Parasites in horses - the most common pests

Like many other animals, horses are not immune to parasites. They are ideal hosts for many parasites due to their habitat in stables, sometimes with other conspecifics, feeding on meadows and pastures and riding out. While most ectoparasites rarely cause serious illness in horses, endoparasites can be very harmful in horses. Lice, worms and the like are sometimes active all year round and feed extensively on the fluids and tissues of your four-hoofed friend. We have put together an overview of the most common parasites in horses, how the animals become infected and how you can help to quickly eliminate the parasite infestation.

Ectoparasites - parasites in the horse's coat

Horses are coveted hosts for numerous ectoparasites due to their year-round outdoor living. By grazing in the pasture, they come into contact with many pests and serve as a food supply for one or two arachnids. The most common ectoparasites in horses include hair lice and lice, mites and also the not entirely harmless ticks.

Hair lice / animal lice

Hair lice and lice are among the most common ectoparasites in horses. While the sucking louse sucks the animal's blood with its sting and feeds on it, the hair louse bites into the horse's coat and skin. They prefer to feed on dander, hair and tissue. The parasites are very prolific and lay up to 150 eggs in their short life of around 1 month.

Infection with lice and hair lice in horses

These ectoparasites are particularly active in the cold season as they seek protection from the weather. Lice and hair lice attach themselves to the horse's mane and tail and hibernate during the cold months. Infection with the pests can occur more quickly, especially in damp and cramped stables. In addition, immunocompromised and sick animals are much more susceptible to infestation. Due to their activity on the horse's skin, the pests cause the animal to feel restless, which can lead to noticeable changes in behavior.

Symptoms

Although hair lice and lice hardly cause any signs of illness, they can have an effect on your four-legged friend's behavior.

• Itching and restlessness
• Wounds due to severe rubbing
• Secondary infections with bacteria
• Patchy coat
• Alopecia (hair loss)
• Dandruff formation

Diagnosis and treatment of hair lice and lice

The advantage of a louse and hair lice infestation is that you can easily see the adult animals and their nits directly in the fur or on the skin of the animal with the naked eye. If you brush the animal and then tap out the brush on a white cloth, you can see the light brown parasites and their eggs on the cloth.

If there are lice and hair lice in your horse's coat, you should act quickly. This is because the pests limit your pet's well-being and put him under stress. The animal should be brushed regularly to curb their spread. A special product against lice and hair lice can drive the parasites away more effectively. You can also use natural products such as coconut oil. You should also disinfect the sore areas and apply nourishing oils. This protects the animal's skin from drying out and stimulates skin regeneration.

It is particularly important to clean the horse's equipment and stabling area to prevent the spread of parasites.

Mites / Autumn grass mites

Mites are arachnids and have over 50,000 subspecies. They are very adaptable and live not only on hosts, but also in the soil, in textiles and of course in the immediate vicinity of a potential host. Mites feed on the horse's body scales, fluids and other tissues, but also on plants, carrion and fungi. As they are active all year round, they pose a permanent threat to the animal. Above all, mange, which is no longer so widespread today, is caused by mites.

Infection: mites in horses

Horses can be infected with mites all year round, but an outbreak of severe symptoms depends on the horse's health and the number of mites on its body. Carriers are, for example, other horses or birds. As these pests are very adaptable and robust, they can survive on your animal or in its environment for a very long time.

Symptoms of mites in horses

• Itching
• Restlessness of the horse
• Dandruff formation
• Behavioral abnormalities: stamping feet, biting and rubbing pasterns
• Crust formation

With severe infestation

• Inflammation
• Bald, reddened areas on the body
• Hair loss
• Secondary infections with bacteria
• Mauke and fungal infestation
• Weight loss

Diagnosis and treatment of mites

Mites often infest the horse's legs, but all other areas of the animal's body are not spared either. Ear mites in horses are a particular burden for the animal. If an infection with these annoying parasites is detected in the horse, action must be taken quickly. Treatment is primarily carried out with an anti-mite agent. These are also available on a natural basis; ingredients such as eucalyptus citriodora oil and geraniol have proven to be particularly effective.

It is also essential to disinfect the bridle and saddlery, as well as to disinfect all stalls and treat other animals. As mites mainly spread on immunocompromised animals, the animal's immune system should be strengthened in a natural way. Malnutrition can be compensated for and a new infestation of mites can be prevented.

Ticks

Ticks are not harmless for horses either. These annoying bloodsuckers can transmit serious diseases, some of which require lengthy treatment. Their preferred territory next to the host are clearings, banks of streams, wetlands and the edges of forests. They mainly live in tall grasses and low bushes. Horses brush off the parasites while riding or the beasts simply attach themselves to the animal and bite.

Infection: tick bites on horses

In horses, ticks like to attach themselves to thin layers of skin and to places where they can absorb the blood of the four-hoofed animal undisturbed. They need this primarily for reproduction. A tick bite in itself has no major consequences for your horse. However, if the tick is infected with bacteria that transmit diseases such as Lyme disease, it can even be life-threatening for the animal. Other dangerous transmission diseases for horses are ehrlichiosis or piroplasmosis. These are sometimes accompanied by unspecific symptoms and can even become chronic.

Symptoms of tick infestation in horses

Ticks are visible to the naked eye on animals. They can simply be pulled out with the appropriate tool. However, if your horse shows symptoms of illness after some time, you should consult a vet. Possible signs of infection after a tick bite are

• reluctance to move
• fever
• Lameness and stiffness
• Pain in the limbs and muscles
• Reduced performance
• Fatigue
• Disturbed coordination of movement
• Lack of appetite
• Bleeding in the mucous membranes
• Weight loss
• convulsions
• epileptic seizures

If some of these symptoms occur in your pet, bacteria may have been transmitted by the tick. The vet can make an accurate diagnosis.

Diagnosis and treatment of ticks

The only effective way to detect ticks on horses is to regularly palpate the body. In particular, areas inaccessible to the horse should be checked for bloodsuckers. If ticks are found on your horse, you can simply remove them with tick tweezers. Grasp the tick as close to the skin as possible and pull it straight out.

Caution: Do not squeeze the tick or treat it with any other means, as it may otherwise release its entire intestinal contents into the animal at once.

You should also disinfect the bite site; a wound ointment can help it to heal more quickly.

Endoparasites - worms in the horse's body

Neither horses nor horse owners are happy about an infestation with endoparasites, as the nasty worms and larvae can sometimes cause serious damage to the body of our four-legged friends. However, an infestation with worms in horses is not that rare. They can quickly become infected while grazing in the pasture, in the stable or from other animals and may not even show any symptoms for months. Regular worming is therefore essential, especially for horses. This should be carried out several times a year. Natural herbs such as sage, wormwood and thyme are suitable supplements. They can strengthen the immune system and have an antibacterial effect. If worms are diagnosed in horses, immediate action should be taken to alleviate the symptoms of the disease and prevent further infections.

Tapeworms

Tapeworms are long white flatworms that are intestinal parasites and settle in the horse's intestines. According to scientific studies, they occur in up to 80% of horses, but rarely cause severe illness. The most common type of tapeworm in Germany and Europe is Anoplocephala perfoliata, others make up less than 3%.

Infection with tapeworms

Tapeworms in horses are comparatively rare. The animals mainly become infected with the parasites in the second half of the year, as infection with tapeworms is only transmitted by moss mites as an intermediate host. Moss mites are found in increased numbers, especially in late summer and early fall. Pastures and wetter areas are their preferred habitat. When grazing, horses ingest infected moss mites and thus swallow the eggs and larvae of the intestinal parasite. The tapeworms eventually colonize the area between the small and large intestine and feed on the food supplies of the intestine by attaching themselves to the intestinal wall.

Symptoms of tapeworms in horses

If your horse is infected with tapeworms, symptoms rarely occur. Only if the infestation is excessive does the horse show signs of illness:

• dull coat
• colic
• diarrhoea
• emaciation
• Inflammation of the mucous membrane in the appendix

With severe infestation

• Ulcers in the intestine
• Inflammation of the mucous membrane
• Blockage of the intestine by the parasites

Diagnosis and treatment of tapeworms

The diagnosis of tapeworms in horses is made by means of a fecal examination. If an infection with these parasites is present, eggs or proglottids (tapeworm limbs) are found in the animal's feces. However, tapeworm eggs are only excreted irregularly in the stool, so a negative result may still indicate an infection with the endoparasites. Fecal samples should therefore be collected and examined over several days.

Regular deworming of horses, several times a year but at least twice a year, can successfully contain the spread of worms. Natural prebiotics can be given to stabilize the gastrointestinal tract after a worm infestation in horses.

Roundworms

Roundworms are threadworms and are found all over the world. They grow up to 50 cm long and are therefore one of the largest endoparasites in horses. According to studies, roundworms occur in up to 80% of foals and young animals. Adult horses, on the other hand, are less affected as they develop immunity over time. Although they can still become infected, they have milder symptoms.

Infection with roundworms

Roundworm eggs are highly contagious and very resistant. They also survive harsh weather conditions. Horses usually become infected with roundworms in the environment. However, your animal can also catch these parasites from contaminated feed. The four-hoofed animal orally ingests the larval eggs of the worm, which hatch in the small intestine and feed on the intestinal mucosa. Via the blood and lymphatic system they reach the liver and finally the lungs, where they are coughed up and swallowed again. They then return to the intestinal tract and are excreted in the feces.

Symptoms of roundworms in horses

The symptoms of roundworm infestation are usually similar to bronchitis and are therefore non-specific:

• Increased accumulation of mucus in the bronchi
• coughing
• fever
• Reduced performance and growth in foals
• Lack of appetite

With more severe infestation

• Increased bacterial and viral infections
• Chronic intestinal inflammation with diarrhea and emaciation
• Colic symptoms

Diagnosis and treatment of roundworms

Roundworms in horses can often be recognized in the faeces when the adult worms are excreted. Otherwise, if suspected, a fecal examination is carried out to identify the presence of eggs or larvae in the horse's stool. If there is no evidence of roundworms in the feces, the horse may still be infected with worms, they have just not yet been excreted . Examinations of horses infected with this intestinal parasite have also revealed bleeding in various organs and nodules in the lungs.

Once a roundworm infestation has been confirmed, the animal must be dewormed with the appropriate deworming medication, several times if necessary. In addition, all other horses in the immediate vicinity should also be given a worming treatment. Disinfection of the stables is also recommended in the event of an infestation.

Strongylids

In Germany, two types of strongylids are particularly common in horses: large strongylids and small strongylids. The large strongyles are among the most dangerous parasites for horses in Germany and Europe. The small strongylids, on the other hand, especially the cyathostomine species with its 40 subspecies, are also relatively common in horses, but cause less damage.

Strongylids are mainly found in young horses up to 6 years of age, but even adult horses are not immune to these parasites and can become infected at any time. Horses that graze are also at a higher risk.

Infection with strongyles in horses

Horses usually become infected with the eggs and larvae of this parasite when grazing in the pasture. They are barely visible to the naked eye and are infectious all year round. While cyathostomins are a non-migratory species and pass through their developmental stages in the intestine, the large strongyles migrate through the bloodstream and organs such as the liver, pancreas and kidneys until they lay their eggs again in the intestine. These migrating larvae make it difficult to make a clear diagnosis and can therefore cause serious damage to the horse's body. If treatment is delayed, infection with large strongyles often leads to death. This is because the adult strongyles feed on the intestinal mucosa, causing damage to the intestinal wall.

Symptoms of strongyles

The most common symptoms after strongylid infestation are

• Diarrhea
• Weakness / lethargy
• Weight loss and emaciation
• fever
• anemia
• oedema
• Colic symptoms

In advanced cases of infestation:

• Thrombosis
• intestinal necrosis
• Intestinal ruptures

The symptoms of strongyles in horses are often non-specific. This makes a clear diagnosis difficult. Even with possible intestinal infarctions as a result of this parasite infection, the horse does not necessarily have to show pain reactions.

Diagnosis and treatment

A diagnosis of large strongyles is usually made on suspicion. A fecal examination can only confirm the infection in a few cases, as strongylid larvae are simply not identifiable in the feces as they remain in the intestine. Therefore, many findings can only be made after the horse has died on the basis of a pathological examination. Small strongyles, on the other hand, are found in the form of adult red worms in the horse's feces.

If there is a suspicion of an infestation with this parasite in the horse, a special worming treatment against strongyles should be used. Moxidectin is a common and promising active ingredient. In addition, intestinal rehabilitation including fluid therapy is recommended due to the severe loss of nutrients. This allows the intestinal mucosa to be rebuilt and the horse receives the most important nutrients.

To prevent this parasite, a strongylid worming treatment should be carried out at least once a year; this is best done in late fall and winter, as horses graze the least at this time of year. As it is mainly young horses that become acutely infected with the parasites, the treatment should be carried out at foal age. If an infestation of strongyles is known, all other horses must also be dewormed for this parasite.

Horse flies

Horse flies (Oestridae), also known as bot flies, are bumblebee-like, brown flies with a light coat of fur. They are in high season in Germany, especially in warm temperatures, usually from June to September. Bot flies produce eggs from which the larvae, known as gizzard flies, hatch in the host. They often infest grazing animals in the pasture.

Infection with stomach flies in horses

The flies lay their yellowish eggs on the horse's hair coat or nostrils by quickly approaching them. The legs, shoulder blades and flanks of the animals are usually affected. The horses lick off the irritating eggs and swallow the parasites. They enter the horse's stomach through the throat and attach themselves to the mucous membrane.

Symptoms of stomach woodlice

Stomach fluke larvae can cause a great deal of damage in the stomach and cause severe pain in the animal. The larvae cause symptoms both in the throat and in the stomach.

• Inflammation of the gums
• Irritation of the palate
• Difficulty swallowing when the larvae are in the throat area
• Pain
• Deteriorated feed intake
• Possible stomach and intestinal ulcers
• Chronic gastritis
• diarrhea

Diagnosis and treatment

The eggs of the botfly are very easy to recognize on horses. An inspection of the coat and the individual limbs can already provide information about an infestation with the eggs. Eggs found in the horse's coat should be removed as quickly as possible. The Dassel knife is a good tool for this.

A gastrointestinal endoscopy is necessary to identify stomach worms inside the horse. However, regular worming of the horse is usually sufficient to reliably remove the larvae of these parasites. Deworming should be carried out in late fall, as the flies are no longer active in winter.

Conclusion

Horses can also be infested by numerous parasites. The most dangerous of these are large strongyles, which can lead to death if treated too late, infected ticks, which transmit other diseases such as Lyme disease, and roundworms, which develop indefinitely in the horse's intestines. Effective and thorough stable hygiene, regular worming and strengthening the horse's immune system can prevent infections and reduce possible long-term consequences in the horse.