Cow Tales: Cows that fail to clean
April 15, 2011
A routine scene plays out regularly across the grasslands in cow-calf veterinary practices each and every spring. Covered in impervious nylon garb with most of my exposed skin covered in one to two layers of protective plastic, I began to gently tug and “unbutton” the fetid tissue lodged past the cervix.
Veterinarians advance on the retained placenta while the producer flanks the enemy, avoiding the less than pleasant aroma ultimately will permeate the building reaching unknown spaces. Some cattlemen find excuses to visit with the receptionist and fill up on diesel coffee that has brewed all day. A few iron-stomached individuals bravely press onward to provide support, or at least show no weakness. Little do they know the sensory cells lining my nasal passages packed up and moved out years ago, possibly while posting my first bloated midsummer lightning strike for insurance purposes. Few things smell as bas as a televised political debate; cows that fail to clean are one.
A retained placenta is defined as failure to pass the fetal membranes within twelve hours after calving. As alluded to earlier, retained placenta is a relatively common occurrence. The incidence rate is much greater in dairies, with up to 20 percent of the cows suffering the post-calving dilemma. The exact cause leading to the offensive fragrance remains unidentified and seems to be multifactorial. Earlier research focused on different vitamin and/or mineral deficiencies as the cause. Vitamin A, vitamin E, and the trace mineral selenium are the most frequently discussed. Data are not always consistent, but there does seem to be a relationship.
More recent research suggests retained placentas are reflections of the health of the immune system as a whole. Scientists have measured decreased white blood cell activity in cows suffering from retained placenta. So, retained placenta results from a sputtering immune system similar to a high-octane funny car with a tank full of diesel. Protein and energy are part of the biological engine that drives the immune system. The expanding uterus decreases feed intake during late gestation. When combined with the increased energetic demand of lactation, the protein and energy status can become unbalanced and act as additional stressors inhibit optimal immune function and increase the risk of retained placenta.
What is the role of the immune system in expelling fetal membranes? The placenta is the specialized tissue produced by the calf to exchange nutrients and waste with the cow. So, the placenta is the fetal tissue that attaches and communicates with the cow’s uterus. Because it is produced by the calf, 50 percent of its genetic makeup comes from the bull. The calf and its placenta are technically considered a foreign substance to the cow much like a cactus spine or cheatgrass awn wedged along a molar. However, the immune system is suppressed in a pregnant cow to keep her from attacking the developing fetus. After calving the immune system ramps up and begins to work at the placenta. Additional changes in oxygen tension, blood flow and uterine contractions normally expel the placenta within three hours.
Cows that fail to clean have an increased risk of uterine infections. The decomposing tissue is a natural wonderland for any number of bacteria. In advanced cases, the lining of the fragile uterus becomes damaged and inflamed. The bacteria and/or toxins they produce can gain entry into the blood stream and create a clinically ill cow. These individuals go off feed, further suppressing their protein and energy balance, creating added shackles for the immune response. The decreased nutrient intake will suppress milk production to varying degrees and can lead to decreased calf vigor. Additionally, the suppression of the immune system leading to a retained placenta also increases the risk of mastitis in the female, further putting her and her calf’s wellbeing at risk.
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Treatment for cows that need to clean are as varied as the causes. Many different remedies have been tried over the years to remove the offensive tissue. Antibiotics have been placed or infused into the uterus or injected for systemic absorption. Antiseptic boluses or solutions have been infused into the bacterial soup to inhibit microbial growth. Various solutions have been used to rinse the malodorous liquid from the dark reaches of the uterus. Additionally, attempts are also made to stimulate the uterus to contract to expel the fetal tissue and the necrotic liquid it creates.
It can be tempting to hastily remove the placenta; however, producers and veterinarians need to use caution. The tissue needs to be handled gently when attempting to manually remove the retained fetid fetal membrane. The placenta can easily tear leaving behind small bits of nasty. The wall of the uterus can be quite delicate and easily damaged.
Treatment results are generally good, but refractory cases can lead to decreased fertility and even death of the cow. Timely intervention is key and producers need to work with their veterinarian to develop a sound approach to therapy. Herd level nutrition should be evaluated when an unusually large number of animals are affected. A vast number of biological functions must work in concert with an amazing degree of unity to conceive, develop a viable calf, give birth, and return to normal estrous cycles in a timely fashion. I stand in awe.
Nerd Word: Lochia – A vaginal discharge occurring during the first week or two after calving.
kenny barrett jr. is a veterinarian at the belle fourche veterinary clinic in belle fourche, sd and pens “cow tales” monthly. learn more about the clinic on the web at http://www.bfvetclinic.com, or drop them an e-mail at: firstname.lastname@example.org to suggest a topic for the next installment of “cow tales.”