Page 350 - Small Animal Internal Medicine, 6th Edition

322 PART II Respiratory System Disorders

BOX 21.1 BOX 21.2
VetBooks.ir Agents Associated With Canine Infectious Respiratory Client Education for Canine Infectious Respiratory
Disease Complex (CIRDC)
Disease Complex (Infectious Tracheobronchitis,
“Kennel Cough”)
CIRDC is like colds and flu in people. The following infor-
Viruses mation is often well understood by the general public
Canine adenovirus 2 regarding colds and flu and correlates well with CIRDC.
Canine influenza viruses (H3N8, H3N2) • More than one type of organism is responsible
Canine parainfluenza virus • Being infected with, or vaccinated for, one
Canine herpesvirus—type1 organism does not prevent being infected with
Canine respiratory coronavirus another
Canine pneumovirus • Some people never get sick
• Some people get sick frequently
Bacteria • More people get sick if they are frequently exposed to
Bordetella bronchiseptica children or the general public
Streptococcus equi, subsp. zooepidemicus • Most people recover without any specific treatment
Mycoplasma cynos • Some people develop pneumonia and some people
Other Mycoplasma spp. die, usually as a result of:
• Particularly virulent organisms
• Underlying respiratory disease (such as bronchitis
or asthma)
• Immune compromise or debilitation
• Being very old or very young
• Vaccines are not completely effective
• Antibiotics are not usually necessary and are
ineffective against viruses

Most dogs with CIRDC are considered to have “uncom-
plicated,” self-limiting disease and do not show signs of sys-
temic illness. Therefore dogs showing respiratory distress,
weight loss, persistent anorexia, or signs of involvement
of other organ systems, such as diarrhea, chorioretinitis,
or seizures, may have some other, more serious disease,
such as canine distemper or a mycotic infection. Sec-
FIG 21.1 ondary bacterial pneumonia can develop particularly in
Photomicrograph of a tracheal biopsy specimen from a dog puppies, immunocompromised dogs, and dogs that have
infected with Bordetella bronchiseptica. The organisms are
small basophilic rods that are visible along the ciliated preexisting lung abnormalities such as chronic bronchitis.
border of the epithelial cells. (Giemsa stain courtesy D. Dogs with chronic airway disease or tracheal collapse can
Malarkey.) experience an acute, severe exacerbation of their chronic
problems, and extended management may be necessary to
resolve the signs associated with infection in these animals.
Be aware that, although rare, B. bronchiseptica has been B. bronchiseptica infection has been associated with canine
documented to cause infection in people. A discussion chronic bronchitis.
regarding the potential exposure of a dog with CIRDC to
immunocompromised individuals is warranted. Diagnosis
Uncomplicated cases of CIRDC are diagnosed on the basis
Clinical Features of presenting signs. However, differential diagnoses should
Affected dogs are first seen because of the sudden onset of a also include the early presentation of a more serious disease.
severe productive or nonproductive cough, which is often Diagnostic testing is indicated for dogs with systemic, pro-
exacerbated by exercise, excitement, or pressure of the collar gressive, or unresolving signs. Tests to be considered include
on the neck. Palpating the trachea easily induces the cough. thoracic radiographs, a complete blood count (CBC), tra-
Gagging, retching, or nasal discharge can also occur. A cheal wash fluid analysis, polymerase chain reaction (PCR)
recent history (i.e., within 2 weeks) of boarding, hospitaliza- testing, paired serology, or other tests for the respiratory
tion, or exposure to a puppy or dog that has similar signs is pathogens listed in Box 21.1. Tracheal wash fluid cytology
common. Puppies recently obtained from pet stores, kennels, shows acute inflammation, and bacterial culture of the fluid
or shelters have often been exposed to the pathogens. can be useful for identifying any bacteria involved in the