Haemobartonellosis In Cats

Written and Submitted by:  Dawn Skupin, Stedam American Shorthairs

About five years ago one of my kitten buyers called me telling me that her cat, Peanut, was under emergency care and required a blood transfusion.  Not knowing why, I asked to speak with the attending veterinarian.  The subsequent conversation with the vet launched me into an Internet exploration on a subject I’d never heard about.  I’d like to share the research I’ve found with you.

Since its discovery in 1942, Haemobartonellosis, formerly known as H. felis, has become known as the cause of feline infectious anemia or feline hemitropic mycoplasmosis.  It is a flea and tick transmitted disease but can also be transmitted by cat bites, blood transfusion and by mothers to their kittens.  It is not known if the spread of this disease from mother to kittens is done prior to the birth of the kittens, (intro utero),  during the birth, or through nursing.

There are two species of this disease.  Mycoplasma haemofelis is the large form of the organism.  It is the most pathogenic form.  And, Candidatus Mycoplasma Haemominutum  is the small form of the organism which is thought to be less pathogenic.  Both are not typical bacteria but belong to a group of microorganisms called mycoplasma which are the smallest free-living type of ‘germs.’

Haemobartonellosis targets the red blood cells which are responsible for carrying oxygen.  It is an acute or chronic disease of domestic cats seen in many parts of the world.  In the cat, the disease can progress the spectrum from no to mild symptoms or only a very slight anemia to a disease that is extremely severe and quite possibly lethal.  Clinical signs of the disease depend on the degree of anemia, the stage of infection, and the immune status of the infected cat.  There is some evidence that the M. haemominutum infections are potentiated by the Feline Leukemia virus co-infection.  Medical signs and physical examination abnormalities associated with anemia include pale mucous membranes, depression, loss of appetite, fast heart and respiratory rates and general weakness.  A fever may occur in some acutely infected cats and is common in chronically infected cats. 

The anemia begins as infected red blood cells are attacked and destroyed by the immune system.  The spleen is one of the major sites of the red blood cell destruction.  The organism attaches itself to the surface of the red blood cells and can be seen under a microscope. This is the most common method of diagnosis.  However, it is easy to confuse the organisms with other red blood cell changes. The number of organisms in the bloodstream can fluctuate dramatically.  There can be many observed in one sample and a sample taken two hours later may reveal no evidence of the organism. In the event of a definite diagnosis, a test called the polymerase chain reaction, or PCR, is available.  Haemobartonella should be considered as a possibility in any anemic cat or any cat with evidence of hemolysis.  Since the appearance of H. felis on the red blood cells is cyclical, the organisms may not be present all the time.  In many cases, treatment is begun even if the diagnosis is only suspected and not confirmed.

Some cats can recover from the disease but become carriers of the organism.  This means the cats look healthy but still have a small number of the mycoplasma in their bodies.  If these cats are stressed it sometimes causes the organisms to multiply and reproduce the disease again in the carrier cat. 

Treatment involves both supportive and specific therapies.  Both the large and small forms of Haemobartonella are gram-negative. Without treatment, one-third of acutely ill cats may die.  Treatment for Haemobartonellosis includes blood transfusion, antibiotics and prednisone.  Blood transfusions are used to temporarily stabilize severely anemic cats by replenishing the number of red blood cells.  The need for transfusion is based on the cat’s overall condition. Note:  It is important that the donor cat for the blood transfusion be screened by PCR testing for Hemobartonellosis.  In a national prevalence study it was shown that 9.8% of the cats used as blood donors were PCR positive for hempplasmas.

Tetracycline antibiotics are employed to eradicate as many H. felis organism as possible.  Doxycycline is probably the most frequently prescribed antibiotics in this class because it usually causes fewer side effects than other tetracyclines.  Suppression of appetite, nausea or vomiting are common signs of adverse drug reaction.  The drugs do not completely eliminate the infection but they appear to lessen the severity of the disease.  Prednisone is frequently prescribed in cases of feline infectious anemia.  This corticosteroid medication is used to help block immune system-mediated red blood cell destruction.  Although Chloramphenicol has also been shown affective against H. felis, it can cause a significant but reversible erythroid hypoplasia that may interfere with the regenerative response.  Azithromycin was not shown to be effective for the treatment of hemoplasmosis.

Finally, prevention of Hemobartonellosis in cats can be achieved by proper flea control and keeping cats indoors.  As with other diseases transmitted by fleas and ticks, flea and tick control is the foundation of prevention.  Products which repel and kill ticks and fleas such as Frontline and Advantage Plus, or other products containing Pyrethrin, are excellent choices for prevention.  Additionally, restraining cats to an indoor environment dramatically reduces the incidence of the disease.

References:

Lappin, Michael R., Haemobartonellosis,. World Small Animal Veterinary Association, 29^th World Congress, 2004. www.vin.com

Lappin, Michael R,  Little, Susan, Winn Feline Foundarion 25, Part One: Hemobartonella. 2003 www.winnfelinehealth.org

Nash, Holly, Haemobartonellosis (Feline Infectious Anemia, Hemotrophic Mycoplamosis) in Cats. www.peteducation.com.

Haemobartonellosis, www.lambertvetsupply.com.

Classification of Differential Diagnoses for Anemia, Merck Veterinary Manual Online, www.merckveternarymanual.com/mvm/index.jsp; 2003