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Sarcoptes scabiei is a widespread, highly contagious skin disease that affects many mammals including humans. The biological characteristics of S. scabiei remain unclear. Therefore, the ability to collect adequate amount of mites for studies is required to advance our understanding of the parasite. The present study aimed to find a method to collect an adequate amount of live S. scabiei mites within a short time frame. The cornified layer and fur from an infected raccoon dog were inserted into a 50-ml catheter tip-type syringe. A 1.5-ml microtube was attached at the tip of the syringe to collect the mites, which crawled out from the cornified layer and fur. Four conditions were examined, and the following condition was determined to be the best: the syringe and microtube were shaded by aluminum foil, and the microtube was heated using a pet heater (36 °C). In addition, the effectiveness of this method as an alternative method to diagnose S. scabiei infections in animal was evaluated. S. scabiei live mites were not detected in the raccoon dog samples 24 h after the administration of medication (ivermectin or selamectin). The present study revealed that this technique was useful to collect adequate amounts of live mites, and the mites prefer a heated environment and actively move when using the shaded conditions. In addition, this technique was effective as an alternative diagnostic technique to detect live mites on an animal body.

The clinical and histologic features of thyroid carcinoma in raccoon dogs have not been previously reported. Three of four raccoon dogs (Nyctereutes procyonoides) over 8 yr of age at the Nogeyama Zoological Gardens developed thyroid follicular cell carcinomas that were detected at necropsy. The affected raccoon dogs were rescued from the wild and were housed at the Nogeyama Zoological Gardens for 8 yr 8 mo, 8 yr 10 mo, and 10 yr 3 mo, respectively. Although all of them appeared lethargic and developed partial alopecia or desquamation of their skin, they did not display any other specific clinical signs associated with a thyroid lesion. Serum thyroid hormone values were examined in two of the affected raccoon dogs and the average and standard deviation values (free-thyroxin [FT4]: 0.078 ± 0.077 pM/L and 0.062 ± 0.0039 pM/L; free-triiodothyronine [FT3]: 3.261 ± 0.765 pM/L and 3.407 ± 0.919 pM/L) were lower than the reference range (FT4: 0.141 ± 0.117 pM/L; FT3: 5.139 ± 2.412 pM/L) derived from a clinically normal raccoon dog. On necropsy, the thyroid lobes were markedly enlarged bilaterally. Histopathologically, the neoplastic cells in the thyroid gland appeared round or oval and columnar or cuboidal with minimal heteromorphism. Moreover, mostly small (but occasionally large) follicles were identified, and the neoplastic cells had infiltrated into the surrounding capsule and blood vessels. The histopathologic features of the thyroid tumors in the raccoon dogs revealed that the tumors were derived from follicular cells.

Sarcoptes scabiei is one of the important external parasites. Although ivermectin is the recommended treatment, many raccoon dogs (Nyctereutes procyonoides) that were rescued and brought to the Kanazawa Zoological Gardens (Yokohama, Japan) have died because of S. scabiei, even after receiving single ivermectin treatment. Therefore, supportive treatment should be required. The present study revealed the number of animals that survived was greater after the administration of ivermectin along with an antibiotic for all raccoon dogs, as well as following the administration of fluid therapy to the debilitated raccoon dogs infected with S. scabiei, immediately after the rescue. During the initial period, treatment to improve the general clinical condition was required prior to deworming treatment for S. scabiei.

The prevalence of Dirofilaria immitis in free-ranging raccoon dogs (Nyctereutes procyonoides viverrinus) was examined in the southeast region of Kanagawa Prefecture, Japan, using a rapid immunomigration (RIM) test kit. Between April 2007 and March 2010, we examined 108 raccoon dogs rescued and housed by the Kanazawa Zoological Garden. D. immitis infection was found in 8 (7.4%) raccoon dogs. This is the first report to reveal the prevalence of D. immitis infection in living raccoon dogs. The prevalence of the infection was lower than previously reported values obtained on postmortem examination. One reason might be that the present study included young raccoon dogs infected with immature worms. Significant high-risk areas of D. immitis infection in the raccoon dogs were not observed.