Diskospondylitis associated with Brucella canis infection in dogs: 14 cases (1980-1991).

A retrospective study of 135 dogs with diskospondylitis revealed 14 dogs with concurrent Brucella canis infection. Sexually intact male dogs and dogs in the southeastern United States appeared to be at higher risk. Results of bacteriologic culturing of blood were less likely to be positive for dogs with diskospondylitis caused by B canis infection than for dogs with diskospondylitis caused by other organisms. Follow-up evaluation of 13 of the 14 dogs revealed complete remission of clinical signs in nine, but serologic test results continued to be positive for B canis infection long after resolution of clinical abnormalities. Radiographic follow-up evaluation in 6 dogs revealed active lesions despite complete remission of clinical abnormalities.     

Serologic prevalence of Dirofilaria immitis,Ehrlichia canis,and Borrelia burgdorferi infections in Brazil

Dogs infected with Dirofilaria immitis, Ehrlichia canis, or Borrelia burgdorferi may show nonspecific clinical signs or may be asymptomatic. In Brazil, E. canis and D. immitis infections are frequently diagnosed based on the presence of classical signs; however, serologic tests are seldom performed to confirm the presence of infection. To estimate the seroprevalence of these three canine diseases in Brazil, 2,553 dogs presented at veterinary practices for various tests, routine treatments, or examinations were evaluated by an in-office commercial ELISA test kit (SNAP 3Dx, IDEXX Laboratories). Each dog was examined by the veterinarian, and a whole-blood sample was collected and immediately tested for the simultaneous detection of B. burgdorferi and E. canis antibodies and D. immitis antigen. D. immitis infection was detected in 51 dogs (2.0%) and E. canis antibodies were present in 505 dogs 19.8%). Only one dog tested positive for B. burgdorferi antibodies.     

Concurrent babesiosis and ehrlichiosis in the dog: blood smear examination supplemented by the indirect fluorescent antibody test, using Cowdria ruminantium as antigen

Giemsa-stained, peripheral blood smears of 67 dogs, showing clinical signs typical of babesiosis or reminiscent of concurrent babesiosis and ehrlichiosis, were examined for the presence of Babesia canis and Ehrlichia canis. Since Cowdria ruminantium cross-reacts with Ehrlichia, the sera of these dogs were also subjected to the indirect fluorescent antibody (IFA) test in which C. ruminantium was used as antigen. Fifty-five per cent of these dogs had mixed infections of B. canis and E. canis, as judged by blood smear examination and serology. The serum of 32% of these dogs with mixed infections reacted positively in the IFA test. Six out of 9 dogs, the blood smears of which were negative for both B. canis and E. canis, were serologically positive for E. canis. Furthermore, sero-conversion from a negative in the initial serum sample to titres of up to 1:160 in a subsequent sample was recorded in 9 out of 13 dogs with suspected mixed infection on blood smear.     

A survey for infection with Dirofilaria immitis, Ehrlichia canis, Borrelia burgdorferi, and Babesia canis in feral and client-owned dogs in the Turks and Caicos Islands, British West Indies

The frequency of infection with Dirofilaria immitis and Babesia canis and seropositivity to Ehrlichia canis and Borrelia burgdorferi in feral and client-owned dogs was determined. Feral dogs were 14.8 and 11.2 times more likely to be seropositive to D. immitis and E. canis, respectively, than were client-owned dogs. None of the dogs tested positive for B. burgdorferi or B. canis.     

Immunity against Babesia rossi infection in dogs vaccinated with antigens from culture supernatants

Soluble parasite antigens (SPA) from different Babesia species have been shown earlier to induce protective immunity when used as vaccine. However, initial attempts to produce such vaccine against Babesia rossi infection using SPA from B. rossi culture supernatants were not or only partially successful. Here we show that when dogs were vaccinated with a vaccine comprising SPA from B. rossi combined with SPA from Babesia canis protective immunity against experimental challenge infection was induced. Immunity was reflected in reduced clinical signs that resolved spontaneously, and reduction of parasitaemia and SPA in the blood. Not a single infected erythrocyte could be found in blood smears of dogs that had been repeatedly boosted (three vaccinations in total). In contrast, three out of four control dogs required chemotherapeutic treatment to prevent death. The fourth control dog showed a transient parasitaemia that resolved spontaneously. Vaccination did not prevent the development of a transient anaemia. It is concluded that a vaccine containing a mixture of SPA obtained from in vitro culture supernatants of B. rossi and B. canis induces protection in dogs against heterologous challenge infection with B. canis (as shown before) or B. rossi.     

Molecular survey of Babesia canis in dogs in Nigeria

An epidemiological study of Babesia canis in dogs in Nigeria was performed. Four hundred blood samples collected from dogs in Nigeria were investigated using nested PCR and sequence analysis. On nested PCR screening, nine samples (2.3%) produced a band corresponding to a 698-bp fragment indicative of B. canis infection. Sequence analysis of the PCR products identified eight samples (2.0%) as B. canis rossi and the ninth (0.3%) as B. canis vogeli. This is the first report of the prevalence of B. canis rossi and B. canis vogeli in dogs in Nigeria.     

Vaccination of dogs against heterologous Babesia canis infection using antigens from culture supernatants

Soluble parasite antigens (SPA) from European Babesia canis can be used to protect dogs against a homologous but not heterologous challenge infection. In this study it is shown that when dogs are vaccinated with a mixture of SPA from both, a European B. canis isolate and a South African Babesia rossi isolate, protective immunity against heterologous B. canis infection is induced. Three groups of five beagle dogs each were vaccinated twice with graded doses of SPA derived from in vitro cultures of B. canis and B. rossi, with a 3-week interval. Saponin was used as adjuvant. Three weeks after booster vaccination immunological responsiveness against heterologous B. canis antigen was measured by seroconversion against infected erythrocytes and lymphocyte transformation using SPA. Upon vaccination dogs produced antibodies against infected erythrocytes and lymphoblastogenic responses against SPA in a dose-dependent manner. Dogs were then challenged with heterologous B. canis parasites. Dogs appeared to be protected against challenge infection, which was reflected in less severe decrease of packed cell volume (PCV) and reduced clinical signs. The level of protection to clinical signs (but not excessive PCV drop) was related to the level of SPA in plasma and spleen size, and not related to peripheral parasitaemia. The results suggest that vaccination with this bivalent vaccine primes T-helper cells that recognise common epitopes on SPA from an antigenically distinct B. canis isolate. These cells provide the essential Th signal to mount an effective and timely antibody response against SPA and parasites or parasitised erythrocytes, which prevents the further development of clinical babesiosis.     

Molecular survey of Babesia infection in dogs in Okinawa, Japan

A total of 80 free-roaming dogs on Okinawa Island, Japan, were examined for Babesia infection using the polymerase chain reaction (PCR) and sequence analysis. Of 80 samples, 12 were positive in a Babesia genus-specific PCR. Consequent species-specific PCR for B. canis and B. gibsoni revealed that 5 (6.3%) and 7 (8.8%) dogs were infected with B. canis and B. gibsoni, respectively. Sequence analysis of the PCR products revealed that the 18S rRNA gene sequence of B. canis detected from dogs in Okinawa was very close to B. canis vogeli with sequence similarity of 99.94%.     

Evaluation of a microplate agglutination test (MAT) for serological diagnosis of canine brucellosis

A microplate agglutination test (MAT) was compared with the tube agglutinin test (TAT), a standard test for the diagnosis of Brucella canis, in terms of the sensitivity and specificity. The results showed that MAT was more sensitive, simpler to perform and easier to read the results than TAT. On top of that the MAT allows us to handle a larger number of samples at once. Using this method we conducted sero-surveillance of the prevalence of B. canis in dogs kept in an Animal Shelter located in Kanagawa Prefecture. Twelve of 485 (2.5%) showed seropositive against B. canis. These results indicate that B. canis infection in dogs is still occurring in Japan.     

Autochthonous cases of canine babesiosis in the canton Solothurn

Starting in November 2003 a series of five clinical cases of canine babesiosis was registered in the region of Oberg?sgen (canton Solothurn). All presented dogs showed increased body temperature, thrombocytopenia and hemoglobinuria, and none of the dogs had been abroad or visited endemic regions in the southern or western part of Switzerland so far. Babesia canis was detected in the blood smears of all five patients, but only three had detectable specific antibodies against this parasite. However, seroconversion was found in a second sample collected from the negative dogs at a later timepoint, confirming the diagnosis of canine babesiosis. The blood samples of two parasitized dogs were used for DNA-isolation and were tested with a Babesia-specific PCR, detecting the 18S rRNA-gene. Sequencing of the amplified products revealed a 100% identity with the sub-species B. canis canis. The ticks Rhipicephalus sanguineus and Dermacentor marginatus are potential vectors for B. canis. In the area where the infection with B. canis was suspected a total of 152 ticks was collected and characterized; one was a female R. sanguineus.Although babesia could not be detected in the latter tick and the final prooffor the complete life cycle is still lacking, it is very probable that B. canis has become autochthonous in the canton Solothurn.     

The immunologic response of dogs to Bartonella vinsonii subspecies berkhoffii antigens: as assessed by Western immunoblot analysis.

Bartonella vinsonii subspecies berkhoffii is a recently recognized zoonotic pathogen that causes endocarditis, granulomatous rhinitis, and granulomatous lymphadenitis in dogs. Isolation of B. vinsonii (berkhoffii) from blood or tissue samples is frequently unsuccessful; therefore, diagnosis is primarily dependent on serologic or molecular testing modalities. Because previous canine serologic studies have used an indirect immunofluorescence assay (IFA), without Western immunoblot (WI) confirmation, the overall objective of this study was to examine the diagnostic use of WI for confirmation of B. vinsonii (berkhoffii) infection in dogs. To confirm that agar-grown and cell culture-grown organisms yielded similar patterns of WI antigenic protein recognition, the 2 preparations were compared using IFA-reactive sera obtained from dogs experimentally infected with B. vinsonii (berkhoffii). Temporal changes in the pattern of antigenic protein recognition were characterized using sera obtained from dogs at various time points after experimental B. vinsonii (berkhoffii) infection. The specificity of B. vinsonii (berkhoffii) WI was examined by testing canine sera that were reactive to B. henselae, B. clarridgeiae, Ehrlichia canis, Rickettsia rickettsii, Babesia canis, Anaplasma phagocytophilum (previously E. equi), or Brucella canis antigens. Clinical accessions including serum samples obtained from B. vinsonii (berkhoffii) culture-positive dogs and B. vinsonii (berkhoffii) culture-negative dogs that were IFA seroreactive to B. vinsonii (berkhoffii) antigens were examined by WI. The results of this study indicate that WI using agar-grown or cell culture-grown B. vinsonii (berkhoffii) antigens produce identical patterns of antigenic protein recognition. After experimental infection, there is a progressive increase in the number of antigenic proteins that are recognized by WI, with the 33-kD antigen representing the first and the most persistent antigen recognized by B. vinsonii (berkhoffii)-infected dogs. Regarding specificity, sera from dogs that were reactive to various heterologous antigens did not recognize B. vinsonii (berkhoffii) antigens by IFA or WI, and sera from dogs experimentally infected with B. henselae did not recognize B. vinsonii (berkhoffii) antigens by WI. Regarding clinical accessions, there was good agreement between B. vinsonii (berkhoffii) IFA test results and WI analysis. Western immunoblot analysis can be used to detect or confirm exposure to B. vinsonii (berkhoffii) in dogs.     

Detection of Anaplasma platys and Babesia canis vogeli and their impact on platelet numbers in free-roaming dogs associated with remote Aboriginal communities in Australia

OBJECTIVE: To detect Anaplasma platys and Babesia canis vogeli infection, using polymerase chain reaction (PCR)-based assays, in free-roaming dogs associated with eight Aboriginal communities in remote areas of Australia and to determine the impact of infection through the assessment of platelet numbers. PROCEDURES: Blood samples from 215 dogs were screened by PCR for A platys and B canis vogeli using established genus-specific DNA primers for the 16S and 18S rRNA genes respectively. Both A platys DNA and B canis vogeli DNA were confirmed from the screening PCR either by sequencing or by the use of species-specific primers. Peripheral blood films from 92 of the 215 dogs were used to estimate platelet numbers through an indirect method. RESULTS: Of 215 dogs, 69 (32%) were positive for A platys, 22 (10%) for B canis vogeli and 24 (11%) for both. The two organisms were detected singularly and as coinfection in all communities. For the 92 dogs in which peripheral blood films were examined, the mean estimated platelet counts for the non-infected dogs was 318 x 10(9)/L, those infected with A platys alone was 256 x 10(9)/L, those with B canis vogeli alone was 276 x 10(9)/L and those infected with both parasites was 169 x 10(9)/L. In young dogs, infection produced significantly decreased mean platelet counts when compared to uninfected dogs. Thrombocytopenia (< 200 x 10(9)/L) was detected in 18 (51%) dogs infected with A platys alone, 3 (33%) dogs infected with B canis vogeli alone, 13 (72%) dogs coinfected, and 8 (27%) uninfected dogs. CONCLUSIONS: A platys and B canis vogeli infection, either singularly or together, was widespread in free roaming dogs associated with remote Aboriginal communities in the Northern Territory and north-western New South Wales. Moreover, both A platys and B canis vogeli infections were associated with a reduction in mean platelet numbers in dog populations, particularly in young dogs. The fact that 51% of dogs infected with A platys alone and 72% dogs coinfected were thrombocytopenic compared to 27% of uninfected dogs suggests that the organism alone or in combination with B canis vogeli has the potential to cause thrombocytopenia and perhaps contribute to a clinical bleeding disorder in infected dogs.     

Efficacy of a modified polymerase chain reaction assay for detection of Ehrlichia canis infection.

Detection of Ehrlichia canis in acutely infected and convalescent dogs is important for effective treatment and control. However, accurate detection has been difficult to achieve, in part because dogs that have been treated therapeutically often remain seropositive for extended periods. A new method, polymerase chain reaction (PCR) assay using biotinylated E. canis-specific primers (PCR-BP), was developed for detection of E. canis. Four dogs experimentally infected with E. canis by intravenous inoculation of whole blood from carrier dogs and 2 naturally infected convalescent carriers were used to compare the specificity and sensitivity of the new method with that of microscopy/blood smear evaluation, serologic test, and conventional PCR assay using E. canis-specific primers. In experimentally infected animals, infection was detected as early as 7 days post-exposure using PCR-BP. Although the 2 naturally infected dogs were positive by serologic test and PCR-BP, both were negative by conventional PCR. Results suggest that the new method is a sensitive assay for detection of E. canis infection. In addition, results were obtained more rapidly than with other PCR-based assays.     

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).     

Comparative performance of tests using cytosolic or outer membrane antigens of Brucella for the serodiagnosis of canine brucellosis

Although some ELISA tests using cytoplasmic or outer membrane antigens of Brucella have been developed to improve the diagnosis of canine brucellosis, the performance of these assays has not been compared. In the present study three ELISA tests using lipopolysaccharide (LPS)-free cytoplasmic proteins (CPs) of Brucella abortus, the lumazine synthase (LS) of Brucella spp. or a hot-saline (HS) extract of Brucella canis containing outer membrane antigens were used to test sera from dogs with suspected or confirmed brucellosis (n=36) and from dogs with pathological conditions other than brucellosis (n=212). In the first group the proportion of positive results was 92, 92 and 81% for the ELISAs with HS, CP and LS, respectively, and 94% of the samples were positive by at least one ELISA test. Three dogs that were negative by agglutination (2ME-RSAT) had a positive result by at least one ELISA, and this discrepancy was attributed to the lower analytical sensitivity of agglutination tests. This hypothesis was confirmed by a serological follow-up of seven dogs recently infected with B. canis in three of which the illness was diagnosed earlier by one or more ELISA tests than by 2ME-RSAT. Among dogs having pathological conditions other than brucellosis, specificities were 94.3, 96.7 and 96.7% for the ELISAs with HS, CP and LS, respectively. This study shows that HS-ELISA and CP-ELISA are highly specific and sensitive for the diagnosis of canine brucellosis and can detect the infection by B. canis shortly after the exposure to the pathogen.     

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.     

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.     

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.     

Brucella canis endophthalmitis in 3 dogs: clinical features, diagnosis, and treatment

Objective  To describe historical, clinical and diagnostic features of dogs with Brucella canis endophthalmitis and the response to medical therapy.
Animals studied  Three dogs with naturally acquired B. canis endophthalmitis.
Procedure  Dogs were treated symptomatically with topical ophthalmic anti-inflammatories and a novel antimicrobial protocol that included doxycycline, enrofloxacin, rifampin and streptomycin.
Results  All dogs presented with chronic or recurrent uveitis in the absence of overt systemic disease. Clinical ophthalmologic abnormalities were unilateral in each dog and included mild-to-moderate anterior uveitis, iris hyperpigmentation, marked vitreal infiltrates, and multifocal chorioretinitis. Dogs were diagnosed with canine brucellosis serologically and by blood culture ( n  = 2 dogs) or polymerase chain reaction of aqueous humor and blood ( n  = 1 dog). Active ocular inflammation resolved in all dogs during treatment, with preservation of vision in 2 dogs. Following treatment, B. canis could not be cultured from blood samples and serological values declined with seronegativity achieved in all dogs after a median of 96 weeks (range: 36–112 weeks) of therapy.
Conclusions  Brucella canis infection should be included in the differential diagnosis for dogs with intraocular inflammation, regardless of previous history or neuter status. This is the first report of apparently successful medical therapy of canine brucellosis with ocular involvement.     

Prevalence of antibodies against Babesia canis in dogs in an endemic area

A survey of 287 dogs for antibodies against Babesia canis in dogs in an endemic area, using ELISA, produced a prevalence of 43 per cent. Antibodies occurred in dogs of all age groups, the prevalence being significantly lower in dogs aged 1 to 6 months than in older dogs. There were no differences between indigenous Nigerian dogs and exotic (foreign) dogs; and between the sexes in the prevalence of antibodies. Antibodies were more prevalent in dogs with B. canis parasitaemia and in those with a higher risk of infection. Also antibodies were detected in some puppies born to seropositive bitches. The ELISA test failed to detect antibodies in 36.1 per cent of dogs with B. canis parasitaemia.