Canine infectious respiratory disease: Challenges and considerations in animal shelters (Proceedings)



Aug 01, 2010

It is common to use the terms "kennel cough" or"infectious tracheobronchitis" when talking about canine infectious respiratory disease complex (CIRDC), this is in many cases not approproiate. The disease complex is not limited to the trachea,and often presents with signs other than coughing. In many shelters CIRDC will present with sneezing, nasal and ocular discharge, and sometimes lower respiratory and/or systemic disease.

Viral pathogens associated with upper respiratory disease in dogs include
      Canine respiratory coronavirus
      Canine herpesvirus
      Canine distemper
      Canine influenza
Bacterial pathogens implicated in CIRDC include:
      Bordetella bronchiseptica
      Mycoplasma spp.
      Streptococcus zooepidemicus (may cause severe systemic disease)

In addition to these pathogens it is likely that secondary bacterial invaders of many species play a significant role in causing more severe disease in some dogs, and we know that we are still unraveling the complicated etiology of CIRDC, as evidenced by the fact that several of the pathogens listed above have only been recognized in recent years.

There's a reason CIRDC is often referred to as "kennel cough" – several of the pathogens listed above are insufficient in themselves to cause disease without the additional stress, high contact rate, and other factors associated with kenneling.

Virtually all pathogens listed above can present with very similar overall clinical presentations. Although Bordetella-induced kennel cough is classically thought of as causing only relatively mild disease, shelters or boarding kennels with crowding, stress and a high load of secondary pathogens provide a synergistic effect and more severe disease is often the result. The cause of CIRDC can therefore not be diagnosed based on clinical signs in a single dog. The pattern of affected animals and clinical signs in a population can however provide some clue as to the likely pathogens. For example, if some animals show distinctive clinical signs, such as neurological signs characteristic of distemper, it is possible that other dogs showing milder disease are also infected with the same pathogen.

Diagnostic testing will often not affect your treatment plan and can be cost prohibitive. You may consider doing diagnostics such as culture and sensitivity or respiratory PCR panels if:
     • signs persist longer than expected
     • Unusually severe clinical signs
     • More frequent disease in population

Acutely affected animals should be sampled.

The ideal sample depends on the localization of clinical signs: if signs are predominantly upper respiratory, deep nasal swabs should be obtained. If lower respiratory disease is suspected, tracheal wash is the preferred specimen.

Samples should be submitted for bacterial culture and sensitivity for Bordetella, Mycoplasma, Streptococcus and others such as http://E.coli/; Klebsiella, Pasteurella, enterobacter etc.

PCR is the most practical option for viral detection; panels are available which include most common viral pathogens. Keep in mind that false negatives may be caused by problems with sample handling or timing. For instance, canine influenza is shed only very early in the course of disease, and may be missed by the time clinical signs are recognized. False positives can occur following vaccination; this has been documented as long as three weeks after vaccination for canine distemper.