While it would be simpler and cheaper to administer vaccinations all at one time, it is important to know what they protect and how long they are effective and schedule vaccinations accordingly. Even though some vaccines are labeled to be given annually they do not provide protection for a full year.
Vaccinations should be postponed in horses that are sick or mares in their first 3 months of pregnancy. Stress, including intense exercise in unconditioned horses can have a negative impact on immune response.
Intranasal vaccines create antibodies that are locally effective but do not create antibodies that would be transmitted to foals in the mareÍs milk.
EEE, WEE
Eastern and Western Encephalitis are both transmitted by mosquitoes. Birds are intermediate hosts, blood can be carried from an infected bird to a horse even though birds do not show signs of illness. EEE and WEE both give relatively short lived protection. In many states horses are vaccinated twice a year, in Wisconsin we can get away with a once a year booster because of our shorter period of warm weather. The best time to vaccinate is close to the beginning of mosquito season.
There have been no reported cases of EEE or WEE in Wisconsin in recent years, there have been in other States including Michigan.
Tetanus
This is a must vaccine for every horse. Once a horse has Tetanus it is very difficult to treat and the majority of horses do not survive. Tetanus is caused by neurotoxins of a Clostridium bacteria that is found in the manure of horses and therefore everywhere in a horseÍs environment. It is an anaerobic bacteria, meaning it does not survive when exposed to air. The danger is when a horse has a small wound, like a nail puncture and the bacteria gets trapped with tissue closing over it. Tetanus vaccinations are one of the most effective and longlasting of the vaccines around. An annual booster usually provides good protection. If the horse suffers a wound and the last vaccination was close to a year ago, it is recommended to rebooster at that point in time.
Rhino (EHV1 & EHV4)
Rhinopneumonitis is an inflammation of the mucosae of the nasal cavities and the lungs caused by Equine Herpes Virus 4. Equine Herpes Virus 1 is the major cause of equine viral abortion and can also cause encephalitis characterized by neurologic signs varying from slight ataxia to enforced recumbency. It is often brought into a barn by horses returning from shows and usually spreads rapidly through air droplets. It is more likely to affect younger and immune compromised including stressed horses
Influenza
Influenza is a very difficult disease to protect against because viruses can show antigenic change (even though not nearly as evident as in human influenza) and bringing out a new vaccine that includes all the different strains is a long, expensive process. According to latest research injectable vaccines protect at best 2 - 3 months. The new intranasal vaccine is creating antibodies that fight the virus where it enters the body, in the nasal passages. It is safe and offers protection for up to 6 months. When given the first time, it has to be boostered within 3 weeks. It cannot be given at the same time as the intranasal strangles vaccine. Influenza is also transmitted by droplet infection and can spread rapidly causing major interruptions to equine activities.
Contagious diseases like Rhino and Influenza are best controlled by immunizing the whole herd at the same time.
Potomac Horse Fever
While some new information emerged regarding transmission, the full life cycle is still not known. It is carried by microscopic crustaceans that have been found in water and on small snails. The water has to be warm in order for these little creatures to live, so in Wisconsin it would be a summer/fall problem. The vaccination is not fully protective. However, it can reduce the severity and duration of the disease. Laminitis can be a complication of Potomac Horse Fever and is less likely to occur in vaccinated horses. The protection offered by vaccine is also relatively shortlived.
Rabies
Rabies is another vaccine that should be given to any horse that lives in an environment that is shared by skunks or bats. These are the main two transmitters of the disease in Wisconsin and there have been cases of it in horses, while few, every year. The disease can be transmitted to humans through the saliva of horses entering a small cut on a personÍs hand. Horses do not show any signs of violence or aggression but are more likely to act depressed so it is something easily to be missed. Unlike small animals, horses have to be boostered for Rabies annually. It can be given pretty much at any time of the year. Broodmares should be vaccinated before they are bred. While the vaccine is administered frequently to pregnant mares and I have not ever heard of a problem with it, it is said to possibly trigger prostaglandin release which could lead to an abortion.
Strangles
The new intranasal vaccine is a rather effective way of protecting your horse. It is rarely causing the side effects seen previously with the injectable vaccine. When given the first time it needs to be boostered within 2-3 weeks. Horses that had the disease before are protected for a number of years and should not be vaccinated within one year of recovery. Strangles is transmitted through discharge from the nose or abscesses and often carried from horse to horse by people or equipment. Isolation and management are critical in controlling strangles outbreaks. The bacteria does not like heat or dryness but survives well in wet condition and shared water tanks are often the source of infection.
Rhino (EHV1)
This is the Equine Herpes Virus that can cause abortion and pregnant mares should be vaccinated at 5, 7 and 9 months of pregnancy as well as 4-6 weeks before the foal is born. The virus may also cause viremia in newborn foals, the foals showing severe mental depression (sleepy foal).
Deworming
All horses have internal parasites and need to be dewormed on a regular basis to avoid damage to the gut. How often depends on the horse's parasite infestation which in turn depends on the horse's environment. While a backyard owner who is very conscientious about manure clean up and disposal, who never feeds the horses on grounds that are contaminated, who mowes and harrows pastures to destroy the piles and expose the larvae to the sun may be able to deworm 3-4 times a year, horses in crowded boarding stables with small, shared paddocks may have to be dewormed as often as every 6 weeks.
While Ivermectin is a safe product that takes care of most internal (and some external) parasites, and there is no known resistance buildup to it, it may be beneficial for economical and other reasons to do some rotation. Ivermectin will eliminate small strongyle larvae while free in the gut and with regular deworming they should never encyst. However if they should it will take Quest or Panacur PowerPac to eliminate them. Tapeworm, and there are some areas around the Great Lakes that have a tapeworm infestation problem, needs Strongid for control. Remember that not all products are safe for young foals. Foals should be dewormed once a month for 6 months with the appropriate dose of Anthelcide which is very safe and efficient After that they go on the adult program.
The table below shows commonly used dewormers by class and associated brand names.
