Vagus indigestion is an insidious, chronic dysfunction of the ruminant (but usually bovine) forestomachs, leading to reduced outflow and therefore chronic bloat, inappetence and weight loss (Parkinson et al 2010). In the opinion of the author, it is rare in beef cattle.
On 1 May 2012, the owner of a herd of 350 Angus breeding cows presented four cows for examination because of failure to thrive. The remainder of the herd was in good condition. The cows had been grazing improved cocksfoot and phalaris pastures.
One mature Angus cow was observed to be in fat score 1.5 with marked left sided abdominal enlargement. The cow was otherwise bright, alert and grazed normally. The clinical findings of significance were that she had a heart rate of 56 beats per minute and had weak but almost continuous rumen sounds on auscultation.
Vagus indigestion was previously regarded as a condition caused by an injury to the vagus nerves as a complication of traumatic reticuloperitonitis. It is now considered to be primarily 'a disturbance of the particle separation processes in the reticulo-rumen attributable to mechanical inhibition of reticular motility associated with extensive inflammatory para-reticular adhesions' (Radostits et al, 2007).
Vagus indigestion is a clinical diagnosis, made in this case because the cow had left sided abdominal distension, bradycardia and a hypermotile rumen. In view of the poor prognosis, no attempt was made to differentiate the causes of ruminal distension with hypermotility (as mentioned in Radostits et al 2007) and the owner was advised to cull the cow.