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The JourneyMy story started in 2007, withan alpaca that had been treatedunsuccessfully for Sarcopticmange over a two-year period.Repeated skin scrapings werealways negative for mites, andyet the symptoms were there.The herd-mates all seemed prettynormal, though eventually a couple of them showed a bit of a scaly area between the toes.A skin scraping from the toe area revealed a single mite. As I studied the mite under themicroscope, it did not lookexactly like a Sarcoptes mite. I consulted textbooks and cameto the conclusion that it must be Chorioptes. I sent the slideout to a parasitologist, who confirmed my suspicion that itwas indeed Chorioptes bovis.Chorioptic mange can affecthorses, cows, and (rarely) sheepand goats, as well as alpacas.Unlike Sacrcoptic mange, it does not affect humans.

Well, now I had a diagnosis. I just needed an effective treat-ment. I consulted with variouscamelid experts, parasitologists,and a veterinary dermatologist.The consensus was “This stuff is really hard to treat.” Nothingseemed to work very well.Injectable ivermectin sometimesreduced the number of mites,but never completely eliminatedthem. The various “Witch’sBrew” mixtures were often usefulin the short term, especiallywhen there were secondary infections present, but the lesionsalmost always came back eventu-ally. Pour on treatments such as Eprinex® and Frontline Plus®

had also been tried withoutmuch success. One clinicianmentioned lime sulfur dip. I had used lime sulfur dip yearsago on kittens. It was smelly andmessy and a lot of work. Theidea of using it on a whole herdof alpacas was not appealing, so I kept it in the back of my headas a last resort and kept looking.

A veterinarian from MerialTechnical Services found somearticles that had been publishedin the UK concerning the use of fipronil on Chorioptic mangein horses and camelids. I decidedto try it and it worked very well.As time went on, I saw otheranimals at other farms with similar symptoms. Diligent skinscrapings turned up Choriopticmites in these animals also. Onceagain, we found it was much easier to recover the mites fromthe healthy herd mates thanfrom the obviously symptomaticanimal. This was consistent withthe findings described in theBritish literature. Fipronil workedwell on these animals also.

The folks at Merial TechnicalServices have been very helpfulto us. Because the British litera-ture provided a dosage, but not a treatment protocol, they pro-vided me with enough Frontline®

Spray to work out the optimumfrequency and duration of treat-ment in our own herd. Doingskin scrapings on every animal in the herd every month was“character building,” but I wasable to determine that treatingevery three weeks for a total of four treatments was the most effective plan.

Mighty Mites:

Chorioptic Skin Disease in AlpacasBy Dr. Ed McCaslin, DVM

Skin disease in alpacas can be due to a variety of different causes: bacteria,fungi, allergies, nutritional problems, and various parasites. One of these parasites is the Chorioptic mange mite.

Chorioptic mange can be a realheadache to the alpaca owner. Difficult to diagnose and even more difficult to treat, this exasperating parasite canmasquerade as its cousin, Sarcoptic mange, or hide out under secondary fungal and/or bacterial infections.Symptoms can be quite variable from one animal to the next, further confusing the situation.

The economic impact of Chorioptic mange due to loss of usable fiber, loss of animal sales, and cost of treatment is hard to estimate, but it certainly is substantial. This does not take into account the discomfort to the animals and the general unthriftiness it creates.

Alpacas are susceptible to at least four different types of mange mites.Unfortunately, the three most commonkinds – Sarcoptes, Chorioptes, andPsoroptes – look very much alike under the microscope. Many times, a vet will give a quick glance, see mites, and assume they are Sarcoptes, longthought to be the most common kind in alpacas. Based on the cases I am now seeing, however, I believe Choriopteshas become the most common type, atleast in Ohio and surrounding states.

SymptomsThis condition often presents as a somewhat “itchy” animal withspotty hair loss, usually aroundthe feet and lower leg region, butit can occur on other areas of thebody, as well. The foot lesionsmay be partially hidden by thefleece and may not be terriblyobvious from a distance (fig. 1),but are quickly apparent whenyou lift the foot and separate thetoes (fig. 2). In longstanding cases,the tissues can thicken, causing thetoes to splay. (fig. 5) The most com-mon sites, other than the feet, arethe axillary (armpit) and inguinal(groin) regions, the perineal (genital) region, and the ventraltail area, but all parts of the bodycan on occasion be involved.

Most of the animals showrather mild symptoms and ownersmay be unaware that there is any-thing wrong. A small percentageof animals (only one or two perfarm) are more severely affectedwith easily visible lesions and hairloss. This is why many people willthink “It can’t be mites becauseonly one animal on the farm isaffected.” This was also consistentwith the British literature. TheBritish authors posit that this is a hypersensitivity, and I concur.

Some of these more severely-affected animals will develop secondary bacterial and/or fungalinfections. These secondary infections are more commonunder humid conditions and lesscommon during dry times.

This disease does not appear torun in family lines. Overcrowdingas can occur through the wintermay contribute to this being spreadmore rapidly through a herd.

Life cycleUnlike Sarcoptic and Psoropticmange mites, which burrowdeep into the epidermis (see fig. 7), the chorioptic mite normally lives its entire three-week life cycle on the surface ofthe skin. The favored locationfor Chorioptic mange mites isthe dorsal skin of the areabetween the toes. Choriopticmites feed on dead skin cells anddander. The female can lay up to90 eggs during its life. Because itis a superficial mite, Chorioptescan be easily dislodged into theenvironment, where it has beenreported that the adult mite cansurvive up to 70 days off thehost in the environment. (Onehardy specimen from our studyeven survived for 11 days com-pletely immersed in mineral oiland under a glass cover slip!)

Unlike the sarcoptic mangemites, the chorioptic mites arenot contagious to humans butwill spread easily to other alpacasand even other livestock like cattle, horses, sheep, and goats.Fomites – physical objects liketoe nail trimmers, groomingtools, halters, bedding, shearingequipment, and the ground itself– can harbor live mites that thenspread to the next animal.

We tried to find a product thatwould eliminate the mites fromthe environment. We found that99% alcohol will kill the mites onshearing equipment and otherfomites. Fipronil will do the same.However, we could not find anything that was safe, effective,and economically feasible for barn floors and paddocks, etc.

As I studied the life cycle of

Figure 1 Affectedfoot, standing.

Figure 3 Same foot,one month post-treatment, hairstarting to regrow.

Figure 4 Same foot,9 months posttreatment.

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Figure 2 Same foot,toes spread.

the Chorioptic mites, it becameapparent why some of the previ-ous treatments had not worked.Injectable ivermectin worksextremely well against Sarcoptesand Psoroptes, which it canreach through the blood vesselsin the epidermis, but is muchless effective against Choriopteswhich stays on the surface, wherethe injectable drug does not penetrate well.

Eprinex® and Frontline Plus®

are applied along the top of theback and depend on transloca-tion via the lipid layer on thesurface of the skin to spread overthe body surface. Since thealpaca has almost no lipid layer,it is not surprising that theseproducts failed to spread fromthe top of the back all the waydown to the feet, where themajority of the Chorioptic mites are found.

DiagnosisAlpacas are susceptible to at leastfour different types of mange mites.Unfortunately, the three mostcommon types – Chorioptic,Sarcoptic, and Psoroptic – will at first glance under a microscopelook remarkably similar, but thetreatments are very different. Evenmany veterinarians will confusethe three if they are not familiarwith the subtle differences. It iscritical for your veterinarian to be able to identify the subtlestructural differences in the mitesto make the correct diagnosis andtreatment recommendations.

Skin scrapings are done using a#10 scalpel blade (held betweenthumb and finger – not on a han-dle) and mineral oil. It is importantto scrape firmly and gently untilyou begin to see capillary bleeding.This insures that you have gonedeep enough not to miss anySarcoptic mites that are burrowed

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Figure 5 Chronic case with thickened tissues andsplayed toes.

Figure 6 Lesions on upper legs and body.

Figure 8 Dr. Ed obtaining a skin scraping.Figure 7 Cross Section of Mammalian Skin.

into the epidermis. Multiple scrap-ings are generally needed.

I can usually get good skinscrapings from the body surfaces or the feet without sedation. Forsevere cases where the animal is inpain or to collect samples from theface and ears (figs. 9 and 10), somesedation may be prudent. I preferto take my time and get a goodsample than to rush and miss adiagnosis. Be sure to have your veterinarian get samples from some of the healthy-looking animals housed with the obviouslyaffected animal. The mites aremuch more numerous and easierto find on them.

Once the sample is on themicroscope slide and the mites are“trapped” under a cover slip, startat 40x magnification and look formovement. The mites are quiteactive at room temperature.

You must move up to the 100xmagnification to identify the mite.The only visible differences are inthe pedicel, the slender stalk thatconnects the small “suction cup” to the end of the leg (fig. 14). Thepedicel of the chorioptic mite isshort and unsegmented, the pedi-cel of the sarcoptic mite is longand unsegmented. The pedicel of the psoroptic mite is long andsegmented. As you can imagine, it is not easy to focus on this tinystructure at the end of a tiny, rapidly-moving leg. At this point,it may be helpful to refrigerate theslide for a little while to slow downthe activity of the mites. Be sure to identify multiple mites fromeach sample before making a finaldiagnosis. It is possible for a singleanimal to be carrying more thanone kind of mite.

Study designThe “Alpaca Grapevine” is marvelously efficient and whenword got out that we had foundan effective treatment, we beganto get referrals from veterinariansand other alpaca farms from several surrounding states. Manyfolks were encouraging us towrite about it, so we decided todo an informal study at our ownexpense. We asked each partici-pating farm to bring the animalthey perceived to have a problemand to also bring an animal theyperceived to be healthy from thesame pen or paddock. We tookan oral history (asked questionsabout onset and duration ofsymptoms and other questionsabout husbandry, etc.) We care-fully examined the skin on eachanimal from ear tip to toenailand from nose to tail. We didskin scrapings on both animalsusing a #10 scalpel blade andmineral oil. We scraped the areabetween the toes on the rightfront and right rear foot of eachanimal and, in addition, didscrapings from anyother area thatshowed hair loss,scaling, thickening,or other changes. In a few of the more severely affected animals, we elected to dobiopsies and culturesfor bacteria and fungus.

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Figure 9 Lesions on ear.

Figure 8 Lesions on nose and face.

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ResultsI have been able to find choriopticmange mites in almost all of the200+ animals that I have exam-ined. I have found live mites oncrias as young as two months ofage and as old as 16 years. Theseanimals came from more than 50different farms in fiveMidwestern states. There wereover 2,000 alpacas representedon these farms. Each of thefarms that came to us did sobecause they had an animal withan obvious problem. Very fewfarms had more than one animalthey were concerned about.Symptoms ranged from itchingto a severe generalized hair losswith secondary infection (pyo-derma) over large portions of thebody.

Most of the “problem” animalshad been under treatment fortheir skin problems using a variety of different products for weeks or months before we saw them. Several had been misdiagnosed as having“ivermectin-resistant Sarcopticmange.” No Sarcoptic mites werefound on any of them. Othershad been diagnosed as fungal,allergic, and zinc deficient.

The interesting thing is thatalmost every “normal” animalthat we saw had some symptomsof Chorioptic mange – muchmilder symptoms than the“problem” animal, but very evident to the trained eye, oftenwithout even bending over. Themost frequent symptoms in these“normal” animals were scaly andthickened skin between the toes.The most severely affected animals consistently yielded thefewest mites on skin scrapings,

whereas “normal” animalshoused with these “problem”ones consistently yielded muchlarger numbers of mites.

We tried doing Scotch tapepreps on some of these animals.The Scotch tape is applied to theskin between the toes and thenapplied to a microscope slide.We had hoped to find a lessinvasive way to detect the mitesand one that alpaca owners could collect without veterinaryassistance and mail off easily fora diagnosis. It did work in somecases, but gave too many falsenegatives, plus it was very diffi-cult with the Scotch tape prepsto visualize the pedicels wellenough to identify the mites reliably.

We were able to follow up atleast in the short term with mostof the participating farms andthe results were overwhelminglypositive. We have only been ableto follow up in the long termwith a few of the participatingfarms, but those who followedthe protocol have cleared all theirmites and remain mite-free. Thenumbers we have right now aretoo small to draw sweeping conclusions, and it is likely thatthe farms participating in the follow-up were among the mostcompliant farms. Because wedealt only with farms that knewthey had a problem of some sort,we cannot generalize these num-bers to the overall population. It would be interesting to studyanimals from farms where all of the animals have healthy skinand see if those animals harborany mites.

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Figure 11 Adult male Chorioptic mite, 400x.

Figure 12 Adult female Chorioptic mite, 400x. Shows location of the pedicel.

Figure 13 Chorioptic miteshowing very short,non-segmentedpedicels. Ph

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TreatmentI have had good success treatingand controlling this conditionwith fipronil (Frontline® Spray)by Merial. Fipronil works byaltering the function of the nervous system of invertebrates.It will kill the mites it contactswithin two hours and will continue to work for up to one month. I have found thatrepeat treatment of affected andcompanion animals every threeweeks, for a total of four treat-ments, gives the best results. (I initially tried treating once amonth and found it inadequate.)

Frontline® Spray doesn’t trans-locate (spread out to areas of thebody that have not been sprayed),although a small amount maytransfer to the axillary (armpit)and inguinal (groin) areas whenthe animal is cushed. It doesn’tenter the body of mammals. Ittravels along the hair follicles andenters the sebaceous glands. It isstored in the sebaceous glands andgradually “wicks out” over thenext 21-30 days.

Fipronil is safe to use on late-term pregnant animals and even nursing mothers, although I avoid applying it directly to theudder while a cria is still nursing.Fipronil is not harmful tohumans or any other mammal,but does carry a warning forhoney bees and fish.

The most effective way to usethe fipronil is to apply it to allfour feet from the fetlock jointdown to the toenails covering thefront, back, and sides of the feet.You should also treat all othervisibly affected areas of the body.Especially look at the armpit,groin area, and perineal region

extending up to the underside of the tail. Application of thefipronil to the face, head, orother sensitive areas should bedone carefully with a gauze padsoaked in the spray. I can gener-ally treat 10 to 12 adult alpacaswith each 500 ml bottle of theFrontline® Spray.

Concurrent use of antibioticslike Naxcel (Upjohn) may beneeded if there is secondaryinfection. Your veterinarian canadvise you as to whether othermedications including topicalantibiotics and/or antifungalswould be helpful.

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Figure 14 Differences between the pedicels of the various mites.

Chorioptic - short, unsegmented pedicel

Sarcoptic - long, unsegmented pedicel

Psoroptic - long segmented pedicel

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Recommendations

If you suspect that you are dealing with Chorioptic mange in your herd, have yourveterinarian do skin scrapings on as many of your animals as possible. Be sure toinclude some apparently healthy animals that are housed with the visibly affected animal(s). Also be sure you veterinarian is aware of the differences in the pedicel(see Diagnosis).

To rid a farm of Chorioptic mange mites:

1. Treat all animals on the farm that are one month old or older with Frontline®

Spray as directed every three weeks for at least four treatments.

2. Remove all organic material from the barn floor to the extent possible.

3. Randomly recheck 10% of herd by skin scrapings 1-2 months after the last treatment to be sure you have eliminated the problem.

4. Be very cautious about buying Frontline® Spray over the Internet. There are a number of companies out there selling counterfeit products.

To keep a farm free of Chorioptic mange mites:

1. Do skin scrapings on all new animals brought to your farm.

2. Whether positive or negative, spray all feet on animals entering the farm or return-ing to the farm, including those returning from shows.

3. Don’t share halters, leads, nail trimmers, or grooming or shearing equipmentbetween animals without cleaning, disinfecting, or spraying with fipronil first.

4. Be careful about contact with other livestock such as cattle, sheep, goats, and horses.

5. Randomly recheck 10% of the herd by skin scrapings every six months.

Wrap upI do believe we can concludeChorioptic mange is much moreprevalent than was previouslybelieved. It also appears thatfipronil can be a useful tool incontrolling it. Some new work is also being done using topicallime-sulfur treatment. It, too,looks promising, but the wholeChorioptic mange mite syn-drome needs a lot more studybefore we can say we have itcompletely understood or canoffer a sure-fire “cure.”

The work behind this studyand this article is a task I could

never have accomplished alone.Patricia Nash has provided muchtechnical support and enthusiasmand most of the photographs.Her daughter, Alexandra Felice,provided the detailed drawings of the pedicels. Mary Jane Foxpatiently held many animals formultiple skin scrapings and alsohelped Patricia test disinfectantsfor the shearing equipment.Finally, without the help of my wife, Dr. Ruthanne, and the countless hours she has con-tributed to this project, it wouldnever have been completed.

Dr. Ed McCaslin, affectionately knownas “Dr. Ed,” grew up on a chicken farmin rural Maine. He graduated from veterinary school at Michigan StateUniversity, where he met and married“Dr. Ruthanne.” Together, they own theLakeshore Animal Hospital in Mentor,Ohio. They also own Promised LandFarm in Chardon, Ohio where they havebeen raising alpacas (and Dr. Ed’s petchickens) since 1995. Dr. Ed has alwayshad a special interest in dermatologyand parasitology. He can be reached at www.blackalpaca.com or blackalpaca@hotmail.com.

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