Page 1472 - Small Animal Internal Medicine, 6th Edition

1444 PART XIV Infectious Diseases

Fluoroquinolones can also be used for R. rickettsii, Myco- fungal infections. In these examples, the normal respira-
plasma, and L-form bacterial infections. Bartonella spp. tory flora that usually only colonizes the tissues can be
VetBooks.ir infections generally are treated with two antimicrobial agents associated with infection. Pasteurella spp. Staphylococcus
spp., Streptococcus spp., Mycoplasma spp., and a variety of
as discussed in the bacteremia section.
Muscle disease from T. gondii infection often resolves
involved. Because the upper respiratory passageways have
during treatment with clindamycin hydrochloride, azithro- gram-negative organisms and anaerobic bacterial can be
mycin, or trimethoprim-sulfonamide (see Table 92.4). Pona- a normal flora, it is difficult to assess the results of culture
zuril at 20 mg/kg, PO, once daily may also be effective for and antimicrobial susceptibility testing or polymerase chain
the treatment of toxoplasmosis. Optimal duration of therapy reaction results from samples collected from these tissues.
is unknown, and no drug consistently eliminated T. gondii The source of the primary insult should always be removed
from the tissues. Although many dogs with neosporosis die, if possible; see Chapter 14 for a review of respiratory
some have survived after treatment with trimethoprim- diagnostic techniques.
sulfadiazine combined with pyrimethamine; sequential The ISCAID Working Group recommends doxycycline at
treatment with clindamycin hydrochloride, trimethoprim- 5 mg/kg, PO, q24h or 10 mg/kg, PO, q24h for the initial
sulfadiazine, and pyrimethamine; or clindamycin alone. For treatment of cats with acute bacterial URI and dogs with
dogs with acute Hepatozoon americanum infection, the com- suspected bacterial causes of the CIRDS (see Table 92.7).
bination of trimethoprim-sulfadiazine, pyrimethamine, and Amoxicillin in cats and amoxicillin-clavulanate in dogs were
clindamycin for 14 days is highly successful; the use of deco- considered the alternate empirical choices. If clinical signs
quinate at 10 to 20 mg/kg q12h with food lessens the likeli- have not resolved within 10 days, the ISCAID Working
hood of recurrence of clinical disease and prolongs survival Group guidelines suggests performing a complete workup,
time. potentially including deep cultures, before using other anti-
biotics like azithromycin, amoxicillin-clavulanate, cefovecin,
or fluoroquinolones (Lappin et al., 2017).
RESPIRATORY TRACT INFECTIONS The ISCAID Working Group recommended that dogs or
cats with suspected bacterial bronchitis be administered dox-
Antimicrobial use guidelines (Lappin et al., 2017) for treat- ycycline while waiting for bacterial culture and antimicrobial
ment of infectious respiratory diseases in dogs and cats were susceptibility results. Dogs or cats with uncomplicated com-
recently published by the Antimicrobial Guidelines Working munity acquired pneumonia should be administered doxycy-
Group of the ISCAID. The Working Group made first-choice cline. Common bacteria associated with pneumonia in dogs
antimicrobial recommendations for acute bacterial upper include E. coli, Klebsiella spp., Pasteurella spp., Pseudomonas
respiratory infections (URIs) in cats, chronic bacterial URIs spp., B. bronchiseptica, Streptococcus spp., Staphylococcus
in cats, bacterial causes of the canine infectious respiratory spp., and Mycoplasma spp. In cats, Bordetella, Pasteurella,
disease syndrome (CIRDS), bronchitis in dogs and cats, and Mycoplasma organisms are commonly isolated. Aspira-
pneumonia in dogs and cats, and pyothorax in dogs and cats tion of GI contents is a common cause of bacterial pneumo-
(see Table 92.7). nia with a mixed population of bacteria. Multiple species
Allergies and irritants most commonly induce serous of bacteria are typically cultured from dogs and cats with
nasal discharge, and antibiotics are not indicated in the man- bronchopneumonia. Bordetella bronchiseptica and S. equi
agement of these syndromes. Many causes of epistaxis are var. zooepidemicus are the most important primary pathogen
local to the nasal cavity or sinuses and include trauma, in dogs and cats; most other bacteria colonize after airways
foreign bodies, masses, and fungal disease that do not have been previously damaged. If consolidated lung lobes are
respond to antibiotic therapy. However, diseases associated detected radiographically, an anaerobic infection should be
with vasculitis also are associated with epistaxis; B. vinsonii, assumed. Dogs or cats with pneumonia and signs of sepsis
E. canis, and R. rickettsii are implicated most frequently in should be administered a fluoroquinolone combined with
this syndrome. Administration of doxycycline may result in a penicillin or clindamycin parenterally while finishing the
resolution of disease if these organisms are involved. See diagnostic workup and then de-escalate therapy as indi-
Chapters 94 and 95 for a complete discussion of the diagno- cated (Lappin et al., 2017). Optimal duration of treatment
sis and treatment of these infectious agents. for bacterial pneumonia is unknown, but the consensus at
If mucopurulent nasal discharge is present in dogs or this time is to reevaluate dogs and cats with pneumonia
cats with other clinical manifestations of upper respira- no later than 10 to 14 days after starting treatment. Addi-
tory disease like congestion and sneezing, there is usually tional studies are needed to determine whether the current
a bacterial component. Primary bacterial pathogens include recommendations for a minimum of 4 weeks of therapy
Bordetella bronchiseptica, Chlamydia felis (cats), and some are needed.
Mycoplasma spp., Pasteurella spp., and Streptococcus equi, Whether species of Mycoplasma infecting dogs and
var. zooepidemicus (dogs). Many dogs or cats with sus- cats are capable of being primary respiratory pathogens is
pected bacterial URIs have bacterial infections secondary unknown. Chlamydia felis in cats is not a common cause
to other primary diseases, including foreign bodies, viral of lower respiratory tract infection. Yersinia pestis causes
infections, tooth root abscesses, neoplasms, trauma, and pneumonia in cats in Western states (see Chapter 99);