The 2017 Antimicrobial Use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats1 cover acute and chronic bacterial upper respiratory infections in dogs and cats, as well as bronchitis, pneumonia and pneumothorax. They include recommendations for first-line treatment for the different syndromes, as well as doses and information about antibiotic options. The full publication is available free online.
This blog focuses on the recommendations for acute canine respiratory infections (canine infectious respiratory disease complex or CIRDC), feline upper respiratory infections (URI) and pneumonia, and focuses on aspects most relevant to shelters.
Diagnostic testing for acute upper respiratory infections
Cytology, culture and PCR tests are not very useful in typical acute disease.
When not to use antibiotics
It’s thought that most URI/CIRDC is caused by viruses.
For cats: “If nasal discharges are serous and lack a mucopurulent or purulent component, the Working Group believes that antimicrobial treatment is not recommended because of the likelihood of uncomplicated viral infection.” The same message for dogs: “The majority of cases of CIRDC are currently believed to be viral in etiology and so antimicrobial administration is often not indicated.”
Bacterial infection should be suspected if there is mucoid or mucopurulent discharge – but this can be caused by viral infection as well.
Even if acute bacterial infection is suspected, the Guidelines recommend a 10-day observation period during which antibiotics should not be used unless the animal has fever, lethargy or anorexia, or is clinically worse. These infections often resolve spontaneously within 10 days.
When to use antibiotics
- If acute bacterial URI is suspected, and the animal has fever, lethargy or anorexia
- If the animal has not improved in the 10-day observation period, or clinical signs are worse after 5-7 days
Waiting a full 7-10 days presents a challenge for shelters, because we want to reduce length of stay and minimize disease transmission. It is probably a reasonable compromise to hold off on antibiotics if the animal remains bright, with a good appetite, and improves clinically within several days.
Antibiotic choice and duration for acute bacterial CIRDC/URI
The Guidelines state that the ideal duration of treatment is not known, but suggest a 7-10 day course. Dr. Kate Hurley has recommended a “treat to failure or treat to cure” approach2, and recent research has questioned the orthodoxy that a fixed antibiotic course is needed for most infections, and that the (usually arbitrary) course must be finished (see Dr. Scott Weese’s blog on the subject3).
The Working Group suggests first-line treatment with doxycycline. Organisms like Chlamydia might require longer courses. (Amoxicillin is also listed as a first-line drug, but would not be a good choice for shelters because it doesn’t cover Bordetella, Mycoplasma or Chlamydia.)
Bordetella is a common cause of bacterial pneumonia, but many other bacteria can be involved. Bacterial pneumonia is often secondary to viral infection in a shelter setting.
In mild cases, oral doxycycine could be used as the initial treatment. In more severe cases, especially if sepsis is suspected, broad-spectrum parenteral antibiotics should be given as soon as possible. First-line treatment should be a combination of a fluoroquinolone and a penicillin or clindamycin. Oral follow-up medication should be based on clinical response and, if possible, culture and sensitivity.
Most veterinary textbooks recommend 4-6 weeks of treatment for pneumonia, but this is not evidence-based. The Working Group recommends reassessment after 14 days. The total duration of treatment should then be based on clinical, hematological and radiographic findings.
- Lappin MR, Blondeau J, Boothe D, et al. Antimicrobial use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases. J Vet Intern Med. 2017;31(2):279-294. doi:10.1111/jvim.14627.
- Hurley K. Knocking the Snot out of Feline URI. Maddie’s webinar; http://www.maddiesfund.org/knocking-the-snot-out-of-uri.htm. 2012.
- Weese S. The “Antibiotic Course” Has Run Its Course. Worms and Germs blog, August 2017; http://www.wormsandgermsblog.com/2017/08/articles/animals/other-animals/the-antibiotic-course-has-run-its-course/. 2017.