Parasites (7)
Equine tapewormsPhoto kindly provided by University of Liverpool Diagnosteq Lab Most horses will be exposed to tapeworm . A horse can become infected at any age; however tapeworm tends to have a bigger impact on very young and very old horses as their immune systems are not as robust.
It is impossible to be certain of infection rates due to the difficulty in detecting infection but studies suggest up to 69%1.
Light infection is common and if limited is unlikely to produce any clinical signs.
In more severe infections they may display some of the following clinical signs:
- Diarrhoea
- Dull Coat
- Poor Growth
- Intermittent Colic Episodes
- Poor performance
- General Lethargy
- Ulceration of the GI lining
- Colic
- Obstruction
- Rupture
- Anaemia
- Un-thriftiness
Diagnostics & Treatment of Tapeworm
We know from the tapeworm life cycle that when the tapeworm sheds its eggs they are dispersed in a segment of its body called the proglottid.
If the proglottid remains intact then no eggs will be found in the faeces in spite of the horse being infected. As a result, tapeworm eggs are rarely detected in faecal egg counts (FEC) even if the horse is infected.
As a result, there are two options - assume the horse is infected and treat periodically (Spring and Autumn) or request a tapeworm antibody ELISA test which can be carried out on blood or saliva.
ELISA Antibody Test
The best approach is to carry out a test called an ELISA antibody test. When a horse becomes infected with tapeworm it will produce antibodies to try and protect itself. The ELISA test is capable of detecting these antibodies.
It could previously only be carried out on a blood sample but can now be carried out on saliva making it much more accessible and cost effective. The antibodies persist for months after an infection so a positive result tells us that the horse has been exposed to tapeworm recently. A positive result and a lack of recent tapeworm treatment allows us to assume that the horse is infected.
Treatment
Ideally, you should carry out an ELISA test before treating for tapeworm to help protect our wormers from resistance.
If you are unable to test you should carry out tapeworm treatment once in the Spring and once in the Autumn.
Which Actives Treat Tapeworms?
| Ivermectin | Moxidectin | Ivermectin / Praziquantel | Moxidectin / Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
| * |
*A double-dose of pyrantel is required to effectively treat tapeworms
Large Strongyles (aka Large Redworms)There are three major species of Large Strongyles, which are Strongylus vulgaris, S edentates, and S equinus. Of these, the most common is Strongylus vulgaris.
The large red worm (strongylus vulgaris) is a very serious parasite but is thankfully no longer very common.
The eggs are ingested by the horse and once hatched, they burrow into the walls of the gastrointestinal tract.
Migration through the blood vessels occurs, until mature, and can cause massive internal damage before they return to live in the intestinal wall. Large Strongyles are blood feeders and they ingest mucosal plugs as they move through the intestine. Anaemia can result from this blood loss.
Heavy infection can result in:
- Ulceration of the GI lining
- Obstruction
- Rupture
- Anaemia
- Un-thriftiness
- Weight loss
- Diarrhoea
- Colic
Large Strongyles can be extremely dangerous to the horse. However, low resistance levels mean that control is relatively straightforward.
Which Actives Treat Large Strongyles
(aka Large Redworms)?
| Ivermectin | Moxidectin | Ivermectin / Praziquantel | Moxidectin / Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
(cyathostomes spp}
Cyathostomes spp infestation in small intestine El parásito más común en equinos es el Cyathostomes Spp (pequeños estróngilos) el cual puede conducir a fuertes infestaciones de vermes rojos y daño a la mucosa del intestino grueso si no es tratado.
Cuando son ingeridas, las larvas penetran la pared del intestino. Se desarrollan y emergen para continuar su ciclo de vida o permanecen en la pared del intestino en estado de hipobiosis (similar a hibernación).
Cuando la temperatura aumenta durante la primavera, las larvas hipobióticas pueden todas emerger a la vez y causar severos daños a la pared intestinal causando perdida de peso, diarrea, shock e incluso la muerte del animal.
No se puede probar directamente la presencia de larvas hipobióticas en la pared intestinal y solo ciertos antihelmínticos pueden usarse para el tratamiento de estas larvas hipobióticas.
CICLO DE VIDA PEQUEÑOS ESTRÓNGILOS
- El caballo ingesta pasto el cual contiene larvas infestivas (L3).
- Las larvas entran en la mucosa del intestino grueso. Una vez en la mucosa, entran en estado de hipobiósis (similar a hibernación) en forma de quiste y emergen después a la luz del intestino como L4, o inmediatamente pueden emerger en dicho estadío. Hay un alto riesgo de daño por un número alto de larvas enquistadas L4 emergiendo desde la mucosa al mismo tiempo.
- La larva L4 se desarrolla y ovoposita en el intestino.
- Los huevos salen del caballo junto con las heces.
- Los huevos en las heces se desarrollan primero a L1, después a L” y finalmente a la forma infestiva L3.
- La larva se mueve hacia el pasto.
- El caballo ingiere el pasto y el ciclo comienza de nuevo.
¿Qué ingredientes activos funcionan contra los pequeños Estróngilos?
| Ivermectin | Moxidectin | Ivermectin/Praziquantel | Moxidectin/ Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
| * |
Nota: Una infestación de vermes rojos puede conducir al daño de la mucosa intestinal si no es tratada.
¿Qué ingredientes activos funcionan contra los pequeños Estróngilos enquistados?
| Ivermectin | Moxidectin | Ivermectin/Praziquantel | Moxidectin/ Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
| ** |
Nota: **Si utiliza febendazol contra larvas enquistadas, se requieren 5 días de tratamiento.
(Dictyocaulus Arnfieldi)
Lungworm can cause coughing and respiratory difficulty in horses, although they are relatively uncommon. These worms are common in donkeys and easily transfer to horses grazing the same pasture.
Horses become infected by eating the worm larvae from the pasture. The larvae will then move to the lungs, where they become adult. These adults, living in the airways, can cause obstruction leading to coughing and breathlessness. The adults lay eggs which are coughed up and swallowed to then be passed out in the droppings; thus continuing the cycle.
Faecal egg count and a variety of other diagnostics can be carried out by a vet if this is suspected and an appropriate treatment determined.
Which Actives Treat Lungworms?
| Ivermectin | Moxidectin | Ivermectin / Praziquantel | Moxidectin / Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
(Oxyuris Equi)
Adult pinworm emerging to lay eggs
The pinworm is a relatively harmless parasite which lives in the large intestine and passes out of the anus to lay its eggs.
The pinworm is a grey/white worm with a long tail, which tapers to a point. While the male is significantly smaller, the female pinworm can reach up to 20cm in length.
Although pinworms live in the large intestine and colon, the adult worm emerges at night to lay eggs on the skin around the rump. After laying her eggs, the female pinworm will then return inside the rectum. A female pinworm can lay up to 60,000 eggs per day.
Pinworm infestations commonly occur in horses older than 18 months, but rarely cause the animal major problems. Unlike many other worms, the pinworm will not cause damage to the horse's digestive system, nor will it cause other internal damage. However, they will cause significant irritation.
The pinworm can cause severe itching around the anus which can occasionally lead to self-trauma.
Biting and licking of hindquarters may also be observed. There are no eggs on faecal examination. However, eggs may be seen in a gelatinous mass around the anus.
Sellotape can be gently pressed on the skin around the anus to pick up eggs and if present a number of treatments can be used.
No eggs will be found on a faecal worm egg count as the adult female worm crawls out of the anus to lay eggs.
Pinworms cause irritation to the horse. Look out for rubbing of the rear end against fences, which can result in damage around the anus.
Which Actives Treat Pinworms?
| Ivermectin | Moxidectin | Ivermectin / Praziquantel | Moxidectin / Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
Bot eggs
The bot (stomach worm) is not a worm but the larvae of Gasterophilus flies.
The adult horse bot fly emerges a during the summer or fall season. After the fly emerges from the pupa, it quickly finds a mate, lays the eggs on the horse's coat and, on grooming, the eggs make their way to the mouth where they hatch in mouth as larvae.
Over winter the larvae burrow into the stomach lining (where they spend 8-10 months) and are then passed out via the faeces and will hatch in the summer.
Significant trauma and ulceration of the stomach can occur following infection.
Disease is also caused by the larvae in mouth. Larvae here create borrowing holes, which in turn become infected. The 3rd stage larvae are passed in the faeces and over winters to develop the following summer.
Infected horses can often show no signs, which is why treatment should be given over the winter months to kill them.
Bots fly larvaePhoto kindly provided by University of Liverpool Diagnosteq Lab
Which Actives Treat Bots (Stomach Worms)?
| Ivermectin | Moxidectin | Ivermectin / Praziquantel | Moxidectin / Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |
Large Roundworms (ascarids)Photo kindly provided by University of Liverpool Diagnosteq LabAscarids, (also known as roundworms) are parasites which are mainly a problem to foals. However, small numbers can also be carried by adults.
The adult worms are very large and can be up to 40cm in length. Once the larvae of this parasite are swallowed, they pass through the gut wall, via the liver to the lungs. Heavy infestations can cause coughing as the larvae travel through the lungs.
Adult worms can cause intestinal impaction. They pose a considerable threat to young horses and their developing immune systems, and they have to potential to kill by triggering colic. Even if a young horse escapes colic, a heavy ascarid burdened young horse will appear depressed and its normal growth will be affected.
The most common ascarid to infect horses is Parascaris equorum.The eggs laid by the large females pass out into pasture protected by a tough shell which equips them well for survival. They can withstand drying conditions and even freezing; waiting for that moment when a passing horse ingests them with grass.
Symptoms of Ascarid Infection In Foals
It goes without saying that the migratory habits of ascarids cause damage. However, the impact of ascarids in the horse will depend upon the degree of infection and the whether the larvae are in their migratory phase.
- When migrating, a horse may well show signs of respiratory problems. It may have a nasal discharge or a cough and possibly a fever. Antibiotics will make no difference as they are not effective against ascarids.
- A heavy burden in the gut will likely show in the classic signs of a poor coat, a loss of weight, a pot-bellied appearance and sluggishness.
- Ascarids present one other notable danger. Their size is such that collectively they have the ability to block the intestinal tract of a young horse and trigger a potentially fatal bout of colic.
Ironically, this colic can be triggered by a dose of drench. The worms are killed, fall away from the intestinal lining and cause a blockage. This is the primary reason that you not only need to drench young horses, but do so regularly to ensure there is no potentially fatal build-up of mature ascarids in the gut.
Symptoms of Ascarid Infection In Adult Horses
Adult horses are symptomless but can carry them and provide a reservoir for infestation to foals.
Which Actives Treat Large Roundworms (Ascarids)?
| Ivermectin | Moxidectin | Ivermectin/Praziquantel | Moxidectin/ Praziquantel |
|---|---|---|---|
| Pyrantel | Praziquantel | Fenbendazole | Mebendazole |