Lambing 2 - Metabolic Diseases of the Ewe
Part 2 of a series of 5 articles:
A well-managed pregnancy should avoid the most common problems, but it’s a good idea to be aware of what might go wrong, what you can deal with yourself, and when to call for expert help. The metabolic diseases described in this article are all life-threatening to the ewe, and in the first two cases, her unborn lambs; so if you are in any doubt about the diagnosis or treatment, call your vet as a matter of urgency, as the ewe and lamb’s survival are dependent on prompt action.
The lamb’s rapid growth in the last few weeks of pregnancy places a huge demand on the ewe’s energy reserves, which, if not met, can disturb her body’s metabolism, especially if she is carrying multiple lambs. Good management and nutrition of the ewe throughout her pregnancy is the first step in avoiding metabolic disease, and monitoring the ewe’s body condition score (BCS) throughout her pregnancy is the best way to ensure that this aspect of her pregnancy is on course, especially during the winter months when a thick fleece may hide her true condition. Aim to maintain a BCS of 3, on a scale of 1-5 with 1 being very thin and 5 being very fat (if you’re unsure how to condition score your sheep, we have posted a video of Adam Henson demonstrating how to do it; search YouTube for “Condition Scoring Sheep”).
There are 3 main metabolic diseases of the ewe, all of which require prompt action if the ewe and her lambs are to be saved. Since the symptoms can be difficult to tell apart without blood or urine testing (which takes up vital time), it’s often advised to treat as though all 3 conditions are present. As soon as you spot the first signs of a problem, bring the ewe into a deeply strawed pen under cover for treatment. In all cases ensure she has fresh water, good hay and concentrate feed, and try tempting her with soaked sugar beet shreds.
Twin Lamb Disease
(Also known as Pregnancy Toxaemia) is a disease of both undernourished and occasionally, overfat ewes, carrying twins or triplets. As the unborn lambs’ growth rate accelerates during the last few weeks of pregnancy, the ewe’s own fat reserves are broken down in her liver into units called ketones. If the energy deficit is too great and the ewe metabolises too much fat, the level of ketones in the blood begins to poison her (ketosis). The quicker the condition is recognised and treated, the better the chance that she and her unborn lambs can be saved - but be aware that the prognosis is poor in many cases.
Symptoms: the first sign you’ll notice is likely to be a ewe standing apart from the flock, not grazing, or not coming to the trough at feeding time. She may be unable to see, and will not move away when you approach her. You may notice she has a foamy mouth and nostrils and is grinding her teeth, which is a sign of head pain, and as you get closer, you may see facial or body twitching. Smell her breath for ketones – the scent of ‘pear drops’ or acetone (like nail polish remover); this will almost certainly mean a diagnosis of Twin Lamb Disease.
Treatment: the ewe’s immediate requirement is for a source of energy and your vet may prescribe a course of intravenous glucose injections (which must be administered by the vet). Alternatively, you can give a form of glucose (glycerol, Propylene Glycol or ‘Ketol’) orally, which is quickly absorbed and rapidly broken down in the liver to provide the glucose the ewe urgently needs. You can buy litre containers of ready to use ‘Ketol’ in most country stores, or ask your vet. Treatment is intensive; an initial dose of 60-100ml should be administered orally as a ‘drench’ and repeated every 4-6 hours until improvement is seen. The ewe should quickly show signs of recovery (eg. renewed interest in food), if not, there may be other factors involved, such as Hypocalcaemia (see below).
If one ewe suffers from Twin Lamb Disease, it may be a whole flock problem, and urgent action should be taken to correct flock nutrition (see last month’s article on Pregnancy Management & Ewe Nutrition).
(Also known as Milk Fever) can occur both in late pregnancy and rarely, during the first few weeks after lambing. The condition can be induced by some form of stress (eg. poor nutrition, extreme weather, dog worrying, too little space in the lambing shed leading to bullying: even moving to a new field can trigger a stress reaction) that interferes with her normal metabolism, in this case leading to low blood calcium.
Symptoms: in the early stages the ewe walks with difficulty, she’ll generally be quiet, sitting with her head up, but not cudding. Her pupils will be dilated, and she may appear to be blind. As the condition progresses, she will become recumbent, laying on her side, or with her chin on the ground unable to raise her head and she may start to produce a frothy fluid from her mouth and nose.
Treatment: if treated soon enough, the ewe will respond quickly and make a full recovery, but speed is of the essence. As the symptoms of Hypocalcaemia can appear similar to those of Twin Lamb Disease, treat for both conditions. To replace the calcium deficit, use a proprietary calcium and dextrose mixture. Warm the solution to body temperature, then using a 18mm gauge needle inject a large dose (50-80ml) subcutaneously (under the skin, as opposed to into the muscle) split across three or four sites and gently massage to spread the fluid and aid absorption into the blood stream. The ewe should respond to this treatment within 30 minutes.
(Also known as Grass Staggers) usually occurs in the first 4-6 weeks after lambing, but can occur before lambing. Fast-growing spring grass is often very low in magnesium, especially if it has been heavily fertilised with nitrogen and potash fertiliser, resulting in low blood magnesium in the ewe, particularly those feeding two or more lambs.
Symptoms: animals will appear over-alert and restless, they may have a staggering gait and be aggressive, if left untreated the condition progresses quickly, causing excitability and spasms, or convulsions, leading to collapse and death in a few hours.
Treatment: treat as an emergency and inject the ewe with 50-80ml magnesium sulphate solution (warmed to blood temperature and injected subcutaneously at 3-4 different sites). Bottles are available from your vet, or animal health counter and will often also contain calcium, which is useful as there may also be an element of Hypocalcaemia involved. Carefully follow the directions on the bottle, and keep it close to hand during the time around and after lambing. You can take steps to prevent ‘staggers’ by having your soil or forage analysed to detect low magnesium, and if so, providing ‘Hi-Magnesium’ buckets or licks in the field pre- and post- lambing. However, there is obviously no guarantee that all the ewes will take a sufficient quantity.
Remember, all these diseases are preventable, and if spotted early enough are treatable, so it’s a good idea to stock up on treatments well in advance of lambing. If you are unsure about administering any of the treatments described above, call your vet as a matter of urgency.
More information on caring for your flock during the breeding season can be found on “The Breeding Flock” DVD.
Next month in 'Lambing 3':
This article first appeared in Smallholder Magazine, February 2012 - written by Carole Youngs of The Smallholder Series.