What is Pleuropneumonia?

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).

What can be done to avoid it?

1. Long distance transport:

Transport longer than 28 hours will likely be harmful in general due to increasing fatigue of the horses (7). Horses transported more than 500 miles were found to have a reduction in pulmonary macrophage function (responsible for clearance of small inhaled particles in the lung) for around three weeks (8). Transportation of any type, especially over long distances, has been thought to be the single most important predisposing factor for the bacterial contamination of the lower respiratory tract, which can develop into pleuropneumonia (6, 9).

2. Head height:

This contamination of the lung associated with transport happens when horses are unable to lower their heads. With their heads raised over an extended period there is a reduced opportunity for mucosal clearance leading to an increased opportunity for lower respiratory tract contamination (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).

3. Air Exchange

To reduce the risk of respiratory tract infections in a stable it is advisable to have an air exchange three times an hour within the horses environment. When you have jet airplanes traveling at speed, air can be exchanged at three times per minute. In trucks and trailers there is also a frequent air exchange. The difficulty comes when a vehicle is stationary, as there is an immediate deterioration in the quality of the air (12).

4. Rest Stops

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). 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.

5. Orientation

Some horses have been found to have strong preferences on which direction they face during transport, although backwards was usually preferred and found to be less physically stressful (13, 14). Horses may develop increased stress levels with a forward orientation, although that has not been found to initiate pleuropneumonia, except in cases where the horses heads were tied (15). Orientation is not what turns out to be an important factor, it is whether a horse is able to lower their head during transport that has been found to be the important factor in the development of respiratory disease.

References

1. FEI transport studies, USA 1999
2. Pub med list
3. AAEP Convention 2004: Controversies in Therapeutics–Immunomodulation by: Kimberly S. Brown, Editor. The Horse.com, February 14 2005 ,Article#5424
3a. Bonnie Rush, DVM, MS, Dipl. ACVIM, (AAEP) Convention in Denver, Colo., Dec. 4-8, 2004.
Catherine Kohn, VMD, PhD, Dipl. ACVIM, professor in the Department of Veterinary Clinical Sciences at The Ohio State University and a veterinarian involved with the United States Eventing Team, 2003 conference USDA.
4. Dehydration, stress, and water consumption of horses during long-distance commercial transport. T.H. Friend, Department of Animal Science, Texas A&M University, College Station.
5. Equine Respiratory Disease Part 2: The Lower Airway by: Michael Ball, DVM August 01 1998 Article # 533 TheHorse.com
6. Aust Vet J. 2000 May;78(5):334-8. Towards an understanding of equine pleuropneumonia: factors relevant for control. Racklyeft DJ, Raidal S, Love DN. Satur Veterinary Clinic, New South Wales.
7. J Anim Sci. 2000 Oct;78(10):2568-80. Dehydration, stress, and water consumption of horses during long-distance commercial transport. Friend TH. Department of Animal Science, Texas A&M University, College Station 77843-2471, USA. t-friend@tamu.edu
8. S. Hobo, et al. from the Equine Research Institute, Japan Racing Association, Tokyo, Japan, entitled “Effect of transportation on the composition of bronchoalveolar lavage fluid obtained from horses”
9. Aust Vet J. 1996 Feb;73(2):45-9. Effects of posture and accumulated airway secretions on tracheal mucociliary transport in the horse. Raidal SL, Love DN, Bailey GD. Department of Veterinary Pathology, University of Sydney, New South Wales.
10. Vet Rec. 1996 Jul 6;139(1):7-11. Effects of transporting horses facing either forwards or backwards on their behaviour and heart rate. Waran NK, Robertson V, Cuddeford D, Kokoszko A, Marlin DJ. Institute of Ecology and Resource Management, University of Edinburgh, School of Agriculture.
11. Acclimating Competition Horses by: Les Sellnow March 01 2006 Article # 6625 Des Leadon, MA, MVB, FRCVS, RCVS, TheHorse.com.
12. Improving Travel Conditions by: Les Sellnow October 01 2005 Article # 6176; theHorse.com.
13. J Comp Pathol. 2005 Feb-Apr;132(2-3):153-68. Effects of orientation, intermittent rest and vehicle cleaning during transport on development of transport-related respiratory disease in horses. Oikawa M, Hobo S, Oyamada T, Yoshikawa H. Equine Research Institute, Japan Racing Association, 321-4 Tokami, Utsunomiya, Tochigi 320-0856, Japan.
14. Equine Vet J. 1994 Sep;26(5):374-7. Body position and direction preferences in horses during road transport. Smith BL, Jones JH, Carlson GP, Pascoe JR.
15. Equine Vet J. 2002 Sep;34(6):550-5. Effects of cross-tying horses during 24 h of road transport. Stull CL, Rodiek AV. University of California, Davis, 95616, USA.

Posted on June 19th, 2007 under transportation • RSS 2.0 feed • Leave a response, or trackback