# Development of a Novel, Non-Invasive Saliva Sampling Method for the Detection of Bovine Respiratory Viruses

## TL;DR

A new non-invasive saliva sampling method was developed to detect respiratory viruses in calves, offering a less stressful alternative to traditional nasal swabs.

## Contribution

The study introduces a novel, non-invasive saliva sampling system for detecting bovine respiratory viruses, improving animal welfare and diagnostic efficiency.

## Key findings

- Saliva collected via cotton rolls was shown to be suitable for detecting key bovine respiratory viruses.
- Important viruses like Bovine Respiratory Syncytial Virus and Bovine Parainfluenza Virus 3 were detected in saliva samples.
- The method was well-received by calves and provided sufficient sample material for testing.

## Abstract

Bovine respiratory disease is a commonly diagnosed health problem in calves. In addition to bacteria, several viruses contribute to the disease, highlighting the necessity for accurate differential diagnosis. The leading sampling method is invasive and distressing for the animals, requiring them to be restrained to collect deep nasal swabs. Therefore, our current study, carried out on five farms with animals showing respiratory symptoms, developed a new saliva sampling system based on cotton rolls. The saliva sampling system was hung in the stalls and the animals were free to chew on the materials. Deep nasal swabs were taken from the sampled animals as the gold standard for method comparison. Saliva showed to be a suitable sample material for the detection of respiratory viruses in cattle. Important viruses involved in the development of the respiratory disease could be detected. Calves in particular have shown great curiosity and interest in the established saliva collection system and it was possible to obtain a sufficient amount of saliva. The investigation of saliva obtained by the non-invasive sampling method has been shown to be suited for the detection of bovine respiratory viruses.

Bovine respiratory disease (BRD) is a major cause of economic loss and impaired animal welfare worldwide, especially in calves. It is a multifactorial disease complex caused by the interaction of viral and bacterial pathogens, environmental stressors and the host immune response. It has to be controlled by preventive measures and rapid pathogen detection. Current diagnostic methods are often time-consuming and impose a high burden on animals during sampling. In this study, we established a novel, non-invasive sampling system that allows the monitoring of viruses associated with BRD based on saliva samples. We selected five farms with animals displaying various degrees of respiratory symptoms. Cows and calves were sampled using the saliva sampling system based on cotton rolls. Additionally, deep nasal swabs were taken for comparison. The samples were tested for viral BRD pathogens using polymerase chain reactions (PCRs). The study showed that saliva is a suitable sample material for the detection of bovine respiratory viruses. Important viruses such as Bovine Respiratory Syncytial Virus, Bovine Parainfluenza Virus 3, Bovine Adenovirus, Bovine Coronavirus and Bovine Rhinitis A and B Virus were detected in saliva samples. While deep nasal swab samples showed slightly higher sensitivity for some viruses, other viruses were detected only in saliva. This highlights the complexity of BRD diagnosis and the limitations of single-site sampling. The introduction of this simple, non-invasive sampling method represents a major step forward in protecting animals and advancing welfare standards in the cattle industry.