Watery Mouth Disease

Sheep Diseases

Watery Mouth Disease

Also known as: E. coli infection in lambs

Watery mouth disease (WMD) is an important bacterial disease of neonatal lambs, especially in an intensive indoor situation. It is most common in lambs between 6 and 48 hours old and can cause severe losses, with morbidity sometimes reaching 24% and mortality of those affected as high as 83% (Eales et al., 1986).

Illustration of the factors which cause Watery Mouth Disease

A combination of factors is responsible for the development of watery mouth. Lambs that have not received sufficient amounts of colostrum are most vulnerable to the disease. These lambs are infected during the first hours of life when they ingest large numbers of Escherichia coli (E. coli) from the ewe’s fleece as they seek the udder, or if their bedding is soiled. The bacteria pass from the abomasum into the intestines. In older lambs, the bacteria are destroyed by acid in the stomach, but in newborn lambs there is no acid (pH=7). In the intestines, the bacteria multiply rapidly, and only when they die do they release endotoxin. A small quantity of endotoxin does not cause a problem, but if large quantities are produced, movement of the gut is depressed (Eales et al., 1985; Gilmour et al., 1985), which leads to further bacterial multiplication and more endotoxin is produced. If the amount of endotoxins produced exceeds the capacity of the liver to destroy it, endotoxaemia occurs, producing the clinical signs of watery mouth (Hodgson et al., 1989).

The initial clinical signs of watery mouth are those of a dull lamb, which within hours shows the characteristic excess salivation. The lamb will become progressively more dull, refuse to feed, collapse and salivate more profusely. Abdominal tympany (swollen gut, full of air, “rattle belly”), and diarrhoea is often observed. The affected lamb will die within hours.

Watery mouth is most common in intensively farmed flocks either indoor flocks or high stocking rates at pasture (Henderson, 2007). Doubles or triplets from lean primiparous ewes are at greatest risk, as this is related to poor early colostrum intake (Eales et al., 1986; Henderson, 2007), as well as lambs born to housed flocks later in the lambing period, when build up of bacteria in the environment is at its highest.

When lambs are first born they must have a sufficient amount of colostrum to avoid watery mouth disease and other conditions such as hypothermia and starvation. Watery mouth disease is a combination of insufficient colostrum intake, and ingestion of bacteria from the environment.

Treating Watery Mouth

Treatment of watery mouth can be very successful, provided it is detected and treated early and continued until the lamb is fit. The aims of treatment are:

1. To prevent starvation and remedy dehydration

Ewe management is crucial in preventing watery mouth. A healthy ewe should lamb and mother well and produce enough colostrum for her offspring whereas undernourished ewes can often exhibit poor maternal care and produce less colostrum and milk.

Feeds by stomach tube of glucose/electrolyte solution, three times a day. This prevents starvation, relieves dehydration and stimulates gut movement – Do not feed colostrum or milk as they will be unable to digest the food. Once body temperature is returned to normal (39 degrees Celsius) and abdominal distension is reduced, then normal feeding can resume.

2. To stimulate movement of the gut – increased movement of the gut reduces the production of endotoxin

Give the lamb an enema to remove the meconium and stimulate gut movement using 20 ml soapy water injected about 5 cm into the rectum. This will also help evacuate bacteria and endotoxins

3. To control bacterial infection that invades the body from the gut

The use of parenteral antibiotics is sometimes advised, however farmers should be aware that this is likely to increase circulating endotoxins initially as they are released from dead bacteria

Affected lambs are often hypothermic and this must not be overlooked, they should be warmed in a warming box or under an infrared heat lamp (J. Childs, personal communication).

Once a number of cases of watery mouth have occurred in an indoor lambing flock, then at-risk lambs can be given an oral antibiotic preparation of spectinomycin at birth. (Hodgson et al., 1999)

(Adapted from (Henderson, 2007; Scott and Gessert, 1996))

Frequently monitor any affected lambs and leave them with the ewe unless they are very sick. Continue this treatment until all symptoms have gone and the lamb is sucking well from the ewe.

Watery Mouth and Welfare

Watery mouth is a painful and distressing condition. A high incidence of lambs suffering from watery mouth on any farm is unacceptable, and action needs to be taken immediately to address the problem. Watery Mouth is after all, largely a preventable disease

Good Practice Based on Current Knowledge

If the incidence of watery mouth on the farm is high, measures should be taken as part of the Flock Health Plan to reduce the incidence. Stockmanship, hygiene and ewe nutrition may all require special attention in order to reduce watery mouth on the farm.

To prevent Watery Mouth in lambs

• Ensure ewes are healthy and in good body condition in the pre-lambing period to enable them to produce sufficient colostrum
• Lamb outdoors if possible
• Make sure the lambs get adequate colostrum during the first 6 hours after birth (50ml/kg in the first 2hrs, 10% of body weight in the first 24hrs)
• Give close attention to lambs at risk (e.g. multiples and lambs from ewes in poor condition)
• Do not carry out castration and tail docking (which is not permitted under AWA-welfare standards) using rubber rings during the first day of life
• Clean lambing pens between ewes and provide plenty of dry fresh bedding
• Dag ewes before lambing

In an outbreak of Watery Mouth

• Feed a glucose/electrolyte solution three times daily by stomach tube to the lambs
• Do not feed colostrum or milk by stomach tube as the lamb will be unable to digest it (once body temperature is returned to normal (39 degrees Celcius) and abdominal distension is reduced, then normal feeding can resume.)
• Consider giving the lamb a soapy water enema to stimulate gut movement
• Corticosteroids may help to alleviate or prevent the development of shock in severe cases
• Continue treatment until all symptoms have gone and the lamb is sucking well from the ewe
• Leave the lamb with the ewe unless it is very sick. This will enable the lamb to commence sucking once recovered