Does your horse back up to objects and itch its legs?
Does your horse stomp their feet?
Your horse could be suffering from feather mites.
Feather mites are caused by a Chorioptic mite that likes to feed on skin debris from the legs of horses. They hide in the feathers and there are reports of them surviving for up to 70 days on or off the horse.
Mite size: 0.3mm
Mite life cycle: 3 weeks
Mite sprint speed: Very fast 😊
Where are they found?
Any horse can have feather mites, however the feathers on horses legs help to keep the mites warm through the winter months, hence feathered legs horses harbour the highest population of the mites.
Do not forget, the mites can also survive in the environment on objects such as fence posts, stables and bedding
Symptoms:
Itching is caused by crawling mites, however, not all horses respond as dramatically. Some horses can have mites without any symptoms.
Another very obvious symptom is dandruff like flakes at the skin surface and through the feathers: Mites feed on this scurf and it can be quite dramatic in chronic cases.
If a horse is very itchy, they can self mutilate and scabs and bleeding can be seen.
Treatment:
Treatment options are varied, but sadly none are licensed in NZ. Studies have been performed, so we have several good options including drugs which act systemically, and also drugs which are applied topically.
In addition there are topical products that can act alongside drugs to help in reducing re-infection.
Due to the life cycle of the mites, it is very important that treatments are repeated to ensure the mites from the hatched eggs are treated which can happen 7-10 days after initial treatment.
Do not forget the environment; treatment options are available for this also.
Will my normal wormer kill mites?
It has been shown that wormers, despite having the correct ingredient to kill the mites, do not reach a high enough concentration at the skin to be effective to reduce mite numbers to zero.
Helpful tips
1: Some horses are hypersensitive/allergic to the mites: This means even a very small number of them can cause severe itching/irritation.
2: Clipping away the feathers with not cure the issues; it can however make some topical treatments easier to apply and increase the kill rate during winter months.
3: In chronic cases of feather mites, thick crusts of skin flakes can form at the back of the knee; this is called Mallanders.
4: Given the ability of the mite to survive in the environment, re-infection poses a significant risk and full eradication is near impossible in many instances.
5: Non-clinical carriers are a likely source of re-infection.