Hemotropic Mycoplasm Infection in Dogs (Hemotropic Mycoplasmosis)

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Definition

Haemotrophic mycoplasmosis, also known as haemobartonellosis, is a bacterial infection in dogs caused by Mycoplasma species. These pathogens attack red blood cells and can lead to anaemia.

The most important facts at a glance

Haemotrophic 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 haemolytic anaemia, 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, especially PCR to detect Mycoplasma DNA. Treatment includes antibiotics such as doxycycline and supportive measures, such as blood transfusions for severe anaemia. The prognosis is often good with timely treatment, but a delayed diagnosis can have serious consequences. Prevention focuses on controlling vectors such as ticks, regular use of tick preventatives, and avoiding contact with infected animals. Blood transfusions should only be given using blood tested for mycoplasmas to minimise the risk of transmission.

Causes

Haemotrophic 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 characterised by a flexible membrane. This makes them resistant to many antibiotics that target the cell wall and creates specific challenges in treatment.

The mycoplasmas that cause haemotrophic mycoplasmosis 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 haemolytic anaemia. This can impair oxygen transport in the body and lead to a range of clinical symptoms.

Symptoms

Symptoms of haemotrophic mycoplasmosis can vary and depend on the severity of the anaemia and the affected dog’s overall health. The most common signs include lethargy, pallor of the mucous membranes, reduced appetite, and weight loss. With severe anaemia, an increased 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 an overload of the liver. Fever, splenomegaly (enlarged spleen), and swollen lymph nodes can also occur, especially when the infection is accompanied by other diseases.

Diagnosis

Diagnosis of haemotrophic mycoplasmosis is made through a combination of clinical examination and laboratory tests. A blood test can reveal anaemia and provide indications of a haemolytic component, such as the presence of spherocytes or an increased bilirubin concentration.

A specific test to detect Mycoplasma DNA, such as polymerase chain reaction (PCR), is crucial to confirm the diagnosis. This method allows direct detection of the pathogens in a blood sample. Because the bacteria may appear in the blood episodically, repeated tests may be necessary to confirm the infection reliably.

Therapy

Treating haemotrophic 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 anaemia, 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 haemotrophic mycoplasmosis depends on various factors, including how quickly the diagnosis is made and treatment is started, the severity of the anaemia, 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 a delayed diagnosis, however, the infection can have serious health consequences and may even be life-threatening. Chronic infections can also lead to recurring episodes of anaemia, requiring long-term medical monitoring.

Prevention

Prevention of haemotrophic mycoplasmosis focuses mainly on controlling the transmitting vectors, especially ticks. Using effective tick preventatives and regular checks for tick infestation are essential to minimise the risk of infection.

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

Frequently asked questions (FAQs)

1. What is haemotrophic mycoplasmosis in dogs?
Haemotrophic 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 most relevant. The pathogens damage red cells and can cause anemia.
2. How do dogs become infected?
Transmission is mainly via ticks, particularly the Brown Dog Tick (Rhipicephalus sanguineus). Transmission via blood transfusion, bite wounds or from dam to puppies is also described. In Central Europe, importation of dogs from the Mediterranean region plays a major role.
3. What symptoms does the disease cause?
Many dogs are clinically inapparent carriers. Symptoms develop only with immune compromise, after splenectomy or with concurrent infections, including lethargy, weakness, pale mucous membranes, fever, weight loss and anorexia. Severe anemia can produce jaundice and dark urine.
4. How is the diagnosis made?
On a blood smear, experienced examiners may identify the pathogen on red blood cells. The most reliable method is PCR, directly demonstrating the pathogen's DNA. Complete blood count, reticulocyte count and a Coombs test help characterize anemia.
5. How is haemotrophic mycoplasmosis treated?
The drug of choice is doxycycline for four to six weeks. Alternatives include enrofloxacin or marbofloxacin. Antibiotics suppress the pathogen reliably but do not always eliminate it, so dogs may remain lifelong carriers. Severe anemia may require transfusion.
6. Is the disease transmissible to humans?
The species relevant in dogs are not considered significant zoonotic pathogens in healthy humans. Individual cases have been described in severely immunocompromised people, but overall public health relevance is low.
7. What is the role of the spleen?
The spleen removes damaged red cells and helps keep pathogen burden low. Dogs without a spleen or with impaired splenic function develop clinically relevant anemia far more often. A known mycoplasmosis is therefore an argument against elective splenectomy unless absolutely necessary.
8. Can dogs infect each other?
Direct dog-to-dog transmission without a vector is possible but inefficient. Bite wounds and shared parasite reservoirs play a larger role. In a kennel with an index case, the entire group should be tested.
9. How can it be prevented?
Effective tick prevention is the most important measure. Modern acaricides — spot-on, tablets or collars — with proven activity against Rhipicephalus sanguineus are suitable. Blood donor dogs should be screened with PCR before each donation to prevent iatrogenic transmission.
10. What is the prognosis?
With timely treatment, the prognosis is good, especially in dogs with an intact spleen. Many dogs remain asymptomatic after therapy even though the pathogen is not fully eliminated. In splenectomized or immunocompromised dogs, relapses are more frequent and prognosis is more guarded.