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However, few issues are more upsetting to dairymen than fighting case after case of clinical mastitis with more and more cows in the sick pen. It represents extra time to properly handle such cows, lost production, vet calls, treatment products, concern about contaminated milk and an occasional dead or culled cow. Clinical mastitis is a highly visible problem and generally produces the impression something has gone wrong. It causes dairies to question everybody and everything including milking equipment, milking procedures, teat dips, housing and the weather.
Clinical Mastitis Symptoms
Examination of milk filters after milking also can be an indicator. The presence of slime and clots on filters indicates clinical cows were milked but that milk is now in the tank.
The relationship between any of these visual characteristics and the specific type of bacteria responsible is generally weak. Culturing milk samples from infected cows is the best tool to determine the species of organisms involved in a clinical case but be cautious with results. Always involve a veterinarian familiar with interpreting milk culture reports to help assess the situation and determine an appropriate course of action.
Clinical Samples -- No Growth Culture Indication
Clinical Mastitis -- Related Factors
Certain bacteria species are more likely to be associated with clinical outcomes than others and there also appears to be an association between season, climate and parity and clinical problems. The hot weather of late spring, summer and early fall tends to be associated with more clinical cases.
Benchmarks -- What’s Normal
Be careful with the numbers. Clinically infected cows may be repeat offenders and a single cow may account for multiple clinical cases. Such cows require special consideration. Looking only at cows developing new clinical infections, in a defined timeframe, helps eliminate the bias of repeat offenders.
When a number of these infections occur in a short period it can cause everyone to think somebody or something has changed and is causing the problem. Teat dips and liners are often switched in an attempt to stop the problem but the actual cause may be something totally different.
Factors Influencing Clinical Mastitis
Contagious bacteria reside primarily in the udders of infected cows and on the teat skin. Minimizing or eliminating mastitis caused by contagious organisms is best accomplished by a rigid program of post milking teat dipping, treatment of cows as they are dried off and culling of chronically infected cows. As contagious mastitis problems are minimized, environmental bacteria become the primary mastitis concern and unfortunately a high percentage of infections caused by this group are likely to cause clinical symptoms.
Why? Many reasons have been offered, all likely play some role. Dry cow treatments are ineffective against coliforms. Also, dry cow products do not persist through until calving. Suppressed immunity, cleanliness of dry cow housing areas and physical characteristics such as leaking milk and swollen udders may play a role. Milk fever, ketosis, lameness, fat cows, displaced abomasums also occur more frequently around calving and during early lactation. These disorders likely pre-dispose cows to mastitis problems even though they may not be the primary cause.
What’s The Cost?
How Do You Prevent It?
Body condition scoring is helpful in assuring cattle are not too fat or thin. Fat cows often have difficulty transitioning to lactation and can suffer from fatty livers and downer cow problems. Early lactation cows may not be able to handle the transition period when they have to use body condition to supplement dietary energy intakes and may suffer ketosis.
Each of these factors can pre-dispose cows to other health problems including clinical mastitis.
Evaluate the contagious mastitis profile in the herd. If it is minimal most mastitis problems are likely to be associated with environmental bacteria and clinical cases. Determine if there is a pattern to the occurrence of clinical cases.
Evaluate pre-milking udder prep procedures. Milking clean dry teats is one of the most effective ways of preventing environmental mastitis and everyone periodically has to be reminded of this. Dirty teats, wet teats and long udder hair all contribute to potential clinical problems due to an increased presence of environmental bacteria.
Prepare for seasonal problems. Coliforms and environmental Streps thrive in bedding and where manure buildups occur. Under warm, moist conditions numbers can dramatically increase exposing teat ends to very high bacteria concentrations. Such conditions are common during spring through late summer in most areas. Maintenance of stall conditions during these periods is critical to minimize problems but it is not only stalls. Each of these conditions causes increased exposure to high levels of environmental bacteria even under conditions that would appear ideal.
Heat can add to problems and force cattle to congregate in shady areas seeking relief. The end result may be buildup of very high levels of bacteria in places that are not normally a concern. These include areas under corral shades, shade trees and similar locations. These situations have to be properly managed to limit problems.
Clinical mastitis is no fun and can be the cause of serious infections and milk loss. Understanding potential causes and proactively taking action to minimize them will help limit the problem.