Hypomagnesemia Tetany,Hypomagnesemia Tetany,Lactation tetany, Grass tetany, Lactation tetany, Grass tetany,

Grass Staggers, Wheat Pasture PoisoningGrass Staggers, Wheat Pasture Poisoning

• It is a complex metabolic disturbance ch. by drop of serum and CSF Mg which lead to hyperesthesia, muscular spasms, convulsions, respiratory distress, collapse, and death.

Occurrence and animal susceptibility• Adult lactating cows are most susceptible due to

the loss of Mg in milk. It is rare in non lactating cattle but has occurred when undernourished cattle were introduced to green cereal crops.

• It occurs mainly when animals are grazed on lush grass pastures or green cereal crops, but can occur in lactating beef cows fed silage indoors.

Magnesium functionsMagnesium functions1- Intracellular function:, • Mg is a major component in many enzymatic reactions

within the cell (> 300 enzymes require Mg for activation(. • Without Mg , biochemical reactions within the cell would

cease and death would occur. 2- Extracellular function:, • Mg is essential for muscle function, nerve cell

conduction, and bone formation. • Although around 70% of the Mg in the body is contained

in the bone, this Mg is not very available to the animal in times of Mg deficiency.

• Therefore, it is essential cows receive supplemental Mg in the diet when faced with a deficiency

EtiologyEtiologyI- Sharp decrease in serum Mg and

Ca deficiency may play a role.

• It occurs after a decrease in serum Mg, when absorption of dietary Mg is unable to meet the requirements for maintenance (3 mg/kg body wt) and lactation (120 mg/kg milk).

• Mg def. occurs in high lact. cow raised on pastures rich in K & Nitro. fertilizers.

• Mg absorption from the rumen may be reduced when K and nitrogen intakes are high and Na and P intakes are low.

II- Contributing / stress factors1- Nutritional Stress• Turning cattle onto winter pasture directly from

low quality pasture. • Grazing on young forage, small grain or ryegrass

pastures, or rapidly growing lush pastures are the most dangerous.

2- Weather stress• The disorder is more common during cool,

cloudy, and rainy weather. • Animals, particularly lactating cows, get grass

tetany most often when grazing cool-season grasses or small grain pastures in spring and fall.

II-Contributing / stress factorsII-Contributing / stress factors3- Soil and fertilizer stress• It occurs most frequently on pastures grown on

soils low in available Mg and high in available K. • Heavy applications of broiler house litter or

other high-nitrogen and K manures may increase the hazard of grass tetany.

4- Mineral contents of feeds.• Forages containing less than 0.2% magnesium

and more than 3% potassium and 4% nitrogen (25% protein) are likely to cause grass tetany under the right conditions. Forages that are high in potassium and nitrogen should also contain at least 0.25% magnesium on a dry matter basis

PathogenesisPathogenesis• Disease occurs when Mg drop to < 1

mg/dl (Norm:1.7-3) that may assoc. with hypocalcaemia (< 8 mg/dl)

• Mg have a role as a transmittors of impulses to the muscular system leading to secretion of acetyl-choline that activate choline esterase resp. for musc. contraction.

• Mg deficiency result in muscular tremors, twitch & spasm.

Acute clinical pictureAcute clinical picture• Cows cease feeding on pasture suddenly.• Contracted muscle and ears.• Hyperesthesia, followed by frenzy

movements, blowing , ataxia • Opisothonus, convulsions, Nystagmus, jaw

movement with frothiness of mouth.• Cows lay down with frequent attempt to

raise. • Slight rise in body temp., pulse & respiration.• Increased force of heart beat.• Cows may die in an hours if not treated

immediately.

Cows and ewes with hypomagnesemic tetanyCows and ewes with hypomagnesemic tetany

Sub acute pictureSub acute picture

• It occurs gradually, cows stays for 3-4 days with inappetance, sad face, increased fore & hind limbs movements.

• Cows are reluctant to move, throw head away.

• Increased frequency of urination and defection assoc. with straining.

• Muscl. tremors, mild convulsions esp. on hind legs and tail with ataxia.

• Hyperesthesia.• Cows may recover or lay down.

Chronic formChronic form• Depression may be the only signs observed

at peak of lactation.• Loss of appetite and weight.• May resemble milk fever signs, but don’t

respond to Ca therapy.Hypomagnesemic tetany in sheep• Clinical signs of hypomagnesemic tetany in

sheep occur when plasma Mg is <0.5 mg/dL• It occurs concomitantly with hypocalcemia• The disease in lactating ewes occurs under

essentially the same conditions and has the same clinical signs as in cattle.

Laboratory findingsLaboratory findings

• Drop in Mg and Ca levels in blood and CSF.

• Signs of muscl. tremors observed when Mg < 0.7 mg/dl., Ca < 5-8 mg/dl

• Mild decrease in serum P, increase in serum K.

• Decreased Mg in urine.

DiagnosisDiagnosis

History: • Grazing of adult lactating cows on lush

green pasture rich in K & N fertilizers.

• Bad weathers

Clinical signs of Ataxia, in coordination, Hyperesthesia, in cows at peak of lactation.

Laboratory: Drop of serum Mg < 0.7 mg/dl

Response to treatment by both Mg and Ca preparations.

Diff. diagnosisDiff. diagnosis

1- Acute lead poisoning (Blindness and frenzy)

2- BSE (Frenzy signs have no relation to Mg)

3-Rabies (down paralysis, Dog biting, No convulsions).

4-Nervous from of ketosis. (Ketonemia, ketonuria)

TreatmentTreatment::• It can be successful if given early and without

excessive handling of the affected animal • 200 ml of Mg sulfate 50% injected under the

skin increased the level of Mg in the blood in 15 min. or

• IV inj of 500 ml. of (Ca Borogluconate 25 %, + Hypophosphate Mg 5 %), 50 ml for ewe. or

• Mg lactate 3.3 % iv or sc. or• Mg gluconate 15 % (200-300 ml iv).• Avoid heart & respiration abnormalities during

IV injection

Hypomagnesemic tetany of calves, Hypomagnesemic tetany of calves, Whole milk tetanyWhole milk tetany

It is similar to that of adult cows.It occurs in calves fed on milk from

dams deficient in Mg.Feeding of calves on food def. in Mg

& suckling from dams in its peak of lactation result in whole Milk Tetany

Clinical signsClinical signs

• First sign is cont. ear movements.• Hyperesthesia.• Tachycardia and normal body temp.• Deviation of head and opisothonus. • Ataxia, dropping of ears.

Clinical signsClinical signs

• Difficulty drinking of water, inability to reach water pucket.

• Muscle tremors esp. with kinking abdomen.

• Convulsions, foot pushing, jaw movement, frothiness.

• Incontin. Urination & defecation.

• Cyanotic m.m before death.

How to avoid HypomagnesemiaHow to avoid Hypomagnesemia

Mg should be given as feed additive:1. Daily oral supplements of Mg oxide 60 g to cattle and

10 g to sheep should be given in the danger period. 2. Mg Oxide 7-8 % mixed with Mollas or water and

sprayed over hay and dry food.3. Let pastures to complete its growth and decrease its K

supply.4. Avoid parturition of cows at winter season and delay it

to the end of winter.5. Avoid stress factors.6. Adequate Soil Phosphorus decreases the Grass

Tetany Potential of Tall Fescue Pasture7. Feeding free-choice mineral that supplies 13-15 g of

Mg / head / day for 30 days prior to and 30 days after turnout will control most grass tetany problems.