Introduction/Causative Agents:
Grass tetany (lactation tetany or transport tetany) is caused by low levels of magnesium (Mg) in the animal. Low levels of magnesium cause decreased energy metabolism and other changes to normal body functions. Blood levels of magnesium should normally be 2.0-3.6 mg/dl.Magnesium must be consumed in the diet. Wheat, cereal crop feeds, and some pastures are usually low in magnesium; therefore, animals grazing on these feeds may develop grass tetany. Magnesium is also lost in the milk. This is why some lactating animals may experience this problem. When animals consuming a low magnesium diet are stressed because of being moved or transported, tetany often results. Calcium levels also appear to play an important role in grass tetany.
Clinical Signs: In the early stages of disease, the animal may go off feed, be very alert, and excitable. The ears and muscles often tremble and the animal can be aggressive when stimulated. With time, the animal has a lack of coordination and may eventually collapse in seizure-like activity. If not treated properly, death can occur within hours.
Diagnosis: Because grass tetany can look like many diseases, it is important to measure blood levels for magnesium. This is done by taking a blood sample to a veterinarian for analysis. Some additional clues can be found by examination of the animal, along with any response to treatment. If the animal dies, a sample of the cerebral spinal fluid or contents of the eye (vitreous) can be tested for magnesium levels. This must be done within 48 hours after the death of the animal.
Treatment: In most cases, give 50-100 mLs of CMPK or another solution that contains magnesium borogluconate (3.2 mg/mL) and calcium borogluconate (21.6 mg/mL), intravenously (IV). This should be given slowly. The heart should be monitored during administration. If any abnormal or irregular beats are noted, discontinue administration immediately! Whatever source of magnesium is chosen, be sure that it includes calcium.
Prevention: Magnesium supplementation in liquid or dry form is required for routine prevention. Magnesium should make up at least 0.12 - 0.18 percent of the diet. The use of magnesium mineral blocks are also very beneficial. Because blood magnesium levels drop within 24 hours after oral administration is discontinued, magnesium must be given on a daily basis.
* Before initiating any treatment, CONSULT A VETERINARIAN!