Scours stink! In one sense, that’s all you need to know.
Like so many other things in life, it’s more complicated than that. What’s really important here is that this disease continues to harm and kill calves, and hurt farm businesses. Diarrhea is the most common disease in pre-weaned heifers, with 21 percent of all heifers affected (Source: NAHMS). And 20-plus years of using vaccines hasn’t changed this statistic.
Let’s dissect this diarrheal enemy, for a better way forward.
If you know the enemy and know yourself, you need not fear the result of a hundred battles – Sun Tzu
1.) Things that cause calf scours
There are multiple contributing factors to scours, including bacterial, viral, parasitic, nutritional and environmental. We’re focusing here on bacterial and viral factors.
Calves usually get infected with E. coli in an environment with poor sanitation. Coronavirus and rotavirus can be caused by a number of factors such as poor sanitation, a dirty environment, stress, and cold and wet weather. A poor-quality colostrum can lessen a calf’s ability to withstand attacks from bacteria and viruses.
Rotavirus is generally found in 75 percent of scours cases. Calves that break with rotavirus are twice as likely to also break with cryptosporidium (an opportunistic disease), and are 17 times more likely to require a respiratory treatment at or before movement to the first group pen.
Because these are nasty bugs, it’s vital to have excellent management practices in place that keep calves healthy and the environment as clean as possible.
2.) The thing that exacerbates calf scours
While it’s common for calves to show the symptoms mentioned for five to seven days, calves can also shed the rotavirus pathogen into the environment post-infection for much longer.
Amplification or significant disease outbreak can occur in a herd when rotavirus spreads among infected calves and gets shed by these calves into their environment. This environmental pathogen load builds up to a level that can overwhelm the immune status of herd mates, creating significant illness and death loss. This is a core driver of new rotavirus infections – large exposure to the pathogen shed into the environment over a short span of time, particularly under stress conditions.
3.) The thing that affects the severity of a scours outbreak
The pathogen load in the environment, as just mentioned, versus the immunity balance predicts the severity of scour breaks. The level of antibodies in a calf’s system is what creates immunity.
An antibody’s job is to bind pathogens so they are no longer infective and cannot multiply. So, if the antibody levels are higher than the pathogen load, infection is avoided. If the level of antibodies versus pathogen load are at balanced levels, you will be getting by but living a bit on the edge. Scour breaks are more likely to be triggered by minor stressors such as temperature fluctuation and feeding inconsistencies.
Now if the pathogen loads are higher than antibody levels, this is when antigens will attach to the gut and reproduce rapidly. The calf will become infected, show clinical symptoms, and the pathogen will be shed into the environment. Shedding amplifies the disease across the herd as it infects herd mates.
4.) Things you can do if scours strikes
Detect it early. Early detection is vital to preventing death due to a scours event. Watery stool is your first sign of scours, which typically leads to dehydration.
You also might see reduced milk intake, weakness, and bloody stool. A rectal temperature of more than 103 degrees Fahrenheit can also indicate presence of this disease.
If you’re in the position of having to treat, consult with a veterinarian for an appropriate treatment plan. Your veterinarian will be able to set up specific protocols for your farm regarding next steps to take after experiencing a scours outbreak, whether that be implementing the use of electrolyte replacement, nutritional and fluid therapy, antibiotics or a combination of these.
5.) Things you can do to prevent scours
Now that you know the enemy, know yourself. How do the precautions you take stack up to top management practices? Find out by reading countering the complexity of scours with a focused effort.