Vaccinations

A debate has been going on in recent years over the importance of vaccinations. In human medicine an increasing number of parents are opting not to vaccinate their children, which is causing concern for health officials. Veterinarians are also concerned that a growing number of unvaccinated pets increase the risk of a disease epidemic.

The importance of vaccination cannot be underplayed, and the success so far of the World Health Organisation’s ‘global polio eradication campaign’ is an illustration of the real value of large scale vaccinating. However, we also need to balance this with the risk of side effects. In the 1990s a type of cancer was linked to inoculations for rabies, necessary when exporting animals to some countries from New Zealand, and feline leukaemia (FeLV). On the whole, the risk of cancer from the FeLV vaccination is about one in 10, 000, or about the same as catching the virus itself. Thankfully, this virus is very uncommon in New Zealand, and by its first year most cats have a degree of natural immunity.

While the incidence of severe side effects through most vaccinations is also thought to be limited to about one case in every 10,000, minor side effects such as lethargy are common. However, if this disappears within 24 hours then it is not of serious concern. If your pet does show signs of abnormal behaviour, or swelling, after a vaccination then contact your veterinarian so that they can ensure your pet is all right. They will also fill in an ‘adverse event’ form which ensures that information about such reactions is accurately recorded.

How often should we give our pets a vaccine?
Puppies and kittens receive some immunity via their mother, but by twelve weeks this becomes fairly weak. It is therefore vital that they receive their initial vaccinations at this time to ensure continued protection against certain diseases.

More debatable is the question of how often our pets should be given a vaccination to boost their immunity. Over the last 15 to 20 years there have been a number of studies looking at how long various vaccines last, with some providing immunity for three or more years.

In New Zealand most companies have now licensed their dog distemper, hepatitis and parvovirus vaccines, and cat vaccines for panleukopaenia, herpes and calicivirus, for three yearly useage. Vaccines for leptospirosis, FIV and infectious bronchitis (kennel cough) still require yearly boosters to maintain good immunity for your pet.

Should you have to take your pet to the vet every year if the vaccine lasts for three years?
For years the veterinary profession has encouraged the practice of annual vaccinations, perhaps leaving the perception that this is the sole reason for the visit. In reality, the veterinarian also performs a comprehensive health check, discusses with you any health, behaviour or diet concerns, and gives you advice about how to keep your pet healthy. This health check is vitally important and the reason why you hear of veterinarians recommending an ‘annual health check’, which may include vaccinations.

As people grow older it is recommended that we have yearly health checks and six monthly hygienist appointments at our dentist. Now, we all know that animals age quicker than people and you can roughly get the human age of your pet by multiplying its age by seven i.e. a 12 year old cat is equvilent in human terms to 84 years. With the rapid changes to our pet’s health over its relativley short life, many veterinarians now think our pets should have six monthly checks, as yearly ones are too far apart. This is especially important in the first year of life and after seven years of age.

These health checks are aimed at discovering any problems before they escalate. This prevention may include vaccinations, dental care, and dietary advice – all tailored to your pet based on clinical findings and lifestyle.

Boarding kennels and catteries
When you book your pet into your favourite boarding establishment, it is very important that that you ask them about their vaccination house rules. Establishments vary a lot on their requirements, which can lead to a lot of confusion (many are now happy with three yearly boosters for certain vaccines). Check that your vaccination booklet is up to date and that your pet has had all the vaccinations they require, and within the stipulated time period.

Always keep your pet’s vaccination booklet in a safe place, and take it along to your veterinarian at their annual health check to be updated. The boarding kennel/cattery will want to see this booklet when your pet checks in.

The future?
Technology is allowing the development of new vaccines. The recent creation of a vaccine against the feline immunodeficiency virus (FIV) is a good example. It had been thought that it would be impossible to create such a vaccine but recent advances have proved this assumption wrong.

There is no doubt that vaccination has been exceptionally successful in New Zealand. It is now uncommon for us to see parvovirus infections (although it is still common in areas with a large number of unvaccinated dogs) and it is rare that the often fatal canine distemper and feline panleukopaenia are seen. With appropriate use of vaccinations it is hoped that this trend of a reduction in serious infectious diseases will continue.

Dog vaccines
Canine parvovirus
A highly contagious disease, causing sudden and severe vomiting and diarrhoea. This is most severe in young dogs and can be fatal without intensive and expensive care.

Canine distemper
Highly contagious. Symptoms include loss of appetite, runny eyes and nose, vomiting, coughing and/or signs of nervousness. Treatment is often unsuccessful. Survivors may end up with permanent damage to the enamel of their teeth or nerve damage, e.g. seizures.

Canine leptospirosis
A severe disease primarily affecting the kidneys, but other organs can also be affected. Symptoms include inability to urinate, high fever, jaundice, vomiting and sore muscles. Dogs that contract this disease are usually found in areas with infected rats, so pets that come into areas that rats frequent (e.g. around fresh waterways, rubbish dumps or farms) are at greatest risk. Humans can also catch Leptospirosis from infected dogs or other species.

Infectious bronchitis (kennel cough)
A complex, highly contagious disease that is seldom fatal. Vaccinated dogs can still contract this disease, although clinical signs are usually mild and short-lived. It can be treated with antibiotic therapy, either orally or by nebulisation - this can be expensive and not always effective. Infection is passed from dog to dog. The risk of infection increases when dogs are grouped together e.g. in boarding kennels, at training classes and dog shows. A vaccine administered as nose drops is the most effective and lasts 6-12 months.

Cat vaccines
Feline enteritis
A highly contagious disease causing loss of appetite, diarrhoea, vomiting, extreme lethargy, dehydration and frequently death. It is most common (and most severe) in young kittens, but can affect cats of any age.

Feline immunodeficiency virus (FIV)
This virus is mainly spread by fighting and is excreted in large amounts in saliva. Entire tom cats have a particularly high incidence of this disease. There is no cure and the recent launch of a new vaccine provides the best protection. A blood test should be performed prior to vaccination to ensure your cat is free of this disease. Currently there is no blood test available in New Zealand to differentiate between vaccinated and infected cats, therefore it is recommended that your cat is implanted with a microchip prior to vaccination to reduce the risk of it being mistakenly identified as suffering from this disease.

Feline viral respiratory disease (cat flu)
A very common and highly contagious disease causing sneezing, runny eyes and nose, mouth and corneal ulcers, and loss of appetite. In severe cases cats may die or be left with a persistent nasal discharge and sneezing (snuffles).

Feline leukaemia (FeLV)
FeLV causes both neoplastic and non-neoplastic disorders. The immune system is depressed predisposing affected cats to other infections and these can often be fatal. FeLV is recognised as a major cause of mortality in cats worldwide, so New Zealand is therefore something of an exception as it is still rare here. The vaccine has been implicated in causing a sarcoma (a tumour) at the injection site. The risk of this appears to be about one in 10,000, but as a result this vaccination is administered in the hind leg or tail. This allows earlier diagnosis of a lump and provides more treatment options.

Feline chlamydia
This disease can cause recurrent bouts of sneezing, conjunctivitis (sticky eyes) and infertility or abortion in breeding queens (rarely it causes a mild conjunctivitis in people). This is a common problem in New Zealand. The vaccine occasionally causes lethargy that can last up to three months although more recent vaccines appear to have reduced this side-effect. The disease is usually treated with a course of antibiotics for three weeks.

Rabbit vaccine
Viral haemorrhagic disease (calicivirus)
Symptoms include fever, lethargy, loss of appetite, spasms, and sudden death, although some rabbits may die without showing any symptoms. This disease has a 90% fatality rate, with death occurring between one and three days after infection. The virus is very hardy and can be transmitted by contact with infected rabbits or their excreta, rabbit products, insects, rodents and contaminated objects. Rabbits that survive the disease may become carriers and spread it to other rabbits. There is no cure for VHD once the animal has been infected, but the Cylap vaccine has proved an effective preventative measure.

- Author Oliver Young