Hayfever in humans is also known as allergic rhinitis, and it is generally associated with an allergy to pollen. It causes annoying symptoms like runny eyes, a runny nose, sneezing, coughing, and itching of the eyes and throat. Although it can progress to more severe breathing difficulties in asthmatic patients. It’s pretty common in people, and those who suffer from it will understand how bothersome it can be. In horses, we don’t see hayfever as such. However, they have their own set of respiratory and breathing problems; of which some can seem to resemble this human condition.

Recurrent Airway Obstruction (RAO) – also known as Equine Asthma 

RAO (now often referred to as Equine Asthma Syndrome) describes a condition seen in horses, middle-aged and above, where inflammation in the airways results from an individual horse having a hypersensitive reaction to certain allergens. These are allergy-inducing entities like hay dust, dust, or mould from bedding, and mites, etc. This leads to an accumulation of mucus and secretions in the lower airways, as well as inflammation of the airways. As a result, affected horses show signs like coughing, lethargy, and, later on, nasal discharge. In most cases, it is a lifelong condition. Some horses with uncontrolled disease can struggle to maintain weight, often having a marked heave-line. This demonstrates the long time frame of the disease. Because it is caused by an increase in the size of the abdominal muscles that are used in coughing and forced breathing.

Once diagnosed, many horses can be well managed. The treatment involves changing their environment to minimise exposure to the potential causes of hypersensitivity. This can mean soaking hay, avoiding dusty bedding, and providing more turnout. In acute bouts, horses often require some medication to help reduce the inflammation and widen the airways, to get their signs under control. 

Summer Pasture-associated Obstructive Pulmonary Disease (SPAOPD)

Quite a mouthful, SPAOPD is the long-winded term we use to describe the syndrome characterised by recurrent bouts of signs. Such as coughing, increased breathing rate, and increased breathing effort is seen in some horses kept at pasture during the summer months. It is believed to be associated with hypersensitivity of the horse to inhaled allergens: like pollens, or moulds, that are present on or around grasses. SPAOPD is very similar to RAO. In fact, it is also known as Summer Pasture-associated Recurrent Airway Obstruction (SPARAO, which is even harder to pronounce!). Like in RAO/Equine Asthma, the airway inflammation and secretions again make it difficult for the horse to breathe normally. This leads to the clinical signs of coughing and altered breathing patterns that we associate with both diseases. In fact, some horses can suffer from both conditions. 

SPAOPD and RAO are diagnosed based on the horse’s signs, the results of an endoscopic examination (where a camera is used to look at the airways in detail), and examination of the airway secretions. In some cases, the airways can be so inflamed as to become infected secondarily by bacteria or viruses. This can make the horse unwell, cause a fever and worsen their breathing.

The treatment for SPAOPD involves preventing the horse from being exposed to the causative allergen(s). In most cases, this means transferring the horse to a well-ventilated stable for the summer months, instead of keeping him at pasture. As in RAO, many horses will need additional treatment with anti-inflammatories and bronchodilators (to widen the constricted airways). This is to help them breathe easier and more comfortably, especially in the acute phases. 

Other things…

Other causes of airway inflammation, as well as upper and lower respiratory tract infections with viruses and bacteria, can also occur. These might +make it appear that the horse has hayfever because he’ll often have a cough or a runny nose. But really the cause is very different. Infections are generally associated with swelling of the lymph nodes, fever, depression, reduced appetite, and, often, copious discharge from the nose. SPAOPD might be suspected from the time of year or the horse’s environment. But it’s important to distinguish between the various different causes of coughing or laboured breathing, in order to ensure that your horse gets the appropriate treatment he needs to get better. 

If you notice that he’s coughing, has nasal discharge, or is showing any change in his normal breathing pattern, then give your vet a call to have him checked out. 

You might also be interested in: