Chorioptic mange - Feather mites.

Chorioptic mites are something that heavy horse owners and heavy horses alike know all too well. They are difficult to get rid of and are a constant battle, always around and always easier to prevent rather than cure.

Heres an image for you from the British veterinary association journal of a chorioptic equus mite so you know what you are dealing with!

 

Chorioptic Equus. (No name given for the person who took this lovely picture - but thank you!)

The chorioptic mite lives on the skin surface and has a mouth adapted to chew at skin debris. They do not burrow into the skin and they do not bite the horse. Some horses do not show any signs of being infested whilst others show a reaction caused by inflammation and the horse can kick the back legs in a stomping motion, bite at the legs or body and rub areas raw. Although this is mostly seen on the lower legs, mites live in the mane and tail too and sometimes other areas on the body. This can lead to patchy areas of hair loss and scaly thickened skin which is then open to bleeding and bacterial infections and are by some believed to lead on to the awful disease CPL (Please see the page chronic progressive lymphedema.  for more information) if left so it is important to prevent infestation or treat them as soon as you are aware that your horse has them. All horses including those without clinical signs must be treated to stop re-infestations as must bedding, rugs, horse lorrys, stables areas etc.

In the UK and most other countries there are no products licensed to treat chorioptic mange.
The main ways people remove an infestation of mites are by using dectomax injections or fipronil spray. Both of these should be used under supervision of a vet and veterinary advice should be sought whilst treating your horse.

The Dectomax injection is an injection licensed for the treatment of certain ectoparasites and endoparasites (mites, lice, worms) in sheep and cattle, containing doromectin which is the same family as ivermectin which is in some horse (and dog) wormers. It is used off license to treat leg mites in horses. Often horses need two injections, given 2- 3 weeks apart. This is a reasonably effective treatment. It is quite oily and this is the main problem with its injection in horses - it can cause a lump at the injection site, which can be painful and in the worse case could develop into an abscess, though this is very rare. It is less likely to occur when the injection is given subcutaneously, but conversely hoses usually find intramuscular injections less painful. This injection must always be done under veterinary supervision. I found this extremely effective. In many countries this is done annually to keep mites at bay and stop infestation as well. It is becoming more regular in the UK and vets here are becoming more used to doing this with horses than they were 10 - 15 years ago.

Application of a spray containing fipronil (Frontline spray) to all legs as indicated by your vet can kill mites. It can be costly, difficult to apply properly and is also not its licensed use although in studies there have been no side effects found so far. I found personally that this did not make much improvement but in clinical tests it is shown as effective as dectomax injections. I would advise to wear a mask when applying this as well as covering arms and leaving your horse tied for around an hour after application because horses with mites will bite at the legs with their teeth and this was my main worry after application. You must spray the base of the mane and top of the tail as well when doing this treatment. You should respray after 2 weeks to make sure you also get all hatching eggs.

There are also specialist washes available now. These are licensed products for use on horses and should be tried first. These are available through your vet and are to be used under veterinary guidance. Sometimes dependent on your circumstances these may not be deemed a suitable treatment for your horse. Please phone your vet for more information on these.

Prevention
I have listed here so examples of products which can be used to help prevention of mites. I have also linked to some products which I personally use, there are of course other products available and this is not advertisement as I am in no way directly or indirectly associated with these companies and this blog does not make any money from advertising, this is just an example to help you if you need examples of the products on the market.

• The legs must be regularly washed and dried thoroughly. A Castile soap (100% olive oil soap) is recommended by many as it is non drying but also oil based and does not contain chemicals if it is a true castile soap. olive-oil-soap-125g

• Parasite shampoos are available such as barrier pesky pest wash linked here shampoos and many others are also available in shops and through your vet.

• When drying the feathers they should be dried using wood flour or sawdust. Not rubbed into the skin which could cause sensitivity with any lesions but gently thrown around the leg from above to dry thoroughly the hair on the legs. 

• Pig oil and sulphur can stop mite infestation and keep scratches and pastern dermatitis at bay please click the link to the page what is pig oil? for more information on this. As most mites are also found in the mane and tail these areas should be treated too.

• Coopers fly repellent plus, which also kills lice is also good at preventing an infestation of mites has instructions on use which should be followed closely. Please read the instructions for more details. intervet-fly-repellant-plus-coopers

• Lincoln insecticidal louse powder is a permethrin based powder with low mammalian toxicity good for stables and animal houses, rugs and bedding and is the only louse powder which kills mites - it is not for use directly upon horses or other animals. I always put a coating of this over my winter rugs before they go into storage over the summer this way I know they will be mite free come winter I also use this regularly around the stable edge when I change my bedding as a preventative. general-care

• Keeping a regular worming routine can stop mites. It has been reported that oral Ivermectin based wormers which active ingredient is Ivermectin can be effective (worming the horse at a standard dose as with usual worming based on the weight of your horse and after reading all the advice on age and usage of that particular wormer- if in doubt please contact your vet for advice). This is using a drug which is known to be safe and is licensed to be given to horses but for a purpose for which it is not intended and so may not be effective. 

Other reading material for this topic.

http://www.equinescienceupdate.co.uk/choriopt.htm