In equine grass sickness, serum amyloid A and fibrinogen are elevated, and can aid differential diagnosis from non-inflammatory causes of colic.

Equine grass sickness (EGS) is a debilitating and often fatal neurodegenerative disease. A presumptive diagnosis of EGS may be made on the basis of clinical signs and subjective ancillary tests, but a definitive antemortem diagnosis can only be made following histopathological examination of intestinal biopsies. It has previously been reported that horses with EGS may show clinical and clinicopathological signs of systemic inflammation. The objective of this study was to (a) quantify acute inflammatory markers in blood samples collected from acute, subacute and chronic EGS cases, and (b) compare them with (i) clinically normal horses co-grazing with acute EGS cases (co-grazers), (ii) horses with other causes of colic and (iii) healthy horses. Serum amyloid A (SAA), serum activin A and plasma fibrinogen were quantified. There were marked increases in SAA and fibrinogen in EGS cases compared with healthy horses, co-grazers and non-inflammatory colic cases. The concentrations of SAA and fibrinogen in EGS cases were not significantly different from inflammatory colic cases. When concentrations of SAA, fibrinogen and activin A in each EGS subgroup were compared, no significant differences were detected. Activin A concentrations were significantly elevated in EGS cases and co-grazing horses; this could reflect the presence of subclinical disease in some horses that do not develop clinical signs of EGS, and suggests widespread exposure to the aetiological agent. When faced with sparse antemortem diagnostic techniques, identification of marked increases in acute phase protein concentrations may help to differentiate EGS from other causes of abdominal pain, such as intestinal obstructions; however, there could be diagnostic difficulty in differentiating other inflammatory abdominal conditions, such as peritonitis or enteritis.

Circannual variation in plasma adrenocorticotropic hormone concentrations in the UK in normal horses and ponies, and those with pituitary pars intermedia dysfunction.

REASONS FOR PERFORMING STUDY: Pituitary pars intermedia dysfunction (PPID) is a common endocrinopathy, frequently diagnosed via plasma adrenocorticotropic hormone (ACTH) concentrations. Seasonal variation in plasma ACTH concentrations has been described in normal horses prompting caution in diagnosing PPID at certain times of the year. The aims of this study were to determine appropriate reference intervals for equine plasma ACTH throughout the year; and to examine the circannual variation of plasma ACTH concentrations in PPID cases. HYPOTHESIS: Plasma ACTH can be used as a test for PPID throughout the year with the use of appropriate reference intervals. METHODS: Data for reference interval calculations were obtained from samples collected from inpatients of Liphook Equine Hospital (non-PPID group, n=156). Data from PPID cases (n=941) were obtained from samples submitted to the Liphook Equine Hospital Laboratory from horses with a clinical suspicion of PPID found to have plasma ACTH concentrations greater than our upper reference interval for that time of year. RESULTS: Upper limits for reference interval of plasma ACTH were 29 pg/ml between November and July and 47 pg/ml between August and October. Circannual variation in plasma ACTH occurred in both non-PPID and PPID horses with the highest ACTH concentrations found between August and October in both groups (P<0.0001). The greatest difference between the 2 populations also occurred between August and October. CONCLUSIONS: Plasma ACTH can be used for the diagnosis and monitoring of PPID throughout the year with the use of appropriate reference intervals. These findings demonstrate an increase in pituitary gland secretory activity during the late summer and autumn in both normal and PPID cases.