Equine APP

Equine Serum Amyloid A Testing

SAA is a major acute phase protein which is synthesized in the liver as part of the acute phase response. It is considered to be part of the first line of defense in response to inflammatory stimuli including trauma, stress, infection, neoplasia, and inflammation. A growing veterinary literature has shown its utility as part of an annual wellness exam and sensitivity for prognostic value in disease states. We have validated this assay in our laboratory and determined in-lab reference intervals.

Summary of recent publication in the July 1 issue of JAVMA (243:113-119, 2013):

Samples from 212 horses from a specialty veterinary practice were examined using measures including CBC, fibrinogen, serum protein electrophoresis, and SAA.

  • Versus mild (<2 fold) increases in total WBC and fibrinogen, marked 75-fold mean increases in SAA were present in clinically abnormal horses with a range of diseases.
  • SAA was present in neglible levels (<10mg/L) in normal animals.
  • Levels in excess of 1000mg/L were routinely observed in animals with severe inflammatory processes related to infection.
  • SAA had the highest diagnostic accuracy for the detection of inflammation.
  • SAA was the most reliable indicator of a patient’s return to health.SAA has been demonstrated to act as a major acute phase protein in horses. Increases are detectable within 24 hours of stimulation and, given its short half-life, significant decreases rapidly occur with a positive response to treatment.

The current results represent cases commonly seen in the equine practice. SAA should be considered as an adjunct test to routine blood work in this species

Some other novel applications of SAA testing in horses:

  • Sports PerformanceSAA levels have been shown to be a potential indicator of performance in endurance horses (Equine Veterinary Journal 42:23-27, 2010). Most of the horses that did not finish the long distance race showed elevated SAA levels. The authors proposed that this elevated biomarker indicated the presence of underlying subclinical disease, overtraining, or minor injuries that worsened with the race. Other anecdotal information has also been presented in a similar application of SAA testing in race horses – see SAA Experiences in Racing. These concepts were also voiced by Pepys et al. (Equine Veterinary Journal 21:106-109, 1989) and Williamson et al. (Australian Equine Veterinarian 29:84, 2010).
  • Body Condition and FitnessSAA levels were found to be significantly associated with body condition score and insulin levels. Acute phase proteins are known to be increased with obesity in humans and other animals. This first report indicates that SAA may be better reflection of obesity related inflammation and laminitis risk (Journal of Veterinary Internal Medicine, 27:157-163, 2013).
  • Monitoring PregnancySAA levels were reported to be increased more than 20 fold in horses with early embryonic loss (Reproduction in Domestic Animals 46:624-629, 2011). SAA levels were also found to increase in an experimental model of placentitis (Canisso et al. American Journal of Reproductive Immunology 72(4):376-385, 2014, Canisso and Ball and da Silva et al., Equine Veterinary Science, 32(7):407, 2013).
  • Monitoring Post Surgery Complications – The trauma of surgery alone is significant enough of a stimuli to induce SAA expression and the level of this biomarker will vary with the intensity of the surgery (Veterinary Surgery 38:762-769, 2009). With healing, SAA levels return to normal range within several days. Baseline and postoperative monitoring of SAA can be valuable to assess the presence of post surgery complications (Equine Veterinary Journal 37:552-556, 2005).
  • Monitoring Complications in Foals – Chavatte and coworkers reported that significantly higher levels of SAA were found in foals with infection versus elevations seen with traumatic or premature birth (Equine Infectious Diseases VI 21:106-109, 1989). Later studies by others similarly reported increased SAA with birth and significant 2-4 fold additional increases in SAA in cases of neonatal septicemia (The Veterinary Journal 176:393-396, 2008, Equine Veterinary Journal 33:599-603, 2001, Equine Veterinary Journal 34:693-698, 2002).
  • General Health AssessmentSAA has been found to increase with a wide variety of health issues. It can be used in diagnostic and prognostic applications with management of bacterial and viral inections. (Equine Veterinary Journal 21:106-109, 1989.).
  • Monitoring Joint Disease – Both experimental models and naturally occuring joint disease have been studied for acute phase protein expression. Synovial fluid and serum samples were found to have high SAA levels in animals with suspected bacterial infection, infectious arthritis, and other high inflammation joint problems (American Journal of Veterinary Research 67:1738-1742, 2006).
  • Diagnosis of Surgical vs. Nonsurgical ColicSAA was found to be elevated in horses with infectious nonsurgical colic versus those with a disease requiring surgery. SAA increases with severe inflammation and supports intervention with medical therapy rather than surgery. This was reported by Dr. Tina Holberg of the University of Copenhagen at the 2013 AAEP meeting.

If you are interested in learning more about the applications of serum amyloid A, please contact the laboratory at 800-596-7390 or email at compathlab@med.miami.edu.