Regular worming is absolutely essential to ensure the health of your horse. Even small parasite burdens can be responsible for weight loss, diarrhoea and poor performance. More seriously, internal parasites are a major cause of colic, which is the single largest cause of mortality in horses.


How Do I Know If My Horse Has Parasites?



Most horses are exposed to some degree of infestation.


Visual Symptoms of Infestation:


- Weight loss
- Rough coat
- Poor general condition
- Signs of abdominal discomfort
- Anaemia
- Diarrhoea
- "Pot" Belly
- Tail Rubbing


However, these outward signs of parasite infestation are not apparent until the worm burden reaches significantly high levels and results in disease.

You can monitor the parasite level on the pasture through simple faecal egg counting techniques. Your veterinarian will be able to advise you on this procedure.

It is also a useful practice to check for expelled worms in the faeces following each anthelmintic treatment.

The only way to protect your horse adequately is to deworm regularly.


Which Internal Parasites Do I Need To Protect My Horse From?


Worms can be divided into two main groups, Roundworms (nematodes) and Tapeworms (cestodes). In addition to this Bots are also an internal parasite of horses (during their larval stages).

However, these outward signs of parasite infestation are not apparent until the worm burden reaches significantly high levels and results in disease. You can monitor the parasite level on the pasture through simple faecal egg counting techniques. Your veterinarian will be able to advise you on this procedure. It is also a useful practice to check for expelled worms in the faeces following each anthelmintic treatment. The only way to protect your horse adequately is to deworm regularly. Which Internal Parasites Do I Need To Protect My Horse From? Worms can be divided into two main groups, Roundworms (nematodes) and Tapeworms (cestodes). In addition to this Bots are also an internal parasite of horses (during their larval stages).

Intestinal threadworms (Strongyloides westeri)

Strongyloides westeri is another important parasite of foals. In pregnant mares the larval stages of this parasite can contaminate milk and infest suckling foals. As newborn foals have very poor immunity, adults quickly establish in the intestinal mucosa and begin blood feeding. This can soon cause the foal to suffer from anaemia and is another important reason why foals need to be wormed in the first two months of life.

Lungworms (Dictyocaulus arnfieldi)

The lifecycle of the lungworm is different to that of other nematodes as adults settle in the lungs (large bronchus) rather than the intestine. This adult stage only occurs in donkeys, however, horses that share pasture with donkeys will ingest eggs and are highly susceptible to the immature stages. When the immature stages migrate to the horse’s lungs they cause a wide range of respiratory disorders. Ivermectin is the only anthelmintic available that controls lungworm, so horses that are grazed with donkeys should be protected with a product such as Equimax® .

Adult bot flies are active over the summer months and lay eggs on the horse’s coat generally between late Spring and early Autumn. The eggs hatch and larvae are ingested by the horse when it licks itself. Larvae then grow and develop in the stomach of the horse and emerge the following spring when they are passed out in the faeces. These larvae develop into adult bot flies in 1-2 months to complete the lifecycle.

The presence of larvae in the stomach creates inflammation resulting in chronic gastritis, constipation and/or diarrhoea. Adult bot flies are a source of external irritation to the horse.