Occurrence of the ear-mite Raillietia auris in cattle in Austria

We describe here the first documented case in Austria of the cattle ear mite Raillietia auris in a four-year-old dairy cow. The cow was mildly depressed, and keratoconjunctivitis was diagnosed in both eyes with Horner's syndrome in the left eye. The animal showed a mild head tilt to the left and a generalized ataxia with a tendency to move to the right side, which became exacerbated if the animal was blind-folded. Head pressing to the right side, dysphagia and a dropped jaw were also observed. Numerous rather mobile ear mites were observed at necropsy in the basal part of the left ear canal. The clinical significance of the cattle ear mite is uncertain and the clinical signs could have been caused by listerial encephalitis, which was also confirmed histologically in this case.     

Infestation of a cattle herd with the ear mite Raillieta auris (Acarina, Mesostigmata)

An infestation with Raillietia auris in a 4 years old cow is reported. For a period of 3 weeks the animal showed an increasing unrest, extreme efforts while trying to feed, and continuous shaking of the head which slanted to the left. After slaughter numerous specimens of the ear-mite R. auris were found in the basic part of the left auditory canal, located in the vicinity of a purulent paste-like plug. Histological examinations of the brain revealed a severe non-purulent meningoencephalitis with necroses of the vascular walls, focal malacia and gliosis. An etiological correlation of these lesions with the mite-infestation, however, is considered to be most unlikely. To the best of our knowledge the occurrence of R. auris in Switzerland was up to now unknown.     

Eradication of elephant ear mites (Loxoanoetus bassoni) in two African elephants (Loxodonta africana)

Elephant ear mites, not previously described in North America, were eradicated in two African elephants (Loxodonta africana) after six otic instillations of ivermectin at 2-wk intervals. The microscopic examination of a clear, mucoid discharge collected from the external ear canals of two wild-born African elephants housed in a New York State zoo for 25 yr revealed live mites (Loxoaneotus bassoni). The cytologic examination demonstrated no evidence of inflammation or infection. Both elephants were asymptomatic with normal hemograms and serum chemistry panels. A diagnosis of otoacariasis was made. Each elephant was treated six times with 5 ml of 1% ivermectin syrup instilled in each ear canal once every 2 wk. Microscopic examinations of clear mucus collected from each elephant's ear canals 9 days after the first instillation of ivermectin were negative for any life stages of ear mites. Microscopic examinations of mucus collected from both elephants' ear canals at 6, 11, and 16 wk, as well as annually post-treatment for 7 yr, confirmed eradication of the ear mites. The L. bassoni ear mite was first identified in the external ear canals of wild, asymptomatic, lesion-free, African elephants culled in Kruger National Park in South Africa. However, a new species in the same genus of mites (Loxoanoetus lenae) was identified at the necropsy of an 86-yr-old Asian elephant (Elephas maximus) living in a circus in Australia. The autopsy revealed a marked, ballooning distension of bone around the left external acoustic meatus, suggestive of mite-induced otitis externa, as seen in cattle infested with ear mites (Raillieta auris). Elephant health care providers should identify the prevalence of, and consider treatment of, elephants in their care infested with ear mites, given the possible risk for adverse health effects.     

Safety and efficacy of ivermectin against ear mites (Otodectes cynotis) in ranch foxes

Efficacy of ivermectin at a dosage of 0.2 mg/kg of body weight was evaluated against naturally acquired ear mite (Otodectes cynotis) infestation in commercially raised ranch foxes (Vulpes fulva). Efficacy of ivermectin given sc twice at 3-week intervals was 97.4%. Toxicosis associated with drug treatment was not observed. Increased dosage of 1.0 mg/kg was given sc to 5 foxes each week for 6 consecutive weeks, and signs of toxicosis or illness were not observed after treatment.     

Suppurative rhinitis associated with Haemophilus species infection in a cat

A young cat with signs of chronic rhinitis was evaluated for underlying anatomical, inflammatory, or infectious disease. Initial diagnostics were significant for the isolation of an unusual pathogen, Haemophilus species. Isolation using a human RapID NH system erroneously identified the isolate as H. segnis, a human pathogen. No database of veterinary pathogens (Haemophilus) are included in the system and animal pathogens will either be erroneously identified or yield a unique biocode not listed. Because of the unique nature of the pathogen we explored the possibility of immunosuppression as a contributory factor to infection. A variety of laboratory tests were employed to evaluate immune function. The clinical indications and utility of immune function testing are discussed. No immune dysfunction was identified.     

Effect of ivermectin on the control of ear mites (Psoroptes cuniculi) in naturally infested rabbits.

We examined the efficacy of ivermectin in the control of ear mites (Psoroptes cuniculi) in rabbits. The study involved 40 female and 35 male rabbits that were known to be naturally infested with ear mites. After a period of acclimation to the animal care facilities, the rabbits were ranked on the visual appearance of any ear lesion and the number of mites on glycerin-dipped ear swabs. The rabbits were then randomly assigned to 1 of 4 treatment groups; vehicle only (group 1), 50 micrograms of ivermectin/kg of body weight (group 2), 100 micrograms of ivermectin/kg (group 3) and 200 micrograms of ivermectin/kg (group 4). The rabbits were treated by SC injections on day 0 and day 14 of the trial; thus, the total dose of ivermectin given to groups 1 through 4, was 0, 100, 200, or 400 micrograms/kg, respectively. The study ended 2 weeks after the last treatment. Ear lesions of the treated rabbits improved significantly (P less than 0.001). By 28 days after the first treatment, the mean number of mites on the ear swabs (both ears) was 57.5 for untreated rabbits and 9.1, 0.5, and 2.5, respectively, for rabbits in groups 2, 3, and 4. The mean number of mites recovered from the ears of the untreated rabbits at necropsy was 24,297. For groups 2, 3, and 4, the mean number of mites recovered from the ears was 5,352, 96, and 96, respectively. The efficacy of treatment with a total dose of 100 micrograms/kg was 77.96%, with 200 micrograms/kg was 99.61%, and for 400 micrograms/kg was 99.61%.     

Chlorfenapyr ear tags to control Haematobia irritans (L.) (Diptera: Muscidae) on cattle

The efficacy of ear tags containing 30% chlorfenapyr (total tag weight=13g) to control natural Haematobia irritans (L.) infestations was evaluated for Holstein heifers in Rafaela, province of Santa Fe, Argentina. A group of heifers (TG) was treated with two ear tags (one tag per ear). A control group (ACG) was maintained in a paddock adjacent to the TG paddock and, a distant control group (DCG) was maintained 700m apart from the other groups. From day 4 to day 98 after treatment, H. irritans infestations of ACG were significantly higher (P<0.05, test of Kruskal-Wallis) than the corresponding infestation of TG, but significantly lower than infestation in DCG, probably due to the proximity of TG. The chlorfenapyr control period, with an efficacy higher than 90% to reduce horn fly populations, lasted for 9 weeks when TG infestation was compared to fly numbers in ACG, but increased to 12 weeks in comparison to DCG. The results of this study show that ear tags impregnated with chlorfenapyr are a useful alternative to pyrethroids and organo-phosphate compounds for horn fly control.