Frosty grass and horses

Q: Is it safe for horses to graze on frosted grass? I recall from my dim, dark pony club days that it can be a cause of colic. Recently, we have moved to Taupo and of course the frosts here will be plentiful compared to our former home in Northland.

Suzanne, Taupo

Vet Dave replies:

There is no solid evidence that frosted grass itself is a risk for medical colic only circumstantial/anecdotal reports. 

Frozen grass will be rapidly warmed in the mouth during normal mastication and mixing with saliva, and then further warmed as it travels down into the stomach. 

There are also unlikely to be any frost-induced changes to the grass that would predispose a colic event. 

It would be easy to attribute an unexplained case of colic (most of the medical colic cases seen by vets are not able to be attributed to a specific event or incident) to recently eaten frosted grass, but the evidence that this is a real factor in inducing colic is just not present. 

I would be more than comfortable for my own horse to be grazing on frosted grass.

 When considering colic in the winter, there are several factors that are more important. Any factor that causes a sudden change in diet or drinking habits can cause colic. With winter being more changeable in weather, horses typically spending less time grazing – either from reduced turn-out time/inclement weather, or both. This leads to a more changeable forage diet, and is a risk factor for colic.

 It is best mitigated by providing easy access to fresh water and forage along with appropriate shelter from the weather where a normal grazing/browsing pattern of eating forage can be maintained as best as possible.

Nutritionist Lucy replies:

Consuming anything very cold can cause issues in mammals, as it reduces the core body temperature – hence why it is dangerous for desperate mountaineers to consume snow. 

However, in horses, the latest thinking is that frosty grass is not a major concern, especially regarding colic. 

The prevailing opinion is that the grass is heated up to a suitable temperature in the horse’s mouth during chewing, and should not pose a threat. 

The link with frost and colic is more likely related to northern hemisphere stabled horses in winter, who stand still for long periods of time. 

This can decrease gut movement, especially when they do not have constant access to high fibre forage, leaving some portions of the gut empty for periods of time. 

Some horses do not like consuming cold forage – and hence again, this may inhibit gut function, leading to increased colic risks.

Previous articleWhen to geld your colt
Next articleTaupo turns it on