New research shows that a simple stall-side blood test can determine whether a horse’s cough is caused by infectious disease or a chronic inflammatory condition.
University of California–Davis and Tufts University researchers worked together to investigate the significance of the protein serum amyloid A (SAA) in the blood of horses with various respiratory conditions. An indicator of inflammation, SAA testing has been used to evaluate and monitor treatment for colic and joint diseases for some time.
The research team reviewed the records of 167 horses referred to clinics for respiratory problems and analyzed stored serum samples related to each case. The horses were divided into four groups based on their blood work and clinical signs: equine herpesvirus-4 (EHV-4), equine0 influenza virus (EIV), strangles (res-piratory disease caused by infection with Streptococcus equi) and noninfectious inflammatory airway disease (IAD, also known as heaves). Serum samples from an additional 40 healthy horses served as controls.
Next, a commercially available stall-side test was used to determine the SAA levels in the stored samples and the results from each of the four groups were compared. The data showed that all of the horses with respiratory conditions had higher levels of SAA than did the healthy control horses. And horses with influenza or other infectious respiratory diseases had significantly higher SAA levels than did those with heaves or other noninfectious inflammatory conditions.
These findings suggest that SAA tests can be useful as a first step in diagnosis. By differentiating between infectious and non-infectious respiratory problems, an SAA test can help veterinarians make better treatment decisions and management recommendations, such as calling for the quarantine of a potentially contagious horse. SAA testing will be particularly beneficial, says Nicola Pusterla, DVM, PhD, “as an adjunct test [similar to a complete blood count and physical examination] to determine health in high-risk horses when an acute infection is suspected and to monitor response to treatment.”
Reference: “Comparison of serum amyloid A in horses with infectious and noninfectious respiratory diseases,” Journal of Equine Veterinary Science, February 2017
This article was originally published in EQUUS 485, February 2018