What are Heaves in Horses?
Heaves in horses occur due to a hypersensitivity disorder from allergens in the environment. The condition starts with mild respiratory symptoms ranging from coughing to nasal discharge and performance-inhibiting respiratory difficulty. Removing the environmental allergen present in the bedding or feed often resolves symptoms.
Heaves are also referred to as Chronic Obstructive Pulmonary Disease (COPD), Recurrent Airway Obstruction (ROA), or broken wind.
Symptoms of Heaves in Horses
Heaves are a common respiratory disease, and symptoms develop between nine and 12 years of age. The early signs of heaves begin with intermittent coughing fits and mild nasal discharge. The symptoms become exacerbated with exercise, stabling, or during feeding times.
Heaves are categorized into three categories, mild, moderate, or severe. The disease progresses with more intense bouts of coughing, especially during winter. There is no gender predisposition for horses suffering from ROA.
Heaves in horses symptoms also include the following signs:
- Flared nostrils.
- Lung sounds.
- Upper airway wheezing.
- Depressed appetite and weight loss.
- Rapid respiration following exercise and increased exercise intolerance.
- In severe cases, respiratory distress occurs due to decreased oxygenation, leading to pale gums or cyanosis (blue-colored gums).
Respiratory distress results from increased inflammation and an overactive immune system. The severity of the condition improves when the allergen in the environment is removed. The main objective of treatment is to decrease inflammation, depress the immune system, and reduce external environmental allergens.
Labored breathing in horses occurs for the following reasons:
- Bronchoconstriction occurs when the smooth muscle tissue lining the lung’s airways tightens, narrowing the airway. Chronic bronchoconstriction results in airway remodeling that increases the risk of respiratory distress.
- Inflammation results from increased white blood cell activity, leading to fluid build-up and swelling that impedes the functionality of the airways.
- Increased mucus production is one of the airways’ primary defense mechanisms, which results in abnormal and viscous mucus that impedes respiration.
Heaves significantly affect a horse’s quality of life in advanced stages, so owners must pay close attention to their horses when stabled or feeding. The condition does not have a high morbidity rate, but it has the potential to become complicated if pneumonia develops.
How do Vets Diagnose Equine Heaves?
The early stages of heaves present subtle signs, so diagnosing the condition is challenging. Veterinarians must thoroughly assess horse breathing problems to determine an underlying cause. The first step in diagnosing an airway disease starts with an in-depth history, including clinical symptoms and environmental influences.
The most obvious symptoms that alert a vet to an underlying airway disorder are chronic coughing, exercise intolerance, and a correlation of dust or pasture allergens causing worsening symptoms.
Additional tests ordered to diagnose heaves include an airway exam through endoscopy and secretion sampling through a bronchoalveolar lavage (BAL). The BAL helps determine the inflammatory secretions’ severity and predominant cell type.
Horses with fevers or nasal discharges may require blood work, but this will not help to rule out other potential causes of heaves.
Veterinarians must consider that some conditions may resemble heaves; these conditions include:
- Collapsing tracheas, especially in miniature breed ponies.
- Lungworm, if the horses co-graze with donkeys.
- Pleural effusion.
- Idiopathic pulmonary eosinophilia.
Heaves in Horses (Treatment)
When addressing heaves in horses, treatments must include management changes and medication. Treating a horse with respiratory difficulties comes with challenges, but consistency and good medication compliance are vital to managing the horse’s symptoms.
Medication without environmental modification is often fruitless because the allergens continue to cause respiratory symptoms unless the stabling, food, and pasture management improve.
Medication for Heaves in Horses
Should a horse’s symptoms not improve with environmental management or feed changes, they may require medication to combat the hypersensitivity reaction.
Medication aims to alleviate symptoms, but ideally, the inciting cause must be found to enable the horse to recover completely.
The following medications are used in treating heaves:
- Oral corticosteroids help to modulate the immune system’s overreaction to an allergen—the inflammation caused by the immune system results in increased airway thickness and overproduction of mucus. To treat heaves in horses, dexamethasone or prednisone are recommended.
Dexamethasone is contra-indicated in founder-prone horses. Prednisone is the safer drug for chronic treatment but is not as potent as Dexa.
- Antibiotics become necessary in horses with secondary bacterial infections.
- Expectorants break down mucus buildup that hampers the airways. This medication makes it easier for a horse to expel excess mucous.
- Oral bronchodilators such as Clenbuterol help dilate (open -up) the airways.
- Aerosolized corticosteroids include beclomethasone dipropionate and fluticasone propionate. Horses with moderate to severe heaves require aerosolized corticosteroids.
- Aerosolized bronchodilators work through the airways and not systemically to open up the airways.
Special equipment is required to administer aerosolized medication efficiently into the lungs. This enables low doses to reach the tissue more effectively. The masks are expensive, but they work well to deliver chronic medication efficiently, making owner compliance easier.
Alternative treatments for treating heaves may include rubbing Vicks VapoRub on the horse’s nostrils. Some owners use essential oils for heaves in horses.
The essential oils decrease inflammation in the airways and can support the immune system, but discussing any holistic or alternative medicines with the attending vet is always crucial.
How Long Can a Horse Live With Heaves?
Early detection of any disease always presents a better prognosis. Chronic airway changes carry a more guarded prognosis as there is a higher risk for secondary complications such as bacterial infections.
If caught in the early stages, owners can start treatment with medication and adjust environmental factors accordingly to ensure the careful management of symptoms. Horses with heaves may live a happy and healthy life with proper treatment, stall, and feed management.
Can a Horse Die From Heaves?
If left untreated, a horse can develop severe secondary infections that lead to pneumonia and an increased risk of death. Severe respiratory distress is challenging to treat, especially if a horse becomes panicked and cannot breathe due to complete airway obstruction.
Horses that become panicked due to dyspnoea are dangerous to themselves and those around them; never approach a horse in severe distress.
Is Riding a Horse With Heaves Recommended?
Any respiratory condition will impede a horse’s performance ability and may result in exercise intolerance. The key to managing a horse with ROA lies within owner compliance. If owners diligently monitor and mitigate their horses’ symptoms, a horse can be used for daily rides, trails, or competitions.
A horse with a compromised quality of life due to respiratory distress should not be ridden.
Unpacking Pasture-Related Heaves
Summer Pasture-Associated Obstructive Pulmonary Disease (SPAOPD) frequently occurs in the southeastern regions of the United States when conditions become more humid and hot during peak grazing times.
Pasture-related heaves occur mainly during the warmer of the year, unlike barn or hay-related heaves.
In horses that suffer from SPAOPD, grazing rotations cannot include pastures in the summer months. A low-dust environment is also crucial to avoid flare-ups and acute respiratory distress.
Chronic labored breathing, with flared nostrils and extended exhalation periods, results in the thoracic respiratory musculature overdevelopment, creating a distinct line of muscle definition known as a heaves line.
Persistent coughing, nasal discharge, dyspnoea (labored breathing), and weight loss occur as the disease progresses.
Are Equine Heaves Genetic?
Research indicates that a few genes predispose a horse to heaves, and their expression depends on the type of dominance passed down from the parent. The combination of the horse’s genetic predisposition to heaves and environmental factors determine their symptoms’ severity.
Breeds such as Warmbloods and Lipizanners are high-risk carriers of the heaves genes, and the severity of the condition increases if both parents carry the heaves gene. Unfortunately, no genetic tests are available yet to identify the carriers of the heaves gene.
How to Manage Heaves in Horses
Managing heaves starts with addressing the horse’s environment to decrease exposure risks to allergens. Determining an episode’s main trigger is critical to limiting exposure and reducing the respiratory challenge in a horse with heaves. Once owners implement changes, results manifest within three to four weeks.
Unfortunately, even the slightest exposure to an allergen may result in a flare-up.
Equine Heaves – Nutritional Support Options
Nutritional support plays a significant role in helping to alleviate the inflammation caused by heaves. In combination with medication and environmental changes, dietary supplements improve respiratory health.
A balance of suitable organic vitamins and minerals, including copper, manganese, and zinc, helps to support the immune system. Below are some additional nutritional considerations for horses with heaves. Antioxidants such as Selenium or Vitamin E help cells regenerate after significant inflammation occurs during an allergy flare-up.
Supplements high in copper, manganese, and zinc include proteinated mineral complexes. Good sources of Selenium occur in selenized yeast proteins.
Natural forms of Vitamin E have better bioavailability but are more expensive. Synthetic forms of vitamin E are more cost-effective, but they compromise on quality as they have lower bioavailability. The beneficial effects of Vitamin E include decreased inflammation and boast antioxidant properties, but only if supplemented above 1000 IU.
Omega-3 fatty acid supplementation offers various anti-inflammatory benefits for horses with heaves. The fatty acids help to decrease the immune system’s overreaction to allergens.
The ideal omega-3 fatty acid is docosahexaenoic acid (DHA) from microalgae or fish oil. Plant-based omega-3 fatty acids are less metabolically efficient.
Studies show that diets high in omega-6 fatty acids are contraindicated as they show pro-inflammatory reactions in horses.
DHA supplementation must occur at 0.04 -0.16 ounces per 1100-pound horse (1250 – 4500 mg of DHA per 500 kg horse) to achieve therapeutic levels. Studies showed that around sixty percent of symptoms decreased in horses with heaves on low-dust diets and DHA supplementation.
Spirulina is a good vitamin, mineral, and protein source derived from blue-green algae. Benefits include antihistamine effects and antioxidant activity.
Jiaogulan is a plant extract from a climbing vine that supports bronchodilation and circulatory health. The combination of 0.035 ounces (2 grams) of Jiaogulan and 0.35 ounces (20 grams) of spirulina administered twice daily decreased respiratory symptoms considerably.
Jiaogulan is contraindicated in pregnant or lactating mares. Horses on non-steroidal anti-inflammatory (NSAIDs) drugs should also not be fed Jiaogulan. Avoid supplementation for at least seven days after the last dose of medication.
Tips for managing hay and barn-associated heaves:
- Good ventilation in the stables is vital, so stable managers must open windows or doors and switch on fans to help increase airflow.
- Hay quality assessment helps to eliminate poor-quality hay that harbors excess dust or molds. Ensure the hay does not contain excess moisture, predisposing the feed to mold.
- Allowing horses to graze in the pastures helps to limit allergen exposure in confined spaces. Most horses with no pasture-related heaves do best if they are always turned out on dust-free fields.
- Soaking feed with water in hay nets also helps to eliminate dust particles during feeding.
- Avoid round bales as they carry higher levels of dust or mold when compared to other forages. Horses are inquisitive, and if they have access to round bales in pastures, they will forage feed from them, which may cause a flare-up.
- Treating hay with a steamer is an option to decrease dust particles. Steaming machines range from single-portion devices to industrial whole-bale steamers. Research shows that horses with heaves fed hay show fewer respiratory symptoms.
- Switching a horse over to a pelleted ration is also an option, as some horses still react to the dust even if their hay is wet. Alternative to hay include cubed hay, or owners can consider a complete pellet ration.
- Adjust the feeding level to chest height as troughs on the ground expose heaving horses to more dust.
- Pay attention to the stall bedding as dusty beddings such as straw or wood shavings are very dusty. Alternatives include peat moss, shredded cardboard, or flax.
- An important consideration for a horse with heaves is the location of its stall. The optimal stall has the most ventilation, away from the feed store, low traffic area, and possibly near an exterior opening door. Horses with heaves should never be stabled under a hayloft or near a dusty indoor area.
- Stable hygiene is essential to decrease dust build-up, but it is imperative to avoid cleaning stalls when the horses are stabled. Also, avoid training arenas that are dusty and indoor.
The Final Say
Heaves in horses requires early detection and intervention to avoid chronic changes and complications to the horse’s airways. The key to managing heaves lies in mitigating environmental allergen contact and modulating the immune system’s reaction to them if exposed.
Heaves can affect a horse’s performance abilities during a flare-up of symptoms. It is always important to recognize signs early and stop exercising immediately to avoid severe respiratory distress. Resting a horse to allow for a full recovery is the best way to preserve a horse’s airway function.
Avoid allergen exposure and ensure good treatment compliance by informing staff and riders about a horse’s respiratory condition with prominent signage, detailed feeding instructions, and medication administration sheets.
Good owner compliance with managing the stables, pastures, feeding, and medical treatments to avoid inflamed airways helps to improve the horse’s quality of life. There is no cure for heaves, but a horse can thrive with good veterinary care and excellent husbandry practices.