Scanning electron microscopy description of a new species of Demodex canis spp

Diagnosis and treatment of demodicosis in dogs and cats: Clinical consensus guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Demodicosis is a common disease in small animal veterinary practice worldwide with a variety of diagnostic and therapeutic options.

OBJECTIVES

To provide consensus recommendations on the diagnosis, prevention and treatment of demodicosis in dogs and cats.

METHODS AND MATERIALS

The authors served as a Guideline Panel (GP) and reviewed the literature available before December 2018. The GP prepared a detailed literature review and made recommendations on selected topics. A draft of the document was presented at the North American Veterinary Dermatology Forum in Maui, HI, USA (May 2018) and at the European Veterinary Dermatology Congress in Dubrovnik, Croatia (September 2018) and was made available via the World Wide Web to the member organizations of the World Association for Veterinary Dermatology for a period of three months. Comments were solicited and responses were incorporated into the final document.

CONCLUSIONS

In young dogs with generalized demodicosis, genetic and immunological factors seem to play a role in the pathogenesis and affected dogs should not be bred. In old dogs and cats, underlying immunosuppressive conditions contributing to demodicosis should be explored. Deep skin scrapings are the diagnostic gold standard for demodicosis, but trichograms and tape squeeze preparations may also be useful under certain circumstances. Amitraz, macrocyclic lactones and more recently isoxazolines have all demonstrated good efficacy in the treatment of canine demodicosis. Therapeutic selection should be guided by local drug legislation, drug availability and individual case parameters. Evidence for successful treatment of feline demodicosis is strongest for lime sulfur dips and amitraz baths.

The status of Demodex cornei: description of the species and developmental stages, and data on demodecid mites in the domestic dog Canis lupus familiaris

Demodecosis canina is one of the most important dog parasitoses, but its aetiology is still not well known. There are currently two known species of demodecid mite specific to the domestic dog Canis lupus familiaris Linnaeus, 1758 (Carnivora: Canidae). These are Demodex canis Leydig, 1859 (Acariformes: Demodecidae) and Demodex injai Desch & Hillier, 2003. There have also been many reports of the so-called 'short form', considered to be a separate species functioning under the name Demodex cornei nomen nudum, for which, however, no formal valid description has been documented. Taxonomic analysis of short forms of dog demodecid mites, associated with the stratum corneum, was performed, in line with the taxonomic criteria of Demodecidae systematics. This form was found to be a distinct species with features that differ from those of the other known species of this family. The species, including the adult and immature stages, is described. It is likely that different Demodex species parasitizing the domestic dog may be responsible for differentiated symptoms and different courses of demodecosis. However, the basis for clarifying this issue should be the correct, unambiguous identification of the species causing parasitosis.

A New Stubby Species of Demodectic Mite (Acari: Demodicidae) From the Domestic Dog (Canidae)

A new species of Demodex was detected in the earwax of a dog with otitis externa in Saitama Prefecture, Japan, in July 2010. The opisthosoma length of the mite was slightly shorter than 1/2 of its body length, which was different from the other species in domestic dogs, D. canis and D. injai, but was similar to the form of mites termed "short-bodied species", including D. cornei. However, the stubby external form was morphologically different from those of "short-bodied species", excluding a case without a species description reported from Greece. Among known species, the mite was similar to D. equi and D. acutipes.

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

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.

Efficacy of orally administered fluralaner (Bravecto™) or topically applied imidacloprid/moxidectin (Advocate®) against generalized demodicosis in dogs

BACKGROUND

This laboratory study compared the efficacy of Bravecto™ (fluralaner), formulated as a chewable tablet, with the efficacy of Advocate® (imidacloprid/moxidectin), formulated for topical administration, against naturally acquired generalized demodicosis in dogs.

METHODS

Sixteen dogs, all diagnosed with generalized demodectic mange, were randomly allocated to two equal groups. Bravecto™ chewable tablets were administered once orally at a minimum dose of 25 mg fluralaner/kg body weight to one group of dogs, while the second group was treated topically on three occasions at 28-day intervals with Advocate® at a minimum dose of 10 mg imidacloprid/kg body weight and 2.5 mg moxidectin/kg body weight. Mites were counted in skin scrapings and demodectic lesions were evaluated on each dog before treatment and at 28-day intervals thereafter over a 12 week study period. Deep skin scrapings (~4 cm(2)) were made from the same five sites on each dog at each subsequent examination.

RESULTS

After single oral administration of Bravecto™ chewable tablets, mite numbers in skin scrapings were reduced by 99.8% on Day 28 and by 100% on Days 56 and 84. Mite numbers in the dogs treated topically on three occasions at 28-day intervals with Advocate® were reduced by 98.0% on Day 28, by 96.5% on Day 56 and by 94.7% on Day 84. Statistically significantly (P ≤ 0.05) fewer mites were found on Days 56 and 84 on the Bravecto™ treated dogs compared to Advocate® treated dogs. A marked decrease was observed in the occurrence of erythematous patches, crusts, casts and scales in the dogs treated with Bravecto™ and in the occurrence of erythematous patches in the dogs treated with Advocate®. With the exception of one dog in each treated group, all dogs exhibited hair regrowth ≥ 90% at the end of the study in comparison with their hair-coat at study start.

CONCLUSIONS

Single oral administration of Bravecto™ chewable tablets is highly effective against generalized demodicosis, with no mites detectable at 56 and 84 days following treatment. In comparison, Advocate®, administered three times at 28-day intervals, is also highly effective against generalized demodicosis, but most dogs still harboured mites at all assessment time points. Both treatments resulted in a marked reduction of skin lesions and increase of hair re-growth 12 weeks after the initial treatment.

Demodicosis caused by Demodex canis and Demodex cornei in dogs

Two mongrel dogs aged between 7 and 9 months 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 @ 500 μg/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.

First report of an unclassifiedDemodexmite causing demodicosis in a Venezuelan dog

For the first time in Venezuela, a case of canine demodicosis apparently caused by a simultaneous infection with an unclassified Demodex and Demodex canis has been observed. The most severely affected area of the dog involved, a 3-month-old male Doberman Pinscher, was the head, particularly the peri-orbital skin. Skin samples of the affected areas were taken and evaluated by both light and scanning electron microscopy. The mites of the unclassified Demodex were smaller than those of D. canis and appeared relatively stout. In the skin scrapings, D. canis outnumbered the unclassified Demodex by a ratio of 30:1, making it unclear if the unclassified Demodex is pathogenic to dogs. A combination of superficial and deep skin scrapings, from a suspected case of demodicosis, may help to reveal other infestations of the unclassified Demodex that would otherwise be masked by concurrent infections with D. canis.

Demodex gatoi-associated contagious pruritic dermatosis in cats--a report from six households in Finland

BACKGROUND

Demodex gatoi is unique among demodectic mites. It possesses a distinct stubby appearance, and, instead of residing in the hair follicles, it dwells in the keratin layer of the epidermis, causing a pruritic and contagious skin disease in cats. Little is known of the occurrence of D. gatoi in Europe or control of D. gatoi infestation.

CASE PRESENTATION

We describe D. gatoi in 10 cats, including five Cornish Rex, two Burmese, one Exotic, one Persian and one Siamese, living in six multi-cat households in different locations in Finland containing 21 cats in total. Intense pruritus was the main clinical sign. Scaling, broken hairs, alopecia and self-inflicted excoriations were also observed. Diagnosis was based on finding typical short-bodied demodectic mites in skin scrapings, skin biopsies or on tape strips. Other pruritic skin diseases, such as allergies and dermatophytoses, were ruled out. In one household, despite finding several mites on one cat, all six cats of the household remained symptomless. Amitraz used weekly at a concentration of 125-250 ppm for 2-3 months, proved successful in three households, 2% lime sulphur weekly dips applied for six weeks in one household and peroral ivermectin (1 mg every other day for 10 weeks) in one household. Previous trials in four households with imidacloprid-moxidectin, selamectin or injected ivermectin given once or twice a month appeared ineffective.

CONCLUSION

D. gatoi-associated dermatitis is an emerging contagious skin disease in cats in Finland. Although pruritus is common, some cats may harbour the mites without clinical signs. In addition, due to translucency of the mites and fastidious feline grooming habits, the diagnosis may be challenging. An effective and convenient way to treat D. gatoi infestations has yet to emerge.