Severe cases Some dogs will develop secondary bacterial pneumonia once infected with canine influenza. Clinical signs of pneumonia include increased respiratory rate or dyspnea, severe lethargy, weakness, and anorexia. (Crawford et al., 2010) This pneumonia may be life-threatening and can require aggressive management. Intravenous fluids, parenteral antibiotics, and oxygen support should be used as needed. Oxygenation should be monitored using pulse oximetry or arterial blood gas; oxygen supplementation should be implemented if the SaO 2 falls below 94% or the PaO 2 falls below 80 mmHg SaO 2 . (Crawford et al., 2010) Saline nebulization may be beneficial to aid in the breakup of bronchial secretions. Coupage and physical activity can also play an important role in stimulating coughing and aiding in the clearance of airway secretions. (Crawford et al., 2010) Bronchodilators such as aminophylline (6 mg/kg to 11 mg/ kg every eight hours), theophylline (6mg/kg to 11 mg/kg every 8 hours), or terbutaline (0.01 mg/kg every 8 hours) can be considered in cases of severe bronchiolitis. (Crawford et al., 2010) Bronchodilators may increase patient comfort while also allowing for more effective airway clearance. Oral or parenteral N-acetylcysteine (150 mg/kg initially, and then 50 mg/kg every 4 to 6 hours via mouth or intravenous catheter, or 50 ml/hour for 30 to 60 minutes every 12 hours by nebulization) has been utilized for its mucolytic effects in canine influenza. However, it may elicit bronchospasm if given via nebulization in patients with pre-existing bronchospastic disease. (Crawford et al., 2010) Therefore, this drug should be used with caution, and patients receiving this medication should be monitored closely. Antibiotic therapy should be guided by culture and sensitivity testing results. Obtain samples for culture and sensitivity via transtracheal wash. If antibiotics must be selected empirically, consider broad-spectrum bactericidal antibiotics that will offer coverage against the most commonly involved secondary bacteria. Common bacteria isolated in influenza-induced pneumonia include Pasteurella multocida, Klebsiella pneumoniae, E. coli, Streptococcus spp., Staphylococcus spp ., and Mycoplasma spp . (Crawford et al., 2010) (Rishniw, 2024) Mildly affected adult dogs may be managed with doxycycline (5 mg/kg every 12 hours), while more severe cases of pneumonia may require fluoroquinolones, extended-spectrum penicillins (such as amoxicillin/clavulanate), or third generation cephalosporins. 4 Enrofloxacin (5 mg/kg every 12 hours) is often recommended if Bordetella bronchiseptica is suspected,
based on in vitro efficacy and enrofloxacin’s excellent distribution to lung tissue. (Crawford et al., 2010) There have been reports of canine influenza associated pneumonia cases that respond poorly to antibiotics. The pneumonia in these cases may be caused by a multidrug- resistant E. coli . Additionally, some severely affected dogs have negative bacterial cultures, suggesting that the virus itself may be contributing to severe alveolar disease and hypoxia. (Crawford et al., 2010) These findings underscore the importance of performing bacterial culture and sensitivity in all cases of influenza-associated pneumonia, if possible. Minimally, culture and sensitivity must be considered in any dog that is responding poorly to empirical therapy. The use of oseltamivir (Tamiflu ™ ) in cases of canine influenza has been debated since canine influenza viruses were discovered in the United States. Oseltamivir and other antiviral drugs have been tested and approved for human use only. There has been little study of the use of these antiviral drugs in dogs, and veterinarians who use these drugs are doing so in an off-label manner. (American Veterinary Medical Association, 2015) There is a theoretical potential benefit to using oseltamivir and other neuraminidase inhibitors, because canine influenza viruses do express neuraminidase, but no studies exist demonstrating a clear benefit. Additionally, oseltamivir is most frequently used in humans early in the course of disease, and dogs typically are not diagnosed with influenza until later in the course of disease, negating much of the benefit of oseltamivir and other antivirals. 4 According to the American Veterinary Medical Association, “antiviral drugs such as oseltamivir that used in humans with influenza A are neither approved nor recommended for dogs or cats with canine influenza.” (American Veterinary Medical Association, 2015) In severely affected cases, resolution of the radiographic lesions and hypoxia may be slow. Often, these animals require several days of hospitalization for close monitoring and supportive care. Decisions about the duration of hospitalization should be based on the clinical status of the dog and not based on laboratory or radiographic findings. Moderate to severe hypoxia may persist in some of these dogs for prolonged periods, but these changes may not be clinically important if the dog is feeling well and not in respiratory distress. If the dog is active, eating well and breathing comfortably on room air, they may be ready for discharge even if their pulse oximetry and arterial blood gases are still low. (Crawford et al., 2010)
TREATMENT: LOGISTICAL CONSIDERATIONS
● Encourage the owner to wait with their dog in the car, instead of bringing their dog into the waiting room. ● Bring the dog into the hospital through a separate entrance. Ideally, this entrance should lead directly to an exam room, reducing the risk of contaminating waiting areas, treatment area, and other areas. ● Examine suspected influenza cases in a “quarantine” room, which should not be used for other dogs until the room has been thoroughly cleaned and disinfected. ● Wear gowns, booties and gloves while examining dogs with suspected infectious disease. ● Wash your hands and clean your stethoscope (with alcohol) after performing your physical exam. (Crawford et al., 2010)
Due to the highly contagious nature of canine influenza, there are a number of important logistical considerations when treating dogs who may be potentially infected with this disease. Sick and exposed dogs must be isolated from other dogs, in order to prevent canine influenza transmission. Additionally, biosecurity measures must be utilized for any staff that may be providing care for these dogs to reduce the likelihood of staff serving as a source of fomite transmission. Recommended steps for examining dogs who may have canine influenza include: ● Schedule dogs with potential canine influenza (coughing dogs with a history of possible exposure or high-risk lifestyle, especially when there is a known outbreak in your area) for late in the work day.
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