Understanding & Care of Waterproof Horse Rugs

No one wants a leaky horse rug, least of all your horse! But often the reason your horse cover is wet underneath isn't what you thought. There's an easy way to check if your horse cover is leaking. But first, let's find out what makes a horse cover waterproof.

What makes a horse rug waterproof?

It might surprise you to know that there are two waterproofing layers in most horse covers sold in New Zealand - like Weatherbeeta rugs.

Weatherbeeta rugs are waterproof due to a combination of a tough outer fabric with a coating that repels water, and a waterproof and breathable membrane on the underside of the outer fabric. Weatherbeeta horse rugs also boast taped seams that also help block water from penetrating. The coating on the horse rug's outer fabric makes raindrops 'bead' and run off the rug, while the inner membrane prevents water from getting through, while still allowing dampness from the horse's sweat to escape and evaporate. These layers work together to keep your horse dry, from the inside, and out.

The waterproofing underlayer that sits on the underside of the tough canvas outer needs to work as a single membrane; once the waterproofing membrane is damaged, the rug can never be completely resealed.

The quality of these waterproofing layers is the biggest differentiator between top quality horse rug brands and lower quality cover manufacturers, and their function is absolutely key to a healthy, comfortable horse. 

The waterproofing layers play two key roles. Obviously the first is to keep water off your horse's skin, but the second is actually to allow water vapour out, off your horse's back. These layers need to keep your horse dry, but also 'breathe', allowing heat and damp out from the horses coat through the horse cover as water vapour. To do this the waterproofing layers let the smaller water vapour molecules escape when the rug is dry (during rain, water will block most holes) - while also being impermeable enough to stop rain from coming through (as water molecules are much larger than vapour molecules). 

Second rate horse cover brands will compromise either on the breathability of these layers, or the durability of the waterproofing layers. This means that either your horse may become dangerously hot and steamy in its rug on warmer days, or the rug's waterproofing later will degrade and begin to leak, leading to your horse becoming dangerously cold and wet in bad weather.

Taped seams will also help reduce water seepage, although in very heavy rain any rug can leak eventually through stitching holes and seams, so look for rugs with these.

How to avoid damaging your horse rug's waterproofing

Things that will damage your waterproof membrane and make your horse's rug more likely to leak include:

• Tears and rips
• leaving rugs in the sun
• harsh detergents
• acidic shampoos and coat conditioners
• water over 35 degrees celcius
• washing does shorten the longevity of your rug's waterproof membrane. If you do wash your rug, avoid agitator top-load washing machines which will twist the fabric.

Hot tip: After a year or two you can add some waterproofing to the outer layer of your cover with a spray on waterproofer like Flair's Rain Repel - but this isn't a substitute for a functioning waterproof membrane.

Why is my horse wet under their rug?

Perspiration: A horse can perspire up to 1 litre per hour. If they are agitated or excited and gallop around in their rug for ten minutes they will become hot and sweaty and get wet, or even foamy, under their rug.

Poor Breathability: If your horse's rug doesn't have good quality breathability, even normal perspiration and condensation due to temperature differentials inside and outside the rug will cause dampness inside the horse's cover. A breathable membrane and outer fabric really does matter.

Wicking: If an under-rug pokes out from beneath your horses cover it will wick wetness in under the waterproof cover over time.

Seepage: If your horse doesn't have a neck cover on, water will seep down inside the shoulder of its cover. This isn't usually an issue as the horse's core will remain warm but if weather is extra cold or it has been raining for a long time you may wish to pop on a combo or neck cover. Some rain can get in around the legs and tail flap but this small amount will not bother your horse if their back, chest and haunches are warm.

Unlined Rugs: If you're using rain sheets in long periods of wet or humid weather, we suggest using a cotton under-rug to help wick away the horse’s perspiration and any condensation. (Just imagine wearing a raincoat on a humid wet day without a nice cotton layer underneath it!)

Hot Tip: You can boost the warmth and weather durability of a rug by choosing higher GSM or adding an extra layer, like a stable doona or fleece under rug as this will create a warmer dry layer under the horse cover where the horse's body heat can help create a layer of extra insulation - and encourage the wicking away of any moisture.

An easy test to check your horse rug's waterproofing

Lay the horse rug down and make a dip in an area with no seams (it may help to place a feed bucket underneath). Pour some water into the dip to create a small pool and wait ten minutes. The horse rug should not allow any water to seep through to the other side.