Epidemiology, genetic divergence and acaricides of Otodectes cynotis in cats and dogs

Otodectes cynotis mite is a common parasite of cats and dogs, survives in the ear canal and causes otitis externa, itching and severe complications. The microscopic examination of ear swabs, skin scraps and faecal samples of 289 cats and 223 dogs revealed that mono-specific and mixed infestations of Otodectes cynotis in cats were (24.56%) and(6.57%) while in dogs were (7.17%) and (4.48%) respectively. The highest rate of infestation was in young cats and the lowest was in elder dogs. The mixed infestations were found in combination with Sarcoptes, Demodex, Dermatophytes, Ticks, Fleas, Ascarids, Dipylidium and Isospora. The RAPD-PCR proved the genetic divergence between cat and dog isolates whereas they are morphologically similar. Selamectin-pour on, Doramectin-subcutaneous injection and Ivermectin-Ear drops were evaluated two weeks post treatment. The rate of success in cats were (96.66%) ,(90.00%) and (83.33%) and in dogs were (77.77%), (75.00%) and (66.66%) respectively. It is concluded that Selamectin pour on is the best acaricide against Otodectes cynotis in both cats and dogs. It is also needed to prepare a vaccine in the future to prevent the infestation with Otodectes cynotis and its complications.


Introduction
Material and methods Animals : 289 cats and 223 dogs were examined along Otodectes cynotis mites are non burrowing, white and very active parasites. They infest several two years in the Teaching Hospital of Department of species of animals including cats and dogs (Scott et al., Medicine and Infectious Diseases, Faculty of 2001). It causes severe mechanical irritation due to Veterinary Medicine, Cairo University. Age, breed, the presence of the mite inside the ear leading to a sex, clinical signs, complications and history of higher activity of ceruminal glands and, consequprevious medications were registered for each ently, the establishment of a favorable environment for examined animal. secondary infections by bacteria or fungi (August, Samples: Ear swabs and waxy materials from ears, 1988). The infestation with Otodectes cynotis mite is skin scrapings and faecal samples were collected from termed otodectic mange (Sweatman, 1958). It is the examined cats and dogs. clinically observed as the infested animals show Acaricides: Selamectin pour on (Revolution®, Pfizer discomfort, intense itch, excessive waxy material or company), minimum dose is 6 mg/kg body weight pus and even audition interference, depending on the applied topically on skin once, Doramectin injection level of parasitism (Gotthelf, 2000). Although the (Dectomax®, Pfizer company), 1 ml/50 kg body importance of mites in cats and dogs as it causes weight injected subcutaneous once, Ivermectin external otitis, information regarding their prevalence (Iveen®, Adwia company) as ear drops once every 3 and the factors influencing their survival is lacking days, were evaluated for treatment of cats and dogs (Gram et al., 1994 andSotiraki et al., 2001). The rates infested with Otodectes cynotis mites. of infestation of Otodectes cynotis were studied in cats Ear swabs: Ear swabs from ear canals of both ears of and dogs at different age groups. The morphological the examined cats and dogs were collected and and genetic divergences between cat isolates and dog examined as described by Richard and David (2001) isolates of Otodectes cynotis were also studied. and Stephen and Dwight (2006) with some Finally, the complications of Otodectes cynotis modifications. Blackish way material of ear canal was infestations were recorded and the three acaricides collected by a disposable ear cotton swab. The were also evaluated in cats and dogs for treatment of collected materials were gently mixed with Tap water Otodectes cynotis infestations. and examined microscopically under low, medium and high magnification power lenses. Otodectes containing separated reaction was spun to collect all cynotis mite were counted per slide and their motility reagents with each other. A 40 µl of paraffin oil was added to each reaction. Then was incubated and was were recorded before and after treatment.
labeled in small ependolf tubes in a set of PCR with the Skin scrapings: Skin scraping was done in cats and following program:dogs infested with Otodectes cynotis mite and suffered from hair loss and skin encrustation. Skin Step-1: Intial denaturation at (94C°/ 3 minutes). scrapings were done according to Richard and David Step-2: Denaturation at (94C°/1 minute), annealing at (27C°/1 minute) and extension at (72C°/1 (2001) with some modifications. Skin was scraped minute), (repeated 39 cycles).
with a scalpel to collect skin tissue scraps. Skin scraps Step-3: Final extension at (74 C°/10 minute) were gently mixed with sodium hydroxide 10 % Step-4: The reaction was preserved at 4 C°/ overnight solution and examined under a microscope to detect Results of RAPD-PCR reactions were detected mites or dermatophyte. In few cases flea and ticks by running of RAPD-PCR products with loading were visually detected during collection of skin buffer in 1.5% agarose gel in 1X TAE buffer. Positive scraps.
result was seen as bands on gel. Faecal examination: Faecal smears were collected Evaluation of Acaricides: Each Otodectes cynotis from cats and dogs infested with Otodectes cynotis mites infested cat and dog was examined before and mite and suffered from diarrhea. Faecal samples were two weeks post treatment by examination of ear swabs collected and examined as previously described by from both ears. Three acaricides , Selamectin pour-on, Chandler et al. (2004).

Doramectin injection and Ivermectin ear drops were
Morphological and genetic divergences of evaluated for treatment of Otodectes cynotis

Otodectes cynotis isolates between Cats and
infestation. The evaluation was depending upon the Dogs: Otodectes cynotis mites detected in ear swaps number of Otodectes cynotis mites per swab, the status of Cats and Dogs were morphologically studied of mites (either living or dead or absent) and level of regarding body and leg sizes as described by Lohse et improvement of clinical signs especially amount of ear al. (2002). DNA from ear swaps containing Otodectes waxy material and degree of itching. cynotis mites was extracted and measured. RAPD-PCR using three different primers was done according Results to (Hugh and Annette, 1994). The three primers were As summarized in tables-1 and 2, and figure-1. H-12 (5`-ACGCGCATGT-3`) (primer-1, P1) , T-20 The mono-specific and mixed infestations of Otodectes (5`-GACCAATGCC-3`)(primer-2, P2) and V-07 (5`cynotis in cats were (24.56%) and (6.57%) while in GAAGCCAGCC-3`) (primer-3, P3), the primers and dogs were (7.17%) and (4.48%) respectively. The RAPD-PCR kits were produced by Gene tech highest rate of infestation was in young cats and the company, Egypt. Three RAPD-PCR reactions were lowest was in elder dogs. done for cat isolate DNA of Otodectes cynotis and the The Mixed infestations of Otodectes cynotis same reactions were done for dog isolate DNA of mites with Sarcoptes, Demodex, Dermatophytes, Otodectes cynotis using the three primers. One control Ticks, Fleas, Ascarids, Dipylidium and Isospora were negative reaction was carried out. Haem-III (DNA marker) was loaded onto gel to know DNA bands detected. Complications of Otodectes cynotis infestations were observed as ear haematoma, in-co-molecular weight. Each reaction was represented by small ependolf tube. Then each small ependolf tube ordination and imbalance, ear scratch and bleeding,  deafness, fever and death. highest in young cats(10.38%) and the lowest in elder dogs (0.89%). Also the mixed infestation of Otodectes The morphological characters of Otodectes cynotis with other parasites and dermatophytosis was cynotis mites from cats and dogs regarding the body the highest in young cats (4.15%) and the lowest in and leg sizes were similar. The RAPD-PCR proved the elder dogs (0.44%). The results showed that the monogenetic divergence between cat and dog isolates whereas specific and mixed infestation of Otodectes cynotis in they are morphologically similar. Result showed that cats were (24.56%) and (6.57%), in dogs were (7.17%) lane-1(Haem-III: DNA marker), lane-2(cat isolate and (4.48%) respectively. It is very clear that the with primer-1), lane-3 (cat isolate with primer-2), lane-4 infestation of Otodectes cynotis in cats is higher than (cat isolate with primer-3), lane-5 (control negative), that in dogs, which may prove the higher susceptibility Lane-6(dog isolate with primer-1), lane-7(dog isolate of cats to Otodectes cynotis. The other parasites with primer-2), lane-8 (dog isolate with primer-3). (22.3%), they reported mono-specific and mixed infestations at the rate of (83.0%) and (17.0%) Discussion respectively in Otodectes cynotis infested dogs. Otodectes cynotis mites can survive in ear canal Rodriguez-Vivas et al. (2003) reported the infestation of both cat and dog and as well as surrounding of Otodectes cynotis in Mexican dogs was (3.5%). environment. It feeds on epidermal debris inside the Although the Cat and Dog isolates of Otodectes ear and is very contagious and, they cause serious ear cynotis were morphologically similar in body and leg irritation and damage if not treated (OIE, 2005). sizes , the RAPD-PCR showed the genetic divergence Rates of mono-specific, mixed and the collective between cat isolates and dog isolates that was proved infestations of Otodectes cynotis in cats and dogs as by presence of different RAPD-PCR bands pattern illustrated in table-1, shows that the rate of monousing three primers as illustrated in figure-6. The specific infestation with Otodectes cynotis was the genetic divergence may explain the higher infestation rate of Otodectes cynotis in cats. We thought that there were two genetically different types of Otodectes cynotis, one in cats and another in dogs. That was reported by Lohse et al. (2002), they characterized the second internal transcribed spacer (ITS 2) of the rDNA of 16 Otodectes cynotis isolates from 11 cats, two dogs, one arctic fox and two ferrets originating from four different continents. In addition, mites from dog, cat and arctic fox were investigated morphologically. Sequence comparisons revealed five different, but closely related genotypes.  with different three routes of administration were 2.