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.     

Cytologic patterns of lymphadenopathy in canine monocytic ehrlichiosis

Background: Recognition of different cytologic patterns in lymph nodes (LNs) from dogs with canine monocytic ehrlichiosis (CME) and noninfectious causes of lymphoid reactivity may have diagnostic utility. Objectives: The aims of the present study were to compare cytologic patterns in LNs of dogs with different phases of CME, to investigate the association of cytologic pattern and presence of Ehrlichia spp. morulae, and to compare patterns of lymphoid reactivity between dogs with CME and those with noninfectious causes of lymphoid hyperplasia. Methods: Cytologic preparations of LNs from 35 dogs with nonmyelosuppressive CME (group A), 16 dogs with myelosuppressive CME (group B), 26 dogs with noninfectious diseases (group C), and 15 healthy dogs (group D) were evaluated. Percentages of lymphocyte types, plasma cells, macrophages, neutrophils, and eosinophils were determined. Samples from dogs in groups A and B were evaluated for the presence of morulae. Results: Cytologic abnormalities in LNs were recorded in 54% of dogs in group A, 88% in group B, 39% in group C, and 0% in group D and were more frequent (P=.02) in dogs with myelosuppressive CME than those with nonmyelosuppressive CME. Plasma cell hyperplasia was more frequent in CME than in noninfectious diseases (P=.03). An association between the presence of cytologic abnormalities and morulae in group A dogs was not found. Conclusions: Dogs with myelosuppressive CME have more lymphoid cytologic abnormalities than dogs with nonmyelosuppressive CME. LN plasmacytosis is the major pattern of lymphadenopathy in dogs with CME and is found more frequently in dogs with CME than in dogs with noninfectious causes of lymphadenopathy.     

Ocular signs of canine monocytic ehrlichiosis: a retrospective study in dogs from Barcelona, Spain

Canine monocytic ehrlichiosis (CME) is a tick-borne disease caused by the rickettsia Ehrlichia canis. Ocular lesions are a common feature of the disease and can be present in all stages. The purpose of this retrospective study was to determine the prevalence, type and response to treatment of ocular lesions associated with monocytic ehrlichiosis in 46 affected dogs presented to the Autonomous University of Barcelona-Veterinary Teaching Hospital (UAB-VTH) from January 2000 to December 2002. Dogs were included in the study only if they had a positive serologic test for E. canis and information about the clinical outcome was available. Eighteen breeds were represented, with the German Shepherd dog (n = 6) being the most common. There were 25 intact and three castrated males, and 16 intact and two neutered females. Twenty dogs (43.4%) were between 5 and 10 years old. Seventeen dogs (37% of all cases of monocytic ehrlichiosis diagnosed during the study period) had ocular signs, and 11 dogs (64.7% of the ocular cases) had only ocular lesions without apparent systemic signs. Exudative retinal detachment was the most common ocular manifestation; other prevalent findings included anterior exudative uveitis and optic neuritis. Five of the 17 cases with ocular lesions (29.4%) had ocular bleeding disorders (hyphema or retinal hemorrhages). All the dogs with ocular disease presented with bilateral signs. Dogs with posterior segment disease had titers against E. canis that were > or = 1 : 320, while lower titers were noted in dogs with anterior exudative uveitis. Two dogs presented with chronic autoimmune panuveitis after ehrlichiosis treatment. Canine ehrlichiosis should be considered in the differential diagnosis of exudative retinal detachment and anterior uveal inflammatory lesions.     

Experimental acute canine monocytic ehrlichiosis: clinicopathological and immunopathological findings

Clinical signs, humoral and cellular immune responses, and microscopic and gross tissue alterations resulting from acute experimental Ehrlichia canis infection in dogs were studied. Four dogs were inoculated with E. canis and four were used as uninfected controls. After a 10-14-day incubation period, infected dogs developed pyrexia up to 41 degrees C for 6-8 days. Antibody titers to E. canis antigen were demonstrable in all inoculated dogs at 30 days post-infection. Necropsy of infected animals revealed pale mucous membranes, generalized lymphadenopathy, splenomegaly, edema and ascites. Microcopically, the main lesions were: lymphoreticular hyperplasia in cortical areas of lymph nodes and spleenic white pulp, periportal accumulation of mononuclear cells and centrolobular fatty degeneration of the liver. Kidneys presented with glomerulonephritis characterized by interstitial mononuclear infiltration. Immunophenotyping of lymphocytes from lymph nodes and spleen sections displayed alterations in IgG, IgM, CD3+ and CD8+ cells population in infected dogs.     

Validation of chemoprevention of canine monocytic ehrlichiosis with doxycycline

Epidemiological (cohort follow-up) and laboratory techniques studies were done to validate a programme of chemoprevention of canine monocytic ehrlichiosis (CME) with this molecule. 614 dogs returning to France after having spent at least 4 months in a CME-endemic area (Africa, Guyana, Middle-East, etc.) were the object of systematic serological testing by indirect immunofluorescence (IFA). The dogs were given 100 mg of doxycycline per os daily for chemoprevention of CME. In addition, HPLC (high performance liquid chromatography) was used to determine plasma levels of doxycycline in 124 of the dogs. The CEM mortality and morbidity rates for the 614 dogs in the chemoprevention programme were nil. The seroconversion rate was 4% (24/614). Seropositive dogs (low titres) were asymptomatic and generally became seronegative after treatment. A study done on 10 dogs shows that doxycyclinaemia was 1.2 (0.94-1.53) microg/ml 2 h after the drug had been administered. After 24 h, the residual concentration was 0.34 (0.26-0.44) microg/ml. Blind doxycyclinaemia tests done on 110 dogs living in Africa (the results for four dogs were nil and therefore eliminated from the study) showed that the minimum observed concentration was always greater than 0.2 microg/ml. Given that, as concerns infection with Ehrlichia spp., the minimum inhibitory concentration of doxycycline is < or = 0.03 microg/ml, dogs receiving chemoprevention treatment should be protected.     

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.     

Assay of fipronil efficacy to prevent canine monocytic ehrlichiosis in endemic areas

Our objective was to evaluate the efficacy of fipronil for the prevention of Ehrlichia canis transmission to dogs by Rhipicephalus sanguineus in two endemic areas situated in Africa (Dakar and Djibouti). We carried out controlled trials in kennels for 1 year on 248 dogs, mainly police dogs and military working dogs. Eight groups were studied in a multi-centre study. Fifty five fipronil treated dogs were located in two separated kennels (G3, 37 dogs in Djibouti and G8, 18 dogs in Dakar). G1 (66 dogs) and G2 (60 dogs) were untreated control groups located in Djibouti, whereas G4 (32 dogs), G5 (13 dogs), G6 (18 dogs) and G7 (4 dogs) were the control groups located in Dakar. The epidemiological status of each group is known. G1 and G2 dogs were not kept in kennels, whereas G3, G4, G5, G6, G7, G8 dogs were housed in equivalent kennels. Tick infestation, clinical status and Ehrlichia seroprevalence were assessed during 1 year (duration of the study). Dog treated with fipronil showed neither canine monocytic ehrlichiosis (CME) nor tick infestations. In all groups of untreated control animals, R. sanguineus tick infestations were frequent, particularly in kennels (G5, G6 and G7) as well as morbidity and mortality due to CME. E. canis infection rates were low for fipronil treated animals: 2.7% (1/37) for G3 and 5.5% (1/18) for G8 group. Among control animals, seroprevalence was maximum (100%) in dogs kept in kennels (G5, G6 and G7 groups) and high among native dogs in Djibouti (G1 group): 69.7% (46/66) and in Dakar (G4 group): 50% (16/32). Dogs belonging to expatriate citizens (G2 group) were less likely to be infected: 21.7% (13/60). The comparison of serological results among French army dogs and French citizen dogs that were introduced in Djibouti for an average of 10 months shows a statistically significant (P<0.001) difference. Among fipronil treated animals (G3 group), 2 dogs out of 55 seroconverted (3.6%) compared to 13 out of 60 dogs (21.7%) in the control G2 group. The results of our study indicate the preventative efficacy of a fipronil monthly treatment to avoid CME in endemic areas. Epidemiological data concerning animals that live in the same endemic areas are an example of the serious consequences (in terms of mortality and morbidity) that are related to the absence of efficient methods for tick-control. In order to protect dogs that are in transit in endemic areas against tick-transmitted diseases, the use of an adapted acaricide product is recommended.     

比格犬埃立克体病病理学研究

为了观察比格犬埃立克体病的病理学变化,用常规病理学方法,对6只人工感染埃立克体(Ehrlichia)的比格犬进行病理解剖学和病理组织学观察。结果:眼观所见最显著的病变是主要器官和皮下出血、淤血,脾、肝肿胀;病理组织学变化的主要特征是淋巴结的严重水肿,脾、肝、肺和肾的血管内及肝血管周围存在浆细胞和淋巴细胞灶性增生,皮肤表皮层变薄、皮肤皮脂腺腺泡上皮和毛囊变性坏死。比格犬埃立克体病的眼观和病理组织学变化与国外文献报道的基本吻合,不同之处是眼观病变更为明显,这可能与分离株的致病性不同有关。     

Ocular manifestations of natural canine monocytic ehrlichiosis (Ehrlichia canis): a retrospective study of 90 cases

OBJECTIVE: To investigate the spectrum, prevalence and treatment response rate of ocular manifestations associated with natural canine monocytic ehrlichiosis (CME) due to Ehrlichia canis. METHODS: The medical records of 90 dogs that were admitted for primary ocular problems and reacted positive for E. canis serum antibodies were reviewed. All the dogs were treated with oral doxycycline. In 79 dogs, a combination of systemic corticosteroids and/or topical anti-inflammatory, mydriatics/cycloplegics and antibacterial agents were applied. RESULTS: The dogs ranged from 0.5 to 15 years in age; 55 were male and 35 female. A total of 19 breeds were represented. In the majority of dogs, ocular abnormalities were noticed in conjunction with other CME-induced clinical signs. In 30/90 dogs, ophthalmic signs were the sole presenting complaint. Unilateral (22/90, 24.5%) and bilateral (68/90, 75.5%) uveitis was the most common ophthalmic diagnosis and was classified as anterior, posterior or panuveitis in 58 (64.5%), 8 (8.9%) and 24 (26.6%) of the dogs, respectively. Bilateral uveitis was significantly more common than unilateral uveitis (P < 0.0001), and anterior significantly more common than posterior uveitis (P < 0.0001) or panuveitis (P < 0.0001). In addition, corneal ulceration (12/90, 13.3%), necrotic scleritis (10/90, 11.1%), low tear production (8/90, 8.9%) and orbital cellulitis (3/90, 3.3%) were seen. Of the 45 (50%) dogs with a satisfactory follow-up, 25 (55.5%), 11 (24.5%), and 9 (20%) showed complete, partial and poor response to treatment, respectively. The number of dogs exhibiting complete resolution of the ocular manifestations was significantly higher than those with partial (P < 0.0001) or poor (P < 0.0001) response. CONCLUSIONS: CME should be considered a major differential for a wide range of ocular manifestations exhibited by dogs residing in the endemic areas of the disease. Anterior bilateral uveitis appears to be the most prevalent ocular lesion and a favorable outcome to systemic and topical treatment may be expected in the majority of the affected dogs.     

Evaluation of a serum-based PCR assay for the diagnosis of canine monocytic ehrlichiosis

The aim of this study was to estimate the relative diagnostic sensitivity and specificity of a polymerase chain reaction (PCR) assay in the serum of dogs with naturally occurring non-myelosuppressive canine monocytic ehrlichiosis (CME), and to investigate the association between PCR positivity and immunofluorescence antibody (IFA) titres for Ehrlichia canis. Serum samples obtained from 38 dogs with non-myelosuppressive CME and 12 healthy dogs were analyzed retrospectively. Each serum sample was analyzed in triplicate using an E. canis-specific nested PCR assay targeting a 389 bp sequence of the 16S rRNA gene. E. canis DNA was amplified in 24 of 38 (63.1%) affected dogs; all samples from healthy dogs were negative. A high level of agreement was found among the PCR replicates (P < 0.0001). Median IFA titre of the 24 PCR-positive dogs was significantly lower than that of the PCR-negative infected dogs (P = 0.0029), indicating that E. canis DNA may circulate prior to the development of a high antibody titre. Serum-based PCR analysis is suggested for the early diagnosis of CME when whole blood samples are not available.     

Usefulness of a rapid immuno-migration test for the detection of canine monocytic ehrlichiosis in Africa

A rapid immuno-migration test for the serological detection of canine monocytic ehrlichiosis, Witness^® Ehrlichia (WE) (Zoetis, France), was evaluated in 528 serum samples from dogs living in endemic areas of West and East Africa: Senegal (N = 208), Ivory Coast (N = 7), Sudan (N = 27), and Djibouti (N = 286). Of these dogs, 200 were French military working dogs (MWD) temporarily residing in Africa. The WE test results were compared with those obtained by indirect immunofluorescence (IFA). The sensitivity of WE was 97% [94.2, 98.7] with a specificity of 100% [98.6, 100]. In MWD, the seroprevalence (IFA) was 7%; in native dogs, it reached 77.1%. This significant difference can be explained by prophylactic measures from which MWD benefit. The WE test represents a simple, fast and reliable test for the detection of anti-Ehrlichia canis antibodies. Its implementation for the diagnosis of clinical cases has been validated in the field, and its use allows easy detection of asymptomatic dogs that may be carriers of E. canis.     

Evaluation of cytology in the diagnosis of acute canine monocytic ehrlichiosis (Ehrlichia canis): a comparison between five methods

The purpose of this study was the comparison of the diagnostic sensitivity between buffy coat (BC), peripheral blood (PB), lymph node (LN), bone marrow (BM) and short-term culture (P-D) cytology that has been based on the detection of Ehrlichia canis morulae, in the acute phase of canine monocytic ehrlichiosis (CME). Their cellular localization, total numbers and microscopic differentials were also investigated. The highest sensitivities were achieved after evaluating 1000 oil immersion fields (OIFs) in BC (66%) and an equal number in LN (60.9%) smears, separately or together (74%). The morulae were more often detected into lymphocytes than monocytes. The highest total number of morulae (n=143) were found in P-D smears. Finally, to avoid false positive diagnoses, platelets, lymphocytic azurophilic granules, lymphoglandular bodies and phagocytosed nuclear material should not be confused with the morulae.     

Equine monocytic ehrlichiosis (Potomac horse fever): a review.

In the late 1970s, a new infectious disease in horses, involving acute enteritis, was recognised in the Potomac River area of Maryland, U.S.A. The causative agent was identified subsequently as a new species of rickettsial organism, later named Ehrlichia risticii. Since then, the disease has been reported in many other states, and in enzootic areas vaccination is common. Signs associated with the clinical disease included depression, fever, anorexia, decreased or absent intestinal sounds, profuse watery diarrhoea and laminitis. However, considerable variation in clinical manifestations has been reported in both the natural and experimental disease. Accurate diagnosis depends on serological testing; currently, the immunofluorescent antibody test (IFA) is used widely, although an enzyme-linked immunosorbent assay (ELISA) has been developed recently. Mortality in untreated cases is 15 to 35 per cent. Antibiotics of the tetracycline series have shown activity against the organism in vitro, in an in vivo murine model and appear to be useful in clinical cases.     

Bone marrow mastocytosis in dogs with myelosuppressive monocytic ehrlichiosis (Ehrlichia canis): a retrospective study

BACKGROUND: Bone marrow mastocytosis has been reported rarely in naturally occurring canine monocytic ehrlichiosis (CME). OBJECTIVES: The aims of the present study were to estimate the prevalence and magnitude of bone marrow mastocytosis in a case series of dogs with natural CME and to assess the association, if any, between mastocytosis and the clinical severity of the disease. METHODS: Seventy-six dogs with confirmed CME (Ehrlichia canis) were included in the study. Affected dogs were allocated into group A (n = 51) without bone marrow hypoplasia and group B (n = 25) with bone marrow hypoplasia. Twenty clinically healthy Beagles not previously exposed to E canis served as controls (group C). The main inclusion criteria for group A were documentation of normocellular to hypercellular bone marrow and complete clinical cure following a 4-week treatment with doxycycline, while those for group B were bone marrow hypoplasia and lack of response to doxycycline. Bone marrow aspirate smears from all 96 dogs were Giemsa-stained and examined for the presence of mast cells, which were calculated as a percentage of 1,000 nucleated cells (NCs). The prevalence of mastocytosis was compared among the 3 groups by the Pearson's chi-square test. RESULTS: Bone marrow mastocytosis (>0.1% of NCs) was found in 5 (20%) dogs in group B (range, 0.5-2.5% of NCs; median, 1% of NCs). One dog in each of groups A and C had 0.1% mast cells in the marrow. The prevalence of bone marrow mastocytosis in dogs in group B was significantly higher (P = .004) than in groups A and C. CONCLUSION: Bone marrow mastocytosis can be seen in a substantial number of dogs with E canis-induced myelosuppression.     

Chronic canine ehrlichiosis (Ehrlichia canis): a retrospective study of 19 natural cases

Nineteen dogs from Greece with chronic ehrlichiosis were studied. The dogs exhibited bicytopenia or pancytopenia, bone marrow hypoplasia, seroreactivity to Ehrlichia canis (E. canis) antigens, and had no history of drug or radiation exposure. Anorexia, depression, severe bleeding tendencies, hypoalbuminemia, and increased serum alanine aminotransferase activity were also hallmarks of the disease. All these animals eventually died, irrespective of the treatment applied. Some dogs were also serologically positive for Rickettsia conorii, Leishmania infantum (L. infantum), and Bartonella vinsonii subspp. berkhoffii. Polymerase chain reaction testing of bone marrow samples revealed E. canis, Anaplasma phagocytophilia, Anaplasma platys, and L. infantum in some dogs. Concurrent infections did not appear to substantially influence the clinical course and final outcome of the chronic canine ehrlichiosis.     

Improved clinical approach to the diagnosis of canine ehrlichiosis

Summary Canine ehrlichiosis is being recognised with increasing frequency in many parts of the world. Based upon a detailed clinical and laboratory examination including a simplein vitro blood culture diagnostic test 373 cases have been classified into seven broad groups. These groups include acute, haemorrhagic, chronic, uraemic, subclinical, carrier state and those with babesiosis. While many of these groups overlap they will assist the clinician in diagnosis and allow the application of specific thereapy before the disease progresses to a chronic irreversible stage.

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Metodologia Clinica Mejorada Para El Diagnostico De La Ehrlichiosis Canina

Resumen La Ehrlichiosis canina es una enfermedad ampliamente conocida a nivel mundial. Con base en exámenes clínicos y de laboratorio detallados, incluyendo una prueba diagnóstica simple de cultivo de sangrein vitro, 373 casos han sido clasificados en siete grupos generales. Estos grupos incluyen la forma aguda, hemorrágica, crónica, urémica, subclínica y de portador crónico y aquellos casos con babesiosis. A pesar de que muchos de estos grupos se confunden, la clasificación adoptada asiste al clínico en el diagnóstico, permitiendo la aplicación de una terápia específica antes que la enfermedad progrese hacia un estado crónico irreversible.

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Amelioration De La Demarche Clinique Pour Le Diagnostic De L'Ehrlichiose Canine

Résumé L'ehrlichiose canine est reconnue avec une fréquence de plus grande dans beaucoup de parties du monde. Basée sur un examen clinique détaillé et des tests de laboratoire, dont une mise en culturein vitro du sang, 373 cas ont été classés en 7 grands groupes. Ces groupes sont: aigu, hémorragique, chronique, urémique, subclinique, porteur et ceux associés à la babésiose. Bien qu'il y ait un recoupement entre ces groupes, ils apporteront une aide au clinicien pour son diagnostic et permettront la mise en oeuvre d'une thérapeutique spécifique avant que la maladie ne progresse à un stade chronique irréversible.

     

Prevalence of canine cataract: preliminary results of a cross-sectional study

Objective In this study 2000 dogs were examined ophthalmoscopically to determine presence of cataract. Materials and methods The dogs examined were predominantly from veterinary hospital populations but also from the Waltham Center For Pet Nutrition, rehoming charities and breeding kennels. Prevalence of cataract was thus determined for different age groups (year cohorts). The age at which prevalence of cataract was 50% (C₅₀) was determined indirectly from a fitted prevalence curve. Results The mean ± standard deviation of C₅₀ for all dogs in the study was 9.4 ± 3.3 years. All dogs over 13.5 years were affected by some degree of lens opacity. C₅₀ was determined for animals of different genders and different breeds. For dogs of six breeds sufficient data were available for calculation of breed‐specific C₅₀. In these dogs C₅₀ was positively correlated with longevity with a least squares correlation coefficient of 0.74. Conclusion The study yields novel findings regarding the prevalence and incidence of cataract in the dog and forms the basis for considerable further work on the epidemiology and pathophysiology of age‐related cataract in the dog.     

Adherence by Staphylococcus intermedius to canine corneocytes: a preliminary study comparing noninflamed and inflamed atopic canine skin

The adherence by three strains of Staphylococcus intermedius to corneocytes collected from healthy dogs was compared to the adherence to corneocytes collected from the inflamed (erythematous) and noninflamed (normal appearing) skin of dogs suffering from atopic dermatitis. All three strains of S. intermedius adhered in greater numbers to corneocytes from both inflamed and noninflamed atopic skin than to corneocytes from healthy dogs. Adherence was greatest to corneocytes from inflamed atopic skin but one strain showed no statistical difference for adherence to inflamed and noninflamed atopic skin. These findings suggest that S. intermedius adheres extensively to both inflamed and noninflamed canine atopic skin. This may be important in the colonization of atopic skin by this microorganism. Strain variation in the ability of S. intermedius to adhere to canine atopic corneocytes is probable.