Page 398 - Problem-Based Feline Medicine

390 PART 7 SICK CAT WITH SPECIFIC SIGNS

Diagnosis Clinical signs

Diagnosis is based on clinical signs and history and Naturally infected cats usually only develop subclin-
confirmed by demonstrating increased thyroid hormone ical infection.
concentrations (total T4, free T4).
Mild, self-limiting fever lasting 48–72 hours has been
Thyroid glands can be palpated in approximately 80% documented in some experimentally infected cats.
of cats with hyperthyroidism, and are unilaterally or
Anterior uveitis and fever were documented in
bilaterally enlarged.
naturally exposed cats.
● Enlarged thyroid glands may not be palpable if the
abnormal thyroid tissue is within the thoracic inlet. Lymphadenopathy.
Complete blood count and a biochemistry panel are Stomatitis and gingivitis have been proposed as
required to rule out diseases such as diabetes mellitus, clinical manifestations.
renal disease, etc.
Atypical seizures occur in some cats.
A TRH stimulation test may be necessary when clin-
ical signs are highly suggestive and total and free T4 Diagnosis
are in the upper region of the reference range for
normal cats. Antibody titers are prevalent in healthy cats, but there
is a poor correlation with blood culture and PCR
Thyroid radionuclide uptake and imaging with pertech- assay results.
netate ( 99m Tc) is also available at some institutions.
Intermittent bacteremia may occur for longer than
Response to therapy with anti-rickettsial drugs (tetracy-
one year following infection, with 25–41% of healthy
cline or doxycycline) is highly suggestive.
cats bacteremic for up to 22 months.
The organism is present within erythrocytes, therefore,
hemolyzing red blood cells increases the sensitivity of
BARTONELLA HENSELLA (CAT-SCRATCH
FEVER) the culture.

Classical signs Differential diagnosis
● Subclinical or mild fever and occasional Other causes of mild transient fever need to be consid-
ocular signs. ered, such as mild cellulitis following a cat fight.
Other infectious causes of anterior uveitis need to be
ruled out, such as toxoplasmosis, fungal diseases,
Pathogenesis
FeLV, FIV, Cuterebra or dirofilaria.
Bartonella henselae is an intracellular bacterium
within erythrocytes.
Treatment
Bacteremia is present in many healthy cats in the pop-
Antimicrobial efficacy has not been clearly demon-
ulation, and cats are reservoirs for infection.
strated.
B. henselae is an important pathogen because of its
Clinical signs of disease have resolved when the cats
zoonotic potential in immunocompromised humans.
are administered doxycycline at 25–50 mg PO q 12 h
● Humans may develop fever, malaise, lymph-
for 28 days.
adenopathy and skin eruptions following cat
scratches or bites. Azithromycin is used in humans and is a safe alterna-
● B. henselae causes bacillary angiomatosis, bacillary tive in cats when administered at 10 mg/kg PO q 24 h
peliosis and encephalitis in human AIDS patients. for 28 days