As a general across the board thing, no. Most horses I have used them on seem fine. As an individual thing, yes they can cause irritation, whether from the materials or extra friction. Gel type ones can be a bacterial breeding ground, so they should be kept well cleaned. And finally, they are an aid in keeping a saddle where you want it, but if the they are being used to hold an ill fitting somewhere it shouldnt be, it could add to a whole host of problems (maybe I shouldn't have to mention that, but cover all the bases)
both my horses use them and are fine. I school in a gel one, but use a small neoprene square under the show pads. Other than the fact they sweat more under them, no issues at all. Much better than the sore backs and cranky horses from having the saddle slide around.
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Think about it this way. If you have on a pair of shoes that don't fit and are pinching your feet, what do you do? You move your toes/foot around as much in the shoe as you can, to alleviate the pressure/pain. Right? Now, apply that to your horse. You have a saddle placed wrong or a saddle that doesn't fit and you have one of those "non-slip" pads under said saddle. No way for said saddle to move around and find a better spot, so it just pinches the withers/back during the whole ride with no relief. When I see a horse with super sore withers, the first thing I find out is whether or not they are using one of those non-slip pads. In most cases, they are. Once they lose the non-slip pad, the wither pain is significantly lessened or goes away.
Years ago, I had a BNT bring a BNT horse to me that I'd worked on previously. Said horse was very sore in her withers. Asked if they used a no slip on her. Found out they'd started using one fairly recently. Told them to quit using it. They did. Less than a week later, mare was pain free in her withers, with nothing else changed. See similar situations so often. I recommend all my clients stop using those unless they are absolutely necessary (which they normally aren't).
The non-slip works great for my horse. His saddles fits him very well (fitted by a very well known saddle fitter). However, I'd been having problems with his jump saddle. The saddle itself wouldn't move at all, even with no breastplate. But, the saddle pad and mattes were shooting out the back. I put the non slip between his back and the pad, and now everything stays were it should. He's a sensitive boy, so I have no doubt he'd make it clear if it hurt. He's conformation makes him VERY prone to back soreness, but his monthly chiropractor sessions show his back is better than ever.
Have a custom saddle and one of my horses has a HUGE wither. Every saddle on this horse slips back. I will either use a elastic breast collar or a no-slip black square pad. He has never had a problem with the pad. I prefer the no-slip pad over the breast collar.
I asked about what can be done about saddle slipping back and they said a wither reduction surgery... So some horses just have large withers that cause the saddle to slip back.
My other horse has big withers too and I have to use a no-slip on him. He is doing just fine in it. And this saddle was fitted to him as well. Even my trainers saddle slips so we always use the no slip pad.
So I like them.
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I use Success brand pads for both my dressage and jumping saddle. They are non-slip on both sides. I have not noted any soreness in my mare. I'm wondering if the incidence of soreness is increased because people use non-slip pads to keep a poorly fitting saddle in place and it is actually the saddle, not the pad, causing the soreness.
A lot of non slip type materials do not breathe as well as leather or fabric. I think that most of the skin issues related to non slip pads and girths is related to excess heat and moisture secondary to this. Personally, when I use non slip girths or pads, I keep them a little extra clean and I make sure to be a little more meticulous about skin and coat care in those areas both before and after riding. Using a liniment rinse seems to keep scruffiness in check. If a horse didn't seem to be tolerating a particular pad or girth, I just wouldn't use it.
Big withers often need a deeper rear gusset to keep the saddle from slipping back. In some cases, though, esp, when you're jumping, hunting, or doing xc, you have to use a breastplate to help stabilize the saddle.
There are many types of no slip pads or "grippy" pads. While I'm not a big fan of the ones like the Nunn Finer, I use a Dixie Midnight, Grandeur or Supracor grip pad almost daily. I spend many, many more hours in the saddle than the average H/J rider (I do endurance) and have never had an issue with any of these soring any of my horses.
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