Tackling Feather Mites

Everything you need to know about Feather Mites
From a thesis on CPL and chorioptes spp. by Kaat Deleux

Feather mites – what are they and how can we get rid of them?

“Treating feather mites is like a day task” is something I hear myself say a lot as I prepare myself to treat my 4 horses and their environment. It is very labour intensive and can be especially hard in winter with colder temperatures and muddy conditions. Let me sum up some facts that people usually don’t know about Chorioptes spp. Because before you treat any parasites, you should know their life cycle.

Chorioptes mites are surface-living parasites. They’ll only penetrate the epidermis (upper skin layer) when the disease becomes chronic. In some cases they can pile up under crusts, making them unreachable by topical antiparasitics.

– The life cycle takes about 3 weeks and is completed on the host. Adult mites can survive off-host for nearly 70 days depending on the presence of skin debris as a food source and the local environmental conditions.

– They feed on skin debris (crusts, dandruff), which means mites are attracted to the feathers because of the hyperkeratosis feathered horses tend to have.

Chorioptes scabies isn’t a zoonotic disease, which means they won’t complete their life cycle on humans.

– Mite populations are usually larger in cold weather conditions. Warm and dry circumstances will lower the survival rate of mites. Usually symptoms will be less severe in summer. In this case they’ll be found mostly around the coronary band.

– Mites seem to be more active during the night, which can cause restlesness and irritation in horses.

– Horses can be asymptomatic carriers.

– Mites move incredibly fast and are very active, thus vets usually have to put some sort of antiparasitic in their mineral oil to keep them still when viewing them under the microscope.

So, what are some clues here? What can we learn from this when treating against mites?

Chorioptes infestations are mostly seen in feathered horses because the feathers cover the damp, enclosed skin surface and protect the mites from extreme temperatures creating the ideal environment! This proves the importance of keeping legs dry and feathers short.

– Removing crusts, dandruff and skin debris is important as they are the nutrition for the mites.

– ALL horses that come into contact with a horse that has clincal symptoms need to be treated!! Asymptomatic carriers can simply reinfect the treated horse, making the treatment useless.

– Because the mites move so fast, it is important to treat the WHOLE body when using a topical agent as they can migrate to other body parts quickly.

– Because the mites live on the surface, systemic antiparasitics don’t work that well. Studies have shown that the mites are never fully eliminated when injecting doramectin (Dectomax) subcutaneously or giving ivermectin orally. They are actually unsure to what extent these systemic endectocides even reach the hair and crusts on the legs, where the mites live.

– Topical antiparasitics are labour intenstive but proven effective. Clipping feathers will make sure the agent reaches the mites better. Even clipping itself could make improvements as some mites will be physically removed from the hairs and skin crusts exfoliated.

Chorioptes spp. mites can survive in the environment on hair and dandruff for nearly 70 days. Therefore stables, brushes and other infected material need to be treated too. You could also simply not use the infected material/tack for a minimum of 4 weeks.

– Topical treatments will not destroy the eggs. The eggs hatch after 5-6 days which is why you’ll need to repeat treatment after 7 days.

How do I know that my horse has feather mites?

Symptoms are usually pretty clear with the horse stomping, biting and itching their legs against objects. But ideally, superficial skin scraping, combing with a fine comb and letting the skin debris fall in a petri dish or acetate tape impression should be performed to make sure it is mites causing the itchiness and not the CPL itself. Multiple tests should be performed as they can be negative. Also test after treatment to ensure they’re gone.

Actual diagnosis based on real evidence is important as registered antiparasitics against Chorioptes spp. are limited. This could become a big issue, as the mites could become resistant leaving us with even less treatment options. This is also the reason why you shouldn’t treat too often or as a preventive measure. Another reason why you shouldn’t overdo treatment is because the lymphatic system and circulation in horses with CPL is already very poor. Putting more stress on it with aggressive treatments isn’t ideal.

Thank you for reading! It is important that we start treating our horses correctly, just like we’re getting more aware of the usage of antibiotics and dewormers. It is shocking how many people treat their horses incorrectly – and I used to be one of them because I was misinformed. Based on my survey with a population of 45 people, only 20% treated their horses fully correctly… Knowledge is power.”

Kaat Deleux, Hogent Belgium graduate 2020, Bachelors Degree in Bio- and Agri-technology with a special interest in CPL and feather mites.

Treatment options

Below is the table from Kaat’s research. Always consult your vet – these are not recommendations, simply a table of findings about the products.

“Generally any acaricide safe to use on animals will do the job. Please contact your vet before administering any of these products. Ask for a skin scraping pre- and post-treatment. Remember to treat ALL horses that come in contact with the infected horse and treat brushes, tack and environment simultaneously. NEVER use Amitraz.”

Kaat Deleux
Feathered horses are more prone to mites but non-feathered horses can have them too, just to a lesser degree so they may be asymptomatic. (Photo credit Jeri Uhrich).
The thicker and heavier the feather, the better the mites are protected from the elements, and the more hyperkeratosis there is for the mites to feed on.
Clipping the legs doesn’t just help by removing the hair – it also exfoliates the skin crusts caused by hyperkeratosis, making treatment easier and more effective.
Under the microscope – a feather mite chrorioptes spp.
Kaat recommends Maxani Honey Complex and Hydralax Spray for cleansing and protecting the legs when clipping
Horses with mite infestations can self-injure by scratching or chewing their legs and stamping their feet. This is especially important to avoid in CPL horses due to the increased risk of infection and reduced healing ability.
Symptoms may be worse in winter as mites prefer lower temperatures.
Photo by Anthony on Pexels.com
Topical antiparasitics are labour-intensive but proven effective.
It’s a good idea to also treat your horse’s stable, grooming kit and rugs.

Never use a Mites treatment without your consulting your vet and always do a patch test

How to use Lime Plus Dip

Moxidectin

A study in 2011 found that moxidectin combined with environmental treatment was not effective.

“Follow‐up examinations over a period of 180 days revealed significantly more skin crusting in the placebo group than in the treatment group. However, no other differences in clinical signs or the numbers of mites detected were found between the two groups. The results of this study suggest that moxidectin in combination with environmental insecticide treatment as used in this study is ineffective in the treatment of C. bovis in feathered horses.

Combined moxidectin and environmental therapy do not eliminate Chorioptes bovis infestation in heavily feathered horses
Silvia Rüfenacht Petra J. Roosje Heinz Sager Marcus G. Doherr Reto Straub Pamela Goldinger‐Müller Vincent Gerber

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