‘a small quantity of either weakened (attenuated, live vaccines) or killed viruses and bacteria (pathogens) or also inactivated bacterial toxins, which are introduced as a vaccine into the body.’ (Studer, HP, Vaccination, A Guide for Making Personal Choices, Floris Books, 2004)

In addition, vaccines contain other substances including traces left over from manufacturing, preservatives and stabilizers, inactivating and detoxifying agents and chemicals to enhance the effectiveness of the vaccine.

The Nature of Flu
Influenza is passed from horse to horse in the form of an aerosol, that is, as infected droplets in the air. It is a difficult virus to stop, because it constantly changes its structure. This is what makes it so successful: the immune system gets one version cracked, then another one springs up. The flu vaccines can only protect against the variety of flu contained in the vaccine. If other types of virus appear, the vaccine can be largely ineffective.

The clinical signs of flu include fever, coughing, nasal discharge, lethargy, fatigue, and loss of appetite. Most horses recover completely within a couple of weeks given good care and rest. Vaccinated horses may still contract flu but tend to show milder signs. Flu can be fatal in foals, especially if they don't get colostrum and horses that are worked while sick may be susceptible to respiratory system infections. If a horse is exposed to the virus, there is a high chance of infection. Peaks in incidence of equine flu are seen in young vaccinated thoroughbreds at the time of the autumn sales and in unvaccinated horses mixing at shows, (‘Maximizing the Benefits of Vaccination against Equine Influenza’, J. R. Newton, A. W. Park and J.L. N. Wood, International Equine Respiratory Diseases, 2004)

Reducing the Risk from Flu
A report from the 8th International Conference on Equine Infectious Diseases states: ‘The most important aspects of therapy and control include the cessation of exercise and training and adequate environmental ventilation ... Maximizing environmental ventilation will decrease spread and help minimize respiratory irritation by dust and allergens... While they [vaccines] decrease the incidence and severity of clinical disease, they rarely prevent infection and shedding,’ 

Holistic vet, Nick Thompson says the best way to improve resistance to flu
is to keep your horse as naturally as possible. ‘Give your horse a healthy life, by keeping it barefoot, not feeding cereals, basing the diet on good hay or grass, a few carrots and a broad spectrum vitamin and mineral supplement, and keep it outside as much as possible.’

Bad Reactions
For this article, I wanted a few case studies from people who believe their horses have had a bad reaction to the flu jab. In fact, I got too many to include here. Everyone I spoke to knew at least one other person whose horse had suffered and I heard anecdotal (though not scientifically proven) accounts of horses developing COPD/RAD and sweet itch after being vaccinated. As the stories show, many owners are convinced that their horses had bad reactions to a flu vaccine, despite denials by some of the vets who administered them. Such denials seem pointless when information is published by organisations that examine the safety of medicines. For example, the European Agency for the Evaluation of Medicinal Products lists the reactions to one brand of flu vaccines as: a swelling at the site of infection, pain and local hyperthermia, increase in temperature, apathy and reduced appetite and, exceptionally, hypersensitivity requiring appropriate treatment. 

As illustrated in the case studies here, the range of reactions reported varied greatly. Nick Thompson points out that usually it is not a ‘bad batch’ of vaccine that causes a bad reaction, but the individual horse’s response to the vaccination. For this reason it isn’t possible to predict which horses will suffer.

Vaccination Frequency
There is not only the question of the necessity of vaccination, but also the regularity with which it is administered. I spoke to four veterinary practices. The recommendations varied, the most intensive being a combined flu-tetanus vaccine , followed by a second a month later , then a third dose six month’s later then yearly boosters. The least intensive was a practice that recommended only tetanus every 18 months, unless the horse was having to go to places where a flu jab was required or was on a large yard with a lot of movement of horses. 
This raises the issue of combining flu and tetanus vaccines. The manufacturers of tetanus vaccines are recommending boosters at 2 or 3 year intervals, depending on the brand. This means that if we automatically vaccinate annually for flu and tetanus, we may be overloading the horse. There is also the possibility that combined vaccines may produce more problems for horses. This is part of the controversy over the MMR vaccine for children. Nick Thompson says, ‘In my opinion, combined vaccines may give more complications,’ though at this point there is no conclusive evidence about this.
Holistic vet Sue Armstrong, of Balanced Being, says, ‘I would recommend vaccinating against tetanus, but it only needs to be done every three years.’

Why the Requirement to Vaccinate?
As with much in the horse world we must look at where the money is. There is little money to be made by keeping horses in the fresh air as much as possible. There is a lot of money to be made by transnational drug companies selling vaccines and by vets administering them. And of course, there’s the racing industry, whose intensive horse-keeping practices foster the transmission of disease in horses whose immune systems are often suppressed due to the level of stress they suffer. Nick Thompson points out, ‘The reason for vaccinating every horse in the UK is that there is a political imperative to do so; it only takes place to protect the racing industry in my opinion.’ 

If flu can be controlled by good management, is not particularly serious for the majority of
horses, and isn’t necessarily prevented by vaccines that may cause ill-health, we have to question whether we should be vaccinating against it at all. If we do choose to vaccinate, we should at least be administering the minimum amount of vaccine necessary to give protection.
So to vaccinate or not to vaccinate? Each owner needs to make the decision based on his or her individual situation, and if you are bound by competition society rules, you will have little choice.

However, there are steps you can take to minimise the risks:

1. Don’t vaccinate for flu unless required to do so by competition authorities or you have an at-risk animal.
2. Don’t vaccinate for flu unless your horse is mixing in close contact with a lot of strange horses and you are worried about the horse contracting flu.
3. Separate flu and tetanus vaccinations.
4. Request a tetanus booster that only needs to be administered every 3 years, eg, Schering Plough’s Equip T
5. Keep your horse’s immune system strong by making its life as ‘natural’ and stress free as possible.
6. If your horse has had a bad reaction to a flu vaccine, and you still want to vaccinate, Nick Thompson recommends having a homeopathic nosode made up from the vaccine and administered 3 weeks before and after the vaccination.
7. Importantly, if your horse does have a bad reaction to a vaccine (or any drug) report it [see below].

In researching this article, I came across numerous papers concerned with improving flu vaccines and and stopping flu, always in racehorses. It would make more sense to minimise infection by putting an end to ‘factory farming’ thoroughbreds and reduce their stress levels so that they can fight infections . But as Cuba Gooding Jnr says, in the film Jerry Maguire, ‘Show me the money’, in that.

“Ryan had always been a bit off, whichever vaccine was used. Then in June 2003 he was vaccinated on the Wednesday afternoon. By Saturday he was really stiff and lumps of fluid, the size of my hand, had come up on his body. The vet claimed it was an allergy to buttercups, but we didn’t have any buttercups. The vet gave him Bute, but by Monday Ryan had full-blown laminitis with pedal bone rotation in one foot. We are still dealing with the effects of the laminitis, with 5o rotation and have changed vets and have a therapeutic farrier.”

“In Feb this year, Jewel was given a combined flu and tet vaccine. He’d been vaccinated yearly up to then. 3 days after the jab, he developed a cough and a high temperature and was generally grotty. A week after the cough he got hives down his neck and under his belly. They were 2” across and lasted a week, then his coat went scaly and scurfy and the hair started come out. This lasted 4 weeks. I’m not going to give him any more flu jabs. His feet, which had been good, went all brittle as well.”

“I’d given Bacchus annual flu and tetanus jabs but this year he reacted really badly. The day after he was lethargic and the next day he was really hang dog. His hindlegs filled and by the third day his body began to fill with fluid and his fur went lumpy like wood chip paper and began to look orange (when he is actually black). On the 4th day the legs were still up but when I turned him out in the manége he got muscle tremors. The vet said he was reacting to the flu vaccine. Bute made no difference and he stopped eating, then the lumps on his skin turned into sores and started weeping. His skin was red-hot to the touch and very tender. He lost 80% of his body hair over 2 weeks and looked like he had mange. The vet said to let the reaction work out of his system. It was a month before he seemed to feel better and it took 3 months for the hair to grow back, and he lost a lot of weight.”

“Molly had done an endurance ride at the weekend. She was flu-jabbed at Wednesday dinner time and by tea time she’d collapsed on the floor. The vet said it wasn’t due to the jab and gave her an antibiotic injection. She picked up for 48 hours then went down again. Over the next week she was up and down, but wouldn’t eat or drink. I insisted on a referral to Liverpool vet school, who said she had no white blood cells, a temperature of 108 F (41C) and put her on a drip. After 3 or 4 days she improved but it’s taken nearly 18 months to get her blood count and temperature back to normal.”

Further information
Nick Thompson, Bath, London, Swinton, 08700 111340, www.holisticvet.co.uk

Sue Armstong, Wetherby, 01937 543 860, www.balancedbeing.com

DEFRA, Veterinary Medicines Directorate, FREEPOST KT 4503, Woodham Lane, Few Haw, Addlestone, KT15 3BR or download and return the form on www.vmd.gov.uk/sarrss/sarrssintro.htm, or contact us for a copy

What Vets Don’t Tell You available from What Doctor’s Don’t Tell You, Satellite House, 2 Salisbury Rad, Wimbledon, LONDON, SW19 4EZ (about cats and dogs)