Fang XlANG，Juan CHEN，Minghe YU，Guohui WANG，Qiumei SHl*，Yanying ZHANG，Yongmei SU，Guangping GAO，Guisheng GAO，F(xiàn)ujin Ll，Hongxue ZHANG，Yu ZHAO

1.Changli Center for Animal Disease Prevention and Control，Changli 066600，China；

2.Key Laboratory of Preventive Veterinary Medicine of Hebei Province/Hebei Normal University of Science and Technology，Changli 066600，China；

3.Wen’an Animal Husbandry and Veterinary Bureau，Wen’an 065800，China；

4.Qilu Animal Health Products Co.，Ltd.，Ji’nan 250100，China

Histopathological Observation of Canine Distemper in Raccoon Dogs

Fang XlANG1，Juan CHEN2，Minghe YU3，Guohui WANG3，Qiumei SHl2*，Yanying ZHANG2，Yongmei SU2，Guangping GAO2，Guisheng GAO2，F(xiàn)ujin Ll4，Hongxue ZHANG4，Yu ZHAO2

1.Changli Center for Animal Disease Prevention and Control，Changli 066600，China；

2.Key Laboratory of Preventive Veterinary Medicine of Hebei Province/Hebei Normal University of Science and Technology，Changli 066600，China；

3.Wen’an Animal Husbandry and Veterinary Bureau，Wen’an 065800，China；

4.Qilu Animal Health Products Co.，Ltd.，Ji’nan 250100，China

In this study，histopathological changes in the heart，liver，spleen，lung，kidney and other organs of raccoon dogs died of canine distemper were observed. According to the results，the lung of infected raccoon dogs exhibited severe hemorrhage and emphysema；the liver was congested and degenerated；the spleen was enlarged；the exhibited severe hemorrhage and hyaline degeneration.Multiple organs of infected raccoon dogs were congested and hemorrhaged with tissue damage，inflammatory cell infiltration and a series of pathological changes.This study laid a solid foundation for clinical diagnosis and treatment of canine distemper in raccoon dogs.

Canine distemper；Histopathology；Raccoon dog

C anine distemper is an acute infectious disease caused by canine distemper virus［1］，which is characterized by biphasic fever，rhinitis，severe gastrointestinal disorders and respiratory tract inflammation，and even encephalitis in a few cases.Various secretions，excrements（nasal mucus，saliva，tears，pericardial fluid，pleuraleffusion，ascites and urine）， blood， cerebrospinal fluid，lymph nodes，liver，spleen，spinal cord and other organs of infected animals contain large amounts of canine distemper virus，and the virus can be excreted outward via respiratory tract secretions and urine.Healthy animals can be infected through respiratory tracts or gastrointestinal tracts by direct contact with infected animals and contaminated air or food［2-3］.Fur-bearing animals such as foxes and minks are extremely susceptible to canine distemper［4］.So far，little information is available on canine distemper in raccoon dogs.In this study，pathological changes in five raccoon dogs clinically diagnosed with canine distemper were observed；typical lesions of liver，lung，spleen，kidney and small intestine of dead raccoon dogs were collected，prepared into paraffin sections and stained with HE for histological observation，aiming at providing reference for clinical diagnosis and treatment of canine distemper in raccoon dogs.

Materials and Methods

Materials

Experimental animals From July 2014 to January 2015，the experiment was carried out with five raccoon dogs with suspected canine distemper as experimental materials in Hebei Normal University of Science and Technology.

Reagents Canine distemper virus diagnostic kit；pathologicalsectionreagents such as paraffin，70% ethanol，80%ethanol，95%ethanol，100% ethanol，xylene，hematoxylin and eosin.

Methods

Diagnosis and necropsy of raccoon dogs with typical symptoms A small amount of serum or tear，saliva and other secretions of infected raccoon dogs were collected，transferred into testtubes containing dilution buffer，and mixed evenly by stirring；several drops of sample dilution was added into sample holes of test strip with a pipette.After 10-20 min，test strips with test line and control line turning red indicated positive results，suggesting that the experimental animal could be diagnosed with canine distemper；test strips without appearance of T line indicated negative results.Raccoon dogs died of canine distemper were necropsied to observe the pathological changes.

Preparation of pathologicalsections The liver，spleen，lung，kidney and small intestine tissues of infected raccoon dogs were collected，fixed with 100 ml/L neutral buffered formalin，prepared into pathological sections in accordance with the literature［5-6］，and embedded in paraffin. The histopathological changes were observed and photographed under the microscope.

Results and Analysis

Clinical diagnosis results

The diagnosis results of five raccoon dogs with suspected canine distemper using canine distemper virus diagnostic kit were positive.

Gross necropsy results

Infected raccoon dogs were emaciated and depressed with disheveled hair，sunken eyes and gum in the eyes.Laparoscopy results indicated bloody ascites， remarkable hepatomegaly with rounded liver edge and an incision extending outward，dark red lung with bleeding points on the surface and bloody foam after extrusion，large amounts of bleeding spots and ulcer lesions on the surface of gastric mucosa，different degrees of congestion and necrosis in duodenum，small intestine and large intestine，large amounts of intestinal mucus，renal congestion，bleeding and swelling， and gallbladder filling，without any other abnormalities.

Histopathological observation results

Liver:as shown in Fig.1，the liver was congested and degenerated with amyloid substances concentrated between hepatic cord and bean shaped gap，forming reddish-brown trabes with varying thickness，and the bean shaped gap was squeezed and became smaller；there were small blisters in hepatocyte cytoplasm and vacuoles in some nuclei.

Spleen:as shown in Fig.2，extensive hemosiderin congestion points were observed；splenic lymphoid tissues were reduced with diffuse necrosis of lymphocytes；individual red pulp macrophages increased.

Duodenum:the duodenum of infected raccoon dogs exhibited surface necrosis，epithelial cell necrosis or shedding，duodenalgland atrophy，duodenal gland cell degeneration and necrosis， swelling， vacuolization；duodenal villi were shortened with surface tissue necrosis；some capillaries were congested； petechial hemorrhagewasobservedaround duodenal gland（Fig.3 and Fig.4）.

Lung:the lung of infected raccoon dogs exhibited alveolar collapse and serious alveolar hemorrhage in some regions with thickened alveolar wall and scattered lymphocytes；in addition，emphysema occurred in some alveolar regions with hyperaemia inside the bronchiole（Fig.5）.

Kidney:as shown in Fig.6 and Fig.7，the kidney hemorrhaged with hyaline degeneration； red-stained homogeneous vitreous bodies were visible.

Discussions

Currently，canine distemper has become a majorobstacle limiting large-scale breeding offur-bearing animals.The number of raccoon dogs died of canine distemper is increasing yearly.So far，canine distemper virus has become one of the major viruses infectingraccoondogs［7-10］.Inthisstudy，different lesions of the infected raccoon dog exhibited varying degrees of hemorrhage，especially the lung，liver and intestinal tract.In addition，the middle and posteriorsegments of smallintestine were dilatate with serous congestion，watery intestinal contents that were mixed with blood，and severe shedding of dark red intestinal mucosa.Funicular mesenteric lymph nodes exhibited cord swelling，congestion and hemorrhage.In some cases，the entire small intestine was congested and hemorrhaged signifi-cantly with mucosal epithelial necrosis，shedding and villousatrophy.The above lesions increase the difficulty of treatment.Therefore，several recommendations have been proposed for the prevention and treatment of canine distemper as follows.①Strengthening comprehensive prevention and control of canine distemper and prohibiting the introduction from epidemic areas. Raccoon dogs introduced from nonepidemic areas should be isolated for observed firstly，and mixed after vaccination.②Prohibiting the breeding of cats and dogs in raccoon dog farms and cutting off contact with these animals.③ Strengthening eradication of rats and all kinds of blood-sucking insects and harmful birds.④ Strengthening inoculation with inactivated or attenuated vaccines against canine distemper virus.Young raccoon dogs should be inoculated within 2-3 weeks after separation in June-July every year；adult raccoon dogs should be inoculated in December-January and June-July，respectively.Specifically，young raccoon dogs are inoculated with 2 ml of vaccines；adult raccoon dogs should be inoculated with 3 ml of vaccines；the immunization period lasts six months.

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Responsible editor：Xiaohui FAN

Responsible proofreader：Xiaoyan WU

貉犬瘟熱病理組織學(xué)觀察

項(xiàng)方1，陳娟2，于明鶴3，王國輝3，史秋梅2*，張艷英2，蘇詠梅2，高光平2，高桂生2，李富金4，
張洪學(xué)4，趙宇2（1.昌黎縣動物疾病預(yù)防控制中心，河北昌黎066600；2.河北省預(yù)防獸醫(yī)學(xué)重點(diǎn)實(shí)驗(yàn)室，河北科技師范學(xué)院，河北昌黎066600；3.文安縣畜牧獸醫(yī)局 河北文安065800；4.齊魯動物保健品有限公司，山東濟(jì)
南250100）

觀察了犬瘟熱病死貉的心臟、肝臟、脾臟、肺臟、腎臟等器官的病理組織學(xué)。結(jié)果顯示病死貉的肺臟嚴(yán)重出血及氣腫，肝臟淤血、變性，脾臟腫大，腎臟出血、透明變性?；疾『训亩嗥鞴侔l(fā)生充血，出血，組織破壞及炎性細(xì)胞浸潤等一系列的病理變化。

犬瘟熱；病理組織學(xué)；貉

河北省科技廳科技支撐計劃（14826613D）；秦皇島市農(nóng)業(yè)科學(xué)研究院項(xiàng)目（2014-04）；秦皇島科技局項(xiàng)目（201502A054）；國家級星火計劃項(xiàng)目（2015GA620002）。

項(xiàng)方（1964-），男，河北昌黎人，高級獸醫(yī)師，研究方向?yàn)槊游锛膊》乐?，E-mail：clxykzx@163.com。*通訊作者，教授，博士，研究方向?yàn)閯游飩魅静》乐?，E-mail：shiqiumei@126.com。

2015-09-23

Supported by Science and Technology Support Program of Science and Technology Department of Hebei Province （14826613D）；Project of Qinhuangdao Academy of Agricultural Sciences （2014-04）；Project of Qinghuangdao Municipal Science and Technology Bureau（201502A054）；China Spark Program（2015GA620002）.

*Corresponding author.E-mail:shiqiumei@126.com

Received:September 23，2015 Accepted:November 15，2015

修回日期 2015-11-15