Page 383 - Problem-Based Feline Medicine

19 – THE PYREXIC CAT 375

MYCOPLASMA HAEMOFELIS AND Classical signs—Cont’d
CANDIDATUS ‘M. HAEMOMINUTUM’ ● Anterior uveitis, retinochoroiditis.
(HAEMOBARTONELLA FELIS)**
● Seizures, ataxia.
● Dyspnea/polypnea.
Classical signs
● Icterus.
● Pale mucous membranes. ● Abdominal discomfort.
● Depression. ● Small bowel diarrhea.
● Anorexia.
● Icterus.
● Splenomegaly. Pathogenesis
● Fever. Gastrointestinal signs, primarily abdominal discom-
fort and small bowel diarrhea, are due most likely to
See main reference on page 530 for details (The Anemic replication of the organism (tachyzoites) in entero-
Cat). epithelial cells resulting in necrosis.

Clinical signs Clinical signs in the acute, fatal form of extraintestinal
disease are caused primarily by tissue damage from the
Classical signs are pale mucous membranes and/or rapidly dividing tachyzoites.
icterus primarily from extravascular hemolysis due to
Tachyzoites begin to disappear from tissues approxi-
complement binding of infected erythrocytes.
mately 3 weeks after infection. The organism may per-
Severe, regenerative hemolytic anemia may ensue. sist in tissues as tissue cysts containing bradyzoites.
Anorexia and depression are typical. Chronic disease may be a result of delayed hypersen-
sitivity reactions and tissue reaction to antibody–-
Fever occurs in 50% of cats in the acute phase, and
antigen complex deposition.
may occur intermittently in chronic infections.
Concomitant illness, such as FeLV, FIV and immuno-
Diagnosis suppression with glucocorticoids, has been reported in
some cases.
History and clinical signs are suggestive, especially if
an immunosuppressive disorder is present concurrently.
Clinical signs
Diagnosis is via demonstration of the organism on
the surface of erythrocytes. Use a marginated blood Gastrointestinal disease.
sample for diagnosis, e.g., ear vein. Multiple blood ● Mild, self-limiting small bowel diarrhea may
smears over a number of days may be required as most occur in the definitive host (cats), but only after
of the organisms are removed from circulation by the ingestion of tissue cysts, oocysts or sporulated
time clinical signs are apparent. oocysts.
● Young kittens are more likely to have gastroin-
Infected cats may be Coomb’s positive.
testinal signs, although mild clinical disease has
A polymerase chain reaction test is available in some been reported in adult cats as well. All newborn
laboratories for diagnosis. kittens experimentally infected developed severe
diarrhea 5–6 days later.
TOXOPLASMA GONDII** Fatal extraintestinal disease (acute course).

● Fatal extraintestinal disease is most likely to occur
Classical signs in transplacentally infected kittens.
● Fever. ● Kittens may be stillborn or exhibit signs that are
● Anorexia/weight loss. severe and rapidly progressive and reflect
involvement of the lungs, liver and CNS tissues.