Hindlimb laminar inflammatory response is similar to that present in forelimbs after carbohydrate overload in horses.

This research investigates the inflammatory response in horse limbs following carbohydrate overload and determines that hindlimb lamina inflammation mirrors that experienced in forelimbs. The findings indicate factors such as weight bearing could influence the onset of laminitis due to systemic inflammation.

Research Objective

The aim of the study was to ascertain the nature of an inflammatory response in a horse’s hindlimb lamina following carbohydrate overload. A known proinflammatory response occurs in the forelimb lamina after carbohydrate administration, but it wasn’t clear whether this was mirrored in the hindlimbs, which are generally less affected by laminitis.

Methods

• Archived laminar samples taken from 12 horses were used. These horses had been given a starch mixture (85% corn starch, 15% wood flour) via a nasogastric tube, producing a carbohydrate overload.
• Six of these horses developed a temperature exceeding 38.9 degrees Celsius (DEV group), whereas the other six demonstrated the start of Obel grade 1 lameness (OG1 group).
• For comparison, a control group (CON) of six horses was also included, these horses were anaesthetised 24 hours after being given water.
• A real-time quantitative polymerase chain reaction for a selection of proinflammatory mediators and MAC387 immunohistochemistry were conducted for all samples.
• The data was nonparametrically analyzed to compare groups.

Results

• An increase in laminar MAC387-positive leucocytes and mRNA concentrations, indicative of inflammation, was seen in both the forelimb and hindlimb laminae of horses from the OG1 lameness group.
• The DEV group horses also showed increased levels of CXCL1 and CXCL8 in the forelimb and hindlimb laminae, further demonstrating an inflammatory response.

Conclusions

• Both the horse’s hindlimb and forelimb laminae show a similar inflammatory response when subjected to carbohydrate overload.
• This suggests that factors other than the carbohydrate overload might play a significant role in laminitis development, such as weightbearing.
• Despite the inflammation present in the hindlimb laminae, laminitis tends to be less severe in these limbs, potentially due to factors like weightbearing and hoof angle.

This research contributes valuable information towards understanding and treating laminitis in horses, highlighting the need to also consider the hindlimbs in septic horses at risk of laminitis.