Summer Cattle Health Issues

Summer is a busy time of irrigating, haying, checking waters, and trying to do something fun with the kids or grandkids while their schedule is less rigid.  While summer is generally a time of relatively good cattle health, here are a few reminders of common summer cattle health issues to watch out for as you ride through the long, hot days ahead.    

Calf pneumonia 

Sometimes Nevada can throw us a few wild weather blips, and when it does, keep your eyes out for calf pneumonia (e.g. dust pneumonia).  While pneumonia might make you immediately think of weaned calves later in the fall, actually 3-11% of calves contract pneumonia while still nursing according to K-State veterinarian Dr. Bob Larson¹.  Calves with scours, calves unvaccinated for respiratory diseases (BVD, IBR, BRSV, Mannheimia haemoliytica, and Pasturella multocida, and calves that didn’t receive colostrum within 24-48 hours of birth are the most susceptible.  Clinical signs that could indicate pneumonia include rapid breathing, lethargy, possible nasal discharge, and a high temperature.  Treatment with an appropriate antibiotic and supportive medications through consultation with your veterinarian is needed quickly if pneumonia is suspected.  

There are a few recent research advances in the study of calf pneumonia.   A new study documented incidences of dairy calf pneumonia at a dairy in the Pacific Northwest following a wildfire smoke event².  While there was not enough data available to specifically link the smoke exposure to pneumonia, it is possible that wildfire smoke could contribute to calf pneumonia in the summer.  New research into the fecal and nasal microbiota of calves by a research team in Canada found that the nasal microbiota changed significantly around 180 days after birth, before weaning or any other stresses³.  These nasal microbiota changes resulted in less Lactobacillus and Streptococcus, two genera that are thought of as protective against pneumonia-causing genera of Mannheimia and Pasteurella.  Fecal microbiota also changed between calf ages of 56 days and 180 days, shifting from Lactobacillus dominance from milk digestion to three other genera that are more associated with fiber digestion, including Oscillospiraceae UCG-005.  When present, this new research found that fecal Lactobacillus and Oscillospiraceae UCG-005 were negatively correlated with nasal microbiotic genera (Pasteurella and Mannheimia) which are often linked to bovine respiratory disease.  The Lactobacillus and Oscillospiraceae UCG-005 seem to be protective against Pasteurella and Mannheimia.   This finding means that there could be potential for development of new preventative therapeutics that help suppress disease-causing bacteria^3.  It will be interesting to find out through future research efforts, if the big changes these researchers found in fecal and nasal microbiota are replicated in other herds, and if there is something about the growth stage around 180 days of age that is causing nasal microbe changes.  This study occurred in an unvaccinated research herd, so it will also be interesting to see if any of these changes can be detected in vaccinated herds.  

Occasionally, what might look like calf pneumonia could actually be calf diphtheria.  Dr. Hannah Rodriguez, UNR teaching professor and owner of Great Basin Veterinary Services, says that she has seen cases of calf diphtheria during the middle of summer.  She says it can look a lot like pneumonia (fever, rapid breathing, coughing, lethargy) but often comes along with a wheezing sound due to obstruction within the upper-respiratory system.  The bacteria causing this disease, Fusobacterium necrophorum or Trueperella pyogenes, normally occurs in the environment, but can take advantage of injuries in the cheeks and mouth and start an infection.  This is a life-threatening disease for the calf if left untreated.  Consult your veterinarian right away if you suspect calves could have diphtheria. If the disease progresses, surgical intervention may be necessary.  A retrospective study in Belgium found that less than 60% of animals requiring surgical intervention made it to market weight, and calves less than 6 months of age fared far worse than their older counterparts⁴. A separate prospective study in the U.S. on 42 feedlot cattle with diphtheria found 93% surgery survival rate to market weight⁵.  It is unknown how many calves in the U.S. might contract diphtheria, but it is estimated 1 to 2% of feedlot cattle can be affected⁵.  The case reports all point to better outcomes the sooner the calf was identified and received treatment.

Foothill Abortion

The talk through the valleys this year is all about the large numbers of ticks people are seeing this summer.  Unlike the hard brown ticks humans often find on their clothes and pets, there is a soft-bodied tick that can transmit an abortive disease to cattle.  Throughout northern Nevada, Foothill Abortion, or Enzootic Bovine Abortion (EBA), can be passed to unvaccinated heifers and unexposed cows from pajaroello ticks (Ornithodoros coriaceus) carrying the bacteria Pajaroellobacter abortibovis⁶.  Cows and heifers that have never been exposed to this bacteria through vaccine or prior tick feeding are at greatest risk of aborting their late-term fetus.  Recent work has also shown that naïve cattle vaccinated or exposed to the bacteria within 60 days of breeding season could also experience early fetal abortions.  Regardless of abortion timing, fetal losses between 40 - 90% can be financially devastating, especially in this current market.  The ticks are most often associated with Ponderosa and Jeffrey pine, juniper, pinyon pine, large sagebrush, and mahogany habitats and they are most active in July, August and September in Nevada⁷.  While most of northern Nevada won’t be seeing any late term abortions until winter and early spring, now is the time to think about planning pasture rotations for unvaccinated heifers, or planning best locations if moving in cows that have potentially never been exposed before.  Actions to take could involve:

1. Trapping ticks and testing for bacteria presence prior to moving heifers into pastures with tick habitat;
2. Avoiding pastures that you suspect could have resulted in EBA in heifers in previous years; and,
3. Running stocker cattle through any suspect pastures prior to running bred heifers in.  

According to UC Davis, the ticks only feed once every 60-90 days, so running heifers into pastures behind other cattle could reduce infection6.  Planning ahead, consider budgeting for testing for EBA of any late-term abortions found this coming winter or spring.  New geographic areas seem to be experiencing Foothill Abortion in Nevada in recent years within the northern Nevada area, but unfortunately, Nevada doesn’t have a tracking mechanism for this disease yet, so reports of geographical expansion are anecdotal for now.   If you find that your herd has contracted EBA, a vaccine is available.  Due to the activated live form of the vaccine being shipped in liquid nitrogen, and the short time frame to thaw and administer vaccine, many producers will want to work with their veterinarian to plan for vaccine administration more than 60 days prior to the next breeding season⁸.  

Pinkeye Monitoring and Fly Control

Pinkeye is a common ailment of cattle, especially during the summer when fly activity is high. Younger cattle that have not already developed some immunity are most often affected. Face flies are well-adapted vectors for transmitting pinkeye causative agents, such as Moraxella bovis and Moraxella bovoculi and infection bovine rhinotracheitis (IBR virus), from clinically infected animals and asymptomatic carriers to uninfected cattle9.  Cattle with eye irritation or injury from high grass, dust, pollen, wind storms seem to be more susceptible to summer pinkeye.  Clinical signs include swelling and redness around the eye, tearing and squinting, then later corneal ulcers form¹⁰.  With appropriate treatment pinkeye usually heals up within 3 to 5 weeks, but infrequently, corneal rupture, cone-shaped bulges, and blindness can occur.  Consult your veterinarian on which antimicrobial treatment is the most appropriate choice for treatment for your herd.  Of course, fly control is an important key in reducing the spread of the infection across the herd.  Fly ear tags, fly bags, and other devices are potential routes for insecticide control of flies.  Vaccination may be considered, but vaccine efficacy has had mixed success¹¹.  Keep in mind, pinkeye cost estimates between weight loss and treatment costs in beef cattle have shown economic costs up to $100 per infected animal¹².    

Coccidiosis

Coccidiosis usually presents in calves as diarrhea or bloody diarrhea and is caused by a parasite infection usually associated with protozoa of the Eimeria genus¹³.  Infected calves will lose weight and could experience damage to intestinal mucosa.   Stress from severe weather, poor nutrition or stress increase susceptibility of calves to coccidiosis.  Eimeria protozoa are found in cows and calves and are often widespread across the pasture environment.  Prevention and treatment for coccidiosis can involve reducing cattle density, treating water with an approved anthelmintic, or conducting frequent moves using electric fencing may reduce contact with feces from infected herd mates¹⁴. Several medicated feeds are also available for preventing coccidia infections.  Rarely, a neurological form of the disease can hit calves, but it is more typically seen in the fall or winter after stresses like weaning and shipping occur. Clinically infected calves will need treated for the infection and may need supportive care for the associated dehydration.  Your veterinarian should be contacted for testing and drug selection such as sulfa drugs and/or appropriate amprolium treatment¹⁵.     

While summer brings long days on the ranch taking care of hundreds of responsibilities, it also brings a few diseases to keep an eye on.  Some of our rangeland pastures are experiencing drought this year and it will be important to also keep an eye on toxic plant exposures if drought continues to intensify.  Weather patterns can shift rapidly so be on the look out for changes in cattle health if any unusual weather occurs.  Working alongside veterinarians, UNR Extension specialists can assist livestock owners in identifying appropriate diagnostic labs for EBA testing, setting up tick traps for capturing and testing for EBA, and any other ranch specific questions or concerns.  

References 

¹Bovine Veterinarian.  2022.  Pinkeye Prevention Preferred: A little protection can outweigh a lot of cure.  UNR https://www.bovinevetonline.com/news/education/pinkeye-prevention-preferred (accessed 7.15.25).

²Larson, M. L. (2025). The Impact of Wildfire Smoke on Milk Production, Health, and Mortality of Holstein Dairy Cattle in the Pacific Northwest (Order No. 31938784). Available from ProQuest One Academic. (3212456504). https://unr.idm.oclc.org/login?url=https://www.proquest.com/dissertations-theses/impact-wildfire-smoke-on-milk-production-health/docview/3212456504/se-2

³Uddin, M.S., Ortiz Guluarte, J., Waldner, M., Alexander, T.W., 2024. The respiratory and fecal microbiota of beef calves from birth to weaning. Systems 9, e00238-24. https://doi.org/10.1128/msystems.00238-24

⁴Pardon, B., De Bleecker, K., Hostens, M., Callens, J., Dewulf, J., Deprez, P., 2012. Longitudinal study on morbidity and mortality in white veal calves in Belgium. BMC Vet Res 8, 26. https://doi.org/10.1186/1746-6148-8-26

⁵Furman, T.J., Grotelueschen, D.M., Knudsen, D., Furman, J., Furman, S., Griffin, D.D., Theurer, M.E., 2018. Case series: Surgical treatment of non-responding diphtheria cases in feedlot cattle via long term tracheostomy. The Bovine Practitioner 132–136. https://doi.org/10.21423/bovine-vol52no2p132-136

⁶Young, A., 2020. Foothill Abortion (Epizootic Bovine Abortion) | Animal Health Topics / School of Veterinary Medicine [WWW Document]. URL https://healthtopics.vetmed.ucdavis.edu/health-topics/livestock/epizootic-bovine-abortion (accessed 7.11.25).

⁷Oliver, M., Nader, G.A., Blanchard, M., Stott, J., Teglas, M., Becchetti, T., and Bushnell, R. 2016.  Cattle Management Strategies to Minimize Foothill Abortion.  University of California Agriculture and Natural Resources, ANR Publication 8566. 6p.

⁸Hygieia Biological Labs. Beef Cattle Vaccine. URL https://hygieialabs.com/beef/ (accessed 7.15.25).

⁹Angelos, J.A., Maas, J. 2009.  Vet Views: Preventing Pinkeye in Your Herd.  School of Veterinary Medicine, University of California Davis, 2009-05. 6p.

¹⁰Boileau, M., Giedt, E.J., Lalman, D., Whitworth, B. Pinkeye.  Oklahoma Cooperative Extension Service VTMD-9128, 4p.

¹¹Stuttgen, S., n.d. Managing and Preventing Pinkeye [WWW Document]. Livestock. URL https://livestock.extension.wisc.edu/articles/managing-and-preventing-pinkeye/ (accessed 7.15.25).

¹²Merck Pinkeye Quantitative Survey, 2021, Farm Journal, Lenexa, KS.

¹³Richards, D.L., Step, D.L., Giedt, E.J. 2016.  Coccidiosis Treatment and Prevention in Cattle.  Oklahoma State University Extension.  VTMD-9129. 2p. URL https://extension.okstate.edu/fact-sheets/coccidiosis-treatment-and-prevention-in-cattle.html (accessed 7.15.25)

¹⁴Rasby, R.  2020.  Calf illnesses: Scours, Coccidiosis | UNL Beef | Nebraska [WWW Document], URL https://beef.unl.edu/scours-coccidiosis/ (accessed 7.15.25).

¹⁵Hoppe, K. and Stokka, G. 2019.  Coccidiosis Affecting Young Calves [WWW Document],  URL https://www.ag.ndsu.edu/news/newsreleases/2019/april-1-2019/coccidiosis-affecting-young-calves (accessed 7.15.25).