Can I put my laminitis-prone horse or pony out to pasture?
Grazing seems like the most natural thing we can allow our horses and ponies-after all, they have evolved to graze and browse in their natural environment. However, grazing may be the ultimate trigger for the painful and debilitating disease, which is why grass intake must be carefully monitored and managed, especially for those who are most at risk.
If your horse or pony has had laminitis and has been completely off grass, you should consider the following before reintroducing it to pasture: –
The horses and ponies that are currently at least risk are those that do not show signs of laminitis, are not overweight, and do not have an underlying metabolic problem, but if they are naturally prone to gaining weight, it is likely that the amount of grass they have access to should be limited.
What is the problem with the grass?
The problem with grass is that it is an abundant source of sugar and energy, and it is difficult to know how much of it your horse or pony is consuming. For many leisure horses and ponies, grazing can provide much more energy than the horse needs, resulting in weight gain and obesity. Then, by consuming a lot of grazing sugar, a turning point is reached that leads to laminitis.
Sugar in grass can come in the form of simple sugars but also storage sugars such as fructose. The combination of the two is referred to as WSC (water-soluble carbohydrates). WSC levels in pasture vary with grass species and environmental conditions, and thus are very difficult to predict.
If you put your horse or pony out to pasture, it is essential that you keep them at a healthy body weight. Pasture-based laminitis management can help you do this. If you are concerned about their weight or their risk of laminitis, then you should avoid grazing them at times when environmental conditions indicate that WSC levels might be high, or when there is a lot of grass available that will inevitably increase their intake.
Methods of restricting access to grass to help manage body weight include the use of a grazing muzzle or so-called “strip grazing.” The grazing muzzle must be carefully introduced to ensure that it fits properly, that the horse knows it can eat and drink with the muzzle on, and most importantly that it is not bullied by others in the field. The National Equine Welfare Council gives some advice on the use of muzzles when grazing for the management of laminitis on pasture: http://www.newc.co.uk/advice/horse-and-donkey-care/grazing-muzzles-2/
What is the best time to graze a horse with laminitis?
This is a difficult question to answer, since in practice the levels of water-soluble carbohydrates are very difficult to predict. In general, the following advice is given regarding attendance:
- Going out early in the morning, removing the horse from the pasture mid-morning. This is because nocturnal herbaceous plants use WSC stores because there is no light available for photosynthesis-the process that produces sugar in plants. Sugar levels decrease during the night, but begin to increase again during the day with higher light levels.
- Try grazing in paddocks sown with naturally sugar-poorer grasses. Some grasses, such as ryegrass, contain much more sugar and are commonly found in the pastures of old dairy farms. However, even typically low grasses can accumulate high levels of WSC under the right environmental conditions, so it is important not to assume that your horse will be safe.
- Avoid grazing when it is bright but cold, such as during bright, frosty winter mornings. Grass is unable to grow below 5°C, but if it is bright it will still photosynthesize and thus produce sugar that will accumulate.
- Drought and overgrazing can lead to higher levels of WSC assimilation as the grass is unable to grow and use its energy reserves.
- The use of a grazing muzzle can help limit WSC intake as the horse is not able to consume as much grass and gets a small amount per bite.
