Review of the Economic Impact of Osteoarthritis and Oral Joint-Health Supplements in Horses

1. Introduction

Osteoarthritis (OA) is the single most common cause of lameness in horses.¹  Indeed, approximately 60% of lameness problems in horses are related to OA.²  The U.S. horse population is currently estimated to be 7.3 million,³  which means that millions of horses currently have this debilitating, performance-limiting musculoskeletal condition. There is no cure for OA. Instead, a multimodal treatment approach is advocated for the management of OA.⁴  In horses, this multimodal treatment approach could involve the use of one or more of the following:

• non-steroidal anti-inflammatory drugs (NSAIDs), both IV and topical,^5a
• intra-articular corticosteroids,^6,7bc
• intra-articular hyaluronic acid,⁸
• intra-articular (but not IM) polysulfated glycosaminoglycans,^8,9d
• avocado-soybean unsaponifiables (ASU),¹⁰
• interleukin receptor antagonist protein (IRAP I and IRAP II),¹¹  and
• extracorporeal shockwave therapy.⁹ 

Dietary modification (omega-3 fatty acids) and nutritional supplements such as glucosamine, chondroitin sulfate, and methylsulfonylmethane (MSM) are also advocated for OA. Although some studies have been performed supporting a select few equine nutritional studies, in general, a dearth of data exists, supporting the use of most commercially available supplements.^12e

Nonetheless, the high prevalence of OA in combination with the lack of a definitive cure for OA have likely contributed to the popularity of oral joint-health supplements (OJHSs) among owners, veterinarians, and trainers alike. OJHSs, according to recent market surveys, are the most popular type of nutritional supplement for horses.13 OJHSs account for approximately one-third (34%) of all horse supplement sales (Fig. 1). Over one-half of all pet supplements sold in the United States are for equine consumption, and 49% of all horse owners purchase and administer some sort of dietary supplement to their horses. In a study of feeding practices in 3-day event horses, the authors found that horses were supplemented with an average of four different oral products daily, including electrolytes, plain salt, and OJHSs.¹⁴
 

Given the high prevalence of OA and horse owners’ documented willingness to purchase OJHSs, the purpose of this review is to relay pertinent information regarding the economic impact of OA and nutritional supplements marketed to support joint health (i.e., OJHSs). The information in this manuscript is anticipated to benefit equine practitioners by providing the necessary tools to select and market quality OJHSs to clients with either OA-affected horses or those at-risk for developing OA. This will not only improve the quality of life of our client’s horses but also improve profitability for veterinary practices.

2. The Economic Impact of OA

In human medicine, OA is a leading cause of morbidity and one of the top 10 causes of disability worldwide.^15,16 The economic impact of OA has been assessed in various studies. In 2005, a Canadian group assessed both direct and indirect costs attributable to OA.¹⁵ Direct costs are those paid to the health-care system and out-of-pocket expenditures paid by the patient for prescriptions, medical devices, transportation, and home adaptations. Indirect costs include lost income or leisure time by the patient because of disease and informal care provided by unpaid caregivers for such activities as assistance with personal care and household and yard chores.

Of the 1,378 patients included in the study, the average annual cost per patient was approximately $10,000 (U.S. dollars). One-fifth of these costs were attributable to direct costs, whereas the remaining 80% of OA-related costs were indirect. Indirect costs related to OA are, therefore, important and as pointed out by the study authors, must be considered, because failure to incorporate caregiver costs “undervalues the cost of illness.”¹⁵

In equine practice, the direct costs of OA include diagnostic and treatment fees charged by veterinarians. Indirect costs include loss of employed or leisure time spent caring for the horse by the owner (or primary caregiver), loss of income of a performance horse when incapable of performance because of OA, and increased work by the owner to care for their horse with OA. If veterinary medicine is similar to human medicine, then the true costs of OA, including both direct and indirect costs, in equine practice can be estimated. For example, if a veterinarian examines a horse for mild to moderate persistent lameness ($50), radiographs two joints ($250), and treats with intra-articular medication ($250), the direct medical costs are approximately $550 (costs estimated using Veterinary Fee Reference17). Additional direct medical costs could include NSAID administration ($20 for an IV dose and $2.50/day for oral administration) and the owner administering an OJHS ($2.00/day). In 1 yr, the direct medical costs could amount to approximately $3,000. If one considers indirect medical expenses, the cost of this horse could be substantially higher—perhaps as high as $15,000/yr.  [...]