Canine Haemoplasma QPCR
Canine haemoplasmas are small bacteria that reside on the surface of red blood cells and can, under certain circumstances, mediate haemolytic anaemia in their host. The bacterium formerly referred to as Haemobartonella canis has recently been renamed as Mycoplasma haemocanis. M. haemocanis usually only induces haemolytic anaemia in splenectomised or immunocompromised dogs (e.g. those on chemotherapy or immunosuppressive corticosteroid treatment). A new canine haemoplasma called ‘Candidatus Mycoplasma haematoparvum’ has recently been described in an anaemic dog which had been splenectomised and was immunosuppressed. Only limited work has been done evaluating the prevalence of infection with canine haemoplasmas in different dog populations. Studies evaluating dogs in Southern France, Switzerland and South Africa have shown prevalences of M. haemocanis infection of between 0.9 and 9% whilst ‘Candidatus M. haematoparvum’ was found in 0.3 to 33% of dogs. A study in the USA found that kennelled dogs had a much higher prevalence of M. haemocanis infection than pet dogs. Thus geographical variation exists. We are currently undertaking a study to determine prevalences of these agents in the UK. Studies on the pathogenicity of canine haemoplasmas are in their infancy. As mentioned above, infection usually only results in haemolytic anaemia in splenectomised or immunocompromised dogs, and asymptomatic latent M. haemocanis infections can be reactivated following splenectomy. Although case reports have been published of haemoplasma infection being associated with anaemia in dogs, an association between anaemia and infection has not been found in the limited epidemiological studies done to date. We know that asymptomatic carrier dogs infected with canine haemoplasmas exist, similar to the situation seen with the feline haemoplasmas, so it is important that QPCR test results for canine haemoplasmas are interpreted in conjunction with clinical and haematological data from the patient.
The Molecular Diagnostic Unit can now perform QPCR tests for the detection and quantification of both M. haemocanis and ‘Candidatus M. haematoparvum’ in canine blood samples. These new tests will be of most use in the evaluation of dogs with haemolytic anaemia, particularly those that are immunocompromised or splenectomised, and the screening of blood donors prior to use. Additionally the quantitative PCR can be used to evaluate response to treatment with appropriate antibiotics such as doxycycline. Since ticks, and possibly fleas, have been implicated in the transmission of haemoplasmas, we recommend that dogs testing positive are given ectoparasite control.
The sample required for the canine haemoplasma QPCR test (M. haemocanis and ‘Candidatus M. haematoparvum’) is 0.5ml EDTA whole blood. Additionally, each haemplasma QPCR includes an internal amplification control to ensure that a valid diagnostic result is produced for every submitted sample.
PCR is the ONLY reliable way to diagnose haemoplasma infection in dogs!
For more information about this assay please see our publications