Page 370 - Small Animal Internal Medicine, 6th Edition

342 PART II Respiratory System Disorders

equal to those in plasma. Nebulization of antibiotics is rarely Moisture reaches only the nasal cavity and the proximal
indicated. trachea. Vaporization is not effective in hydrating deeper
VetBooks.ir lines Working Group of the International Society for Com- regions of the lungs. However, the more proximal effect can
Based on recommendations of the Antimicrobial Guide-
still provide some relief, particularly in animals with nasal
panion Animal Infectious Diseases (ISCAID), dogs and cats
simply by placing the animal in a steamy bathroom or in a
with mild pneumonia suspected based on history to be from discharge. Humidification is convenient and can be achieved
infection with B. bronchiseptica or Mycoplasma spp can be small room with an inexpensive vaporizer, which is readily
treated with doxycycline (5 mg/kg q12h PO or 10 mg/kg available at pharmacies.
q24h; followed by a bolus of water). However, broader cover- Nebulization is necessary to provide moisture deeper into
age is indicated in these patients if systemic signs of disease the airways. Nebulizers generate small, variably sized drop-
such as fever, dehydration, lethargy, or respiratory compro- lets, with a diameter ranging from 0.5 to 5 µm, as is required
mise is present (Lappin et al., 2017). to reach the deeper airways. Several types of nebulizers are
For other animals with mild or moderate clinical signs, available. Disposable jet nebulizers are readily available and
oral antibiotics that can be initiated include amoxicillin- inexpensive, and they can be attached to bottled oxygen or
clavulanate (dogs, 11 mg/kg q8h; cats, 12.5 mg/kg q8h), ceph- to an air compressor (Fig. 22.1). Effective, inexpensive por-
alexin (22-25 mg/kg q12h), and trimethoprim-sulfonamide table compressors are commercially available if needed for
(15 mg/kg q12h). Fluoroquinolones are reserved for animals home use. The nebulizing solution is delivered to the animal
with resistant gram-negative infections. through a face mask. The particles can be seen as a mist.
Animals with severe clinical signs or possible sepsis Excellent information on the use and cleaning of nebulizing
should be treated initially with broad-spectrum intrave- equipment in the home can be found on the Web sites of
nous antibiotics that provide coverage for gram-negative many large human hospitals where patient information is
and gram-positive aerobes and anaerobes. A fluoroquino- provided for the management of cystic fibrosis or bronchial
lone in combination with ampicillin with sulbactam (20 mg/ asthma.
kg of ampicillin q6-8h) is commonly used. This combina- Sterile saline solution is used as a nebulizing solution
tion has the advantages of availability of oral formulations because it has mucolytic properties and is relatively nonir-
for continuation of therapy after hospitalization, and the ritating. Premedication with bronchodilators has been sug-
flexibility of de-escalation if clinical response and culture gested as a way to reduce bronchospasms, although the use
results support doing so. Alternatively, meropenem (8.5 mg/ of saline alone in dogs does not usually cause problems.
kg SC q12h or 24 mg/kg IV q12h in dogs; 10 mg/kg IV, It is recommended that nebulization be performed two
IM, SC q12h in cats) or the combination of an amino- to six times daily for 10 to 30 minutes each time. Nebu-
glycoside (e.g., amikacin, 15 mg/kg IV q24h in dogs and lization should be followed immediately by physiotherapy
10 mg/kg IV q24h in cats) and ampicillin with sulbactam to promote the expectoration of exudate that may have
can be used. If Toxoplasma infection is among the differ- increased in volume with rehydration. Nebulizers and tubing
ential diagnoses, usually in cats, clindamycin (10-15 mg/ should be replaced after no more than 24 hours of use in
kg PO, SC q12h in cats) can substituted for the ampicillin
with sulbactam in combination with a fluoroquinolone (see
Chapter 98).
Antibiotic treatment should be continued for at least 1
week after clinical signs have resolved. Guidelines for patient
monitoring are provided later in this section.
Airway Hydration
Drying of secretions results in increased viscosity and
decreased ciliary function, which interfere with the normal N
clearance mechanisms of the lung. Thus the water content of
airway secretions must be maintained and airways must be
hydrated in animals with pneumonia. Animals with any evi-
dence of dehydration should receive fluid therapy. Diuretics
can cause dehydration, and their use is relatively contraindi-
cated in such animals.
Additional moisture for the airways can be provided FIG 22.1
through humidification or nebulization. Such therapy is par- Disposable jet nebulizers are readily available and
ticularly recommended for animals with areas of consolida- inexpensive. Sterile saline solution is placed in the nebulizer
(N). Oxygen enters the bottom of the nebulizer (open
tion or with suspected decreased airway clearance, such as arrow), and nebulized air exits the top (closed arrow).
those with bronchiectasis. Humidification refers to the satu- Nebulized air is delivered to the animal with a face mask,
ration of air with water vapor. Depending on the tempera- as shown here, or it can be delivered into an enclosed
ture, the volume of water that remains as vapor is limited. cage.