Diagnosis And Treatment Experimental Research On Canine Ehrlichiosis

Objective: Infect beagle dogs with ehrlichiosis through inculation, make records and analysis the clinical features, inclusion body of blood cell, results and sequences of blood and spleen extract by PCR, biochemistry and routine indexes changes of blood, pathological changes and changes of all these items above after treatment with Doxycycline Hyclate. It is supposed to prompt the research on canine ehrlichiosis diagnosis and treatment in China, also contribute to human ehrlichiosis research.Methods:①Healthy beagle dogs were infected by blood samples from natural infected ehrlichosis dogs in China through vein injection.②Recorded clinical symptoms such as temperature, consciousness, stool, urine, cough, vomiting, blood speckle on skin, etc.③Made blood smears of postfebrile beagle dogs, then dyed them by Gimesa, the ehrlichia pathogen inclusion bodies were observed through light microscope; Blood were collected to make electron samples, then the samples were observed through electron microscopy. ④Detected the blood samples of postfebrile beagle dogs by PCR, then the PCR products are purified and sequenced.⑤Blood samples were obtained from 6 Beagle dogs before and after infection, then detected biochemistry indexes and routine indexes of blood by automatic biochemistry apparatus and automatic globulimeter respectively, the dataes were analyzed by statistic method.⑥Pathological sections of Organ samples from the two untreated beagle dogs were made by routine method, dyed by H.E, then observed and photographed under microscope.⑦4 sick dogs were treated by Doxycycline hydrochloride through oral medication, compared these indexes before and after treatment by statistic method, then evaluated the therapeutic efficiecy.Results:①Clinical symptoms: the incubation period is 5 to 19 days after beagle dogs were injected with ehrlichia, dogs presented acute fever, depression, appetite declining, serious weight loss, conjunctiva pale gradually, subcutaneous hemorrhage. A few dogs presented diarrhea with blood stools, blood urine, cough and vomit. The untreated dogs were extraordinary emaciated, with severe secondary infection, and got exhaustion in 27 and 35 days after innoculation respectively.②Pathogen observation: Blood smears of all 6 postfebrile beagle dogs were detected with ehrlichia pathogen inclusion bodies with purple dyeing; more than one pathogens were in cytoplasmic vacuoles of mononuclear cells and platelets with electron microscope observation.③PCR detection and sequencing: All 6 beagles dogs were PCR positive after fever, the spleen samples from two untreated dogs were PCR positive too; the sequencing results showed that one of the PCR products had a 98% similarity with ehrlichia Gzh982, while the other was 99% similar to ehrlichia Gzh981;④Blood biochemistry and routine: RBC, WBC, HGB, HCT, PLT, RDW, MPV, LYM, MONO and RDW significantly decreased (P＜0.05) after fever in blood routine detection; ALT and AST significantly increase (P＜0.05), while ALB decreased significantly (P＜0.05). The other indexes didn't have any significant changes.⑤Histopathology examination: Obvious subcutaneous hemorrhage and stagnation of blood were found in the major tissues and organs, and severe swollen enlargement in spleens and livers by macroscopic way; The histological-pathological changes were characterized by severe dropsy in lymph node, accumulation of lymphocytes and plasma cells in blood vessels in livers, spleens, lungs and kidneys, and accumulation of lymphocytes and plasma cells in Lamina propria of urinary bladder;⑥Therapeutic test: The body temperature of 4 beagle dogs dropped at the second day after treated with Doxycycline Hyclate, and the clinical symptom of the four dogs got better; 4 days after treatment, the body temperature dropped to normal level, appetite and consciousness got better obviously; 15 days after final treatment, there was no ehrlichia inclusion body in cytoplasmic vacuoles of mononuclear cells and platelets of blood smears with purple dyeing, the indexes of blood biochemistry and blood routine restored to normal level in all 4 treated dogs; the clinical symptoms of the 2 untreated beagle dogs served as control group deteriorated gradually, died at the 27th and the 35th day post fever respectively.Conclusions:The results showed all six beagle dogs infected ehrlichia successfully. It was the first time that the blood biochemistry and blood routine changes, histopathology changes and treatment of canine ehrlichosis in China were studied systematically. It proved once again the pathogen was ehrlichia Gzh982 and ehrlichia Gzh981 in ehrlichosis dogs in China.