Heya, I saw this & couldn't help myself... Among the myriad of other things, I am also an inventor, maverick, animal trainer, service dog handler/ trainer & medical professional...
Yeah, I know crazy but what can I say... A long time ago I was just starting training service/working dogs & was nothing short of pissed at the availability of decent harnesses & assistive tech!
After considerable research I created a new design that may be able to be adapted for your purposes... Most importantly, if you follow certain guidelines, there no risk of harm or injury to the animal (not the case with just about the rest of the options available)!
The 1st piece is materials... Simply put, don't put ANY SYNTHETIC FIBERS NEXT TO THE DOGS SKIN! Realistically anything other then real leather is a big no-no! If you have the money, the best leather (& the only thing I use) is full thickness kangaroo house- drum stuffed (though I reoil myself with a nice solid fat), vegetable tanned...
For those who think I am heartless, kangaroos are pests in Australia, are sustainably harvested/managed/hunted, breed like crazy, are actually quite nasty if you get anywhere near them & are actually in my opinion the most environmentally friendly leather available!
More importantly, it is the strongest, most durable, gentle on living tissue leather available... I still have my 1st harness & it looks brand new more then a decade later! It also has an unique ability to not damage the animals coat or skin with long term, especially near continuous use!
If you have some doubts, look at most dogs necks, their coats are destroyed/damaged under wear the collar sits... It can even cause massive sores... Sure synthetic are the worst but even leather will do it with sufficient duration/intensity/forces but kangaroo doesn't do it... I have had dogs wear my harness for more then a decade & if you remove the harness, the coat/skin underneath is indistinguishable from untouched areas! Up until the day my last personal service dog died he wore that harness day in & out but there was not even a broken hair!
To increase the strength enough to support a grown adult &/or XL dog, I actually took 2 identical pieces of kangaroo leather & sandwhiched pieces of tubular nylon webbing. I used varying widths ranging from 3" to 2" to 1" with multiple layers microfiber nylon cut into the shape of the chest plate, backstrap & chest strap... Those are measures based on the dogs anatomy... With smaller or larger animals the dimensions all change...
Actually this design has proven to be strong enough to safely withstand the enormous forces that happen when an unanticipated fall occurs when climbing... Dogs have rappelled off cliffs, helicopters, been lowered through pipes, windows, etc... But that version requires the additional leg straps to ensure the dog doesn't invert & potentially fall out of the harness; it also prevents hip damage from the hind quarters dangling unsupported! The additional leg straps will probably be important in your use... Basically any applications that the dog is suspended should have the additional leg straps...
In terms of the actual design... If someone tells me how to add pictures, I will post some of the harness so you can better understand but until then....
The design is a combo of the "Ruffwear" "Webmaster" (the shape & shaped profile with a min 5 point harness with a proper belly strap) & traditional agitation harness design in the front & shoulder region (such don't have the belly strap or shaped designs)... I'll include a couple links to show what I mean... I also increased the width of all the straps continuously throughout because most designs cut into the dogs body...
Respectively...
http://www.ruffwear.com/Web-Master-Harness_2
http://www.elitek9.com/3-Point-Agitation-Harness/productinfo/H13/
I am not recommending those products or stores, each missed the boat completely but at least give an understanding of what I am talking about...
I also must strongly recommend no one use the other types of harness (especially the "H", "X" or "Y" designs), they are not fit for a dogs anatomy & can cause significant damage & suffering! The designs I mentioned come closer but screws everything up with some bad decisions...
Webmaster's worst is the tiny straps that can actually cut into the dog (cheap, $ saving) & does not have a leather option, only synthetic...
The agitation design doesn't have belly straps, puts uneven pressure on the spine, straps still narrow, no hind quarters/lower body support, etc...
However the design I am recommending eliminates those issues...
I use lambskin or fur to pad things when appropriate... Some dogs can't stand the smell though & I have to switch to an alternative... My last service dog found the smell too much & couldn't think straight trying to chase the scent, so it was easier to just use the leather alone as it didn't effect him!
I used only solid metal buckles typically used in horse tack but now I use Cobra (not raptor, I don't like their rep) military buckles as they are rated & comprehensively tested... They don't come undone on their own (even with help from the dog) & can withstand the more demanding forces involved... I tried the raptor because it's cheaper but had constant problems & complaints, I ended up having to recall any with raptors & replacing with cobras at my cost...
I am no longer making the harness for others but my designs are freely available to any who wish to use it... All I ask is you are honest & give due credit for the original designs... Just like I give for the designs that I adapted or encorporated...
Also if I do end up posting any original drawings/diagrams, please note, I am not good at drawing... So yeah, I am well aware I suck at drawing!
If you want to reduce the weight of the harness, you can use spectra/dyneema/ cuben fiber webbing/fabric instead of nylon... Definitely stick with full thickness hide, but if you have a really small dog, you can use multiple layers of split top grain leather... If you do so... At least 2 layers of split per layer of full thickness for small to medium, 3 for medium to large & 4 for large to extra large & 5 for the giants (I double the full thickness for the giants)...
If you are going to double tubular webbing, the best way is to put 1 inside an another... If you stitch it, you weaken it... Especially with sharp instead of rounded needles & machine sewing...
Another nice thing is the kangaroo leather can be sewn on a regular sewing machine & be washed in a washing machine (don't use a dryer & reoil it after)...
Adam
Btw- I'll try to come back & address the actual support device later on...
Yeah, I know crazy but what can I say... A long time ago I was just starting training service/working dogs & was nothing short of pissed at the availability of decent harnesses & assistive tech!
After considerable research I created a new design that may be able to be adapted for your purposes... Most importantly, if you follow certain guidelines, there no risk of harm or injury to the animal (not the case with just about the rest of the options available)!
The 1st piece is materials... Simply put, don't put ANY SYNTHETIC FIBERS NEXT TO THE DOGS SKIN! Realistically anything other then real leather is a big no-no! If you have the money, the best leather (& the only thing I use) is full thickness kangaroo house- drum stuffed (though I reoil myself with a nice solid fat), vegetable tanned...
For those who think I am heartless, kangaroos are pests in Australia, are sustainably harvested/managed/hunted, breed like crazy, are actually quite nasty if you get anywhere near them & are actually in my opinion the most environmentally friendly leather available!
More importantly, it is the strongest, most durable, gentle on living tissue leather available... I still have my 1st harness & it looks brand new more then a decade later! It also has an unique ability to not damage the animals coat or skin with long term, especially near continuous use!
If you have some doubts, look at most dogs necks, their coats are destroyed/damaged under wear the collar sits... It can even cause massive sores... Sure synthetic are the worst but even leather will do it with sufficient duration/intensity/forces but kangaroo doesn't do it... I have had dogs wear my harness for more then a decade & if you remove the harness, the coat/skin underneath is indistinguishable from untouched areas! Up until the day my last personal service dog died he wore that harness day in & out but there was not even a broken hair!
To increase the strength enough to support a grown adult &/or XL dog, I actually took 2 identical pieces of kangaroo leather & sandwhiched pieces of tubular nylon webbing. I used varying widths ranging from 3" to 2" to 1" with multiple layers microfiber nylon cut into the shape of the chest plate, backstrap & chest strap... Those are measures based on the dogs anatomy... With smaller or larger animals the dimensions all change...
Actually this design has proven to be strong enough to safely withstand the enormous forces that happen when an unanticipated fall occurs when climbing... Dogs have rappelled off cliffs, helicopters, been lowered through pipes, windows, etc... But that version requires the additional leg straps to ensure the dog doesn't invert & potentially fall out of the harness; it also prevents hip damage from the hind quarters dangling unsupported! The additional leg straps will probably be important in your use... Basically any applications that the dog is suspended should have the additional leg straps...
In terms of the actual design... If someone tells me how to add pictures, I will post some of the harness so you can better understand but until then....
The design is a combo of the "Ruffwear" "Webmaster" (the shape & shaped profile with a min 5 point harness with a proper belly strap) & traditional agitation harness design in the front & shoulder region (such don't have the belly strap or shaped designs)... I'll include a couple links to show what I mean... I also increased the width of all the straps continuously throughout because most designs cut into the dogs body...
Respectively...
http://www.ruffwear.com/Web-Master-Harness_2
http://www.elitek9.com/3-Point-Agitation-Harness/productinfo/H13/
I am not recommending those products or stores, each missed the boat completely but at least give an understanding of what I am talking about...
I also must strongly recommend no one use the other types of harness (especially the "H", "X" or "Y" designs), they are not fit for a dogs anatomy & can cause significant damage & suffering! The designs I mentioned come closer but screws everything up with some bad decisions...
Webmaster's worst is the tiny straps that can actually cut into the dog (cheap, $ saving) & does not have a leather option, only synthetic...
The agitation design doesn't have belly straps, puts uneven pressure on the spine, straps still narrow, no hind quarters/lower body support, etc...
However the design I am recommending eliminates those issues...
I use lambskin or fur to pad things when appropriate... Some dogs can't stand the smell though & I have to switch to an alternative... My last service dog found the smell too much & couldn't think straight trying to chase the scent, so it was easier to just use the leather alone as it didn't effect him!
I used only solid metal buckles typically used in horse tack but now I use Cobra (not raptor, I don't like their rep) military buckles as they are rated & comprehensively tested... They don't come undone on their own (even with help from the dog) & can withstand the more demanding forces involved... I tried the raptor because it's cheaper but had constant problems & complaints, I ended up having to recall any with raptors & replacing with cobras at my cost...
I am no longer making the harness for others but my designs are freely available to any who wish to use it... All I ask is you are honest & give due credit for the original designs... Just like I give for the designs that I adapted or encorporated...
Also if I do end up posting any original drawings/diagrams, please note, I am not good at drawing... So yeah, I am well aware I suck at drawing!
If you want to reduce the weight of the harness, you can use spectra/dyneema/ cuben fiber webbing/fabric instead of nylon... Definitely stick with full thickness hide, but if you have a really small dog, you can use multiple layers of split top grain leather... If you do so... At least 2 layers of split per layer of full thickness for small to medium, 3 for medium to large & 4 for large to extra large & 5 for the giants (I double the full thickness for the giants)...
If you are going to double tubular webbing, the best way is to put 1 inside an another... If you stitch it, you weaken it... Especially with sharp instead of rounded needles & machine sewing...
Another nice thing is the kangaroo leather can be sewn on a regular sewing machine & be washed in a washing machine (don't use a dryer & reoil it after)...
Adam
Btw- I'll try to come back & address the actual support device later on...
(which thankfully she hasn't needed since going on the Pyridostigmine meds, which make her almost normal again).