Feline Infectious Anaemia: Haemoplasma Signs, Diagnosis and Treatment

By Dr Duncan Houston

A cat can lose a dangerous amount of oxygen-carrying capacity before an owner realises how unwell they are.

Pale gums, weakness, rapid breathing and a sudden refusal to eat may be caused by feline haemoplasmosis, historically called feline infectious anaemia or haemobartonellosis. The disease occurs when haemotropic Mycoplasma bacteria attach to red blood cells and contribute to their premature destruction.

Some infected cats remain completely well. Others develop severe haemolytic anaemia, require a blood transfusion and can die without prompt treatment.

The key is not simply whether a PCR test is positive. What matters is which haemoplasma species is present, whether it explains the anaemia and whether the cat is stable enough to wait for antibiotics to work.

Quick Answer

Feline haemoplasmosis is an infection caused by bacteria that attach to red blood cells and may trigger haemolytic anaemia. Typical signs include pale gums, weakness, reduced appetite, fever, rapid breathing and a fast heart rate.

A cat with very pale gums, laboured breathing, collapse, severe weakness or reduced responsiveness needs emergency veterinary care. PCR testing is the preferred diagnostic test, and doxycycline is commonly used as first-line treatment, together with oxygen, transfusion or other supportive care when required. (ABCD cats and vets)

Feline Haemoplasmosis at a Glance

Question	Practical answer
What causes the disease?	Haemotropic Mycoplasma bacteria attached to red blood cells
Which species is most dangerous?	Mycoplasma haemofelis
Can healthy cats test positive?	Yes. Subclinical carrier infections occur
What are the main signs?	Pallor, lethargy, weakness, poor appetite, fever, rapid breathing and rapid heart rate
How is it diagnosed?	CBC, reticulocyte count and species-specific PCR on EDTA blood
Is a blood smear reliable?	No. It has poor sensitivity and can produce false-positive results
What is the main antibiotic?	Doxycycline
Are steroids routinely needed?	No
Can a blood transfusion be required?	Yes, when anaemia is severe and clinically destabilising
Can the infection return?	Yes. Some cats remain carriers and may occasionally relapse
Should healthy carrier cats be treated?	Usually not
Is there a vaccine?	No

The three main feline haemoplasma species differ substantially in pathogenicity, so a positive result should always be interpreted alongside the cat’s clinical signs and haematology. (ABCD cats and vets)

What Is Feline Haemoplasmosis?

Feline haemoplasmosis is caused by haemotropic mycoplasmas, a group of very small bacteria that attach to the surface of erythrocytes, or red blood cells.

The organisms were historically classified as Haemobartonella, which is why older veterinary records may use terms such as:

• Haemobartonellosis

• Feline infectious anaemia

• FIA

• Feline haemotropic mycoplasmosis

• Feline haemoplasmosis

Unlike many other bacteria, haemoplasmas have no cell wall and cannot currently be grown using routine bacterial culture. This lack of a cell wall also means that antibiotics such as penicillins and cephalosporins do not effectively treat the infection. (ABCD cats and vets)

Which Haemoplasma Species Affect Cats?

The three principal species are:

Mycoplasma haemofelis

This is the most pathogenic feline haemoplasma.

It can cause severe, acute and sometimes fatal haemolytic anaemia in an otherwise healthy, immunocompetent cat. Some cats develop only mild disease, while others deteriorate rapidly.

“Candidatus Mycoplasma haemominutum”

This is the most commonly detected feline haemoplasma in many populations, but it is usually less pathogenic.

Most infected cats remain asymptomatic. Clinically significant anaemia is more likely when the cat has concurrent disease, chemotherapy, immunosuppression or FeLV infection, although occasional disease has been reported without an obvious comorbidity.

“Candidatus Mycoplasma turicensis”

This organism is also considered less pathogenic than M. haemofelis.

Most infections do not produce severe anaemia unless another illness, infection or immune-compromising condition is present. (ABCD cats and vets)

Does a Positive PCR Mean the Cat Has Infectious Anaemia?

No.

A positive PCR means haemoplasma DNA was found in the blood. It does not automatically prove that the organism is responsible for the cat’s current illness.

The result is more convincing when:

• M. haemofelis is detected

• The cat has acute haemolytic anaemia

• The anaemia is regenerative or becoming regenerative

• Other causes of anaemia have been excluded

• The cat improves with appropriate antimicrobial treatment

A positive “Candidatus M. haemominutum” or “Candidatus M. turicensis” result in a severely anaemic cat should prompt an active search for concurrent disease rather than assuming the haemoplasma explains everything.

A clinically normal, non-anaemic PCR-positive cat may simply be a carrier. (ABCD cats and vets)

How Do Haemoplasmas Cause Anaemia?

Haemoplasmas attach to the surface of red blood cells and can directly damage the cell membrane.

The affected cells may become more fragile and have a shortened lifespan. The spleen, liver, bone marrow and other tissues then remove damaged or abnormal red cells from circulation.

Most of the haemolysis is considered extravascular, meaning red cells are removed and destroyed by macrophages outside the bloodstream, particularly within the spleen and liver. A smaller amount of intravascular haemolysis may also occur in some cats. (ABCD cats and vets)

Is the Anaemia Immune-Mediated?

The immune system contributes to red-cell destruction, but the relationship is more complicated than ordinary primary immune-mediated haemolytic anaemia.

Some haemoplasma-infected cats develop:

• Persistent red-cell agglutination

• Cold agglutinins

• A positive direct Coombs’ test

• Antibodies bound to erythrocytes

However, experimental evidence suggests that these antibodies may develop after haemolysis begins and may disappear with antibiotics and supportive care alone. This is one reason corticosteroids are not automatically recommended for a haemoplasma-positive cat. (ABCD cats and vets)

Is the Anaemia Always Regenerative?

No.

Haemoplasmosis typically causes a regenerative macrocytic, hypochromic anaemia. The bone marrow responds by releasing reticulocytes and sometimes nucleated red cells.

Regeneration may not yet be obvious during the first few days of acute red-cell loss. Some cats also present with poorly regenerative or apparently non-regenerative anaemia, particularly when there is concurrent disease or bone-marrow dysfunction.

A low reticulocyte count therefore does not completely exclude haemoplasmosis, but it makes a broader investigation especially important. (ABCD cats and vets)

How Do Cats Become Infected?

The natural transmission route remains uncertain.

Blood Transfusion

Transmission through infected donor blood is proven.

A clinically healthy carrier cat can transmit haemoplasma organisms to a transfusion recipient. All feline blood donors should therefore undergo PCR screening rather than being selected solely because they appear healthy and test negative for FeLV and FIV. (PubMed)

Fighting and Bite Wounds

Aggressive interactions are considered a possible natural transmission route.

Haemoplasma DNA has been detected in saliva, gingiva and claw beds, and the consistent association with male sex, outdoor access and fighting-type lifestyles supports the possibility of blood transfer during aggressive encounters.

This route remains plausible rather than conclusively proven. (ABCD cats and vets)

Transmission From a Queen to Kittens

Vertical transmission has been suggested but has not been definitively confirmed in cats.

It may occur during pregnancy, birth or nursing, but the practical importance of each possible route remains unclear. (ABCD cats and vets)

Do Fleas Transmit Feline Haemoplasmas?

Fleas have traditionally been blamed as the main source of feline haemoplasma infection. Current evidence does not support that claim.

A recent systematic review found that several older flea studies used non-specific PCR primers that generated false-positive haemoplasma results. When more specific methods are used, haemoplasma DNA appears to be rare in cat fleas, and experimental transmission through flea feeding or ingestion has been unsuccessful or extremely limited.

Fleas are therefore unlikely to be a major natural vector, although routine flea and tick prevention remains sensible because the transmission route has not been fully resolved and parasite control provides many other health benefits. (PubMed Central (PMC))

Which Cats Are Most at Risk?

Studies have identified several recurring associations, although not every study produces identical results.

Cats more likely to be PCR-positive include:

• Male cats

• Cats with outdoor access

• Older cats

• Non-pedigree cats

• Stray or feral cats

• Cats likely to fight

• Cats with FIV or FeLV in some populations

• Cats with concurrent illness or immunosuppression

Young cats may develop more severe clinical disease after acute M. haemofelis infection even though increasing age is often associated with a greater likelihood of testing positive overall. Indoor-only cats can also be infected. (ABCD cats and vets)

Does FeLV Make Haemoplasmosis Worse?

FeLV infection may increase the risk or severity of haemoplasma-associated disease, particularly with the less pathogenic species.

However, a cat with FeLV and anaemia may also have:

• Bone-marrow suppression

• Lymphoma

• Myelodysplasia

• Immune-mediated disease

• Chronic inflammation

• More than one infection

The anaemia should not automatically be attributed to haemoplasmosis simply because both tests are positive.

FIV and FeLV testing is an important part of the investigation, but neither result replaces a complete anaemia work-up. (ABCD cats and vets)

What Are the Signs of Feline Infectious Anaemia?

Clinical signs depend on:

• How quickly the red-cell count falls

• How severe the anaemia becomes

• Which haemoplasma species is present

• The cat’s age and general health

• Whether concurrent disease is present

• Whether the cat has time to compensate

Common Signs

Affected cats may develop:

• Pale gums

• Lethargy

• Weakness

• Reduced appetite

• Weight loss

• Dehydration

• Intermittent fever

• Hiding or reduced interaction

• Reduced activity

• Rapid breathing

• Rapid heart rate

• A soft or “haemic” heart murmur

• Weak or bounding pulses

Some cats develop an enlarged spleen as it removes abnormal red blood cells from the circulation. (ABCD cats and vets)

Does Haemoplasmosis Cause Jaundice?

It can, but jaundice is less common than many owners expect from a haemolytic disorder.

The gums, whites of the eyes or inner ears may appear yellow when bilirubin accumulates. However, jaundice also occurs with liver disease and bile-duct obstruction, so its presence does not confirm haemoplasmosis. (ABCD cats and vets)

Is Eating Litter a Typical Sign?

No.

Pica may occur in some anaemic animals, but eating litter or dirt is not a dependable hallmark of feline haemoplasmosis and should not be described simply as an iron craving.

A cat eating litter requires a broader assessment for anaemia, gastrointestinal disease, nutritional imbalance, stress or another medical problem.

How Worried Should You Be?

Lower Risk

The cat has:

• Mild pallor

• Slightly reduced activity

• Normal breathing at rest

• Normal appetite

• No weakness or collapse

• A mild anaemia found incidentally on blood testing

What it may mean: Early disease, chronic compensated anaemia or an unrelated mild anaemia is possible.

What to do: Arrange prompt veterinary investigation. Do not wait several weeks for the gums to become visibly white.

Moderate Concern

The cat has:

• Obvious pale gums

• Lethargy

• Reduced appetite

• Faster resting breathing

• Reduced ability to jump or play

• Intermittent fever

• Weight loss

• A confirmed moderate anaemia

What it may mean: Oxygen delivery is becoming compromised, and active haemolysis or another significant cause of anaemia may be present.

What to do: Seek same-day veterinary assessment.

High Concern

The cat has:

• Very pale or nearly white gums

• Marked weakness

• Rapid breathing

• Persistent tachycardia

• Refusal to eat

• Difficulty standing

• Yellow mucous membranes

• Dark urine

• Severe or rapidly worsening anaemia

What it may mean: Severe haemolysis and inadequate oxygen delivery are possible.

What to do: Treat this as urgent. Hospitalisation, oxygen and blood transfusion may be required.

Critical

The cat has:

• Collapse

• Open-mouth or laboured breathing

• Minimal responsiveness

• Inability to stand

• Grey or white gums

• Weak pulses

• Hypothermia

• Severe agitation followed by exhaustion

• Seizures

• Signs of shock

What it may mean: Life-threatening tissue hypoxia or circulatory collapse is occurring.

What to do: Attend an emergency veterinary hospital immediately.

When Is This an Emergency?

Seek immediate veterinary care when your cat develops:

• Very pale, white or grey gums

• Open-mouth breathing

• Pronounced abdominal breathing effort

• Collapse or near-collapse

• Severe weakness

• Inability to stand or walk normally

• A rapid decline over several hours

• Minimal response to their surroundings

• Yellow mucous membranes with marked lethargy

• Dark red or brown urine

• A very fast heartbeat with weakness

• Seizures

• Complete food refusal with signs of severe anaemia

A cat with severe anaemia should be handled gently and exposed to as little stress as possible. Excitement and struggling increase oxygen demand when oxygen-carrying capacity is already limited.

Call the hospital before travelling so the veterinary team can prepare oxygen, blood typing, crossmatching and transfusion equipment.

What Else Can Cause Pale Gums or Anaemia?

A positive haemoplasma test should not end the investigation prematurely.

Blood Loss

Possible causes include:

• Trauma

• Gastrointestinal bleeding

• Bleeding into the chest or abdomen

• Flea or hookworm infestation

• A bleeding tumour

• A clotting disorder

• Surgical or procedural blood loss

Other Causes of Haemolysis

Important possibilities include:

• Primary immune-mediated haemolytic anaemia

• Oxidative injury

• Paracetamol toxicity

• Onion or garlic exposure

• Zinc toxicity

• Neonatal isoerythrolysis

• Transfusion reactions

• Babesiosis or cytauxzoonosis in relevant regions

Reduced Red-Cell Production

Possible causes include:

• Chronic kidney disease

• FeLV

• Bone-marrow disease

• Cancer

• Severe chronic inflammation

• Iron deficiency from chronic blood loss

• Myelodysplasia

• Drug or toxin exposure

Pallor Without Anaemia

Gums may look pale because of:

• Shock

• Severe pain

• Hypothermia

• Peripheral vasoconstriction

• Low blood pressure

This is why a gum-colour photograph cannot replace examination and a packed cell volume.

What To Do Right Now

1. Keep the Cat Quiet

Place the cat in a secure carrier with soft bedding.

Do not encourage walking, playing or climbing. Minimise handling and keep other pets away.

2. Contact a Veterinarian

Report:

• Gum colour

• Breathing rate and effort

• Appetite

• Ability to stand and walk

• Recent fights or bite wounds

• Outdoor access

• Flea and tick prevention

• Previous blood transfusions

• Current medication

• Possible toxin exposure

• FeLV and FIV history

3. Do Not Give Human Iron Supplements

Not every anaemic cat is iron deficient.

Most haemoplasma-associated anaemia occurs because red cells are destroyed, not because the diet lacks iron. Unnecessary iron can cause gastrointestinal irritation and, in excess, toxicity.

4. Do Not Start Leftover Antibiotics or Steroids

The wrong antibiotic may be ineffective, and treatment before blood collection can reduce PCR sensitivity.

Prednisolone may suppress immune control of the infection and increase bacteraemia. It should not be given routinely to a suspected haemoplasma case. (ABCD cats and vets)

5. Avoid Force-Feeding a Breathless Cat

Do not give food, water or oral medication to a cat that is struggling to breathe or cannot swallow safely.

The immediate priority is stabilisation and oxygen delivery.

How Do Veterinarians Diagnose Feline Haemoplasmosis?

Complete Blood Count

The CBC determines:

• Red blood cell count

• Haemoglobin

• Haematocrit or packed cell volume

• Red-cell size and colour

• White blood cell changes

• Platelet count

Serial PCV or haematocrit measurements help determine whether the anaemia is stable, improving or progressing rapidly.

Reticulocyte Count

Reticulocytes are immature red blood cells released by the bone marrow.

An increased aggregate reticulocyte count supports regenerative anaemia. However, regeneration may take several days to become measurable after acute haemolysis.

Blood Smear Examination

A freshly prepared blood smear may show small coccoid, rod-shaped or ring-shaped organisms attached to red cells.

Blood-smear examination has major limitations:

• Reported sensitivity is only approximately 0% to 37.5%

• Organism numbers fluctuate

• Organisms can disappear from circulation rapidly

• Organisms may detach in stored EDTA samples

• Stain precipitate can mimic haemoplasmas

• Howell-Jolly bodies can be mistaken for organisms

• Cytology cannot reliably identify the species

A positive smear can support an immediate presumptive diagnosis in a heavily infected cat, but PCR confirmation is still recommended. A negative smear does not rule the infection out. (ABCD cats and vets)

Species-Specific PCR

PCR on EDTA whole blood is the preferred diagnostic test.

It is more sensitive and specific than microscopy and can identify:

• M. haemofelis

• “Candidatus M. haemominutum”

• “Candidatus M. turicensis”

• Mixed infections

The blood sample should ideally be collected before antibiotic treatment. Effective doxycycline treatment can cause organism numbers to fall dramatically within only a few days and may produce a negative PCR result despite a clinically relevant recent infection. (ABCD cats and vets)

Additional Testing

The wider investigation may include:

• Biochemistry

• Bilirubin

• Urinalysis

• FeLV antigen testing

• FIV antibody testing

• Saline agglutination

• Direct Coombs’ testing

• Blood typing

• Crossmatching

• Abdominal ultrasound

• Thoracic imaging

• Faecal parasite testing

• Investigation for gastrointestinal blood loss

• Bone-marrow testing in selected non-regenerative cases

The exact work-up depends on whether the pattern suggests haemolysis, blood loss, reduced production or more than one process.

How Should a PCR Result Be Interpreted?

M. haemofelis Positive With Acute Haemolytic Anaemia

This is the combination most likely to represent clinically important haemoplasmosis.

Treatment should usually begin promptly, particularly when the cat is systemically unwell.

Less Pathogenic Species Positive With Severe Anaemia

A positive result may still matter, but other causes should be sought.

The veterinarian should look for:

• FeLV

• FIV

• Cancer

• Immunosuppression

• Chemotherapy

• Bone-marrow disease

• Other infections

• Blood loss

• Primary immune-mediated haemolysis

PCR Positive but Clinically Healthy

This commonly represents subclinical carriage.

Routine antibiotic treatment is not generally recommended because:

• The cat is not clinically ill

• Treatment may not clear the organism

• Relapse is uncommon

• Antibiotic exposure has risks

• A positive result may persist despite clinical health

The major exception is a potential blood donor, who should not donate while PCR-positive. (ABCD cats and vets)

PCR Negative After Antibiotics

This does not conclusively exclude recent infection.

Organism numbers may have fallen below the detection limit after treatment. The result must be interpreted alongside the pre-treatment history, haematology and response.

How Is Feline Haemoplasmosis Treated?

Treatment has two priorities:

1. Control the bacterial infection

2. Keep the cat alive while the red-cell population recovers

Stabilisation and Supportive Care

Depending on severity, treatment may include:

• Oxygen

• Careful intravenous or enteral fluid support

• Packed red blood cell transfusion

• Nutritional support

• Temperature support

• Monitoring of blood pressure and oxygenation

• Treatment of concurrent disease

Anaemic cats can be vulnerable to fluid overload, particularly when occult heart disease is present. Intravenous fluids and blood products must therefore be administered according to the individual cat’s perfusion, hydration and cardiovascular status. (ABCD cats and vets)

When Is a Blood Transfusion Needed?

A transfusion is considered when anaemia is sufficiently severe to compromise oxygen delivery.

The decision is not based on one PCV value alone. Important findings include:

• Collapse

• Severe weakness

• Rapid or laboured breathing

• Persistent tachycardia

• Altered awareness

• Poor perfusion

• Continued rapid decline

• Failure to compensate

Packed red blood cells are preferred when available because they replace oxygen-carrying cells while limiting unnecessary fluid volume.

Cats should be blood typed, and crossmatching may be recommended depending on transfusion history, age and local protocol. Donor blood should come from a haemoplasma PCR-screened donor. (ABCD cats and vets)

Which Antibiotics Are Used?

Doxycycline

Doxycycline is the usual first-line treatment for acute M. haemofelis-associated disease.

Current ABCD guidance lists:

• 5 mg/kg by mouth every 12 hours, or

• 10 mg/kg by mouth every 24 hours

A two-week course is usually adequate for an uncomplicated case showing a rapid clinical response. Treatment may be extended to two to four weeks when response is incomplete, disease is severe or the clinical circumstances justify attempting more complete organism suppression. (ABCD cats and vets)

Doxycycline Administration Matters

Doxycycline tablets and capsules can lodge in a cat’s oesophagus and cause:

• Severe oesophagitis

• Ulceration

• Oesophageal stricture

Every tablet or capsule should be followed by food or several millilitres of water as directed by the veterinarian. A suitable paste or professionally compounded formulation may be preferable in some cats.

“Compounded liquid is always safest” is too simplistic. Some liquids are extremely bitter, difficult to dose or variable in stability. The best formulation is the one the veterinarian can dose accurately and the cat can receive safely. (ABCD cats and vets)

Marbofloxacin and Pradofloxacin

These fluoroquinolones may be used as second-line treatment when:

• Doxycycline is not tolerated

• Clinical response is inadequate

• Severe or recurrent M. haemofelis infection persists

• Attempted organism clearance is considered necessary

Pradofloxacin has demonstrated strong activity against experimentally induced M. haemofelis infection and may be more effective than doxycycline at achieving long-term suppression in selected cases. Fluoroquinolones should still be reserved appropriately rather than used automatically as first-line treatment. (PubMed)

Is Enrofloxacin Recommended?

Enrofloxacin is not a preferred feline fluoroquinolone because it carries a risk of irreversible retinal toxicity, even though this reaction is uncommon.

Safer alternatives are generally selected where available. (ABCD cats and vets)

Do Penicillins or Cephalosporins Work?

No.

Haemoplasmas lack a cell wall, so beta-lactam antibiotics such as penicillins and cephalosporins do not target them effectively. (ABCD cats and vets)

Does Azithromycin Work?

Azithromycin has not shown reliable efficacy for feline haemoplasmosis and is not considered an appropriate substitute for doxycycline. (ABCD cats and vets)

Should Prednisolone Be Used?

Not routinely.

Although red-cell destruction has an immune component and Coombs’ testing may be positive, most cats recover with antibiotics and supportive care alone.

Immunosuppressive corticosteroids may:

• Increase haemoplasma bacteraemia

• Promote reactivation of subclinical infection

• Complicate concurrent infection

• Produce avoidable adverse effects

Current ABCD guidance recommends considering corticosteroids only when:

• The Coombs’ test is positive

• The cat has failed to respond appropriately to antibiotics

• Primary immune-mediated haemolytic anaemia remains a significant alternative diagnosis

A positive Coombs’ test by itself is not enough to justify prednisolone. (ABCD cats and vets)

How Quickly Should the Cat Improve?

When doxycycline is effective, organism numbers can fall rapidly and clinical improvement may begin within approximately three days.

However:

• The PCV may continue falling briefly before stabilising

• Bone-marrow regeneration takes time

• Weakness may persist after haemolysis is controlled

• Concurrent disease may delay recovery

• A severely anaemic cat may still require transfusion

A cat that deteriorates, fails to stabilise or shows no meaningful improvement needs reassessment rather than simply waiting until the antibiotic course is finished. (ABCD cats and vets)

Does Treatment Eliminate the Infection?

Not always.

A cat may recover clinically while remaining PCR-positive or developing intermittent low-level bacteraemia.

In selected severe, recurrent or high-risk M. haemofelis cases, a protocol involving four weeks of doxycycline followed by two weeks of marbofloxacin in cats remaining PCR-positive has produced apparent organism clearance.

This more intensive clearance protocol may be considered for:

• Severe recurrent disease

• Cats with immunodeficiency

• Cats living with particularly vulnerable cats

• Cats intended for blood donation

• Other situations where persistent carriage creates a significant concern

It is not required for every uncomplicated cat that responds promptly to treatment. (ABCD cats and vets)

Should Healthy Carrier Cats Be Treated?

Generally, no.

Treatment is not routinely recommended when a cat:

• Is clinically well

• Has no anaemia

• Has no evidence that the organism is causing disease

• Is not being considered as a blood donor

Treatment may fail to clear the infection completely and can expose the cat to medication adverse effects without a clear clinical benefit. (ABCD cats and vets)

A carrier cat cannot be described as completely non-infectious simply because flea control is maintained. The natural transmission route remains uncertain.

Preventing fighting and blood exposure remains prudent, and carrier cats must not be used as blood donors.

How Should Recovery Be Monitored?

Monitoring may include:

• Serial PCV or haematocrit

• Reticulocyte count

• Heart and respiratory rates

• Appetite

• Body weight

• Gum colour

• Bilirubin

• Temperature

• Clinical strength and activity

Severely anaemic cats may need PCV reassessment within hours or one to three days. More stable cats may be rechecked after several days or one to two weeks depending on the initial findings.

Routine repeat PCR is not required for every uncomplicated case that responds rapidly. Quantitative PCR is more useful when:

• Disease is severe

• Relapse occurs

• Clearance is being attempted

• The response is incomplete

• The cat has important concurrent disease

Can the Disease Return?

Yes.

Some cats remain chronic carriers after apparent recovery. Bacteraemia can fluctuate, and rare clinical reactivation or recurrent anaemia may occur.

Relapse becomes more concerning when:

• The original treatment was incomplete

• The cat remains PCR-positive

• Immunosuppression develops

• Another serious disease is present

• The cat receives immunosuppressive medication

• Anaemia returns shortly after treatment

One report documented recurrent anaemia in several cats around 11 days after completing a 21-day doxycycline course, illustrating why early post-treatment monitoring may be appropriate in severe cases. (ABCD cats and vets)

What Is the Prognosis?

The prognosis is generally good when haemoplasmosis is recognised and treated promptly.

Cats with mild or moderate M. haemofelis disease often respond quickly to doxycycline and supportive care.

The prognosis becomes more guarded when the cat has:

• Profound anaemia

• Collapse or respiratory compromise

• Delayed treatment

• FeLV or another serious concurrent disease

• Bone-marrow dysfunction

• Multiple infections

• Severe dehydration

• Inadequate response to antibiotics

• Recurrent haemolysis

Untreated acute M. haemofelis infection can be fatal, and severe cases may require blood transfusion before antibiotics have had time to work. (ABCD cats and vets)

How Can Feline Haemoplasmosis Be Prevented?

There is no haemoplasma vaccine.

Screen Blood Donors

Every feline blood donor should undergo species-appropriate PCR screening.

A normal examination and negative FeLV and FIV tests do not exclude haemoplasma carriage. (ABCD cats and vets)

Reduce Fighting

Practical measures include:

• Keeping cats indoors or within secure outdoor enclosures

• Neutering cats not intended for breeding

• Introducing household cats gradually

• Providing separated food, water and litter resources

• Reducing conflict in multi-cat homes

• Treating bite wounds promptly

Fighting has not been conclusively confirmed as the principal transmission route, but it is biologically plausible and fits several recognised epidemiological risk factors. (ABCD cats and vets)

Use Sterile Equipment

Needles, syringes and instruments that contact blood must never be shared between animals without appropriate sterilisation.

Maintain Parasite Prevention

Fleas are unlikely to be a major vector based on current evidence. Nevertheless, regular feline-safe flea and tick prevention remains prudent for overall health and because every possible natural transmission route has not been excluded. (ABCD cats and vets)

Monitor High-Risk Cats

Cats with outdoor access, fighting histories, FIV, FeLV or previous haemoplasmosis should be examined promptly if pallor, lethargy or appetite loss develops.

Can Humans Catch Feline Haemoplasmas?

Feline haemoplasmas are not considered a significant human health risk.

Rare molecular reports have identified haemoplasma infections in immunocompromised people, including an isolated report involving M. haemofelis. These reports suggest that zoonotic transmission may be biologically possible, but there is no evidence of a substantial routine risk from living with an infected cat.

Normal hygiene and cautious handling of blood remain appropriate, particularly for immunocompromised people. (ABCD cats and vets)

Common Feline Haemoplasmosis Mistakes

Assuming Fleas Are the Confirmed Main Route

Flea transmission has not been convincingly demonstrated and is now considered unlikely to explain most natural infections.

Diagnosing the Disease From a Blood Smear Alone

Smears frequently miss infection and can produce false-positive results from staining artefacts.

Treating the PCR Result Instead of the Cat

A positive carrier cat without anaemia does not automatically need antibiotics.

Assuming Every Positive Species Causes Severe Anaemia

M. haemofelis is substantially more pathogenic than the other two main feline species.

Starting Prednisolone Automatically

Steroids are not routine treatment and may worsen bacteraemia or reactivate infection.

Giving a Dry Doxycycline Tablet

Doxycycline must be followed by food or water to reduce the risk of oesophageal ulceration and stricture.

Giving Iron Without Confirming Iron Deficiency

Haemolysis is not the same as dietary iron deficiency.

Focusing Only on the PCV

A cat’s need for hospitalisation or transfusion depends on clinical stability, rate of decline and oxygen delivery, not one laboratory number alone.

Failing To Investigate Concurrent Disease

FeLV, FIV, blood loss, bone-marrow disease, toxins and primary immune-mediated haemolysis may be equally or more important.

Allowing a Carrier Cat To Donate Blood

All feline blood donors should be haemoplasma PCR-negative.

Frequently Asked Questions

Can fleas give a cat infectious anaemia?

Flea transmission has not been proven, and current evidence suggests fleas are unlikely to be a major haemoplasma vector. Flea prevention is still recommended for general health and because the natural route of transmission remains incompletely understood. (ABCD cats and vets)

How quickly does doxycycline work?

Cats with uncomplicated M. haemofelis disease often show clinical improvement within approximately three days. Severe anaemia may still require transfusion or intensive support while red-cell production recovers. (ABCD cats and vets)

Will my cat always remain PCR-positive?

Not necessarily. Some cats clear the infection, while others remain intermittent or chronic carriers. Clinical recovery does not guarantee complete organism elimination.

Can an infected cat live with other cats?

Many carrier cats live normally within multi-cat homes. Because transmission is not fully understood and fighting may be involved, prevent aggressive interactions and do not use an infected cat as a blood donor.

Should a healthy PCR-positive cat receive antibiotics?

Usually not. Current guidance does not recommend treating a clinically healthy, non-anaemic carrier unless there is a compelling individual reason to attempt organism clearance. (ABCD cats and vets)

Final Thoughts

Feline infectious anaemia is not diagnosed by finding one dot on a blood smear or one positive PCR result.

The most important points are:

1. Feline haemoplasmas are bacteria that attach to red blood cells.

2. Mycoplasma haemofelis is the most pathogenic species.

3. The other principal species usually cause milder or subclinical infection.

4. Severe haemolytic anaemia can occur in otherwise healthy cats.

5. The natural route of transmission remains uncertain.

6. Blood-transfusion transmission is proven.

7. Fighting is a plausible transmission route.

8. Fleas are unlikely to be the major vector once assumed.

9. Pale gums, weakness and rapid breathing require prompt assessment.

10. Collapse or open-mouth breathing is an emergency.

11. Blood-smear examination is unreliable.

12. Species-specific PCR is the preferred diagnostic test.

13. Samples should ideally be collected before antibiotics begin.

14. Doxycycline is the usual first-line treatment.

15. Doxycycline tablets must be followed with food or water.

16. Corticosteroids are not routinely recommended.

17. Blood transfusion may be lifesaving in severe disease.

18. Healthy PCR-positive carriers usually do not require treatment.

19. Feline blood donors should be screened by PCR.

20. The prognosis is generally good when treatment begins promptly.

The mistake that causes the greatest harm is focusing only on identifying the organism while overlooking whether the cat is currently able to deliver enough oxygen to the brain and vital organs.

Treat the infection, certainly. But stabilise the anaemia first when the cat is already losing the race.

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ASK A VET™ can help you organise PCR results, serial PCV measurements, medication records and changes in gum colour, appetite or breathing while you continue working directly with your veterinary team. A cat with white gums, marked breathing effort, collapse, severe weakness or reduced responsiveness still requires immediate hands-on emergency treatment.