Transit tetany typically occurs in sheep subjected to transport stress, but it can also occur in sheep deprived of feed or water during yarding and handling. Affected sheep are hypocalcaemic and sometimes hypomagnesaemic. Older, fat, pregnant ewes or lactating ewes are most at risk, but it can occur in sheep of any age. Sheep grazing lush pastures or concentrates prior to transport and forced to exercise immediately after transport are also more susceptible1.
A mob of approximately 200 lambs was brought in three days prior to crutching on a well-managed sheep/cropping property in the Murraylands area. The four-month-old lambs were grazing lush cereal/legume pasture and travelled a short distance to yards where they were provided with good quality hay for two days whilst being crutched. All the lambs had a complete vaccination and parasite management history.
On release from the yards and whilst moving them back to the paddock, 15 lambs collapsed, some developed arched necks, were frothing at the mouth and two died. After a period most recumbent lambs appeared to recover and continued to the paddock, but one lamb remained recumbent, weak and unable to stand.
The lamb that remained recumbent was examined the following day. It was found to have normal clinical signs, and good mucous membrane colour, no evidence of injury or central nervous signs, but did appear weak. The lamb was not blind.
Treatment of 2 mls of thiamine injection2 was given intramuscularly and the lamb observed, and a blood sample was taken for analysis. Two more injections of thiamine were given at four-hour intervals and the lamb recovered and returned to the mob.
|General biochemistry||Specimen: Serum|
|Sodium||160||mmol/L||<142 - 152)>|
|Potassium||5.1||mmol/L||(3.9 - 5.4)|
|Chloride||114||mmol/L||(95 - 103)|
|Bicarbonate||23||mmol/L||(21 - 28)|
|Urea||3.6||mmol/L||(3.0 - 7.1)|
|Creatinine||44||µmol/L||(106 - 168)|
|Calcium||1.80||mmol/L||(2,30 - 2.80)|
|Phosphate||4.76||mmol/L||(1.62 - 2.36)|
|Magnesium||0.4||mmol/L||(0.9 - 1.3)|
|GLDH||53||U/L||(7 - 76)|
|B-OH Butyrate||1.6||mmol/L||(0.5 - 0.6)|
|Protein||63||g/L||(60 - 79)|
|Albumin||38||g/L||(24 - 30)|
|Globulin||25||g/L||(35 - 57)|
|T. Bilirubin||3||µmol/L||(2 - 9)|
|Alk Phos||170||U/L||(70 - 390)|
|GGT||2||U/L||(20 - 52)|
|AST||360||U/L||(60 - 280)|
|CK||4891||U/L||(100 - 547)|
|Cholesterol||2.2||mmol/L||(1.3 - 2.0)|
Increased haematocrit and albumin were consistent with dehydration, and dehydration also likely explained the hypernatraemia and hyperchloraemia. This animal was also ketotic, indicating significant negative energy balance. Ketosis could potentially produce the clinical signs reported. Low calcium could reflect poor nutrition and/or parasitism, particularly as there was also hypoglobulinaemia, and low calcium could also have contributed to recumbency. Hypomagnesaemia likely reflected decreased feed intake. Mild muscle injury was likely secondary to tremors and/or recumbency.
The history, clinical findings and laboratory results supported a diagnosis of transit tetany. It is possible that the sheep also had thiamine deficiency as it apparently responded to thiamine treatment. Differential diagnoses included exhaustion, polioencephalomalacia and lead poisoning – in the latter two diseases, animals appear blind.1
Recommended treatments for this condition include magnesium sulphate and calcium borogluonate. In other circumstances I have seen good results with treatment of sheep giving 30-50% solution of “Vytrate” liquid orally (about 500mls) and propylene glycol.
The 15 affected lambs that initially collapsed and recovered may have been “shy feeders” and may not have eaten hay in the two days whilst in yards or had good access to water.
Episodes like the one reported here may be prevented by including some calcium/magnesium and Vitamin B1 solution in stock water in yards at these times, for example “TransForce Liquid © 3”.
2. Vitamin B1 Injection Ceva Animal Health Pty Ltd – dose 1- 2 mls by IM or SC injection for lambs
3. TransForce Liquid – a Transition supplement for Cattle and Sheep Compass Feeds