12/01/2023
Great post, Thanks Gareth!
Why do ‘cresty’ necks suddenly go rock hard?
This information is relevant and useful to people who own horses with Equine Metabolic Syndrome and are in danger of laminitis or whose horses are intermittently ‘footy’. Understanding this will help with rehabilitation.
Dr Deb Bennett PhD (who has conducted many dissections), that “the horse's "crest" is made of fibro-fatty sub-cutaneous (adipose) tissue similar in texture to high-density foam”.
Have you ever wondered how it is that the ‘crest’ of the neck can harden so rapidly? Sometimes overnight?
The actual reason is because it goes ‘turgid’ (it fills with fluid). Like foam, the crest tissue can take up water like a sponge; so it swells and hardens because fluid ‘leaks’ into it, filling the interstitial spaces until it is hard as a rock, and ‘softens’ when electrolyte balances are corrected thereby allowing fluid to be resorbed.
When the crest swells with edema, other parts of the horse's body like the abdomen and the hooves (significantly the digital cushion is made of similar material, it is a thick wedge of fibro-fatty subcutaneous tissue) -- are liable to be in trouble, too.
Hardening of the ‘crest’ coincides with not only spring and autumn growth spurts but also potassium and nitrogen spikes in autumn and winter grasses. It coincides with early signs of laminitis which are ‘stiffening’ of gait and being ‘footy’.
It is a sure indication that one cause of ‘pasture related laminitis’ is as much to do with mineral imbalances, (particularly potassium and nitrogen excesses concurrent with salt deficit) as sugars and starches. It explains why short Autumn grass can cause laminitis when analysis shows soluble sugars + starch content is only 7.5% while potassium is 3.4%, sodium only 0.154%, nitrogen 5.8%, nitrates 2290mgs/kg (far too high, in mature grass/hay they are undetectable).
It is one of the many reasons clover is such a ‘no-no’ for EMS/laminitis equines and a likely explanation why there are some insulin resistant/elevated insulin horses that can't tolerate Lucerne (alfalfa) and is why Lucerne can perpetuate laminitis when everything else is being done ‘right’.
People who own horses with EMS are aware they need to pay attention to this vital sign: that just before a horse has a bout of laminitis, the normally soft and spongy crest stands up firm and hard. Then they can immediately reduce potassium/nitrogen intake by eliminating short, green grass replacing it with soaked hay and make sure they add salt to feeds and not rely on a salt lick. If action is taken quickly enough in these early stages, laminitis can be averted, you can ‘dodge a bullet’.
Soaking hay for about an hour not only reduces sugars but also reduces potassium levels by 50%.
Therefore a very important aspect of EMS and laminitis is that identifying and addressing mineral imbalances (particularly high potassium/nitrogen & low salt) are equally as important as sugar and starch content when rehabilitating individuals and assessing suitability of forage for these compromised equines.
