causing lymphoma and leukaemia.
What is a vaccine?
A vaccine is a medication that teaches the cat’s immune system how to fight a disease, without having to actually contract that disease (with all the risks that that entails). There are different ways of doing this – modified-live vaccines contain a weakened version of the live organism (triggering a stronger and faster response, but more tricky to handle the vaccine); inactivated vaccines contain a dead one (no risk of the bug mutating, but a weaker response because the immune system knows it isn’t really a threat). There is also a newer type called a subunit vaccine that contains genes from a dangerous bug inserted into a harmless one to get the best of both worlds. Most vaccines also contain a chemical called an adjuvant to increase the effectiveness of the immune response – but the adjuvant is also responsible for many of the side effects.
There are also homeopathic vaccines known as nosodes, but we do NOT recommend these because sadly there is no evidence that they provide any protection whatsoever.
How does it work?
A cat’s immune system (like ours) is an incredibly ruthless killing machine. However, different diseases need different strategies to defeat them.
The immune system has 2 basic parts:
- The Innate Immune System – this is a series of barriers (like the skin) to stop infectious agents getting in, chemicals (like lysozyme in tears, or complement in the blood) and cells (neutrophils and macrophages) that attack anything unexpected. This system doesn’t need to know what the invader is, and doesn’t need to learn. However, likewise, it cannot learn – if a bug learns how to evade it (which many can), it cannot then overcome that bug. As a result, cats have a second part:
- The Adaptive Immune System. This is the part of the immune system that learns how to fight a specific infection. It can use B-cells to make antibodies (proteins in the blood that act as homing missiles, locking on to a particular foreign protein and attacking it); or it can tell T-cells to hunt down and destroy infected body cells. The Adaptive Immune System can’t fight something it’s never seen before – but once it recognises how best to kill that particular invader, it remembers for months, or even years.
Vaccination aims to improve the way that the Adaptive Immune System responds to an infection, by letting it try out different modes of attack in safety (i.e. by using a non-dangerous form of the bug – a bit like a pilot who practices flying in a simulator where the risk of actually hurting themselves is really low).
The reason that this is important is that it takes several days, or even weeks, for the immune system to mount the right kind of response – so the natural response may be too slow, allowing the bugs to multiply unchecked. For some diseases, antibodies are fully protective, but for others, the antibody may make the disease more dangerous because a T-cell cytotoxic response is needed – so again, we need to try and teach it how to respond in safety.
Are they safe in cats?
However, no medication is 100% safe (if anything claims to be, it probably isn’t doing anything at all). The most common reactions are mild lethargy, poor appetite or tenderness at the injection spot for a few days. Very, very occasionally (less than 1 in 10,000 injection) more serious symptoms may be seen, such as vomiting, diarrhoea or a significant lump forming – mostly due to the effects of the adjuvant.
There is also a form of tumour called a Feline Injection Site Sarcoma or FISS that is associated with injections (of anything, even water!) under the skin of a cat. The risk is thought to be less than 1 in 20,000, however.
THE BOTTOM LINE
Should I vaccinate my cat?
In most cases – yes. The risk from disease is much, much higher than the risk of side effects.
As a team, we use a very modern vaccine that covers all the most up to date strains of the diseases, and does not contain an adjuvant. This helps to give the best results while minimising the risk of side effects. This vaccine also allows us to select annually what diseases your cat needs to be covered for (the protection given against some diseases last longer than for others). This means we can make sure that we can maintain their protection without overvaccinating.
However, not all cats can be safely vaccinated, and if your cat is at particularly high risk, our vets will be able to help you decide what the best course of action is.