Granulocytic Ehrlichiosis in Dogs from North Carolina and Virginia

Medical records of 3 dogs from North Carolina and 3 dogs from Virginia with ehrlichial morulae in circulating neutrophils were studied retrospectively. Two clinically distinct disease syndromes, including chronic, moderate to severe anemia (n = 3) and polyarthritis (n = 2) were associated with canine granulocytic ehrlichiosis (CGE) in these dogs. One dog was clinically healthy, and abnormalities were not detected during physical examination. Clinical signs were nonspecific and included fever, lethargy, anorexia, vomiting, and diarrhea. The most frequent laboratory abnormalities were normocytic normochromic nonregenerative anemia, moderate thrombocytopenia with large platelets, lymphopenia, and eosinopenia. Considerable variability was found in the serologic responses to Ehrlichia equi, Ehrlichia canis , and Ehrlichia chaffeensis antigens among the 5 dogs for which stored sera were available for indirect fluorescent antibody testing. Polymerase chain reaction amplification and sequencing of portions of the 16S rRNA gene from blood (collected in ethylenediaminetetraacetic acid) of 1 severely anemic dog (dog 3) and 1 polyarthritic dog (dog 4) resulted in DNA sequences nearly identical to the GenBank accessions for Ehrlichia ewingii. The DNA sequence from a 3rd dog (dog 5) was most similar to that of E. canis. Serologic or molecular results support the possibility of E. ewingii, E. equi , and E. canis coinfection or serologic cross-reactivity among canine granulocytic and monocytic Ehrlichia species in dogs from North Carolina and Virginia. Variability in response to tetracycline or doxycycline treatment was noted in these dogs, with more rapid resolution of signs in dogs with polyarthritis. We report the 1st cases of CGE in dogs from North Carolina and Virginia, including recognition of CGE in a healthy dog.     

Experimental primary and secondary infections of domestic dogs with Ehrlichia ewingii

In this study, the infection dynamics of Ehrlichia ewingii, causative agent of granulocytotropic ehrlichiosis in dogs and humans, was examined in experimentally infected dogs by using a combination of physical examination, hematologic and biochemical analyses, and molecular and serologic assays. For the experimental trials, blood from an E. ewingii-infected dog was inoculated intravenously into two na?ve dogs and two dogs with prior experimental exposure to E. ewingii (both were negative for E. ewingii DNA by polymerase chain reaction (PCR) assay, but seropositive from initial infection 8 and 10 months prior to challenge). A negative control dog was inoculated with blood from a negative dog. The two primary infection dogs were positive for E. ewingii DNA on DPI 4, remained consistently positive until DPI 60, and were intermittently positive until the end of the study (DPI 144). The two primary infection dogs developed antibodies reactive to E. ewingii by DPI 28 and remained seropositive for the duration of the study. Primary infected dogs had intermittent fever, thrombocytopenia, and leukopenia and some dogs were hyperphosphatemic and/or had elevated ALP levels. The two challenge dogs were positive for E. ewingii DNA on DPI 4 and 18, which was similar to the primary infection dogs, but the duration of E. ewingii DNA detection was shorter. Also, the two challenged dogs did not develop pyrexia or show any hematologic or biochemical abnormalities. E. ewingii was successfully transmitted between dogs by Amblyomma americanum, but not Rhipicephalus sanguineus. This study provides data on the infection dynamics of E. ewingii in dogs during primary and challenge infections and suggests that prior exposure may lessen clinical disease during subsequent infections.     

Ehrlichial infection in Cameroonian canines by Ehrlichia canis and Ehrlichia ewingii

Ehrlichia chaffeensis and Ehrlichia ewingii are agents of emerging human ehrlichioses in North America and are transmitted primarily by Amblyomma americanum ticks, while Ehrlichia canis is the globally distributed cause of canine monocytic ehrlichiosis (CME) and is transmitted by the brown dog tick, Rhipicephalus sanguineus. Although E. canis and Ehrlichia ruminantium are endemic in Africa, the presence of ehrlichial agents in dogs and ticks in Cameroon has not been investigated. The objective of this study was to determine the prevalence of ehrlichial infections in Cameronian dogs using a combination of serologic and molecular methods. Peripheral blood was collected, clinical signs and the presence or absence of ticks on dogs (n=104) presenting for various reasons at local veterinary clinics around the Mount Cameroon region were noted. IFA identified 33 dogs (32%) with antibodies reactive with E. canis, and reactivity of these sera with all major E. canis antigens (200, 140, 95, 75, 47, 36, 28, and 19-kDa) was confirmed by immunoblotting. Multicolor real-time PCR detected ehrlichial DNA (E. canis (15) and E. ewingii (2)) in 17 dogs (16.3%), all of which had attached ticks at time of presentation. The dsb amplicons (378 bp) from E. canis and E. ewingii were identical to gene sequences from North American isolates. This study identifies canine ehrlichiosis as a prevalent unrecognized cause of disease in Cameroonian canines.     

Doxycycline clearance of experimentally induced chronic Ehrlichia canis infection in dogs

BACKGROUND: Ineffective clearance of Ehrlichia canis after doxycycline administration has been reported despite the fact that the recommended treatment for canine ehrlichiosis is doxycycline. The effectiveness of doxycycline in clearing E canis infection from the blood and tissues of dogs requires additional evaluation. HYPOTHESIS: Doxycycline (5 mg/kg PO q12h), administered for 4 weeks, will eliminate E canis infection from the blood and tissues of experimentally infected dogs. ANIMALS: Fifteen Walker hound-mixed breed dogs were inoculated subcutaneously with E canis-infected canine histiocytic cells 4 months before doxycycline treatment. METHODS: Four dogs were treated with doxycycline (5 mg/kg PO q12h for 3 weeks), 5 dogs were treated with doxycycline at the same dosage for 4 weeks, and 5 control dogs were not treated. Dexamethasone (0.4 mg/kg i.v.) was given after treatment to precipitate recrudescence of any remaining E canis organisms. Platelet counts, anti-E canis immunofluorescent antibodies, and polymerase chain reaction (PCR) detection of E canis deoxyribonucleic acid (DNA) in blood and tissues were evaluated. RESULTS: E canis DNA was not detected in the blood and tissues of doxycycline-treated dogs after treatment. Platelet counts were within reference intervals, and E canis antibodies decreased. Spontaneous clearance of E canis infection occurred in 2 of 5 control dogs. Three control dogs had E canis DNA detected in blood and tissues, platelet counts remained low or within the reference interval, and E canis antibodies remained high. CONCLUSIONS AND CLINICAL IMPORTANCE: As administered in this study, doxycycline cleared E canis from the blood and tissues of experimentally infected dogs.     

Evaluation of granulocytic ehrlichiosis in dogs of Missouri, including serologic status to Ehrlichia canis, Ehrlichia equi and Borrelia burgdorferi.

Canine granulocytic ehrlichiosis was diagnosed in 37 dogs by finding ehrlichial morulae in 0.1 to 26.2% of their blood neutrophils and eosinophils. All 37 dogs had clinical signs of arthritis or muscular stiffness. Titer to Ehrlichia canis was determined in sera from 31 of the 37 dogs; 25 dogs had titer ranging from 1:20 to 1:5,120. In the other 6 dogs, titer to E canis was less than 1:10. The most common hematologic abnormality in these dogs, other than rickettsiemia, was thrombocytopenia. Granulocytes infected with ehrlichial organisms were not found in another 10 dogs that had clinical signs of arthritis or muscular stiffness. Of these 10 dogs, 3 had titer to E canis ranging from 1:40 to 1:320. Titer in the other 7 dogs was less than 1:10. Ehrlichial morulae were not found in the granulocytes of 18 healthy dogs. Of these 18 dogs, 9 had titer to E canis ranging from 1:20 to 1:5,120. Titer in the other 9 dogs was less than 1:10 Titer to Borrelia burgdorferi was determined in dogs with granulocytic ehrlichiosis, arthritic dogs without detected rickettsiemia, and in healthy dogs. Low titer determined by 2 laboratories was considered to be nonspecific reaction in all 3 groups of dogs and, thus, did not indicate that the arthritic disorders were attributable to canine borreliosis.     

Serum cardiac troponin I concentration in dogs with ehrlichiosis

Background: Ehrlichiosis is a multisystemic disease with the potential to cause cardiomyocyte injury in naturally infected dogs.
Hypothesis: Myocardial injury occurs in dogs infected with Ehrlichia canis .
Animals: One-hundred and ninety-four dogs from Brazil with clinical and laboratory abnormalities indicative of ehrlichiosis. Sixteen healthy dogs served as controls.
Methods: Electrocardiogram, echocardiogram, noninvasive blood pressure measurement, and serum cardiac troponin I (cTnI) concentrations were evaluated. Serologic assays and PCR determined the exposure and infection status for E. canis, Anaplasma spp., Babesia canis vogeli, Bartonella spp., Borrelia burgdorferi, Dirofilaria immitis, Ehrlichia chaffeensis, Ehrlichia ewingii, Leishmania chagasi , and spotted-fever group Rickettsia . Dogs were assigned to groups according to PCR status: E. canis infected, infected with other vector-borne organisms, sick dogs lacking PCR evidence for infection, and healthy controls.
Results: E. canis -infected dogs had higher serum cTnI concentrations than controls (median: 0.04 ng/dL; range 0.04–9.12 ng/dL; control median: 0.04 ng/dL; range: 0.04–0.10 ng/dL; P = .012), and acute E. canis infection was associated with myocardial injury (odds ratio [OR]: 2.67, confidence interval [CI] 95%: 1.12–6.40, P = .027). Severity of anemia was correlated with increased risk of cardiomyocyte damage ( r = 0.84, P < .001). Dogs with clinical signs of systemic inflammatory response syndrome (SIRS) were at higher risk for myocardial injury than were other sick dogs (OR: 2.55, CI 95%: 1.31–4.95, P = .005).
Conclusions and Clinical Importance: Acute infection with E. canis is a risk factor for myocardial injury in naturally infected Brazilian dogs. Severity of anemia and SIRS might contribute to the pathophysiology of myocardial damage.     

Ehrlichia and Babesia infections in dogs in The Netherlands

A retrospective study was performed at the Department of Clinical Sciences of Companion Animals at Utrecht University amongst 75 dogs diagnosed with a Babesia canis and/or an Ehrlichia canis infection. The majority of the dogs had visited an endemic area (most often the Mediterranean area or the Dutch Antilles), but two dogs became infected with Babesia in the Netherlands. Babesia infections were associated with a stay in an endemic area and an incubation period that are both significantly shorter (less than 3 months) than those for Ehrlichia and co-infections (more than 3 months). Reasons for the owner to seek veterinary attention (lethargy, anorexia, fever), findings from the physical examination (pale mucous membranes, hepato-/splenomegaly) and laboratory results (anemia, thrombocytopenia, hypo-albuminemia) were highly aspecific, making serology or PCR mandatory for diagnosing infections. Antigenic stimulation by the parasite sometimes resulted in immune-mediated diseases such as immune-mediated hemolytic anemia, thrombocytopenia, glomerulonefritis, and polyarthritis and in the case of ehrlichiosis in hypergammaglobulinemia. Specific therapy (imidocarb-diproprionate and/or doxycycline) was necessary, and because combined infections were common, it was considered appropriate to administer both drugs while the definitive diagnosis was being established. The prognosis was reasonably good, with almost half of all patients showing no clinical signs after treatment, although Babesia and co-infections were associated with a significantly longer survival sometimes resulted than Ehrlichia infections.     

Detection of platelet-bound antibodies in beagle dogs after artificial infection with Ehrlichia canis

Six dogs were infected with Ehrlichia canis by intravenous injection of heavily infected DH82 cells. All dogs developed typical signs of canine monocytic ehrlichiosis. Using flow cytometric technology, platelet-bound IgG (PBIgG) were detected in 5 of the 6 dogs after experimental infection with E. canis over a period of 3-10 days post infection (PI). The first detection of PBIgG was made as early as day 3 PI in 2 out of 6 dogs, and on day 5 PI in 1 dog. On day 7 PI, PBIgG was detected in 2 dogs, and on day 10 PI in 3 out of 6 dogs. This is the first report documenting the presence of PBIgG following E. canis infection in dogs. This finding further supports the theory that the thrombocytopenia seen in canine monocytic ehrlichiosis has an immunological component and that exposure to an infectious agent, in this case the rickettsia E. canis, can trigger autoimmune mechanisms. Due to the heterogeneous appearance of PBIgG among the infected dogs it was concluded that other non-immunological mechanisms are probably also involved in the pathogenesis of the thrombocytopenia seen in canine monocytic ehrlichiosis.     

Serological survey for Ehrlichia canis in urban dogs from the major population centres of northern Australia

OBJECTIVE: To detect evidence of Ehrlichia canis infection of dogs from the major population centres of northern Australia, if present. DESIGN: Serological investigation for E. canis. PROCEDURE: The sera of 316 domestic dogs, collected from the northern Australian population centres of Townsville, Cairns, Darwin, Kununurra and Broome from May 1997 to August 1999, were investigated for evidence of infection with E. canis. Samples were tested for antibodies to E. canis using an indirect fluorescent antibody (IFA) test. The buffy coats from blood of dogs whose serum reacted in the IFA test were subsequently tested with a nested PCR to detect E. canis DNA. When available, blood from these dogs was injected into suckling mice, which were then examined for clinical disease and tested for the presence of E. canis antibodies. RESULTS: Of the 316 samples tested seven reacted in the IFA test for E. canis. None of the dogs from which these samples were obtained exhibited clinical signs of acute or chronic ehrlichiosis. The six positive samples available for testing were negative when tested with the nested PCR. Suckling mice inoculated with blood from three of the dogs whose serum was positive by IFA test showed no signs of clinical disease nor did their give positive reactions in the IFA test. CONCLUSIONS: No evidence of E. canis infection was confirmed in any of the dogs examined. Northern Australia would appear to remain free of this obligate parasite.     

Outbreak of canine monocytic ehrlichiosis in Saudi Arabia

BACKGROUND: Canine monocytic ehrlichiosis (CME) is a widespread tickborne infection of canids caused by Ehrlichia canis, a gram-negative obligatory intracellular bacteria belonging to the family Anaplasmataceae. CME is reported to have worldwide distribution, but its presence in a region requires the presence of the vector, the brown dog tick Rhipicephalus sanguineus. OBJECTIVE: This purpose of this report was to describe an outbreak of CME in a colony of dogs resident in the eastern region of Saudi Arabia. METHODS: History, presenting clinical signs, and the results of a CBC, biochemical panel, and serology (using a commercial test for E canis antibodies) were evaluated in 9 male Labrador Retrievers between October and December 2006. RESULTS: The majority of dogs presented with severe lethargy (7/9) and acute anorexia (5/9), and had fever (7/9) and generalized lymphadenopathy (7/9). The most common laboratory abnormalities were anemia (8/9), leukopenia (7/9), and hypoalbuminemia (6/9). Thrombocytopenia was found in only 2 dogs, 1 of which had increased bleeding tendency. Ehrlichia morulae were identified in blood films from 4/9 dogs and serologic test results were positive in 7/9 dogs. Confirmation of Ehrlichia sp infection was obtained in 1 dog by using a genus-specific real-time PCR assay. Four dogs had tick infestation; the ticks on 1 dog were identified as R sanguineus. All of the dogs had a rapid clinical response to doxycycline hyclate. CONCLUSIONS: This report, to our knowledge, is the first to describe the presence of a pathogenic Ehrlichia organism affecting dogs in Saudi Arabia. Additional molecular studies are necessary to confirm E canis infection, and to identify the strain of the organism.     

Molecular evidence supporting Ehrlichia canis-like infection in cats

Currently, the pathogenic role of Ehrlichia canis in cats has been proposed predominantly on the basis of the serologic evidence of natural infection and the infrequent detection of morulae-like structures within the cytoplasm of leukocytes in cats. The purpose of this report was to provide molecular evidence supporting E. canis-like infection in 3 cats that had clinical manifestations consistent with canine ehrlichiosis but lacked antibodies to E. canis antigens. Serum from all 3 cats contained antinuclear antibodies (ANAs). The predominant disease manifestation was polyarthritis in 1 cat and bone marrow hypoplasia or dysplasia. accompanied by pancytopenia or anemia and thrombocytopenia, in 1 cat each. The alignment of E. canis partial 16S ribosomal DNA (rDNA: 382 nucleotide positions), amplified from EDTA blood samples from each cat, was identical to each other and was identical to a canine isolate of E. canis (GenBank accession number AF373613). In 1 cat, concurrent treatment with corticosteroids may have interfered with the therapeutic effectiveness of doxycycline for the elimination of E. canis-like infection. To further define the spectrum of ehrlichiosis in cats, polymerase chain reaction (PCR) testing may be necessary until serologic testing is thoroughly validated in experimentally or naturally infected cats. In addition, until E. canis has been isolated from cats and several tissue culture isolates are available from disparate geographic regions for detailed comparative genetic study, the molecular evidence presented in this study supporting E. canis-like infection in cats must be interpreted with caution.     

Failure of imidocarb dipropionate to clear experimentally induced Ehrlichia canis infection in dogs

The recommended treatment for canine ehrlichiosis is tetracycline or its analog doxycycline, although recent reports have documented ineffective clearing of Erchlichia canis after doxycycline administration. Imidocarb dipropionate is used as an alternative treatment to tetracycline or is used in conjunction with doxycycline. The effectiveness of imidocarb dipropionate in clearing Ehrlichia species from the blood and tissues of dogs with E. canis infection has not been thoroughly evaluated. Fifteen dogs were experimentally infected with E. canis. Ten dogs were treated with imidocarb dipropionate (6.6 mg/kg, IM, 2 injections given 2 weeks apart). Five infected control dogs were not treated. Blood samples from all 15 dogs were E. canis DNA positive by PCR assay by 3 weeks after inoculation (PI), and E. canis antibodies were detected by IFA assay by 1 week PI. Blood platelet counts in all dogs were below the reference interval by 4 weeks PI. E. canis DNA was detected in bone marrow and splenic aspirates by PCR assay 4 weeks PI but not before infection. Bone marrow aspirates were E. canis DNA positive by PCR assay in 14/15 dogs, and splenic aspirates were E. canis DNA positive by PCR assay in 13/15 dogs. Blood samples from all treated and control dogs remained positive for E. canis DNA by PCR assay, and platelet counts remained below preinoculation values 13 weeks PI (6 weeks after 2nd treatment). As administered in this study, imidocarb dipropionate did not clear experimental E. canis infection in dogs.     

Canine Ehrlichiosis in Six Dogs with Persistently Increased Antibody Titers

Chronic ehrlichiosis was diagnosed in six dogs on the basis of increased immunofluorescent antibody titers to Ehrlichia canis. Although clinical signs varied, all six dogs were anemic, hyperglobulinemic, and an IgG monoclonal gammopathy was documented in five dogs in which serum protein electrophoreses were performed. All dogs were treated with tetracycline for at least 14 days; four dogs also received immunosuppressive drugs. Clinical signs resolved within 1 week, hematologic abnormalities resolved in 1 to 5 months, and increased globulin concentrations normalized in 1 to 15 months; however, E. canis antibody titers remained increased for 15 to 31 months after initiation of treatment. Results of this study show that increased E. canis titers can persist in dogs with ehrlichiosis for many months after clinical recovery.     

Prevalence of Ehrlichia canis infection in thrombocytopenic dogs from Rio de Janeiro, Brazil

BACKGROUND: Infection with Ehrlichia canis causes a highly variable, multisystemic disease in dogs. Nevertheless, many clinicians in Rio de Janeiro, Brazil, use the presence of only thrombocytopenia to make a presumptive diagnosis of E canis infection. OBJECTIVE: The objective of this study was to determine the prevalence of E canis in thrombocytopenic dogs from Rio de Janeiro, Brazil, using polymerase chain reaction (PCR). METHODS: Following DNA extraction of whole blood samples from 226 dogs, PCR assays were done using primers for rickettsial DNA (including Ehrlichia spp, Anaplasma platys and A phagocytophilum) and using E canis-specific primers (16S rRNA gene). Dogs were grouped as thrombocytopenic and nonthrombocytopenic based on platelet counts. The null hypothesis that there was no difference in the prevalence of E canis in these groups was rejected at P<.05. RESULTS: Thirty-six (32.1%) of the thrombocytopenic dogs and 4 (3.5%) of the nonthrombocytopenic dogs were positive for rickettsial gene sequences (P<.0001). Further, 30 (26.8%) of thrombocytopenic dogs and 4 (3.5%) nonthrombocytopenic dogs were positive for E canis-specific gene sequences (P<.0001). CONCLUSIONS: Although the prevalence of E canis infection was higher in thrombocytopenic dogs, less than one third of these dogs had demonstrable E canis infection. Thus, thrombocytopenia is not specific for the detection of E canis infection and should not be used solely to establish a diagnosis of canine ehrlichiosis, even in a geographic area with relatively high disease prevalence.     

Monoclonal Gammopathy Associated With Naturally Occurring Canine Ehrlichiosis

Clinical, hematologic, and immunologic findings for 14 dogs with Ehrlichia canis monoclonal gammopathy were studied retrospectively. Epistaxis, anemia, thrombocytopenia, hypoalbuminemia, hypergammaglobulinemia, and proteinuria were documented in the majority of these dogs. The serum protein electrophoresis pattern was characterized by a distinct narrow-base monoclonal spike, by a broad-base monoclonal spike, or by a monoclonal spike superimposed on a polyclonal gammopathy. The monoclonal spike disappeared following tetracycline treatment for ehrlichiosis. The long-term prognosis following treatment was generally good. The diagnostic features of monoclonal gammopathy due to myeloma were compared with those of E. canis monoclonal gammopathy. Owing to numerous similarities in clinical, hematologic, and immunologic findings, we conclude that an E. canis antibody titer should be determined in all dogs in which a diagnosis of benign monoclonal gammopathy is contemplated or definitive evidence of myeloma, leukemia, or macroglobulinemia is lacking.     

Ehrlichia canis infection in two dogs that emigrated from endemic areas

Two dogs, emigrated from Zambia and China to Japan, were diagnosed with Ehrlichia canis infection. Both cases had thrombocytopenia, non-regenerative anemia, and hypergloblinemia with polyclonal gammopathy. Case 1 had ataxia of the hind limbs. Severe meningitis was revealed by magnetic resonance imaging examination. Intracytoplasmic inclusions were observed in mononuclear cells of cerebrospinal fluid. Case 2 had a history of bilateral epistaxis, and severe pancytopenia was noticed in complete blood count. Diagnosis was finally achieved by nested polymerase chain reaction and sequence analysis. Thus, even in non-endemic areas, E. canis infection should be included in the differential diagnosis of clinically ill dogs that emigrated from endemic areas.     

Ehrlichia canis in dogs in Yucatan, Mexico: seroprevalence, prevalence of infection and associated factors

The aim of this study was to determine the prevalence of infection, seroprevalence, and factors associated with antibody response to Ehrlichia canis in dogs of Yucatan, Mexico. The study was carried out in four veterinary clinics located in Merida, the capital city of Yucatan, Mexico. Blood samples were obtained from a total of 120 dogs, and each animal was physically examined to determine age and sex, as well as to record any clinical signs of platelet-related bleeding. Blood samples were analyzed for antibodies to E. canis using an ELISA test, and thrombocyte counts were calculated. Blood smears were prepared to detect typical morulae in leukocytes. The prevalence of infection, seroprevalence and associated factors were calculated. A primary screening was performed using 2 x K contingency tables of exposure variables. All variables with P< or =0.20 were analyzed by a logistic-binomial regression. Fifty-three (44.1%) of the 120 dogs were found to be seropositive to E. canis. In six dogs (5.0%) typical morulae of E. canis were observed in monocytes. These six cases were positive for antibodies and were thrombocytopenic. The following factors associated with seropositive animals were: platelet-related bleeding (Yes: OR=10.26, CI=2.50-42.16, P=0.001), thrombocytopenia (Yes: OR=18.91, CI=4.47-80.03, P=0.000) and age (2-4 years: OR=6.77, CI=1.76-25.97, P=0.005; >4 years: OR=4.24, CI=1.04-17.21, P=0.043).     

Mixed Ehrlichia canis, Hepatozoon canis, and presumptive Anaplasma phagocytophilum infection in a dog

A 5-month-old, female, mongrel dog was admitted to the Clinic of Companion Animal Medicine, Aristotle University of Thessaloniki, Greece, with depression, anorexia, fever, peripheral lymphadenopathy, splenomegaly, oculonasal discharge, nonregenerative anemia, and mild thrombocytopenia. Cytology of Giemsa-stained buffy coat, bone marrow, and lymph node aspiration smears revealed numerous morulae in mononuclear leukocytes and in neutrophils, and Hepatozoon canis gamonts in neutrophils. The dog was seropositive to Ehrlichia canis (immunofluorescence assay [IFA]) and Hepatozoon canis (ELISA) but not to Anaplasma phagocytophilum (IFA). A nested polymerase chain reaction performed on bone marrow aspirates was positive for E canis. This method was not applied for the detection of A phagocytophilum. Treatment with doxycycline and imidocarb dipropionate resulted in both clinical and parasitologic cure. This is the first reported case of a mixed infection with E canis, H canis, and presumptive A phagocytophilum. The findings emphasize the value of cytology in offering a quick and inexpensive diagnosis in mixed tick-borne infections of dogs.     

Typical and atypical manifestations of Anaplasma phagocytophilum infection in dogs

Eighteen clinically ill dogs, naturally infected with Anaplasma phagocytophilum, were examined at a veterinary practice in Baxter, Minnesota. A clinical examination, complete blood cell count, enzyme- linked immunosorbent assay (ELISA) for A phagocytophilum, Borrelia burgdorferi, and Ehrlichia canis antibodies and Dirofilaria immitis antigen, and a polymerase chain reaction test for A phagocytophilum DNA were obtained for all dogs. Physical examination findings included fever, arthropathy, lymphadenopathy, epistaxis, acute gastritis, cervical hyperpathia, and central nervous system dysfunction. Complete blood cell count abnormalities included thrombocytopenia, morulae in neutrophils, anemia, leukopenia, eosinopenia, lymphopenia, and monocytosis. Seroreactivity to A phagocytophilum was found in 61%, B burgdorferi antibodies in 17%, and D immitis antigen in 5% of the dogs. Fever, arthropathy, neurologic dysfunction, and epistaxis are clinical syndromes that can be associated with A phagocytophilum infection. Treatment with doxycycline resulted in rapid resolution of clinical signs in all dogs.     

Evaluation of neutrophil oxidative metabolism in canine monocytic ehrlichiosis

BACKGROUND: Canine monocytic ehrlichiosis (CME) is a tick-borne disease caused by Ehrlichia canis, a rickettsia that infects the monocytes of dogs. This infection can result in a chronic and life-threatening disease. Thrombocytopenia, mild anemia, and leukopenia are the most common hematologic findings in CME. OBJECTIVE: To investigate the role of peripheral blood neutrophils in CME, an evaluation was conducted of their functional state during the acute phase of the disease in dogs experimentally infected by E canis. METHODS: Seven dogs were inoculated with E canis, and 3 remained as uninfected controls. All dogs had physical exams and hematologic tests (CBC and nitroblue tetrazolium [NBT] reduction) during a 6-week period. RESULTS: There was no difference (P > .05) in spontaneous NBT reduction results between the 2 groups of dogs throughout the 6-week period of observation. Nevertheless, when stimulated, the neutrophils showed higher activity in the infected group (P = .01) on weeks 4 and 5 after infection. CONCLUSION: Infection by E canis has no influence on neutrophil oxidative metabolism even though during the remission period of the acute phase of the disease, the neutrophils seem to be more reactive under stimulation.