Spotlight on Medicines: Osteopen and pentosan polysulfate in canine osteoarthritis
ADVET - what the adverts say and what they’re not telling you! is part of Veterinary Prescriber’s monthly Medicines News. In ADVET we take a critical look at promotional claims for a veterinary product, check if the claims are justified, and highlight other information that vets might need before making a decision about using the product. This edition features Osteopen, a prescription‑only veterinary medicine containing pentosan polysulfate sodium, a semi-synthetic polymer with fibrinolytic, lipolytic and mild anti-coagulant activities. Osteopen is licensed in the UK for the treatment of lameness and pain associated with degenerative joint disease in skeletally mature dogs.
Promotional claims for Osteopen
We looked at an online promotional brochure [accessed 15 January 2026] for Osteopen, aimed at UK vets. The online brochure makes several claims that we think aren't fully justified. For instance, the claim that it is “The latest osteoarthritis solution” implies it is a new type of osteoarthritis treatment, whereas it is in fact a generic version of a product that has been available for more than a decade.
Contraindications, interactions and adverse effects to consider
ADVET also highlights other information needed to make a benefit-risk decision about the treatment for an individual patient. Other factors to consider about Osteopen include the limited evidence on pentosan polysulphate, contraindications, interactions and adverse effects, which are all explained in our CPD module on pentosan polysulfate and canine osteoarthritis. The module (available to subscribers) provides a structured, independent review of the pharmacology, clinical trial data, contraindications, interactions and adverse effects of this group of drugs.
There are many contraindications listed in the UK product information for Osteopen, including liver or kidney impairment, blood or coagulation disorders, use in skeletally immature dogs and use during the peri-operative period.
Osteopen should not be used alongside NSAIDs (especially aspirin) or steroids, or within 24 hours of receiving them. It is not recommended to be used in pregnant or lactating dogs and should not be used around parturition (due to anticoagulant effects).
Rare and very rare adverse effects include injection site reactions, vomiting, depression and lethargy. Pentosan polysulphate has an anticoagulant effect and many special precautions for use are because of this.
Why independent information on Osteopen and pentosan matters
ADVET exists to assess the promotional claims for veterinary medicines and check whether they are backed up by evidence. It is a service for vets, many of whom do not have the time to do this research themselves. We also highlight the additional information that vets might need before deciding whether to use a product. ADVET is part of the monthly Medicines News available to subscribers to Veterinary Prescriber. For more see our website at http://www.veterinaryprescriber.org"www.veterinaryprescriber.org
As a subscriber you can read the full ADVET about this product and the many other editions of ADVET, featuring other veterinary products.
ADVET is part of our subscriber‑funded Medicines News service at Veterinary Prescriber, which means our analysis is not sponsored by the manufacturers of the products we review. If you are getting information on veterinary medicines for free, it is always worth asking who is paying for it and why – and whether the evidence being presented stands up to scrutiny.