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April 2009 Archive for Cattle Healthline

RSS By: Dan Goehl, DVM, Beef Today

Dan Goehl, DVM, and his wife own and operate Canton Veterinary Clinic in Canton, MO, where Dan works primarily with stocker and cow/calf beef operations.

Watch for Grass Tetany

Apr 20, 2009

By Dan Goehl

 


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Grass tetany, or hypomagnesemia, is a metabolic disorder that can affect adult beef cattle. This syndrome is a result of low magnesium levels in the circulatory and nervous systems, and it is most common when lactating cows graze lush green pastures including annual ryegrass, small grains (i.e., oats, rye, wheat), and cool-season perennial grasses (i.e., tall fescue). 

The occurrence of the syndrome is seasonal and related to the flush of new forage growth associated with the onset of spring. The syndrome is more frequent when pastures have been fertilized with potassium and nitrogen and when solids are naturally high in potassium and low in sodium. Onset of disease is related to low magnesium intake, high potassium and low sodium intakes, and low blood calcium levels (due to peak lactation). 

Early identification, appropriate treatments, and prevention are keys to minimizing negative herd impacts from this disease.

Symptoms:

Cows in early stages of grass tetany may be restless, isolated from herd, and stop eating. Individuals may also be easily excitable, and may run away or charge when disturbed.  These animals may walk with a high-stepping action of the forelimbs when excited. 

Later stages involve uncoordinated walking and eventually staggering and falling to ground. Animals will be unable to get up and typically suffer from excessive muscle contractions, seizures and eventually death.  The progression of clinical signs is relatively quick, and the first signs noted may be a down cow or a dead animal.  Diagnosis of the syndrome is typically based on the type of animal affected, time of year, and a physical examination. The diagnosis can be confirmed by your veterinarian with blood work illustrating a low magnesium level.

Treatment:

Due to the rapid progression of the disease, treatment is most successful early in the disease progress. Prognosis for recovery is related to the time interval between onset of clinical signs and institution of treatment. Treatment of affected animals will involve increasing the magnesium blood levels. 

The most rapid and effective method is through intravenous therapy, and you should consult your local veterinarian for prompt treatment of down animals. Success of intravenous treatment will depend on appropriate product selection, rate of administration, and monitoring animal’s response to determine proper dosages.  Follow up treatments for individuals may include oral magnesium gels.

Prevention:

Ideal management of grass tetany or hypomagnesemia is prevention of the syndrome. Prevention techniques involve Mg supplementation and forage management. 

The most reliable method of prevention is supplemental feeding of magnesium on a daily basis immediately prior to and during the grass tetany season. The appropriate levels can be incorporated into the ration as a part of a free-choice mineral or a pre-mix added to a ration. A reasonable goal for magnesium levels is 14% magnesium mineral with a projected intake of four ounces per head per day. 

Supplementation should start four to six weeks prior to expected onset of spring lush grass growth. Remember that magnesium is not very palatable to cows, so mineral consumption should be monitored and formulation adjusted to be sure adequate intake is achieved.

Adding legumes to pastures alters forage composition and increases pasture quality and improves levels of magnesium. Appropriate fertilization techniques should be employed by regularly testing pasture soils and applying appropriate levels of lime, nitrogen, phosphorus, and potassium. 

In summary, low magnesium or grass tetany, can cause a severe disease syndrome in beef cows.  The disease typically affects lactating cows grazing lush grasses.  Treatment success is dependant on early identification of disease and prompt treatment by your veterinarian. 

Prevention is key to management and centers on magnesium supplements for the cow herd during the susceptible period.  If you have more questions about grass tetany in your area, please contact your local veterinarian.

 

Dan Goehl, DVM, and his wife own and operate Canton Veterinary Clinic in Canton, MO, where Dan works primarily with stocker and cow/calf beef operations. Dan is also partner in Professional Beef Services, LLC, which offers herd consultation and helps in data management and marketing of beef cattle.

 

Prolapses part of spring

Apr 06, 2009

By Dan Goehl


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Aaaahh – spring.  This is the time of year my wife wonders if I am coming or going. I often joke that I spend my time pulling things out of cows and putting things back. I thought I would focus on the putting things back. 

Prolapses are an inevitable part of spring. They can happen during any month of the year but in general spring is when we see the majority of cases. There are basically three types of prolapses that we deal with--rectal, vaginal and uterine. It is important to understand the differences between them to evaluate the urgency of the situation and the longevity of keeping the animal in the herd. 

Rectal prolapse is usually seen in young, yearling age animals although it can be secondary to a vaginal prolapse. Often these are the result of young bulls riding one another. A rectal prolapse if identified early is rarely life threatening. These are not “emergencies” but need to be tended to within hours of diagnosis.  The general process involves giving the animal an epidural to numb the area. This is done by inserting a small amount of a drug called lidocaine in the space between the last movable vertebrae. After this takes affect the prolapse is replaced. 

To understand the mechanics of replacing a prolapse think of a sock turned inside out. All three prolapses are similar in principle and must be completely inverted back to their original position; just as you would a sock being turned inside out before putting it on. I then place a purse string suture which encircles the rectum to keep the prolapse from reoccurring. When rectal prolapses are left unattended too long they become necrotic, meaning the flesh begins to die, and become much more difficult to rectify. Often this tissue will have to be amputated.

Vaginal prolapses occur most often due to relaxation of ligaments prior to or post calving. The tissue that is seen is either the vaginal cavity or the cervix. These are also not life threatening if addressed early. The downside is that a cow with a vaginal prolapse will likely have one again the following year. There are varying techniques employed to fix these depending on the stage of pregnancy and personal preference. Often a stitch is placed similar to a rectal prolapse but it has to be removed from a pregnant cow before she can give birth. 

It is important to be able to distinguish between a vaginal and uterine prolapse. A uterine prolapse is a life threatening event and needs to be addressed as quickly as possible.  Uterine prolapses occur immediately post calving and can be distinguished by a huge mass of tissue that has knots on it about the size of a small child’s hand. These are cotyledons that connect to the placenta and pass nourishment to the fetus during pregnancy.  Due to the fact that the fetus resides in the uterus it is impossible to have a uterine prolapse in a pregnant cow. 

Although these are the most urgent of the three types of prolapse we have discussed, they have the best long-term prognosis. The immediate danger is from bleeding due to rupture of the uterine arteries. If the cow does not suffer severe blood loss or shock then her reproductive future should not be impaired. 

Rectal, vaginal and uterine prolapses all require attention and warrant a call to your veterinarian.  It is helpful to know the difference so you know the urgency of the situation.  Good luck with spring calving!

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