Vaccinations help keep many infectious diseases under control and only mildly symptomatic. The protection provided by vaccines is based on the idea that as many individuals as possible have been vaccinated, making the disease pressure small and preventing the spread of diseases in the equine population.
Sick horses should not be vaccinated, as their immune response is out of balance and the production of new antibodies, which is the purpose of vaccination, may be abnormal, potentially further aggravating the illness. Furthermore, horses should not be vaccinated while receiving cortisones or certain other drugs, as these reduce vaccine effectiveness to inadequate levels. In normal circumstances, foals should not be vaccinated before six months of age, as antibodies obtained from the mother inhibit the formation of an immune response.
The equine vaccination programmes in Finland accord with those commonly used elsewhere in Europe. However, in Finland horse owners must always independently determine the sufficiency of previously received vaccines when entering competitions.
Equine vaccination is initiated at six months of age. Until that time, protection is provided by antibodies received by the foal in the milk of the mare.
Tetanus vaccination: Protects horses against tetanus, which is caused by toxins produced by Clostridium tetani bacteria. These are common soil bacteria, which is why humans as well should make sure their immunisation against tetanus is valid. Horses must be vaccinated against tetanus at approximately six months of age. A booster vaccine is given 21 to 92 days later and another one roughly one year subsequently. Thereafter, tetanus boosters are given at roughly two-year intervals.
There are combination vaccines for tetanus and equine influenza that can be used to vaccinate horses simultaneously against both diseases.
Influenza vaccination: Protects horses against viruses that cause influenza (influenza A virus). Equine influenza viruses are highly contagious and cause respiratory tract–related epidemics around the world.
After primary immunisation, many vaccine producers recommend a new vaccination roughly every six months. Young horses in particular (under four years of age) should be vaccinated every six months.
Riding horses receive a second vaccine 21 to 92 days from the first vaccination in the primary vaccine series. The first booster vaccine is given within seven months of the second primary vaccination, after which vaccines are given at intervals of up to 12 months. Horses participating in international competitions must be vaccinated within the preceding six months (+21 days).
Trotters receive a second vaccine 21 to 62 days from the first vaccination in the primary vaccine series. Trotters born in 2020 or later are vaccinated for a third time in the primary vaccine series 120 to 180 days after the second primary vaccination. Subsequently, trotters are vaccinated every 12 months.
If vaccines are given more than 12 months apart, the programme must be reinitiated from the primary vaccine series.
Herpes: Reduces respiratory tract infections and abortions caused by herpesvirus (EHV 1, EHV 4). As the effectiveness of vaccines against infections is uncertain, it is important to vaccinate all horses in the stable to reduce the disease pressure. There are no vaccines against herpesvirus infections of the central nervous system. Horses can be vaccinated against herpesvirus by giving the first vaccine in the primary vaccine series at six months of age, after which the second primary vaccine is given four weeks later and the third three months from the second. After this, boosters are given at six-month intervals. Pregnant mares can be vaccinated against herpesvirus in the second, fifth and ninth month of pregnancy.
Rabies: Rabies is a viral disease of the central nervous system, and is most commonly transmitted through the bite of an infected animal. Rabies vaccination is recommended for horses travelling to countries where rabies occurs (e.g., Russia and eastern Europe).
Botulism: Protects horses against the disease caused by toxins produced by type B Clostridium botulinum bacteria. Because of its uncertain effectiveness and significance, the product is used only to a limited degree in Finland.
Systematic parasite control minimises the risk of parasites to equine health and the infection pressure caused by parasite eggs spread in the environment. Furthermore, it preserves the effectiveness of antiparasitic drugs and slows the development of antiparasitic resistance.
Many internal parasites have developed resistance to drugs, making drugs ineffective against them. Resistance is generated as a result of unplanned, frequent and long-term mass medication. In addition, insufficient drug doses can promote the development of resistance. Once present, resistance does not fade.
Parasite control plans are drawn up on the basis of manure samples, the living environment, and the health status and age of the horse. For adult horses, manure samples should be collected twice a year to check parasite status and vermicide effectiveness.
Horses are treated against the Strongylida suborder (e.g., small nematodes) if the number of parasite eggs exceeds 200 per gram (EPG). Horses diagnosed with eggs of a large nematode, equine roundworm or tapeworm are always treated with drugs. It must be taken into consideration in the parasite control plan that not all parasite eggs are visible in manure samples.
For the first six months, foals are treated more frequently than fully grown horses. Parasite control is initiated at roughly 10 weeks of age. In the case of horses under four years of age, parasite control measures often must be taken more frequently than in adults, as unlike adult horses they have not yet developed resistance against parasites. This is why for young horses manure samples should be checked three times a year.
The most common internal parasites in Finland are small nematodes (Cyathostominae), Strongylus vulgaris from among large nematodes, equine roundworms (Parascaris spp) and tapeworms (Anoplocephala perfoliata). In Finland, internal parasites cause health problems mainly in foals and young horses.
Small nematodes (Cyathostominae) are the most common internal parasite group in adult horses, but can occur in horses of all ages. Usually, the infection is asymptomatic.
Adult horses are usually resistant against the equine roundworm (Parascaris equorum), making roundworm infections rare among them. Because of the large size and effective egg-laying of the parasite, a high number of parasites can cause intestinal obstructions in foals. Other symptoms include coughing when larvae migrate to the lungs.
The larval forms of large nematodes (e.g., Strongylus vulgaris) can cause circulatory disturbances in intestinal blood vessels, which can result in colic symptoms.
Tapeworm eggs do not necessarily appear in manure samples, which is why grazing horses should be treated against tapeworms in the autumn. Strong tapeworm infections can cause colic symptoms.
The equine pinworm (Oxyuris equi) causes itchiness around the tail, as the parasites lay eggs close to the anus.
The intestinal threadworm (Strongyloides westeri) causes symptoms primarily in foals (diarrhoea, colic symptoms, slow growth and skin symptoms), as older horses are resistant against it.
The botfly (Gastrophilus spp.) is an insect that lays eggs in the horse’s fur coat, most often in the foreleg area, from which they travel to the horse’s stomach when the horse rubs its nose or mouth against the laying site. Botfly infections are usually asymptomatic, but can damage mucous membranes in the mouth, throat and stomach.