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  • Writer's pictureLeslie Graham

What is a Clostridial?- Understanding Vaccines.

Vaccine labels have lots of big scientific words and can be very confusing. It is important to understand the diseases that each vaccine is protecting against. Something like the word clostridial. Most ranchers relate this term to blackleg. However, that is not the only disease that a seven or eight-way clostridial is protecting against.

First, let's try to understand the word clostridial. Clostridial diseases are caused by prokaryotic bacteria. Prokaryotic refers to a cell that lacks a nucleus and membrane-bound organelles. This just means the cell is not divided by membrane walls but instead is one open space. The prokaryotes in cattle are large, anaerobic, spore-forming, rod-shaped, gram-positive bacteria. Spores are a dormant form of bacteria that can live in the soil or in the intestinal tract of animals. Clostridial diseases occur when living organisms or dormant spores are activated and begin reproducing in tissues. This bacteria will produce toxins that spread infection and begin to cause symptoms of the disease. Some clostridial diseases that affect cattle include blackleg, bacillary hemoglobinuria, malignant edema, botulism, enterotoxemia, and tetanus. I am not going to go into detail about each disease in this blog post but please reach out if you have any questions about any of the diseases or check out the Merck Veterinary Manual for detailed information on these diseases. There are many different options for clostridial vaccines on the market for cattle. Selecting the correct vaccine for your herd involves a discussion with your vet and an understanding of the disease risks of your area. The clostridial diseases Not all clostridial vaccines include the bacteria strain for tetanus, therefore, when castrating bulls, ensure you have the correct clostridial with protection against tetanus. Some clostridial vaccines include protection against Haemophilus somnus which is a severe respiratory disease that can also spread to other organs of the body. H. somnus is often fatal to feeder cattle and therefore understanding your risk factors will help with vaccine selection and in turn, decrease mortality risks.

Another common product used in feeder cattle is a vaccine for pneumonia bacteria. However, the bottle reads "Bovine Rhinotracheitis-Virus Diarrhea-Parainfluenza 3-Respiratory Syncytial Virus-Mannheimia haemolytica-Pasteurella multicide Vaccine". This is directly from a Bovilis Vista Once box. That just looks like a lot of big scientific words that don't actually tell a producer much. So let's try to simplify this. Vaccines like this are directed at bacteria that cause bovine respiratory diseases (BRD) and bovine viral diarrhea (BVD).

The most common bacteria to cause BRD include Mannhemia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. Viral pathogens can also be involved such as bovine herpes virus 1 (IBR) and bovine viral diarrhea virus (BVDV). BRD develops as a response to environmental factors, host factors, and pathogens. Stressors in the environment and the host will negatively affect the immune system in the animal and open that animal up to attacks from these pathogens. This is why many BRD cases are seen in extreme temperature changes or stress events, such as weaning and feedlot induction. Most of these bacteria will colonize in the upper respiratory tract (ex. rhinotraceitis) but can move down to the lower respiratory tract to cause diseases like bronchopneumonia. This is the reason for the development of intra-nasal vaccines. The goal of these vaccines is to combat the bacteria directly at the source before colonization occurs. However, some of these bacteria will migrate through the body and cause problems elsewhere. For example, mycoplasma can move through the body and cause mastitis or arthritis.

BVD does not only refer to the symptoms of diarrhea caused by this virus but the immunosuppression caused by these infections. A large concern with BVD is persistently infected cattle, which are cattle that carry and shed the virus but often have no clinical signs. These animals

will spread the virus very quickly to pen mates. I could do a whole blog post about BVD and the effect it has on cattle. However, to keep this simple I just want to make it clear that these pneumonia vaccines also provide protection against BVD.

The majority of the vaccines on the market that are directed toward these organisms claim to have the same coverage. Therefore, the selection of this product depends on your preference, experience, and veterinary advice. These products are modified live vaccines and require reconstitution (mixing) of the freeze-dried vaccine powder with a diluent. This will be the first year we are trying out an intranasal vaccine for our feedlot cattle. We are going to test it against cattle that are given an injectible to observe the response differences.

Hopefully, this brief summary of clostridial and BRD vaccines will help you decide on the correct treatment for your calves as they transition onto feed. This is a stressful time for calves and giving them immunity boosts is the best way to decrease morbidity and mortality. I was trying not to overwhelm anyone with information but if you would like more you can reach out to me or you can check out websites such as the Merck Veterinary Manual. They provide a lot of information on vaccines as well as disease epidemiology, clinical signs, and treatment.



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