What Does a Runny Nose Mean for Horses?

Mary H. Bell, VMD, answers this reader question.
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Q:My horse has had a runny nose on and off for the last few weeks. There is no discharge and he doesn’t seem to have any breathing issues. Should I be concerned?
—Name withheld by request

A: A runny nose is a sign of something not quite right in the horse’s respiratory tract. For the dressage horse, addressing any sign of a breathing problem is particularly important. A correct frame in the dressage horse has been shown to increase airflow resistance. Additionally, a large number of horses in this discipline are warmbloods, and airway disease in the warmblood is often missed because there may not be easily recognizable signs such as a nasal discharge or a cough. In these horses respiratory compromise may have training or connection issues, but because they do not cough or have a runny nose, the underlying problem, difficulty breathing, is slow to be identified.

Your horse may have a respiratory disease that is infectious and poses a risk to other horses. He may be developing an allergy in a portion of the respiratory tract or may have any one of a number of conditions that is not contagious or allergenic. If your horse has a nasal discharge, there are things that you should note: 

• Does the discharge come from one or from both nostrils?

• What does it look like—is it clear, white or yellow, and is it thin or thick?

• Is it all the time? If not, how frequent?

• Under what circumstances do you notice it—in the stall, while riding, while untacking or while grazing?

A nasal discharge can be the result of a bacterial or viral infection or of inflammation of either the upper (nose and throat) or lower (lower trachea and lung) airway. Horses who have not been exposed to diseases and who have not been vaccinated are like young children heading to school, and sometimes the parents have a lowered disease resistance.

Strangles (Streptococcus equi) is a bacterial disease in horses that is most commonly associated with abscesses between the ramus of the mandible. However, disease can occur in the absence of visible abscesses. There is a very effective vaccine against strangles. The discharge is usually thick and yellow and copious. The horse usually goes through a stage of not eating or reduced eating and of having a temperature that is above normal. He can have a cough.

There are a number of viral diseases in horses. They usually result in a transient increase in temperature, thin milky discharge, cough and being a little off. There are effective vaccines for equine influenza, for the respiratory component of equine herpesvirus 1 and 4 and, in the U.S. but not yet in Canada, for equine rhinitis virus. The discharge can change to yellow with a secondary bacterial infection. Secondary bacterial infections are more common in young horses or in horses with a lowered immune response. It takes time for the bronchi and lungs to heal from a virus infection (several weeks) and it is important to give your horse sufficient time to recover before returning to work.

In the case of a horse with a nasal discharge and an elevated temperature, your veterinarian is your best advisor. Biosecurity measures and vaccination and good husbandry are your best preventers. Sick and exposed horses should be isolated from healthy and unexposed horses on the property and biosecurity protocols should be put in place (see the biosecurity-related websites below).

A discharge from one nostril suggests a number of possible causes including an infection of the guttural pouch, the sinuses, etc. A foul smell coming from one nostril suggests there is a blocked pathway from the mouth to the sinus, usually the result of a damaged molar. In the event of a unilateral discharge that is there more than once, I suggest you call your veterinarian because catching something early pays dividends. If there is blood in the discharge or if the discharge is blood only, whether from one nostril or two, call your veterinarian.

Sometimes allergies affect the nose and sinuses. This type of allergy is usually seasonal, associated with pollens and can be accompanied by head-shaking. There is often a lot of snorting. The discharge is usually thin and can have a bit of a milky appearance. Allergies that affect the lungs are not uncommon in the dressage horse. These horses spend most of their non-working time in a stall. This increases their exposure to dust and molds. Over time, horses are likely to develop allergies to dust, molds, feed, bedding, pollens, specific plants or trees. 

There are two types of lower-airway conditions that are seen in the athletic horse: inflammatory airway disease (IAD) and recurrent airway obstruction (RAO), also referred to as heaves. The second is probably a progression of the first. These are horses who may cough up mucus. They may have a brief nasal discharge when they drop their head after work. The RAO horse usually has episodes of significant exercise intolerance. The cells recovered from a lung wash can help determine what the horse has and what treatment regimen is best followed. Environmental control, sometimes custom allergy serum and specific medication all can be of value in alleviating symptoms.

So when your horse has a runny nose, what are you going to do?

1. Take it seriously. Because a healthy respiratory system is so important to the dressage horse to ensure energy, comfort and compliance, small signs of dysfunction should not be ignored.

2. Note the character of the discharge and write it down with a date and a note as to what the horse was doing prior to the discharge.

3. Take the horse’s temperature. If this is immediately after work and it is elevated, take it again in 20 to 30 minutes after you have cooled your horse out.

4. Tell the person responsible for
the barn.

5.Your veterinarian can help advise you from here.

Mary H. Bell, VMD, is a licensed FEI Veterinary Delegate for dressage and jumpers and an FEI treating veterinarian. Based in Puslinch, Ontario, Canada, she operates Mannington Equine Services. 

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