Demodex Canis Research Articles

Morphological Characterization of Arthropod Ectoparasites by Scanning Electron Microscopy

Arthropods constitute a diverse and largest animal phylum of invertebrates. They consist of over 80% of all known animal species and occupying almost every known habitat including marine, freshwater, land and air. Arthropods are important to the ecosystem and to humans. In this context, arthropods ectoparasites cause serious disease to humans and animals and subsequently leading to annual total economic loss. Therefore, an identification of the arthropod ectoparasites is an important tool for the diagnosis and controlling human and animal infections. Hence an identification of the arthropod ectoparasites by electron microscopy needs collecting arthropod ectoparasites, and handling as well as using previous collected data on mite, lice, bed bugs, and fleas. In the present study, the following arthropod ectoparasites: Demodex canis ,Pediculus humanus, Haematopinus asini, Linognathus africanus, Cimex lectularius, Ctenocephalides canis were collectedand 20%(6/30), 3.61%(3/83), 10%(2/20), 46.67%(7/15), 20%(2/10), and 23.33%(7/30) of these arthropod ectoparasite species, respectively were examined.

Density measurement of Demodex canis by qPCR and analysis of serum cytokine levels in dogs with different clinical forms of demodicosis

ObjectivesTo quantify (by qPCR) the density of Demodex canis mites in the skin of dogs with demodicosis and in healthy dogs, as well as measuring the serum concentrations of interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, and tumour necrosis factor-alfa (TNF-α). MethodsFifty-four dogs were divided into three groups: localized demodicosis (LD, n = 16), generalized demodicosis (GD, n = 22), and control group (CG, n = 16). All dogs were subjected to skin scraping, blood collection, and skin biopsy. DNA extraction was performed and the parasite density was established by qPCR. Serum cytokine concentrations were obtained by flow cytometry. ResultsThe median number of mites in the skin of the GD (6.2 × 104 copies/μL) and LD dogs (1.2 × 104 copies/μL) was statistically higher than that in the CG dogs (8.7 × 102 copies/μL). Whereas there were no significant differences in median IL-1β, IL-8, IL-10, IL-12, and TNF-α levels among the study groups, there was a statistically higher IL-6 concentration in the LD dogs than in the healthy dogs. ConclusionsAccording to our results, qPCR is an effective method for measuring the density of D. canis in the canine integument. In addition, the activation of the acute-phase immune response in localized demodicosis can be induced by IL-6 activity.

Skin mites in mice (Mus musculus): high prevalence of Myobia sp. (Acari, Arachnida) in Robertsonian mice.

Myobia sp. and Demodex sp. are two skin mites that infest mice, particularly immunodeficient or transgenic lab mice. In the present study, wild house mice from five localities from the Barcelona Roberstonian system were analysed in order to detect skin mites and compare their prevalence between standard (2n = 40) and Robertsonian mice (2n > 40). We found and identified skin mites through real-time qPCR by comparing sequences from the mitochondrial 16S rRNA and the nuclear 18S rRNA genes since no sequences are available so far using the mitochondrial gene. Fourteen positive samples were identified as Myobia musculi except for a deletion of 296bp out to 465bp sequenced, and one sample was identified as Demodex canis. Sampling one body site, the mite prevalence in standard and Robertsonian mice was 0 and 26%, respectively. The malfunction of the immune system elicits an overgrowth of skin mites and consequently leads to diseases such as canine demodicosis in dogs or rosacea in humans. In immunosuppressed mice, the probability of developing demodicosis is higher than in healthy mice. Since six murine toll-like receptors (TLRs) are located in four chromosomes affected by Robertsonian fusions, we cannot dismiss that differences in mite prevalence could be the consequence of the interruption of TLR function. Although ecological and/or morphological factors cannot be disregarded to explain differences in mite prevalence, the detection of translocation breakpoints in TLR genes or the analysis of TLR gene expression are needed to elucidate how Robertsonian fusions affect the immune system in mice.

Antioxidant Status and Lipid Peroxidation in Erythrocyte of Dog Infested with Demodex canis

The study was conducted on fifteen dogs (n = 8 demodicosis, n = 7 healthy) brought to Veterinary Clinics, Bihar Veterinary College Clinics to determine Antioxidant Status and Lipid Peroxidation in erythrocyte of Demodex canis infested dog. Activity of catalase (CAT) and superoxide dismutase (SOD) and Thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) concentration were estimated in erythrocytes of dogs. Activity of CAT, SOD and TBARS concentration were higher in infected dogs than healthy dogs while and GSH concentration was higher in healthy dog than infected dogs. The results of the present study suggest that Demodex canis infestation cause oxidative stress in erythrocyte of dogs. Keywords: Demodex, SOD, GSH, Antioxidant, CAT Cite this Article Ajeet Kumar, Anil Gattani, Singh GD., et al. Antioxidant Status and Lipid Peroxidation in Erythrocyte of Dog Infested with Demodex canis. Research & Reviews: Journal of Veterinary Science and Technology (RRJoVST). 2015; 4(2): 1–3p.

Canine demodicosis

Canine demodicosis, which is caused by the follicular mite Demodex canis, is one of the most common skin diseases, especially in the young dog. Demodicosis can be localized or generalized; in the latter a parasite-specific cellular immunosuppression, which is genetically transmitted, is the cornerstone of its pathogenesis. Alopecia - hypotrichosis, erythema, hyperpigmentation, lichenification, papules, scales and crusts, first appear on the face and front limbs, to spread eventually to the other parts of the body. Superficial or deep staphylococcal pyoderma is a common complication, especially in the generalized form of the disease. Diagnosis will be confirmed by the presence of the mite in high numbers and at various developing stages in the skin scrapings. Treatment is not recommended for the localized form, which is almost always self-limiting. Various ectoparasiticides have been used in the generalized form of the disease, either for topical (amitraz) or systemic application (ivermectin, mylbemycin, moxidectin), with good results. Treatment is terminated when not a single parasite can be found in the skin scrapings on 2-3 consecutive monthly re-examinations. The animal is considered cured if there have not been any relapses one year since the end of the acaricidal treatment.

Two morphologically distinct forms of Demodex mites found in dogs with canine demodicosis from Vladivostok, Russia

Abstract The aim of this study was to investigate the morphology of Demodex canis and Demodex sp. cornei found in six dogs with canine demodicosis. A deep skin scraping technique was used for Demodex mite detection. Measurement data of 52 adult D. canis mites (26 females, 25 males and one specimen whose sex could not be determined) and 39 adult Demodex sp. cornei mites (22 females, 14 males and three specimens whose sex could not be determined) were reported. The correlation between body size of both Demodex species were estimated by the Student’s t-test. There was a significant correlation between short-tail and long-tail forms and total body length and length of the podosoma and opisthosoma (p<0.05). A significant difference was not found between the length of the gnathosoma and short-tail and long-tail forms (p>0.05). Demodex sp. cornei and D. canis, found in dogs from Vladivostok, were smaller than species from other countries. However, the present data did not significantly differ from other studies with D. canis and Demodex sp. cornei descriptions.

Detection, Prevalence and Phylogenetic Relationships of Demodex spp and further Skin Prostigmata Mites (Acari, Arachnida) in Wild and Domestic Mammals.

This study was conceived to detect skin mites in social mammals through real-time qPCR, and to estimate taxonomic Demodex and further Prostigmata mite relationships in different host species by comparing sequences from two genes: mitochondrial 16S rRNA and nuclear 18S rRNA. We determined the mite prevalence in the hair follicles of marmots (13%) and bats (17%). The high prevalence found in marmots and bats by sampling only one site on the body may indicate that mites are common inhabitants of their skin. Since we found three different mites (Neuchelacheles sp, Myobia sp and Penthaleus sp) in three bat species (Miotis yumanensis, Miotis californicus and Corynorhinus townsendii) and two different mites (both inferred to be members of the Prostigmata order) in one marmot species (Marmota flaviventris), we tentatively concluded that these skin mites 1) cannot be assigned to the same genus based only on a common host, and 2) seem to evolve according to the specific habitat and/or specific hair and sebaceous gland of the mammalian host. Moreover, two M. yumanensis bats harbored identical Neuchelacheles mites, indicating the possibility of interspecific cross-infection within a colony. However, some skin mites species are less restricted by host species than previously thought. Specifically, Demodex canis seems to be more transmissible across species than other skin mites. D. canis have been found mostly in dogs but also in cats and captive bats. In addition, we report the first case of D. canis infestation in a domestic ferret (Mustela putorius). All these mammalian hosts are related to human activities, and D. canis evolution may be a consequence of this relationship. The monophyletic Demodex clade showing closely related dog and human Demodex sequences also supports this likely hypothesis.

Parasites and vector-borne diseases in client-owned dogs in Albania: infestation with arthropod ectoparasites.

To establish the diversity and seasonality of ectoparasite infestation in client-owned dogs in Albania, 602 dogs visiting four small animal clinics in Tirana from March 2010 to April 2011 inclusive were examined for ectoparasites by full body search and total body comb. In addition, ear swab specimens collected from all dogs and scrapings taken from skin lesions suspicious of mite infestation were examined for parasitic mites. Overall, 93 dogs (15.4%, 95%CI 12.6-18.6) were demonstrated to be infested, and nine species of ectoparasites were identified: Ixodes ricinus, 0.8%; Rhipicephalus sanguineus s. l., 8.1%; Demodex canis, 0.2%; Sarcoptes scabiei, 0.7%; Otodectes cynotis, 2.8%; Ctenocephalides canis, 4.8%; Ctenocephalides felis, 3.0%; Pulex irritans, 0.2%; and Trichodectes canis, 0.2%. Single and multiple infestations with up to four species of ectoparasites concurrently were recorded in 67 (11.1%, 95%CI 8.7-13.9) and 26 dogs (4.3%, 95%CI 2.8-6.3), respectively. On univariate analysis, the category of breed (pure breed dogs vs. mixed-breed dogs), the dog's purpose (pet, hunting dog, working dog), the housing environment (mainly indoors/indoors with regular outside walking vs. yard plus kennel/run), the history of ectoparasiticide treatment and the season of examination were identified as significant (p < 0.05) factors predisposing dogs to various ectoparasites, while the variables dog's age, gender, the dog's habitat (city, suburban, rural) and the presence/absence of other pets were not significant predictors. Multivariate logistic regression analysis for factors associated with overall ectoparasitism revealed that dogs treated with ectoparasiticides at least once per year (odds ratio [OR] = 0.24; p < 0.001) had a significantly lower risk of infestation compared with dogs not treated against ectoparasite infestation. Dogs examined during spring, summer and autumn (OR = 7.08, 7.43 and 2.48, respectively; all p < 0.001) had a significantly higher risk of infestation than dogs examined during winter. By providing basic data on the infestation with ectoparasites in client-owned, veterinary-cared-for dogs from Albania for the first time, the results of this survey should emphasize the need of an increase of attention to ectoparasites in dogs by both veterinarians and dog owners.

Prevalence of ectoparasites in dogs of Shimoga, Karnataka.

A study was carried out to ascertain the status of ecto-parasites infesting dogs of Shimoga region. A total of 120 dogs with the history of skin problems presented to the local hospitals and local pet clinics of Shimoga region were screened for different ecto-parasites. The ticks, fleas and lice were collected, processed and identified. The skin scrapings were also collected from the affected dogs and processed for identification of mites. Out of 120 dogs examined, 59 (49.1%) had harboured ecto-parasites. Among 59 infested pet dogs, 22 (37.28%) positive for Fleas, 18 (30.5%) for ticks, 09 (15.2%) for Lice, 07 (11.8%) for Sarcoptic mange and 03 (5.0%) were for Demodectic mange conditions. The two species of fleas were identified as Ctenocephalides canis 13 (59%) and Ctenocephalides felis 9 (41%). The ticks and lice species were identified as Riphicephalus sanguineus and Trichodectus canis respectively. The mite species infecting dogs were identified as Sarcoptes scabeii and Demodex canis based on the morphological character. The Prevalence of ectoparasites was more in stray and adults dogs compared to pet dogs and puppies respectively.

A survey on endoparasites and ectoparasites in domestic dogs and cats in Vladivostok, Russia 2014

The present survey aims to establish the prevalence of ecto- and endoparasitic infestations in dogs and cats in Vladivostok city in 2014. Between December 2013 and December 2014, 157 dogs (68 females and 89 males) and 80 cats (29 females and 51 males) were included in a study conducted in the School of Natural Sciences, Far Eastern Federal University and veterinarian hospitals in Vladivostok. For each animal, ectoparasites and Demodex spp. were identified with the help of cerumen and epidermis samples microscopy. Endoparasites were identified through standard coproscopical examinations of fresh fecal samples using the sedimentation–flotation methods. Endoparasites, including gastro-intestinal helminths and protozoans, were identified in 51% of the cats, Toxascaris leonina being the most commonly diagnosed (7.8%). As for ectoparasites in the cats, Otodectes cynotis only was identified (75%). Endoparasites were identified in 26.8% of the dogs, the most common endoparasite diagnosed being Ancylostoma caninum (10.3%). Dogs in the age groups 13 to 36months and cats over 3years of age showed significantly higher infection rates – 33.3% and 46.6%, respectively. In 97 dog fecal samples examined, only one type of parasite was found. In 51 cat fecal samples examined, only one type of endoparasite was found in 50 cats (94.7%) and 1 sample (5.3%) contained 2 different endoparasites. As for canine ectoparasitism, O. cynotis (Acari: Psoroptidae Conoor, 1984) (29.4%), and Сheyletiella yasguri (Acari:Cheyletidae Leach, 1815) (2.1%) were identified. Prevalence of Demodex canis (Acari: Demodicidae Nicolet, 1855) amounted to 6.25%.Conclusions: This survey demonstrates that parasitism is far from being rare among Vladivostok's cats and dogs' populations.

Identification of a third feline Demodex species through partial sequencing of the 16S rDNA and frequency of Demodex species in 74 cats using a PCR assay.

Demodex cati and Demodex gatoi are considered the two Demodex species of cats. However, several reports have identified Demodex mites morphologically different from these two species. The differentiation of Demodex mites is usually based on morphology, but within the same species different morphologies can occur. DNA amplification/sequencing has been used effectively to identify and differentiate Demodex mites in humans, dogs and cats. The aim was to develop a PCR technique to identify feline Demodex mites and use this technique to investigate the frequency of Demodex in cats. Demodex cati, D. gatoi and Demodex mites classified morphologically as the third unnamed feline species were obtained. Hair samples were taken from 74 cats. DNA was extracted; a 330 bp fragment of the 16S rDNA was amplified and sequenced. The sequences of D. cati and D. gatoi shared >98% identity with those published on GenBank. The sequence of the third unnamed species showed 98% identity with a recently published feline Demodex sequence and only 75.2 and 70.9% identity with D. gatoi and D. cati sequences, respectively. Demodex DNA was detected in 19 of 74 cats tested; 11 DNA sequences corresponded to Demodex canis, five to Demodex folliculorum, three to D. cati and two to Demodex brevis. Three Demodex species can be found in cats, because the third unnamed Demodex species is likely to be a distinct species. Apart from D. cati and D. gatoi, DNA from D. canis, D. folliculorum and D. brevis was found on feline skin.

Serum detection of IgG antibodies against Demodex canis by western blot in healthy dogs and dogs with juvenile generalized demodicosis

The aim of this study was to investigate the presence of canine immunoglobulins (Ig) G against Demodex proteins in the sera of healthy dogs and of dogs with juvenile generalized demodicosis (CanJGD) with or without secondary pyoderma. Demodex mites were collected from dogs with CanJGD. Protein concentration was measured and a western blot technique was performed. Pooled sera from healthy dogs reacted mainly with antigen bands ranging from 55 to 72kDa. Pooled sera from dogs with CanJGD without secondary pyoderma reacted either with 10kDa antigen band or 55 to 72kDa bands. Pooled sera from dogs with CanJGD with secondary pyoderma reacted only with a 10kDa antigen band. The results of this study suggest that both healthy dogs and dogs with CanJGD develop a humoral response against different proteins of Demodex canis.

The main factors influencing canine demodicosis treatment outcome and determination of optimal therapy.

The main idea of this research was to evaluate the efficacy of canine demodicosis conventional treatments using mathematical analyses. All available papers published between 1980 and 2014 were used in this study. One hundred six clinical trials enrolling 3414 cases of generalized demodicosis in dogs are studied. Dogs entered in the analysis were only the ones in which the disease occurred naturally, excluding the studies in which transplantation of Demodex canis mites was done from other animals. In conventional acaricide treatments, sorted according to active substances (moxidectin, amitraz, doramectin, ivermectin, and milbemycin oxime), the way of application (spot-on, dips, orally, or subcutaneous), concentration, and interval of application were used as input parameters in mathematical modeling. Data of interest were the treatment outcome, the number of dogs that went into remission, the number of animals not responding to treatment microscopically, the average duration of therapy, the follow-up period, the number of patients with disease recurrence, the number of adverse effects, and the number of animals with side effects. Dogs lost to follow-up or when the treatment was discontinued, due to various reasons not in connection with the therapy protocol, were not considered. Statistical and mathematical analyses were applied for prediction of the drugs' effectiveness. Developed mathematical models showed satisfactorily r (2), higher than 0.87. Good evidence for recommending the use of milbemycin oxime PO (0.5mg/kg, daily) and moxidectin spot-on (Advocate®, Bayer) weekly is found. A bit less effective therapies were based on ivermectin PO (0.5mg/kg, daily), moxidectin PO (0.35mg/kg, daily), and amitraz dips (0.05% solution, weekly), respectively. It is important to keep in mind that Advocate® is recommended by the manufacturer for use in milder cases.

Skin impression with acetate tape in Demodex canis and Scarcoptes scabiei var. vulpes diagnosis

This study compares the efficacy of skin impression with acetate tape and the deep skin scraping test to find D. canis and S. scabieiin dogs. During six months, 134 samples were collected by both techniques from 115 dogs treated at the dermatology service of the Veterinary Hospital of the Federal University of Santa Maria (HVU-UFSM). Of these patients, 27 had demodicosis and 12 had scabies. The impression with acetate tape test (ITT) was shown to be significantly superior to the deep skin scraping test (DSST) in finding D. canis and S. scabiei mites (p = 0.007). Based on our results we could conclude that acetate tape impression is a reliable method for diagnosing and monitoring therapy of dermatopathies caused by mites and can be used to replace the traditional deep skin scraping method. In addition, since it is less traumatic for the dog, this method shows more acceptance by the owner.

Clinical and parasitological evaluation of pour-on fluazuron and ivermectin for treating canine demodicosis

The objective of the study was to evaluate the efficacy of pour-on formulations of fluazuron and ivermectin in different therapeutic protocols for treatment of demodicosis by means of quantifying mites with skin scraping, histological and clinical evaluation in dogs. Eighteen dogs with skin scrapings positive for Demodex canis were evaluated, divided into three groups. All the animals were treated every 14 days, completing 6 treatments for each animal (days 0, 14, 28, 42, 56 and 70). In group 1, pour-on 2.5% fluazuron was used at the dose of 20mg/kg; in the group 2 pour-on 2.5% fluazuron at a dose of 20 mg/kg in association with pour-on 0.5% ivermectin at the dose of 0.6mg/kg; and in group 3, pour-on 0.5% ivermectin alone was used, at the dose of 0.6mg/kg. The treatment was evaluated and monitored through skin scrapings and clinical follow-up of the lesions every 14 days for 84 days, and through histopathological examination at the end of each treatment protocol. The success rate was defined as the percentage of dogs in each group that had negative skin scrapings after the treatment: this was 16.67% for group 1, and 50% for groups 2 and 3. The reduction in mite counts reached effectiveness of 67.66%, 88.99% and 84.29% for groups 1, 2 and 3 respectively. The Wilcoxon test showed that there was a significant difference between the number of mites before and after treatment in groups 2 and 3. The histopathological examination revealed that only group 1 showed no significant difference in the intensity of infestation between days 0 and 84. Clinically, there was no significant difference between the evaluation before and after treatment in the three groups. pour-on 2.5% fluazuron and pour-on 0.5% ivermectin were not effective for treating canine demodicosis, either in association or as single therapy, when applied every 14 days for a period of 70 days. Quantification of mites using skin scrapings and histological evaluation proved to be ineffective, either one as sole therapeutic evaluation parameters, for canine demodicosis.

Molecular identification and phylogenetic study of Demodex caprae.

The DNA barcode has been widely used in species identification and phylogenetic analysis since 2003, but there have been no reports in Demodex. In this study, to obtain an appropriate DNA barcode for Demodex, molecular identification of Demodex caprae based on mitochondrial cox1 was conducted. Firstly, individual adults and eggs of D. caprae were obtained for genomic DNA (gDNA) extraction; Secondly, mitochondrial cox1 fragment was amplified, cloned, and sequenced; Thirdly, cox1 fragments of D. caprae were aligned with those of other Demodex retrieved from GenBank; Finally, the intra- and inter-specific divergences were computed and the phylogenetic trees were reconstructed to analyze phylogenetic relationship in Demodex. Results obtained from seven 429-bp fragments of D. caprae showed that sequence identities were above 99.1% among three adults and four eggs. The intraspecific divergences in D. caprae, Demodex folliculorum, Demodex brevis, and Demodex canis were 0.0-0.9, 0.5-0.9, 0.0-0.2, and 0.0-0.5%, respectively, while the interspecific divergences between D. caprae and D. folliculorum, D. canis, and D. brevis were 20.3-20.9, 21.8-23.0, and 25.0-25.3, respectively. The interspecific divergences were 10 times higher than intraspecific ones, indicating considerable barcoding gap. Furthermore, the phylogenetic trees showed that four Demodex species gathered separately, representing independent species; and Demodex folliculorum gathered with canine Demodex, D. caprae, and D. brevis in sequence. In conclusion, the selected 429-bp mitochondrial cox1 gene is an appropriate DNA barcode for molecular classification, identification, and phylogenetic analysis of Demodex. D. caprae is an independent species and D. folliculorum is closer to D. canis than to D. caprae or D. brevis.

Case study: generalised demodicosis in a Chihuahua

Canine demodicosis is a common dermatosis and occurs when there is excessive proliferation of Demodex canis within the hair follicles and sebaceous glands. The mite is not entirely responsible for the pathological process and the disease is multifactorial with genetics, immune status, other cutaneous fauna and hormones all playing a part to varying degrees. The disease is classified as canine localised demodicosis or canine generalised demodicosis according to the extent of the disease. This article considers a case of demodicosis encountered by the author in practice. It demonstrates the need to consider demodicosis as a differential in juvenile onset seborrhea and the need to sometimes consider a variety of treatments before resolution of clinical signs is achieved.

Demodicosis caused by Demodex canis and Demodex cornei in dogs.

Two mongrel dogs aged between 7 and 9months in a same house were presented to the clinics with a history of chronic dermatitis associated with pruritus. Clinical examination revealed presence of primary and secondary skin lesions on the face, around the ears, chin, neck, fore limbs and lateral abdomen. Examination of skin scrapings revealed Demodex cornei (majority) and D. canis (minority) in both the dogs. By using hair pluck examination D. canis were detected and by tape impression smears examination large number of adult short-tail Demodex mites were found. D. cornei was identified by based on the morphological characters including short opisthosoma with blind and round terminal end. Mean length of total body, opisthosoma of both types of the mites were differed statistically significant (P<0.01) but gnathosoma and podosoma did not differ significantly (P>0.05). Dogs were treated with daily oral ivermectin @ 500μg/kg/day, external application of amitraz along with supportive therapy. After completion of 45 days of therapy dogs were recovered completely without any side effects.

Morphometry Of Demodex Canis And Demodex Cornei In Dogs With Demodicosis In India

In the two years period of research on canine dermatology at College Hospital of College of Veterinary Science Tirupati, 32 dogs with derma- tological problems found to have demodicosis. In these cases demodicosis was confirmed by clinical examination, microscopic examination of scrapings and tape impression smears collected from the lesions. In these two different types of Demodex mites were identified based on their habitat and morphology along with micrometry. Micrometry was carried out on 320 mites of two different types of Demodex collected from the all the cases. Demodex canis was identified in skin scrapings with pointed opisthosomal terminal end and mean body length of 211.81± 14.86 µm and mean width of 37.68±0.31 µm. Demodex cornei was noticed in tape impression smears and identification was based on its mor - phology (stubby farm with a blunt posterior opisthosoma end) and its mean length of 137.15 ± 37.72 µm and mean width of 38.28±0.19 µm. Lengths of total body and opisthosoma of both types of the mites differed statistically significantly but, gnathosoma and podosoma did not differ significantly.

Phylogenetic analysis of Demodex caprae based on mitochondrial 16S rDNA sequence

Demodex caprae infests the hair follicles and sebaceous glands of goats worldwide, which not only seriously impairs goat farming, but also causes a big economic loss. However, there are few reports on the DNA level of D. caprae. To reveal the taxonomic position of D. caprae within the genus Demodex, the present study conducted phylogenetic analysis of D. caprae based on mt16S rDNA sequence data. D. caprae adults and eggs were obtained from a skin nodule of the goat suffering demodicidosis. The mt16S rDNA sequences of individual mite were amplified using specific primers, and then cloned, sequenced, and aligned. The sequence divergence, genetic distance, and transition/transversion rate were computed, and the phylogenetic trees in Demodex were reconstructed. Results revealed the 339-bp partial sequences of six D. caprae isolates were obtained, and the sequence identity was 100% among isolates. The pairwise divergences between D. caprae and Demodex canis or Demodex folliculorum or Demodex brevis were 22.2-24.0%, 24.0-24.9%, and 22.9-23.2%, respectively. The corresponding average genetic distances were 2.840, 2.926, and 2.665, and the average transition/transversion rates were 0.70, 0.55, and 0.54, respectively. The divergences, genetic distances, and transition/transversion rates of D. caprae versus the other three species all reached interspecies level. The five phylogenetic trees all presented that D. caprae clustered with D. brevis first, and then with D. canis, D. folliculorum, and Demodex injai in sequence. In conclusion, D. caprae is an independent species, and it is closer to D. brevis than to D. canis, D. folliculorum, or D. injai.