A retrospective analysis of canine, feline, and equine respiratory polymerase chain reaction panels performed at the New York State Animal Health Diagnostic Center (January-December 2023).

Overview

• This study analyzed respiratory PCR test results from dogs, cats, and horses submitted to the New York State Animal Health Diagnostic Center in 2023 to identify common pathogens and factors affecting detection rates.

Study Purpose and Design

• The researchers conducted a retrospective analysis of laboratory data from respiratory PCR panels performed on samples collected from canines, felines, and equines over one year (January – December 2023).
• The main goal was to understand which respiratory pathogens are most commonly detected and to evaluate factors that influence the probability of pathogen detection to guide veterinary diagnostic submissions.
• They used statistical tests such as chi-square (χ2) and Fisher exact tests to compare associations between different variables (e.g., pathogen type, sample timing, and species).

Sample and Pathogen Findings

• A total of 1,902 respiratory panel tests were analyzed:
  • 705 canine samples
  • 189 feline samples
  • 1,008 equine samples
• Most common pathogens detected in each species were:
  • Dogs: Mycoplasma cynos detected in 66% of canine respiratory panels
  • Cats: Mycoplasma felis detected in 60% of feline respiratory panels
  • Horses: Streptococcus equi subsp equi detected in 39% of equine respiratory panels
• Common coinfections identified were:
  • Dogs: Canine parainfluenza virus and Mycoplasma cynos
  • Cats: Mycoplasma felis and feline calicivirus
  • Horses: Streptococcus equi subsp equi and equine rhinitis virus B

Influence of Sample Timing and Type

• Samples collected during acute stages of canine respiratory illness were more likely to test positive than those from chronic cases:
  • Odds ratio (OR) = 2.7, meaning acutely ill dogs had about 2.7 times the odds of a positive test
  • 95% confidence interval (CI) for OR: 1.7 to 4.5
• Viruses were more commonly detected than bacteria in acute canine respiratory cases (OR = 4.7; 95% CI, 2.6 to 8.2).
• For upper respiratory samples:
  • Dogs and cats had higher probabilities of detecting bacteria than viruses:
    • Dogs and cats bacterial detection: χ2 < 0.0001, OR = 1.6 (95% CI 1.3 to 2.1)
    • Dogs and cats viral detection: χ2 < 0.04, OR = 2.1 (95% CI 1.1 to 3.9), but overall bacteria more probable
  • Horses had a lower probability of detecting bacteria compared to viruses in upper respiratory samples:
    • χ2 < 0.0001, OR = 0.4 (95% CI 0.33 to 0.57)

Clinical and Diagnostic Implications

• The study highlights certain key pathogens that veterinarians and diagnosticians should consider when interpreting respiratory PCR panel results in dogs, cats, and horses.
• The timing of sample collection relative to illness onset is critical, with samples taken during acute illness phases being more likely to yield positive results.
• Providing accurate clinical history and collecting samples during acute stages are important to maximize diagnostic yield and utility.
• Veterinary clinicians should be aware of the varying likelihood of bacterial versus viral detection depending on species and sample type to inform treatment decisions.

Summary

• This retrospective review of nearly 2,000 respiratory PCR panels identified species-specific common pathogens and important factors influencing test outcomes.
• It underscores the importance of acute-phase sampling and clinical context for optimal use of respiratory panel diagnostics in veterinary medicine.