Willow tetany
Pasture tetany also known as pasture fever is a disease in ruminants that results from a magnesium deficiency in the organism. Magnesium is the muscle necessary to convey the cyclic relaxation of the muscles. If there is a lack of magnesium, the muscles will cramp ( tetany ).
Causes and Occurrences
Pasture tetany can result from insufficient magnesium in the feed ( primary magnesium deficiency ), but also when the absorption of magnesium from the feed is reduced ( secondary magnesium deficiency ). A secondary magnesium deficiency mainly occurs when the potassium content of the feed is significantly too high (e.g. instead of 1% more than 3% of the dry matter). In ruminants, magnesium absorption takes place almost exclusively in the rumen . For the uptake of Mg ++ from the interior into the rumen epithelial cell there is a potential-dependent transport (presumably through an ion channel) and a potential-independent transport which presumably takes place via cotransport with chloride ions. The release of Mg ++ from the rumen epithelium to the blood takes place through a Na + -Mg ++ exchanger.
Pasture tetany occurs primarily when the animals are raised to pasture, as the potassium content in young grass is significantly higher than in older grass. In addition, cold spells in spring are particularly dangerous due to their effects on the growth of the young grass and thus on its potassium content. A typical, clinical picture is the so-called "lying down" of the animals, i. In other words, they are no longer able to stand and lie (depending on the degree of severity / deficiency) in the chest or side position on the floor.
Due to the relatively balanced feed rations in cattle husbandry, the disease plays a completely subordinate role in dairy cattle today or has been replaced by other metabolic diseases ( milk fever , abomasum displacement, etc.).
Clinical picture
A clinically manifest pasture tetany shows itself in cramps, which usually begin with ear beating and violent winking and later appear with stiff, crossed hind legs. There are frequent twitching of the limb muscles and a straight head due to spasms of the neck muscles. Often there is strong excitement, which can go as far as running against obstacles and increased aggressiveness. Within a few minutes to hours, the patient becomes stuck with his head stretched back and legs rowed, as well as apathy . Any external stimulus can trigger new seizures. Eventually the animals become somnolent or even fall into a coma . Palpitations and severe dyspnoea are typical . Death occurs without treatment from cardiovascular failure.
treatment
The success of the treatment depends on how quickly a therapy is initiated. If cramps already occur, self-healing can no longer be expected; with timely veterinary intervention, 70% of the animals can be saved. The initial treatment takes place by administering Mg ++ -containing infusions with constant control of the heart rate. Oral administration of magnesium oxide is then possible.
prophylaxis
- Mg-administration: Before driving out pasture, give a mineral feed rich in magnesium.
- Do not add any sudden feed changes from winter to summer ration or structured feed.
- Improvement of the magnesium absorption: additional feeding of NaCl, increase the crude fiber content of the feed ration, omission of extreme K and N fertilization
- Avoiding stress
Individual evidence
- ↑ PW. von Engelhardt, Gerhard Breves: Physiology of domestic animals . Georg Thieme Verlag, 3rd edition 2009, ISBN 9783830410782 , p. 392.
- ↑ a b Gerrit Dirksen et al .: Internal Medicine and Surgery of Cattle . Georg Thieme Verlag, 5. Afl. 2006, ISBN 9783830441694 , p. 1094