By Logan Landfried, DVM
Thanks to countless advances in veterinary medicine, our equine companions are living longer than ever. Like humans, the aging process affects horses at different rates and in different ways. It is important to remember that age is not a disease, but certain management and husbandry changes may be required to best support our equine partners.
Dental care: Horses are hypsodonts, meaning their teeth continually erupt throughout most of their life to replace the natural wear caused by chewing. However, after a certain point there is no more tooth to erupt and the occlusal (or chewing) surface becomes smooth. This can become an issue due to loss of grinding surfaces, leading to an inability to properly chew and digest hay, which can predispose horses to choke and colic. Additionally, older horses often develop gaps (or diastemata) between their teeth, which can pack feed and predispose to periodontitis. Older horses should have regular (once to twice yearly) dental exams and equilibrations (“floats”) to assess the status of their teeth, reduce sharp points and hooks and evaluate the need for dietary changes or more advanced dental care. If your horse is quidding (dropping pieces of partially chewed hay or feed), is losing weight or has foul-smelling breath, then it is time for a dental exam!
Diet: As mentioned, many older horses are no longer able to properly chew long-stemmed forage and are instead maintained on a complete feed, chopped, pelleted, or cubed hay products, soaked beet pulp, or a combination of the three. Additionally, the gastrointestinal tract often becomes less efficient at absorbing nutrients as horses age. A complete feed, such as equine senior, is formulated to provide 100% of daily nutritional requirements without the need for forage. Always consult with your veterinarian before making any major dietary changes. Knowing your horse’s metabolic status (discussed below) can also guide feeding recommendations, as starch intake often needs to be limited in horses with Cushings, Equine Metabolic Syndrome and laminitis. Additional considerations include feeding older horses in small and frequent meals as opposed to few and larger meals, as well as feeding alone so herd dynamics do not cause undue stress or rapid ingestion. Cubed and pelleted hay products, as well as beet pulp, should be well-soaked to reduce the risk of choke.
Vaccination/deworming: Similar to the GI tract, older horses’ immune systems also become less efficient over time. Therefore, maintaining a regular vaccination and deworming schedule is paramount in caring for older horses. Core vaccinations are given once or twice yearly depending on geographic location. Risk-based vaccines such as those protecting against EHV, Equine Influenza, Potomac Horse Fever, Botulism and so on are given based on potential for exposure. Older horses tend to have higher parasite burdens compared to their younger counterparts, so appropriate deworming is essential for maintaining weight and decreasing shedding. General recommendations include deworming twice yearly with ivermectin or moxidectin with inclusion of praziquantel at least once. The best way to ensure your horse is adequately dewormed is by performing regular fecal egg counts.
Joint care: Arthritis in older horses is often inevitable and management of joint pain is often multi-tiered. Simple ways to maintain joint health include light exercise (such as consistent turnout), regular farrier work, stretches to preserve range of motion and weight control to reduce unnecessary stress on joints. Oral joint supplements are hit-or-miss depending on your horse’s ability to absorb the active ingredients, but some owners report positive results when utilizing supplements supported by strong scientific research. Injectable joint supplements, such as Adequan or Legend, have more scientific evidence supporting their use. Many older horses are given oral NSAIDs such as firocoxib (Equioxx) daily; this is a less potent but overall safer alternative to long-term phenylbutazone or Banamine administration. More invasive options include intra-articular injections, which can consist of a multitude of products, or occasionally facilitated ankylosis (fusing) of certain joints, the latter of which is only considered in specific cases.
Metabolic testing: Older horses are prone to developing endocrine disorders such as Pituitary Pars Intermedia Dysfunction (PPID, Cushing’s Disease) and Equine Metabolic Syndrome (EMS). PPID is caused by a benign tumor of the brain that ultimately causes elevations in cortisol. This can lead to clinical signs such as a long haircoat, muscle loss, increased drinking and urinating, laminitis and recurrent infections due to decreased immune status. Diagnosis includes a blood test measuring a hormone called ACTH, and treatment typically involves daily administration of a drug called pergolide. EMS can occur with or without PPID and is largely characterized by insulin dysregulation (ID). ID has been directly associated with development of metabolic laminitis, which is a very painful and often life-ending condition of the hooves. Clinical signs of EMS and ID include overweight horses with regional deposits of fat throughout the neck, shoulders, ribcage and tailhead. Diagnosis includes measuring blood insulin at baseline and after administration of oral Karo syrup. Both PPID and EMS horses are managed with appropriate husbandry such feeding as low-starch grain, soaking hay and restricting grazing to certain times of the day. Several SGLT2 drugs have also shown promising results but require regular bloodwork to monitor for side effects.
Respiratory: Equine asthma is a common condition of older horses. Inhaled irritants cause the immune system to overreact and become inflamed and constricted. Clinical signs range from mild to severe and can include coughing and increased respiratory effort. A “heaves line” may be appreciated due to increased use of thoracic musculature. Severe equine asthma can progress to episodes of significant respiratory distress. Treatment is heavily centered around environmental management and limiting exposure to irritants as well as tapering courses of steroids and bronchodilators as needed. Older horses should be monitored for coughing and other respiratory concerns. Feeding round bales, storing hay above stalls and stalling when barn aisles are swept or blown have been shown to cause significant airway irritation for asthmatic horses.
