Page 1470 - Small Animal Internal Medicine, 6th Edition

1442 PART XIV Infectious Diseases

anaerobic organisms should be used. An aminoglycoside Azithromycin, potentiated sulfas, and potentially ponazuril
or quinolone for gram-negative organisms combined with are alternative anti-Toxoplasma drugs. Optimal treatment
VetBooks.ir ampicillin, a first-generation cephalosporin, metronidazole, for dogs with Neospora caninum infection of the CNS is
unknown, but the combination of clindamycin or azithro-
or clindamycin for gram-positive and anaerobic organisms
is a commonly prescribed combination treatment with the
acutely affected dogs because of the potentially poor
final choice made based on the likely site of bacterial entry. mycin with potentiated sulfas should be considered in
Second- and third-generation cephalosporins, ticarcillin prognosis.
combined with clavulanate, and imipenem are some of the
other antimicrobial agents with a four-quadrant spectrum.
For bacteremia, without endocarditis, antimicrobial GASTROINTESTINAL TRACT AND
agents should be administered intravenously for at least 1 to HEPATIC INFECTIONS
3 days, and clinical and clinicopathologic evidence of
response documented before conversion to oral therapy. The Oral administration of antimicrobial agents is rarely indi-
oral treatment is selected on the basis of culture and antimi- cated for bacterial GI infections in dogs or cats because of
crobial susceptibility results, and duration of therapy will negative effects on the GI microbiome and availability
vary based on the source of the bacteremia. For example, if of alternate therapies like diets and probiotics (Torres-
antibiotics are used parenterally in a bacteremic parvovirus Henderson et al., 2017). However, antibiotics are sometimes
puppy, continued oral therapy is not required after resolution needed for the treatment of small intestinal bacterial over-
of clinical signs of disease. growth, hepatic encephalopathy, cholangiohepatitis, hepatic
For patients with valvular endocarditis, administration of abscessation, Boxer colitis, and infection by Helicobacter
intravenous (IV) antibiotics for at least 7 to 14 days followed spp., Campylobacter spp., Clostridium perfringens, Giardia
by subcutaneous (SC) administration for 7 to 14 days before spp., Cryptosporidium spp., Cystoisospora spp., Tritricho-
conversion to oral therapy is recommended by some authors monas foetus, and Toxoplasma gondii (see Table 92.5).
(Calvert and Thomason, 2012); oral antibiotic therapy may Administration of parenteral antibiotics may be indicated in
be indicated for months. Optimal treatment for valvular dogs and cats with bacteremia from translocation of enteric
endocarditis from bartonellosis in dogs has not been deter- flora or with Salmonella infection. The American College of
mined, but the combination of at least two drugs is generally Veterinary Internal Medicine has recently published a con-
required. Although optimal protocols are not known, fluo- sensus statement on the treatment of enteropathogenic bac-
roquinolones combined with doxycycline, azithromycin, or terial infections in dogs and cats (Marks et al., 2011). For
rifampin may be required in some cases (see Chapters 6 and most GI infections, dietary manipulation and probiotics
94). Administration of amikacin for the first 5 to 7 days of could also be beneficial or resolve the diarrhea so antimicro-
therapy is indicated for dogs or cats with endocarditis associ- bial agents are not required.
ated with bartonellosis. For aerobic or anaerobic bacteria, the Giardia spp. infections often respond clinically to the
blood culture can be rechecked 1 and 4 weeks after discon- administration of metronidazole, but infection is usually not
tinuation of therapy to confirm control of the infection. eliminated. Administration of a probiotic and institution of
Whether there is clinical utility to performing Bartonella a diet change should be considered concurrently when treat-
spp. serology or culture after successful treatment is unclear ing dogs or cats with suspected giardiasis (Fenimore et al.,
(see Chapter 94). The prognosis in dogs and cats with bacte- 2017). Administration of metronidazole benzoate at 25 mg/
rial endocarditis is guarded to poor because of damage to the kg q12h orally (PO) for 7 days was effective in suppressing
infected heart valves (see Chapter 6). cyst shedding to below detectable limits in 26 cats (Scorza
and Lappin, 2004). This is the maximal dose of metronida-
zole that should be used; CNS toxicity can be induced by
CENTRAL NERVOUS SYSTEM overdosing or as a cumulative neurotoxin. Fenbendazole is
INFECTIONS the most commonly used alternate drug in dogs and cats.
Febantel is also potentially effective in both species and is
Azithromycin, chloramphenicol, trimethoprim-sulfonamide, labelled for this use in some countries (Bowman et al., 2009).
metronidazole, and the quinolones penetrate the CNS and Metronidazole has the advantage of helping treat secondary
are often considered for empirical treatment of suspected small intestinal bacterial overgrowth and may have antiin-
bacterial infections of this system (see Table 92.4). Anaerobic flammatory effects. Nitaxoxanide also can be used to treat
bacterial infection and rickettsial infections (Ehrlichia spp. Giardia spp. infected dogs and should be considered for use
and R. rickettsii) of the CNS occur in some cases, making when Cryptosporidium spp. co-infection and diarrhea are
chloramphenicol a logical first choice. Multiple other drugs, detected concurrently (Moron-Soto et al., 2017). Although
including penicillin derivatives, tetracyclines (doxycycline), ronidazole can be effective for the treatment of Giardia spp.
and clindamycin, may cross into the cerebrospinal fluid infection, it is generally reserved for the treatment of T.
(CSF) when inflammation exists. Clindamycin achieves ade- foetus infections (Fiechter et al., 2012).
quate brain tissue concentrations in normal cats and can be For T. foetus infections of kittens (and rarely, puppies),
used for the treatment of toxoplasmosis (see Chapter 98). ronidazole at 30 mg/kg PO q24h for 14 days often eliminates