Equine Physiology & Nutrition

The type of feed the horse eats is what determines what fuel is available for the horse to use during exercise. So it is important to figure out the optimal diet for your horses. Although there has been research showing the benefits of fat supplementation over feeding grain in equine diets, many people still prefer to add grain to the diet thinking it is better for their horses. This paper is one of the more recent showing that fat supplemented horses used less glucose during endurance exercise than the horses whose diet was supplemented with sweet feed. That means that that their limited glycogen stores are used up faster than when they are fed the higher fat diet. So, it is the horses fed higher fat without the grain whose energy systems will benefit in endurance exercise. And on top of what to feed for best performance is that the traditional high grain diet may be a root cause of many problems, including laminitis, obesity, diabetes and tying up.

See the post including abstract at Argamak's nutritional site

Pleuropneumonia is inflammation and fluid build up both within the lung and pleura. The pleura is the space between the lungs and chest wall. Horses develop pleuropneumonia from contamination of the lower respiratory tract, their lungs, with bacteria that normally occurs in the upper respiratory tract, upper throat and nose (1).

How often do horses get it?

It is surprisingly common for horses to develop pleuropneumonia following shipping (2). One study found that 12% of horses developed respiratory ailments and up to 30-40% of horses were affected following air transportation (3a). Pneumonia, which developed following transport longer than eight hours, has resulted in death (3).

How can you tell?

Horses with pleuropneumonia may present with fever, depression, coughing, nasal discharge, and lack of appetite (3, 4). Horses might not show clinical signs for two or three days following transport and so checking temperature is advisable up to a month after shipping (3). In addition, inflammation of the pleura is an extremely painful disease process creating pain between the ribs and sometimes causing a reluctance to walk (4).

What can I do once my horse is sick?

Treatment relies on long-term antibiotics, supportive therapy, and possibly drainage of the fluid from the thoracic cavity. There are numerous complications that can occur with pneumonia, including colic and founder along with anaerobic and other opportunistic infections. Treatment is usually more successful if no complications occur, although it still can take up to six months (4, 5). The death rate from pleuropneumonia has decreased because of aggressive treatments that are now available, however, it is probable that infected horses will never return to their athletic potential, or even their former use (6).

Horses have been found to have a reduction in pulmonary function for around three weeks following shipping (8) and transportation of any type has been found to be a predisposing factor for the bacterial contamination of the lower respiratory tract, which can develop into pleuropneumonia (6, 9).

This contamination of the lung happens when horses are unable to lower their heads. There is a reduced opportunity for mucosal clearance leading to an increased opportunity for lower respiratory tract contamination with raised heads (6). Basically it is the inability of horses to lower their heads during transport that is a primary cause of pleuropnemonia as they can't clear mucous from their throats (6, 10). Horses confined with their heads elevated for 24 hours develop an accumulation of purulent airway secretions (and associated increased numbers of bacteria) in the lower respiratory tract and show a decrease in tracheal mucociliary clearance (11).

It was found to be very important to have long rest stops where horses are removed from the trailer, and the trailer is cleaned (13). When a vehicle is stationary there is also an immediate deterioration in the quality of the air (12). The combination of the horses being able to get food and water while resting and traveling in a clean compartment reduced both transportation stress and respiratory infections.

Note: The full article and references are available here.