Bacterial infection of red blood cells in dogs (Hemotropic Mycoplasmosis)

  • Synonyms: Haemoplasmosis, canine infectious anaemia, haemotrophic mycoplasmosis, infectious anaemia, haemobartonellosis
  • Occurrence: rarer
  • Location of disease: General/Whole body
Author: Dr. med. vet. Gisa Löwe | Last modified: 22.08.2026
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Definition

Hemotropic mycoplasmosis, also known as hemobartonellosis, is a bacterial infection in dogs caused by mycoplasmas. These pathogens attack red blood cells and can lead to anemia.

The most important facts at a glance

Hemotropic mycoplasmosis in dogs is caused by bacteria that settle on red blood cells and stimulate the immune system to attack these cells. This leads to hemolytic anemia, which impairs oxygen transport in the body. Symptoms include loss of appetite, apathy, pale mucous membranes, fever, weakness, jaundice, increased respiratory rate, joint pain, and ocular inflammation. Rarely, bluish mucous membranes, weight loss, and dehydration may also occur. Diagnosis is made through clinical examination and laboratory tests, particularly using PCR to detect mycoplasma DNA. Treatment includes antibiotics such as doxycycline and supportive measures, such as blood transfusions in severe anemia. The prognosis is often good with timely treatment, but delayed diagnosis can have serious consequences. Prevention focuses on controlling vectors such as ticks, regular use of tick repellents, and avoiding contact with infected animals. Blood transfusions should only be performed with blood tested for mycoplasmas to minimize the risk of transmission.

Causes

Hemotropic mycoplasmas are a group of bacteria that settle on the surface of red blood cells. These bacteria are atypical because they have no cell wall and are characterized by a flexible membrane. This makes them resistant to many antibiotics that target the cell wall and creates specific challenges in treatment.

The hemotropic mycoplasmas that occur in dogs belong to the genus Mycoplasma. The best-known species are Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum. These microorganisms can be transmitted by vectors such as ticks and possibly through bites or blood transfusions.

The infection damages red blood cells, triggering the body’s immune response. The immune system begins to attack the infected blood cells, leading to hemolytic anemia. This can impair oxygen transport in the body and lead to a range of clinical symptoms.

Symptoms

Rare symptoms:

The symptoms of hemotropic mycoplasmosis can vary and depend on the severity of the anemia and the overall health of the affected dog. The most common signs include lethargy, pallor of the mucous membranes, reduced appetite, and weight loss. In severe anemia, accelerated heart rate and shortness of breath may also occur.

In some cases, dogs also show signs of jaundice, indicating excessive destruction of red blood cells and liver overload. Fever, splenomegaly (enlarged spleen), and swollen lymph nodes may also occur, especially when the infection is accompanied by other diseases.

Therapy

Treating hemotropic mycoplasmosis usually requires a combination of antibiotic therapy and supportive measures. Doxycycline is often the antibiotic of choice because it is effective against mycoplasmas. Treatment may take several weeks to ensure the bacteria are effectively eliminated.

In severe cases with significant anemia, a blood transfusion may be necessary to quickly replace red blood cells and ensure the body’s oxygen supply. Supportive care, including fluid therapy and nutritional support, may also be needed to promote recovery.

Prognosis and follow-up care

The prognosis for dogs with hemotropic mycoplasmosis depends on various factors, including how quickly the diagnosis is made and treatment is started, the severity of the anemia, and the dog’s overall health. With timely and appropriate treatment, the prognosis is often good and most dogs recover fully.

Without treatment or with delayed diagnosis, however, the infection can have serious health consequences and even become life-threatening. Chronic infections can also lead to recurring anemia episodes that require long-term medical monitoring.

Prevention

Prevention of hemotropic mycoplasmosis focuses primarily on controlling the carrier vectors, especially ticks. The use of effective tick repellents and regular checks for tick infestation are crucial to minimize the risk of infection.

Furthermore, dog owners should ensure that their animals do not come into contact with unknown or potentially infected dogs, especially in areas where the disease is prevalent. For dogs requiring blood transfusions, it is important to ensure that the donor blood has been tested for mycoplasmas to avoid the risk of transmission.

Outlook on current research

Hemotropic mycoplasmosis is an infection with very small bacteria that attach to red blood cells and can thereby trigger hemolytic anemia. In small animal medicine, the cat is primarily the focus of research; there, Mycoplasma haemofelis, “Candidatus Mycoplasma haemominutum”, and “Candidatus Mycoplasma turicensis” are considered the most important pathogens. M. haemofelis is usually the most pathogenic representative.

The most important research outlook currently concerns diagnostics. Blood smears under the microscope are unreliable, while PCR methods are now considered the best method. New studies are even developing multiplex or triplex PCRs that can distinguish several pathogen species simultaneously. This is clinically important because mixed infections occur and morphology alone is not sufficient.

A second focus is pathogen biology. Hemotropic mycoplasmas are not yet cultivable, so classical resistance tests are lacking. At the same time, there is increasing evidence that behind previously known groups there may be additional, genetically hidden species or lineages.

Transmission also remains unclear: blood contact appears to be more important than vectors, but the natural route of infection has not yet been conclusively clarified; there is also no vaccine yet. Overall, research is therefore aimed at more precise diagnostics, better assessment of risk and pathogenicity, and in the long term at more targeted therapies.

Frequently Asked Questions (FAQs)

1. What is hemotropic mycoplasmosis in dogs?
Hemotropic mycoplasmosis is an infection with cell-wall-deficient bacteria of the genus Mycoplasma that attach to the surface of red blood cells. In dogs, Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum are particularly relevant. The pathogens damage the erythrocytes and can thus trigger anemia.
2. How do dogs become infected?
Transmission occurs predominantly through ticks, especially the brown dog tick (Rhipicephalus sanguineus). Transmission through blood transfusions, bite injuries, or from mother to puppies has also been described. In Germany, the import of dogs from the Mediterranean region plays a particularly important role.
3. What symptoms does the disease cause?
Many dogs are clinically asymptomatic carriers. Symptoms such as lethargy, weakness, pale mucous membranes, fever, weight loss, and loss of appetite only occur with immune deficiency, after spleen removal, or with concurrent other infections. In severe anemia, jaundice and dark urine may occur.
4. How is the diagnosis made?
In experienced hands, the pathogens can be identified on the erythrocytes in a blood smear. The most reliable method is PCR, which directly detects the pathogen's DNA. Additionally, a complete blood count, reticulocyte count, and Coombs test are performed to assess the extent and type of anemia.
5. How is hemotropic mycoplasmosis treated?
The treatment of choice is doxycycline for four to six weeks. Alternatively, enrofloxacin or marbofloxacin may be used. The antibiotics reliably suppress the pathogens but do not always completely eliminate them, so dogs may remain lifelong carriers. In severe anemia, a blood transfusion may be required.
6. Is the disease transmissible to humans?
The species relevant in dogs, Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum, are not considered significant zoonotic pathogens in immunocompetent humans. In isolated cases, infections have been described in severely immunosuppressed individuals, but the overall significance is low.
7. What role does the spleen play?
The spleen removes damaged erythrocytes and thus keeps the pathogen load low. Dogs without a spleen or with impaired splenic function develop clinically relevant anemias much more frequently. A known mycoplasmosis is therefore an argument against elective splenectomy unless it is absolutely necessary.
8. Can dogs infect each other?
Direct transmission from dog to dog without a vector is possible but not very efficient. Bite injuries during dominance fights or shared use of parasite reservoirs play a greater role. Within a breeding population, the entire population should be tested if an index case occurs.
9. How can it be prevented?
Effective tick prevention is the most important measure. Suitable options are modern acaricides as spot-on, tablet, or collar with proven efficacy against Rhipicephalus sanguineus. Blood donor dogs should be tested by PCR before each donation to rule out iatrogenic transmission.
10. What is the prognosis?
The prognosis is good with timely treatment, especially in dogs with an intact spleen. Many animals remain asymptomatic after therapy, even if the pathogen is not completely eliminated. In splenectomized or immunosuppressed dogs, relapses are more common and the prognosis remains guarded.

Literature

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  • Messick, J. B. (2003). New perspectives about hemotrophic mycoplasma (formerly Haemobartonella and Eperythrozoon species) infections in dogs and cats. Veterinary Clinics of North America: Small Animal Practice, 33(6), 1453–1465. https://doi.org/10.1016/j.cvsm.2003.08.002
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