Polysulfated glycosaminoglycan (PSGAG) is a slow-acting disease-modifying agent used to treat degenerative joint disease. Although labeled for intramuscular use, it is commonly given by owners via a subcutaneous (SC) route. There is little information on adverse events related to SC administration or what other therapies are used concurrently with PSGAG. We hypothesized that SC PSGAG is perceived by owners as having minimal adverse events and that it would most often be given with other therapies. Owners (n = 378) were surveyed about their perceptions regarding SC PSGAG prescribed to dogs at one veterinary rehabilitation clinic. Complete surveys were provided for 69 dogs (two owners had multiple dogs). Overall, 13/69 (18.8%) dogs had an adverse event reported during the use of PSGAG. Most events were considered minor (stomach upset, loose stool, pain at injection site, fear) and did not lead to discontinuation of PSGAG. One dog experienced a moderate adverse event (persistent gastrointestinal symptoms) and one a severe adverse event (thrombocytopenia, bruising), which resolved after discontinuing PSGAG. PSGAG is most commonly administered along with other medications and rehabilitation therapies. The present study demonstrates that SC administration of PSGAG is well tolerated in most of the dogs, with primarily mild, self-resolving adverse events.