Osmotic fragility of erythrocytes in clinically normal dogs and dogs infected with parasites.

The osmotic fragility of the erythrocytes was measured in blood samples collected from randomly selected healthy and infected dogs at a dogs' rescue shelter. The dogs were classified into six groups on the basis of the final diagnoses from clinical, post mortem and laboratory findings. The minimum (less than 5 per cent) and maximum (more than 90 per cent) haemolysis of the erythrocytes of the clinically normal dogs (group 1), occurred in 0.60 per cent and 0.30 per cent solutions of sodium chloride (NaCl). For the non-anaemic hookworm-infected dogs (group 2a) the respective values were 0.8 per cent and 0.4 per cent NaCl, and for the anaemic hookworm-infected dogs (group 2b) they were 0.85 per cent and 0.5 per cent NaCl, respectively. The erythrocytes from dogs with Babesia canis (group 3), concurrent hookworm and B canis (group 4) and Ehrlichia canis infections (group 5) had minimum haemolysis in 0.75 per cent NaCl and maximum haemolysis at between 0.20 per cent and 0.35 per cent NaCl solutions. The derivative fragiligrams for groups 2a, 2b, 3 and 4 were shifted to the left, whereas the fragiligram for group 5 was similar to that for the clinically normal dogs (group 1). The left shift for the hookworm-infected dogs was due to the increased osmotic fragility of a minor sub-population of the erythrocytes, but for the dogs infected with B canis major sub-populations of the erythrocytes had an increased osmotic fragility.

Infections with Babesia canis and Ehrlichia canis in dogs in Zimbabwe.

Of 105 dogs examined at a veterinary hospital in Harare, Zimbabwe, 52 per cent had antibodies reactive with Ehrlichia canis in indirect fluorescent antibody tests, 26 per cent had Babesia canis parasites in peripheral blood smears and 17 per cent had both infections. None of the dogs with serological evidence of ehrlichiosis had typical E canis morulae detectable in blood smears. The infections were regarded as incidental findings not readily related to the reasons for examination in 46 per cent of the dogs with antibodies to E canis and 17 per cent of the dogs with both infections. The most common laboratory abnormalities were anaemia and thrombocytopenia and the prevalence and severity of these in concurrent infections were intermediate to those found in individual infections. There were no pathognomonic clinical signs or laboratory abnormalities which could be used to distinguish between individual and concurrent infections. However, there was a significantly higher prevalence of non-regenerative anaemia in dogs with antibodies to E canis than in dogs with both infections. The prevalence of thrombocytopenia was significantly higher in dogs with babesiosis than in dogs with antibodies to E canis and the prevalence of hyperglobulinaemia was significantly higher in dogs with both infections than in dogs with antibodies to E canis.

Western blot and indirect fluorescent antibody testing for antibodies reactive with Ehrlichia canis in sera from apparently healthy dogs in Zimbabwe.

Sera were collected from apparently healthy dogs in 3 major centres in Zimbabwe to establish the prevalence of antibodies reactive with Ehrlichia canis by indirect fluorescent antibody (IFA) testing at titres of 1/20 or greater. The overall seroprevalence was 42% (39/93) with dogs from Mutare (40%) and Harare (33%) having similar rates which were lower than those for Bulawayo (68%). The majority of the IFA positive dogs from Harare (67%) had no haematological or biochemical evidence of canine ehrlichiosis. Total protein, albumin and globulin values were determined in sera from blood collected from Bulawayo and Mutare and all values were within normal reference ranges. Western blot profiles of sera from dogs with IFA titres of greater than 1/160 were similar to those using sera from dogs experimentally infected with E. canis Oklahoma strain. Our results indicate that an organism which is antigenically very similar or identical to E. canis is present in Zimbabwe and that dogs are commonly exposed to this organism.

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.

Feline haemobartonellosis: clinical, haematological and pathological studies in natural infections and the relationship to infection with feline leukaemia virus.

Haemobartonella felis infection was demonstrated in 38 cats which could be divided into four groups as follows: group A, feline leukaemia virus (FeLV) free cats with H felis infection alone; group B, FeLV free cats with H felis infection and other clinical conditions; group C, FeLV positive cats with H felis infection but no clinical manifestation of FeLV related or any other intercurrent disease; and group D, FeLV positive cats with H felis infection and clinical manifestations of FeLV related or other diseases. Cats in group A were healthy carriers of the infection and none was anaemic, whereas some in group B had clinical haemobartonellosis and anaemia. This anaemia was mainly mild, normocytic and normochromic. Most of the cats in group C and all in group D were more severely ill and anaemic, the anaemia usually being macrocytic and hypochromic. Splenomegaly occurred only in groups C and D. Treatment with tetracyclines did not eliminate H felis from any of the cats and blood transfusions were ineffective in promoting long term recovery from anaemia in cats with intercurrent H felis and FeLV infections. The findings in the cats in groups C and D were further compared with those in a fifth group of cats which were infected with FeLV but free of H felis.

A comparative study of the efficiency of acridine orange and some Romanowsky staining procedures in the demonstration of Haemobartonella felis in feline blood.

A comparison of the relative efficiency of acridine orange with some Romanowsky staining procedures indicated that acridine orange is superior in demonstrating the presence of Haemobartonella felis in feline blood. Of the Romanowsky staining procedures, that of May-Grunwald-Giemsa was at least one and a half and about twice as efficient as the Giemsa and Leishman methods, respectively.

Haemobartonella felis infection in cats from the Glasgow area.

A survey of 155 cats for Haemobartonella felis infection in the Glasgow area revealed a prevalence of 23.2 per cent. The infection occurred in all age groups and there was no significant difference between sex or breed type. Infection with H felis was more prevalent among cats with fleas and those with feline leukaemia virus infection than among the other cats in the sample. H felis organisms identified were mainly coccoid with diameters between 0.63 micron and 1.73 micron. Rod forms, found in two cats, had lengths ranging from 0.79 micron to 1.1 micron and diameters between 0.17 micron and 0.24 micron.