By Kerry Schneider, DVM, Midstate Veterinary Services, Cortland, NY
Tis the season for calf pneumonia. And often trying to approach the problem, especially in the face of an outbreak, can be daunting. A practical way to troubleshoot the issue is to look at the age of the calves when they first experience symptoms. This provides an idea of potential breaks or holes in the protocols around that stage of life. When this does not reduce new cases or holes cannot be found, other options exist such as diagnostics and lung ultrasound.
Using age as a factor can help guide the initial approach to the problem. If seeing pneumonia in calves less than one week of age, aspiration pneumonia is commonly the reason. Tubing calves their first colostrum is a great way to have successful passive transfer but can increase the risk of aspiration. Ensuring proper tubing protocols and training for the responsible people can reduce this risk. Calves now have smaller average body weights (<80lbs) with the increased use of sexed semen and if aspiration seems to be a continued problem with proper training, splitting the colostrum feeding into two even feedings (such as 3qt and 3qt instead of 4qt and 2qt) within the first 8 hours of life can help reduce this issue.
Often pneumonia cases around two weeks of age are viral mediated. The big viral culprits are IBR, BRSV, and PI3. Mature cows can have latent viral infections which do not cause apparent disease, but immune suppression at calving can cause activation and viral shedding. This immune suppression is why cows are more prone to pneumonia after freshening and how calves can get exposed to the virus at birth. A common practice to mitigate the impact of this exposure would be an intranasal vaccine (Inforce 3 (Zoetis) or Nasalgen 3 (Merck)) for the calf at or around birth. These vaccines cover IBR, BRSV, and PI3, and due to the method of delivery, trigger an immune response through IgA not IgG, which provides additional protection beyond maternal antibodies. The intranasal vaccines can be given as part of calf processing (alongside naval dipping, colostrum feeding, etc), so it is easy to add into a standard protocol reducing the chance it will be done inconsistently.
Older calves can still be impacted by viral pneumonia but often there is a bacterial component. Two common bacterial pathogens (Pasteurella multocida and Mannheimia haemolytica) tend to be opportunistic, proliferating due to previous viral pneumonia or environmental stressors such as weaning, transport, grouping or weather, all leading to immune suppression. Management can play a role in preventing bacterial pneumonia by focusing on stress reduction during a calf’s life. This can include not weaning too early or avoiding large group transitions (singe hutch to 10 or greater). Ensuring proper ventilation, not overcrowding calf barns, providing water and extra calories in winter is especially important. But outbreaks still occur and often calf housing is restrictive on stocking and transition. If management and housing fixes do not seem to reduce cases, adding another vaccine may help. There are injectable or intranasal vaccines that stimulate protection against Pasteurella and Mannheimia with the most common being Once PMH (Merck). This product can be combined with Nasalgen 3 (Nasalgen 3-PMH (Merck)) so that a viral booster can be provided at the same time. This vaccine should be given 1-2 weeks prior to the age outbreaks are seen. The intranasal vaccines work within hours, but often a calf will start to have lung changes and pneumonia well before you see clinical signs so vaccinating earlier will hopefully ensure the best protection.
Unfortunately, other bacteria can cause lung disease at varying ages, such as Mycoplasma bovis or Salmonella Dublin. S Dublin is most commonly spread via an oral route through maternal shedding in manure at calving or colostrum and M bovis from older calves to younger via nose-to-nose contact, shared waterers, or aerosols in overcrowded calf barns. Sampling calves is the most accurate method to diagnose these pathogens. There are several ways to collect samples with the least invasive being nasal swabs and the more invasive being tracheal/bronchial washes or even necropsy. It is easier to start with nasal swabs and if these do not determine the primary issue, having a veterinarian do more invasive diagnostics is always an option. For simple nasal swabs, two can be collected per calf with one placed in bacterial growth medium and another swab placed in sterile saline for viral PCR. This can help determine if the right vaccines are being utilized and are they provided at the right time.
Another tool a veterinarian can use to determine when pneumonia begins is by routine lung ultrasound. As stated before, lung disease starts before clinical signs are seen. A lung lobe may have congestion in one or two locations and the calf may not necessarily show the fast breathing, snotty nose generally associated with pneumonia. Ultrasound can help determine when it starts so that vaccination can occur prior to that or measures can be taken for early treatment, hopefully reducing severity.
As always, a veterinarian can help with every stage--whether its adding vaccines to protocols, working with maternity and calf processing to ensure a clean environment and proper colostrum management, or further diagnostics when basic core vaccines do not seem to be helping.
Occasionally, we are fortunate to feature a guest veterinarian, and give Dr. Locitzer a much needed rest. This issue, we introduce Kerry Schneider, DVM, a graduate of Cornell Veterinary Medicine who can be reached at Midstate Veterinary Services, 806 Rte. 13, Cortland, NY 13045, (607) 753-3315, info@midstatevet.com
Posted: to Organic Production on Sat, Jan 10, 2026
Updated: Sat, Jan 10, 2026
