Owning a horse in athletic work and competition well past the age of 20 is becoming a common phenomenon. Maintaining the health of that senior athlete can be a challenge, so it is important to reevaluate the health and management plan frequently. First, it is important to recognize when a horse reaches senior status, as age is not the only factor. It is crucial to be proactive and not wait until there is a serious injury to adjust. There are several areas to monitor, including diet and supplements; veterinary care, including evaluation of metabolic status and the use of targeted regenerative therapies; training schedules; and lastly, level of work. By adjusting to these areas, we are now able to keep senior athletes performing longer and living healthier, happier lives.
NUTRITION
Nutritional management in older horses is tailored to the specific husbandry and needs of the animal. Causes of weight loss in the otherwise healthy older horse include poor or changing dental health, pain, bullying in the pasture, increased nutritional needs, parasitism and changing metabolic status. Weight gain can be attributed to decreased metabolic rates and metabolic-associated diseases such as PPID and insulin-resistance.
DENTAL DISORDERS
Most elderly horses and ponies have some form of dental disease, and the degree of dysfunction and abnormalities present can be dramatic in otherwise healthy-appearing individuals. The frequency of dental examinations of geriatric patients should increase and be tailored to the abnormalities noted, as pathologies can progress surprisingly quickly.
PERIODONTAL DISEASE
Most geriatric horses have some degree of periodontal disease. Periodontal disease is the presence of disease and loss of tissue in those structures that surround the tooth or teeth. It is reported that the incidence of periodontal disease changes with age. There was a 40% prevalence in horses three to five years old; this fell in horses five to 10 years old and then increased to 60% in horses older than 15 years.
Gingival hyperemia, edema, ulceration, deepening periodontal pockets, and packing of feed material into the spaces between teeth are the classic signs of periodontal disease. In cases of advanced disease, there is significant loss of alveolar bone. Periodontal inflammation may result in attempted repair with the production of excess cementum over the surface of the reserve crown. In some cases, this may progress to a form of hypercementosis and the production of nodules of cementum.
EQUINE ODONTOCLASTIC TOOTH RESORPTION AND HYPERCEMENTOSIS (EOTRH)
Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a dental disease that occurs in middle-aged and geriatric equines. The progressive disease involves two processes:
A proliferation of irregular cementum to stabilize the teeth. Resorption can occur without hypercementosis, but the converse does not occur. Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) is an extremely painful condition that most often affects permanent incisors (front teeth) and canine teeth. Thoroughbreds and Warmbloods older than 15 years of age make up about half of the reported cases, but horses from any breed or sex can be affected. EOTRH is diagnosed through a combination of dental examination, patient history, and radiography. It is important to note that EOTRH can occur concurrently with or separately from periodontal disease, which can complicate diagnosis.
For mild cases, regular care may include removal of feed accumulation between teeth, topical medications, antibiotics, pain management, and dietary modifications. However, the disease is painful and progressive, and there is currently no way to slow its disease progression. Surgical removal of teeth and affected tissues is recommended in severe cases. Owners should be aware that dietary management will change after incisor extraction, but the benefit of pain relief far outweighs the management difficulties if owners are willing.
METABOLIC DISORDERS PPID RESPIRATORY DISORDERS – EQUINE ASTHMA
Equine asthma (EA) is an inflammatory disease of the lower airway in which there is an abnormal pulmonary immune response to nonpathogenic stimuli. It is a pulmonary hypersensitivity to inhaled particulates such as inorganic compounds of dust, fungal spores, aerosolized endotoxin and air pollutants. Equine asthma syndrome has undergone many name changes over the years and was formerly known as inflammatory airway disease (IAD), recurrent airway obstruction (RAO) and heaves. The current nomenclature refers to IAD as mild to “moderate equine asthma” and RAO as “severe equine asthma”.
This new classification system implies that horses with similar clinical presentations can vary widely in terms of disease severity and that this is not a disease continuum. Horses with mild to moderate symptoms do not necessarily develop severe disease over time. Severe equine asthma is more commonly diagnosed in middle age to older horses (older than seven years) and is uncommon in horses younger than four years of age. These cases can be either barn-associated, or pasture-associated and as the names simply, differ in their environmental associations. Significant overlap exists in the treatments for both presentations. Effective treatment involves a combination of medical therapies and strategies to control or limit environmental exposure to triggering factors.
Treatment can become more challenging as the patient ages. Combination therapy with corticosteroids and bronchodilator therapy is a commonly employed treatment strategy for affected patients. However, these therapies may be contraindicated in patients with co-morbidities such as insulin resistance or Cushing’s disease/PPID. Reduced exposure to dust and molds is the cornerstone of successful management of horses suffering from asthma or RAO, and this becomes even more important in the geriatric patient. Appropriate drug therapy will be incompletely effective if environmental management is not implemented.
ENVIRONMENTAL MANAGEMENT
Long-term medical therapy must be coupled with environmental management to be successful. The first and most important step is to remove the patient from the offending agent. For hay-associated asthma, this means removing the horse from the barn and housing on pasture. For pasture-associated asthma, remove from pastures and house in a stall. Environmental allergens should be reduced wherever possible. Low-dust bedding such as cardboard or large wood shavings are the least allergenic. Even stall mats alone are appropriate to reduce allergens in the short term.
Long-term environmental changes can be more difficult. It is important to stall horses with EA away from certain environments such as dusty or dry areas, below hay lofts, or freshly mowed pastures. Hay is another source of allergens for horses with EA. Dietary inhaled dust can be reduced by pretreating hay by soaking or steaming. Every effort should be made to avoid feeding dry hay, especially round bales. Alternative hay sources can be helpful. Good-quality alfalfa hay is associated with fewer respiratory problems than grass hay. Other low-allergen feed options include complete pelleted feed or soaked feed, soaked beet pulp, and soaked hay cubes.
Hay steaming is an important part of environmental control. Steaming is effective at reducing mold content in hay by 100-fold. Hay steamers aim to reach and uniformly diffuse a temperature of 100 degrees Celsius (C) throughout the entire hay bale. When steaming is not possible, soaking hay is preferable to feeding dry hay. The hay may need to soak for several hours to effectively remove allergens. It should also be drained well to avoid creating mold and bacteria. This can be a time-consuming and messy option.
SYSTEMIC CORTICOSTEROIDS
Systemic corticosteroids are the mainstay of medical therapy. Systemic dexamethasone (IM or IV) has been shown to decrease the clinical signs associated with EA and increase lung function. This level of improvement is not matched using any other systemic steroids. The reliable and rapid improvements seen with dexamethasone administration justify its use but with steroid use for any clinical condition, there are detrimental effects to consider.
- Dexamethasone: 0.05 mg/kg PO q 24h taper to lowest effective dose.
- Prednisolone: 1.1 – 2.2 mg/kg PO q 24h (less effective than dexamethasone)
- Inhalant options include: Ciclesonide (Aservo) as a metered-dose inhaler, Budesonide (MDI or nebulized) or Fluticasone (MDI or nebulized).
BRONCHODILATORS
Bronchodilators work by reducing airway obstruction and bronchoconstriction and work well in combination with corticosteroids. The two most used bronchodilators are the beta-2 agonists. Albuterol is available by inhalation (nebulization or MDI) only and has no oral absorption. A longer-acting beta-2 agonist is clenbuterol (Ventipulmin) dosed at 0.8 mcg/kg PO every 12 hours. This is an FDA-approved drug that also has tocolytic properties. Salmeterol is a long-acting beta-2 agonist that has shown some effectiveness in horses with severe equine asthma for approximately six hours. The onset of action is slower than other options, taking up to 60 minutes to take effect, making it less practical as a rescue option.
ADDITIONAL THERAPIES
Immunomodulators such as interferon-alpha 50 to 150 IU PO for five days have been shown to decrease BAL neutrophils in mildly affected horses but have not been studied in severely affected horses. Omega-3 fatty acids may help downregulate the immune response but require long-term therapy for full effect.
EXERCISE AND MANAGEMENT OF MUSCULOSKELETAL INJURIES
Consistent exercise is crucial for the long-term health of the geriatric athlete. It is always a concern when significant changes in exercise are necessary due to injury or illness. Increased recovery times are well established in human geriatric patients. Cardiovascular fitness declines rapidly, and musculoskeletal fitness follows.
REFERENCES
- Couetil LL, Cardwell JM, Gerber V, et al. Inflammatory airway disease of horses–revised consensus statement. J Vet Intern Med 2016;30(2):503–15.
- Davidson, E.J. Controlled Exercise in Equine Rehabilitation. Vet. Clin. N. Am. Equine Pract. 2016, 32, 159–165.
- Fairbairn SM, Lees P, Page CP, et al. Duration of antigen-induced hyperresponsiveness in horses with allergic respiratory disease and possible links with early airway obstruction. J Vet Pharmacol Ther 1993;16(4):469–76.
- Kirschvink N, Di Silvestro F, Sbai I, et al. The use of cardboard bedding material as part of an environmental control regime for heaves-affected horses: in vitro assessment of airborne dust and aeroallergen concentration and in vivo effectson lung function. Vet J 2002;163(3):319–25.
- Leguillette R, Tohver T, Bond SL, et al. Effect of dexamethasone and fluticasone on airway hyperresponsiveness in horses with inflammatory airway disease. J Vet Intern Med 2017;31(4):1193–201.
- Nogradi N, Couetil LL, Messick J, et al. Omega-3 fatty acid supplementation provides an additional benefit to a low-dust diet in the management of horses with chronic lower airway inflammatory disease. J Vet Intern Med 2015;29(1):299–306.
- Oestergaard AS, Mathiesen MH, Karlsen A, et al. In acutely admitted geriatric patients, offering increased physical activity during hospitalization decreases length of stay and can improve mobility. Transl Sports Med. 2018; 1: 46-53. https://doi.org/10.1002/tsm2.2
- Stubbs, N.C.; Kaiser, L.J.; Hauptman, J.; Clayton, H.M. Dynamic mobilisation exercises increase cross sectional area of musculus multifidus. Equine Vet. J. 2011, 43, 522–529.
About the Author
Laura Riggs, DVM, PhD, DACVS, DACVSMR
Dr. Laura Riggs is an associate professor and the service chief of equine surgery in the Department of Veterinary Clinical Sciences at Louisiana State University. She is a 2001 graduate of the University of Tennessee, College of Veterinary Medicine. Following graduation, she completed a large animal rotating internship and surgery residency at the University Of Georgia College Of Veterinary Medicine. In 2007, she became a Diplomate of the American College of Veterinary Surgeons. The same year she completed a PhD in veterinary physiology at the University of Georgia. In 2016, she became a Diplomate of the American College of Veterinary Sports Medicine and Rehabilitation. Since 2008 Dr. Riggs has been a member of the clinical faculty in the Veterinary Teaching Hospital at Louisiana State University where she is actively involved with clinical, teaching and research activities in the Equine Health and Sports Performance program.