This time of year when we get an early flush of grass one needs to be cognizant of grass tetany, especially in milking cows.
The herd may have multiples cases in short order. Once clinical signs occur and cattle go down chances of recovery are very poor so treatment wise they are a true emergency.
Early in the course of the disease treatment is very successful and your veterinarian will try and initiate steps to prevent further cases. This article will discuss clinical signs treatment administered by your veterinarian and most importantly steps to prevent this often-fatal syndrome caused by a magnesium deficiency or a potassium magnesium calcium imbalance. A complicated thing I know but often initially treatment is the same in the form of magnesium calcium phosphorus intravenous solutions.
In a classic case of grass tetani cattle (especially mature cows) become weak staggery go down and develop tetanic convulsive fits. Paddling with the front feet and snapping of the eyelids can also occur with heavy breathing and foaming at the mouth.
When your veterinarian examines affected cattle they often find a very high heart rate and potentially elevated temperature from all the hard work the muscles are doing. Not much else is found and since the cow is down veterinarians often administer a combination of calcium, phosphorus and magnesium much the same as one would treat a milk fever as these three minerals together or in combination may be low enough to cause a downer cow.
Most clinics are now set up to do in house blood work so many veterinarians will often grab a blood sample before they begin to check for the levels of these minerals. We often see magnesium and calcium low together. Occasionally we look for high potassium another macromineral as it can lead to a secondary grass tetani. Since one can’t remove the potassium the treatment is more magnesium to get the ratio right. If one can determine feed or soils that are higher in potassium that helps with prevention going forward.
The real problem with grass tetany is it generally comes on very suddenly without warning and death can be very sudden. Post mortems show very little and often leaves the veterinarians scratching their heads unless clinical signs are seen.
Treatment initiated before they go down or just as they go down is often successful. If down for a time, treatment although it may reverse some signs cattle seldom get up. So as the producer, a suddenly down cow is really a veterinary emergency.
The combination of calcium, phosphorus, magnesium products are often given by slow intravenous injection and more can be given subcutaneously or intraperitoneally. Your veterinarian when giving it intravenously will often listen to the heart so if problems occur administration can be quickly slowed down or stopped.
Farmers can then be trained to watch for new cases and if the magnesium combination can be given intraperitoneally or subcut quickly enough that may be enough. I generally when giving the intravenous product tie the head with a halter to the backleg so they cant get up before the entire treatment is given. Generally one bottle IV and one bottle by another route is the normal treatment. Repeating may be necessary but do this under advisement from your veterinarian.
If one cow is magnesium deficient it is not uncommon for more cases to develop rapidly and one must assume the whole herd could be borderline deficient.
In almost all cases I have seen mineral feeding has been sporadic to non-existent for the past year. Magnesium is what you call a macromineral along with the likes of calcium and phosphorus. These deficiencies may be a long time coming. Stresses like weather changes, starvation for even 24 hours, heavy pregnancy or milk loss from sucking by well doing calves will lead to deficiencies. In a group of cows the lactating ones are usually first affected.
Changes to lush green pastures coupled with inclement weather can also precipitate an outbreak (lush grass lowers the magnesium level). Pastures fertilized with nitrogen fertilizer also. I have seen a group of well doing heifers on a sound mineral program that were starved for 24 hours to facilitate spaying have an outbreak when the weather turned inclement.
Not only do we want to treat clinical cases when they occur we want to prevent further cases from developing by getting the much needed magnesium into them. Force feeding or drenching with magnesium oxide may prevent further cases if along with this we start supplementing with a good mineral program containing magnesium.
Good trace minerals will have macrominerals such as calcium, phosphorus and magnesium as well as many micro minerals such as copper and zinc. All three macrominerals cause downer cows but most definitely the most serious of these deficiencies in beef cattle is magnesium.
You can see your mineral program is absolutely key to preventing this sudden killer of cattle. Some areas have needed to increase the levels of the standard amounts of magnesium because of severe deficiencies or if the soil and subsequent growth contains too much potassium. Work with your veterinarian and nutritionist or feedmill to make sure you have adequate of the macrominerals in your program and always keep a close eye on cattle in times of stress or fast growth of forage or in inclement weather.
Not all cattle will eat adequate amounts of minerals even though we have it out for them and I suggest larger producers have a few bottles of the calcium magnesium phosphorus to have on hand. It is good to have a large animal IV set to make it easier to administer the product. Maybe double check with the clinic before you give it but if administered in time can save a cow’s lif.
As previously mentioned, producers usually give it subcutaneously or intraperitoneal if it is approved that way. If you have been trained and are skilled at giving it intravenously it must be given slowly usually over about 15 minutes.
This is a condition that is entirely preventable so by supplying good quality minerals you can prevent grass tetany as well as many other mineral deficiencies in your herd. Most other deficiencies come on slower but grass tetani is rather dramatic and it is the sort of drama we can use less of in our cattle herds.
Here’s to a great grazing season everyone.
