For those wondering about the ongoing animal studies and whether or not Pentosan Polysulphate Sodium is disease modifying, most of us already know that the vet industry has used this drug in animals, in injectable form, under the brand name - Cartrophen - for many, many years.
The Cartrophen website has the following drug info (see full text below). Note: The BOLD/ITALICS highlight is MY edit. Enjoy 
Cartrophen Vet is a revolutionary advance in the treatment for arthritis in dogs. In fact millions of dogs enjoy the benefits of this superior and tested technology with it continuing to treat millions of dogs after 20 years of use in the treatment of arthritis in dogs.
Cartrophen Vet (100mg/mL pentosan polysulfate sodium) is a prescription only, injectable, sulphated sugar of plant origin.
It has many sites of action within the underlying processes of the arthritis disease which helps maintain joint health, including preserving joint cartilage. It is therefore classified as a disease modifying osteoarthritis drug (DMOAD).
Cartrophen Vet is an injection given by your vet in a similar way to a vaccine with four weekly doses. This is a convenient way to ensure that your pet receives the appropriate dosage without daily regimen. It is essential that your dog complete all 4 injections to ensure optimal benefit and modification of the disease process. 80% of pets respond quickly to the initial course with a reduction in lameness and pain and a subsequent increase in activity and well-being. The frequency of treatment varies from once a year for mild cases and up to three times a year for severe cases. Your veterinarian may vary this regimen to obtain the optimum reduction of arthritic symptoms.
Cartrophen Vet works to modify the underlying arthritic processes to relieve pain and lameness. Improvements from Cartrophen Vet result in long-term effects lasting beyond the treatment period of 4 weeks up to one year in some cases.
Cartrophen Vet has been shown to exhibit the following modes of action:
- 1. Stopping the destructive enzymes that break down cartilage, which is the body’s natural shock absorber
- 2. Stimulate the body’s production of cartilage
- 3. Stimulate the body’s production of joint lubricant
- 4. Clear the blockages in blood vessels to deliver nutrition to the joint and bone
- 5. Stimulate the production of anti-oxidants that block damaging free
radicals
(20min delay)