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25-03-2013 | Veterinary medicine | Article

Inflammatory responses could help diagnose equine EGS


Free abstract

medwireNews: Evidence of increased acute phase proteins (APP) in the serum and plasma of blood taken from horses with equine grass sickness (EGS) indicates the presence of an inflammatory response, say researchers.

The finding could have diagnostic benefits considering the significant differences observed in APP levels from horses with EGS, those who co-grazed with horses with EGS, horses with other types of colic, and healthy horses, they write in Veterinary Record.

"When faced with sparse objective antemortem diagnostic techniques for EGS, identification of marked increases in APP's may help to differentiate EGS from other causes of abdominal pain, such as simple colon obstructions or intestinal strangulations," suggest Victoria Copas (Liphook Equine Hospital, UK) and co-workers.

Current diagnostic methods rely on histopathologic examination of intestinal biopsies, which can be expensive and invasive, they add.

The team collected blood samples from 40 horses with EGS, 15 horses and ponies that co-grazed with EGS animals, 18 horses with inflammatory and non-inflammatory colic other than EGS (including peritonitis and strangulating small intestinal lesions), and 20 clinically healthy horses (controls).

Concentrations of Serum amyloid A (SAA) - an APP that rises markedly in response to natural inflammation - were significantly greater in inflammatory colic cases compared with horses that were healthy, those that co-grazed with EGS horses, and non-inflammatory colic cases. SAA concentrations in EGS horses were not significantly different from those with inflammatory colic, however.

The research team also tested concentrations of fibrinogen - a slower-moving APP than SAA - in 55 animals not including co-EGS-grazing horses. Concentrations were significantly greater in horses with EGS than those that were healthy or that had non-inflammatory colic, at an approximate mean of 4 g/l versus 3 g/l and 2 g/l. Again, there was no significant difference in fibrinogen concentration between horses with EGS and inflammatory colic cases.

Overall, "SAA and fibrinogen concentrations were increased in EGS compared with healthy control horses, confirming that a significant systemic inflammatory response is present in EGS cases," write the authors.

They add that while the origin of these inflammatory responses remains unclear; "the presence of enteric inflammation in EGS cases, and the associated risk between EGS and grazing, suggest that the likeliest source is the intestinal mucosa."

Fewer significant associations were apparent in Activin A concentrations between the groups of horses, with no significant differences between co-grazing horses and animals with EGS.

By Sarah Guy, medwireNews Reporter