Volume 5 Issue 8
Dr. Susan Kerr, WSU Extension
Experienced livestock caretakers know to be on the lookout for pneumonia during winter months. Animals tend to congregate more in cold and wet weather, which intensifies concentrations of disease-causing organisms. Cold and wet animals are also more stressed, predisposing them to disease. One would think summer conditions would preclude most cases of pneumonia in livestock. Nevertheless, “summer pneumonia” is a syndrome to learn about because its consequences can be severe.
Predisposing Factors
Factors that predispose animals to summer pneumonia are unknown but may include:
- Dry and dusty conditions that irritate the lining of the respiratory tract and facilitate entry of resident pathogens
- Poor colostrum quality or insufficient quantity resulting in failure of passive transfer of protective maternal antibodies
- Decreasing protection from maternal antibodies as animals age
- Large daily temperature ranges (hot days and cold nights), though the mechanism is unknown
- High humidity because moist air supports more pathogens than dry air
- Age (pre-weaned calves, lambs and kids are most at risk)
- Inadequate nutrition, including selenium deficiency
- Mixing of groups and ages of animals, which stresses animals, increases pathogen shedding, and exposes individuals to new pathogen strains
- Separating youngstock from dams for prolonged processing periods, causing stress to both groups
- Crowding under shade and in barns, increasing pathogen density and ammonia fumes
- Poor environmental sanitation
- Poor ventilation, including hot and still air
- Any factor that stresses animals.
Calf with pneumonia. Note nasal discharge, drooping ears, lowered head, dull and sunken eyes, and depressed attitude.
The Agents
The Bovine Respiratory Disease Complex includes viral agents (Infectious Bovine Rhinotracheitis virus, Bovine Viral Diarrhea virus, Parainfluenza-3 virus, and Bovine Respiratory Syncytial virus) and bacterial agents (Mannheimia haemolytica, Histophilus somni, Pasteurella multocida, Mycoplasma bovis, and others). The viral agents are often the initiating force, irritating the respiratory track lining and its protective mechanisms. Many of the bacterial agents that invade secondarily are actually common and non-problematic residents of the upper respiratory tract and only cause problems when they gain entry to the lungs.
The Ovine Progressive Pneumonia and Caprine Arthritis and Encephalitis viruses can predispose sheep and goats, respectively, to respiratory disease. There is some evidence they can be affected by the Bovine Respiratory Syncytial virus as well. Various Pasturella and Mycoplasma species can be isolated from clinical cases of small ruminant pneumonia.
Signs of Illness
Signs of pneumonia can range from subtle to fatal, depending on when noticed. Changes in behavior may be noticed early in disease progression, including decreased activity and reduced self-grooming. Drooping ears, lowered head, coughing, nasal discharge, reduced feed intake, and increased respiratory rate and effort follow; fever will be detected if temperatures are taken. As the condition progresses, open-mouth breathing may be seen. Animals will extend their neck and stand with forelegs away from their body to make respiration easier. Severely-affected animals will be reluctant to move and will have difficulty keeping up with the herd/flock—indeed, this is the sign managers sometimes first detect in affected individuals.
Treatment
As prey animals, ruminants hide signs of illness to avoid the attention of predators, but this behavior can work to their detriment. Less astute caretakers may not see early signs of illness, so pneumonia may be quite advanced when it is finally detected. Treatment outcomes are less successful in prolonged cases.
A local veterinarian will be the best resource person to consult when summer pneumonia is suspected. Laboratory tests from early cases will help identify the agents involved and determine treatment regimes. It is critical to recognize and treat pneumonia cases promptly—especially in young animals—before permanent damage is done and animal health permanently compromised.
Animals with pneumonia must be handled very carefully. They are highly stressed already and the added stress of handling may prove fatal. They should be provided a shaded and dry area and provided appropriate hay, cool water, and trace mineral loose salt. Dehydrated animals would benefit from electrolytes. If not eating well, sick animals may prefer fresh grass or browse brought to them. To protect the rumen, avoid feeding grain if sick animals are not eating much forage. Ensure excellent ventilation without drafts and protect animals from irritating dust and ammonia fumes.
Sick animals should be isolated from healthy animals, but may need a companion to reduce the stress of being in isolation. Healthy animal chores should be done before sick animal care; wash hands, change clothes, and disinfect boots after handling sick animals.
Management Steps to Prevent Summer Pneumonia
Ensuring water and feed quality and quantity, providing adequate shade/shelter opportunities, addressing sanitation, and minimizing stress will go a long way to preventing pneumonia year-round. Whether on range, pasture, or in barns, animals should not be overcrowded and ventilation should be regularly assessed to ensure quality and lack of irritants.
A veterinarian should be consulted to develop an appropriate vaccination program. Many different vaccines and combinations are available—mostly for cattle—and a veterinarian will be able to develop a farm-specific protocol based on goals, management practices, risks, and disease history. As with other extra-label drug use, vaccines approved for use in cattle cannot be used in other species without the oversight of a licensed veterinarian knowledgeable about the herd and with whom the livestock owner has a business relationship. Many vaccinations have a meat and/or milk withholding period, too.
Those taking animals to fairs, shows, breeding appointments, etc. introduce added risk to their farm. Any animal taken to another premises should be quarantined from one to three months when taken home. They are at risk of contracting diseases from other animals and surfaces at the exhibition and bringing these diseases back to the home herd.
Conclusion
The need for prompt diagnosis and treatment of pneumonia cannot be overstated. Livestock caretakers should monitor their charges at least once daily to assess them for signs of pneumonia and other important diseases, taking temperatures, examining individuals, and contacting their veterinarian about animals for whom they have concern. Although there is increasing public criticism of the use of antibiotics in food animals, antibiotics are completely appropriate and indicated in cases of pneumonia and offer an animal’s best hope for recovery.