Bronson, J., DVM: Respiratory

By Dr. Joanna Bronson | http://bronsonvetservices.com/ Winter brings challenges for keeping our horses well. Among those challenges are keeping horses warm and dry and out of cold winds without compromising their need for turnout with ample exercise and fresh air. With winter confinement, respiratory problems tend to spread rapidly in closed barns. Whatever the weather does, fresh air is crucial to the health of a horse. Keeping cross ventilation flowing is essential since stabled horses, especially those affected with Heaves, are exposed to more dust and contaminants than horses that live outside with shelters for protection. Horses get colds. They experience runny noses with nasal discharges that range in color from clear to yellow or white. Some nasal discharge is normal, however, if the discharge has an odor or is profuse, take his temperature to check for fever. A horse’s normal body temperature ranges from 99-101 degrees. It is good to have a basal temperature recorded for each horse, as temperatures vary by animal. If he is sick, a horse’s eyes may be runny or inflamed. He may also exhibit a dry cough that may change to a very moist discharge as his fever rises. Sick horses will probably be lethargic and “off their feed.” A horse’s normal respiration rate is 12-16 breaths per minute. Anything out of that range may indicate breathing distress. There are many possible causes of respiratory infections in horses. Some form of bacterial exposure is behind most cases; however, infections may also be viral, fungal, or parasitic. Strangles is the most well known bacterial respiratory tract infection and is extremely contagious. It usually stays in the upper portions of the respiratory tract (the throat and local lymph nodes) but can spread to the lungs. Almost 10% of horses who have had Strangles end up with chronic guttural pouch infections. The possibility of organ damage from abscesses is also a threat. There is a Strangles vaccine. Horses who travel or who are exposed to other horses should always be vaccinated against this disease. Other viruses including Picorna, Parainfluenza, Corona, and Adenoviruses can all cause respiratory diseases in other animals and occasionally affect horses, especially foals or older horses. Equine Viral Arteritis is caused by the Pestivirus which can cause abortions, severe leg/belly edema and respiratory problems. Fungal Infections are not as common as bacterial and viral infections. These infections most often occur in the guttural pouches or in the lungs of horses with chronic lung conditions. Horses who have been on long-term antibiotic treatment for bacterial infections are more susceptible to fungal problems when the gut flora are weakened by the antibiotics. A probiotic can help stabilize their immune systems. Parasitic infections such as the larvae of roundworms can migrate into the lungs. Young foals and weakened or aged horses are most susceptible. As they age, horses tend to build up sufficient immunity to protect themselves from this infection. Threadworms (Strongyloides) can affect young horses, as they enter through the skin and migrate to the lungs. Lungworm infestations migrate to the lungs, are then coughed up, swallowed, and passed in the horse’s manure. Heavy exercise, poorly ventilated stabling, and shipping are triggers for bacterial infections. Horses with compromised immune systems such as chronic allergies or weak lungs are at risk for developing bacterial pneumonia (and viral infections). Foals and older horses are most susceptible. To prevent the spread of the infection, it is essential to isolate sick horses from other horses as soon as they begin showing symptoms. The Herpes virus (rhinopneumonitis) or the common cold is the most widespread infection and can invade other organs. Once a horse is infected, the virus remains in his system for the remainder of his life. Symptoms are more severe in foals and older horses and range from a slight snotty nose to fever and cough. The horse’s immune system will eventually conquer the existing infection but exposure to stress or another illness can reactivate the virus. Even if a horse does not show symptoms, he can still shed the virus to others. With viral infections, the most uniformly severe infections in horses appear in the form of equine influenza. This virus can cause high fevers and lung damage along with potential complications. Affected horses may be sick for as long as a month or more, and need a longer recovery period. With any respiratory infection the key to prevention and cure is catching the problem early, vaccinating when appropriate, and monitoring your horse’s daily health. Dr. Joanna Bronson graduated from Michigan State University College of Veterinary Medicine in 2000 at the top of her class. Following graduation, she worked as an intern at a large equine referral practice in Cleveland, Ohio specializing in lameness, surgery, and racetrack medicine. In 2005, she opened Bronson Veterinary Services in Coldwater, Michigan. What started as an ambulatory only practice, quickly grew to a full-service equine, small animal hospital and surgical center. The now three doctor practice provides medical, surgical, reproductive, and preventative care services for Branch County and the surrounding area. Dr. Bronson lives with her husband, two children, and a variety of pets. In her spare time, she enjoys going to horse and cattle shows with her family, attending various sporting events, and working around the family farm.