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dog and cat assay data sheet
Mycoplasma haematoparvum
‘Candidatus
Mycoplasma haematoparvum’ (CMhp)
is a small hemotropic mycoplasma (hemoplasma) that attaches to the
surface of erythrocytes, primarily in dogs. The
Candidatus prefix is used
because the organism has never been grown in culture and therefore
lacks a fully validated species name.
It was first described in 2005 from a splenectomized dog with hemic
neoplasia. Phylogenetically it is closest to the feline hemoplasma ‘Candidatus
Mycoplasma haemominutum’ (about 94% 16S rRNA gene identity) and
only distantly related to the other major canine hemoplasma,
Mycoplasma haemocanis. On Romanowsky-stained blood smears, CMhp appears as tiny (~0.3 µm) coccoid organisms, usually single or in pairs on red cells. M. haemocanis more often forms chains, so the two can sometimes be distinguished microscopically when organisms are numerous—though cytology is still unreliable for diagnosis. Dogs and some wild canids are the main hosts. Organisms resembling CMhp have rarely been reported in cats. Infection occurs worldwide; prevalence varies by region and population (often higher in shelter dogs than pets) and is frequently lower than that of M. haemocanis. Co-infections are well documented. Natural transmission is incompletely understood. The brown dog tick (Rhipicephalus sanguineus) is suspected, along with blood transfusion, possibly fighting or bites, and possibly vertical transmission. Experimentally, infection can be passed by injection or ingestion of infected blood. Most infected dogs remain clinically well. Hemolytic anemia is uncommon and is seen mainly in splenectomized or immunocompromised animals, or those with concurrent disease. Signs may include lethargy, mucosal pallor, and weakness; fever is often absent. Anemia is typically regenerative and may have an immune-mediated component. A small number of case reports have linked CMhp to immune-mediated hemolytic anemia. CMhp is generally regarded as less pathogenic than M. haemocanis. PCR on whole blood (preferably species-specific real-time PCR) is the diagnostic method of choice (Baker et al., 2010, Tasker, 2022). Blood-smear cytology is insensitive because the organisms are very small and parasitemia is often low or intermittent (Baker et al., 2021).
Treatment is usually doxycycline as first-line therapy, or a
fluoroquinolone, given for several weeks, plus supportive care
(including transfusion if anemia is severe). Clinical improvement is
common, but complete clearance often fails and dogs may remain
carriers. Corticosteroids are sometimes added when immune-mediated
hemolysis is present. Utilities:
References:
Barker EN, Tasker S, Day MJ, et al. Development
and use of real-time PCR to detect and quantify Mycoplasma haemocanis
and “Candidatus Mycoplasma haematoparvum” in dogs. Vet Microbiol.
2010;140(1-2):167-170.
Barker EN, Tasker S. Hemotropic Mycoplasma
infections. In: Sykes JE, Greene CE, eds. Greene’s Infectious Diseases
of the Dog and Cat. 5th ed. Elsevier; 2021:chap 58.
Tasker S. Hemotropic Mycoplasma. Vet Clin North Am
Small Anim Pract. 2022 Nov;52(6):1319-1340. Specimen
requirement: 0.2 ml whole blood in EDTA (purple top) tube;
or 0.2 ml fresh, frozen or fixed tissue; or 0.2 ml cell culture. Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions. For all specimen
types, if there will be a delay in shipping, or during very warm
weather, refrigerate specimens until shipped and ship with a cold pack
unless more stringent shipping requirements are specified. Frozen
specimens should be shipped so as to remain frozen in transit. See
shipping instructions for more
information. Turnaround
time:
2 business days
Methodology:
Qualitative real time
PCR Normal range: Nondetected |
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