Vaccination and Your Pet Part 1

‘We should aim to vaccinate every animal and to vaccinate each individual less frequently’
(Guidelines for the vaccination of dogs and cats – World Small Animal Veterinary Association 2006)

Vaccination is the great success of veterinary medicine; lives have been saved, serious illness prevented and some diseases have almost been eradicated. However, there is always discussion about how often we should vaccinate our pets and vaccination protocols are under constant review by the veterinary profession. The vaccine requirements will vary between diseases and also between individual pets. It is always best to discuss with your vet your pet’s individual risk of exposure to viruses, so you can follow a vaccination protocol suitable for them.

WHY VACCINATE?

Vaccines can not only help prevent serious illness and disease but for some viruses it is the only form of effective treatment available, for example Parvovirus, Distemper and Rabies . Also, it is a requirement of most kennels and catteries that animals who stay in them are vaccinated regularly. Additionally, animals who travel abroad on the PETS scheme must be vaccinated against rabies in order to be allowed to return to the UK. However, despite the best efforts of the veterinary profession only 40-50% of the pet population is vaccinated and it is the remaining 50-60% of unvaccinated animals which account for the occasional outbreaks of disease.

HOW DO VACCINES WORK?

When an animal is vaccinated, you are essentially giving the body a ‘dry run’ at fighting off disease, so they are prepared if they are ever exposed to the real thing. The vaccines contain weakened versions of the viruses that cause disease. There are two main kinds of vaccine; ‘modified live’ and ‘killed’.

Modified live vaccines contain a live version of the virus which has been weakened so the body can fight it off. The modified virus is able to multiply inside the animal and so closely mimics a real infection. This means, however, there is the possibility for mutation of the virus and it can cause disease in weak or ill animals. This is why your vet will insist your pet is healthy before it is vaccinated and, in the case of bitches or queens, is not pregnant, as any foetuses could be damaged. The main advantage of a modified live vaccine is that it stimulates a greater body response, which leads to higher and longer lasting levels of protection. Examples of modified live vaccines include Distemper and Parvovirus.

Killed vaccines contain dead viruses. A dead virus cannot multiple or mutate in the body but injecting it will still cause the body to react to fight it off. The rabies vaccine is a dead virus as we cannot run the risk of a live version mutating and being able to cause disease. A killed vaccine is safer than a live one so it can be given to sick or pregnant animals without causing them further illness. However, a killed vaccine will need to be given in two doses to cause adequate levels of protection in the body and they require more regular injections that the modified live vaccines as this protection is not as long lasting.


HOW OFTEN SHOULD WE VACCINATE?

This is this subject that causes the most controversy that surrounds vaccination and it is a subject which is under constant review by the veterinary profession. By far the most important times in an animal’s life to vaccinate are when they are very young and when they have reached their first year.

PUPPIES AND KITTENS

In puppies and kittens the biggest factor affecting the efficacy of vaccinations is the Maternally Derived Anti-bodies (MDA). This is the protection they receive from their mothers via the colostrum. This remains active for between 8 and 12 weeks. The MDA gives protection against most of the diseases we vaccinate against, which means if we vaccinate when the MDA levels are still high, they will de-activate the vaccines and there will be no lasting protection in the body. This is why we wait until pups and kittens are at least 8 weeks old before we vaccinate and why they receive more than one injection, two to four weeks apart, so if the first is destroyed by the MDA, the second should work. For the modified live viruses a single vaccine should be enough to provide suitable levels of protection, if the MDA has waned, but for killed viruses 2 injections no more than four weeks apart will always be required.

There has been a recent move to finish puppy vaccines at ten weeks old in order to allow for early socialisation, which is very important for their behavioural development. However, this has been associated with outbreaks of parvovirus in young animals, as there will be some individuals where the MDA levels haven’t fallen enough by ten weeks, and so this practice is currently under review. If puppy vaccines are finished at twelve weeks of age, vets expect 98% of individuals to gain adequate levels of disease protection. There are some breeds of dog, Rottweilers and Dobermans in particular, which seem to be resistant to the vaccines. Many vets will advise these breeds are given a final vaccination at 16 weeks. Indeed in some areas where canine infectious disease is prevalent, many vets will advise all pups are given a final vaccination at 16 weeks. The World Small Animal Veterinary Association (WSAVA) advises all pups are vaccinated at 8, 12 and 16 weeks of age.

Kitten vaccines are widely accepted to start at nine weeks of age and finish three weeks later at twelve weeks of age. Although socialising kittens is important, they do not need to be exposed to as much as pups so there is less pressure for the vaccine course to finish. Also, as most vets advise kittens are kept indoors until six months of age, when they can be neutered, they are unlikely to be exposed to disease at a young age.

Click back to my page and onto the next blog post to read part 2