The causes and circumstances of diarrhea in neonatal lambs and kids are similar to those in newborn calves. Intensive lambing practices and shed-lambing increase the potential for disease and buildup of infectious agents and can be associated with serious outbreaks of diarrhea. The serotypes of enteropathogenic Escherichia coli that cause secretory diarrhea in calves also do so in lambs, and the approach to diagnosis, treatment, and control is similar. Similarly, rotavirus, coronavirus, and cryptosporidia (see Cryptosporidiosis) also cause outbreaks of diarrhea in lambs. (Also see Intestinal Diseases in Ruminants: Diarrhea in Neonatal Ruminants.) Lamb dysentery caused by Clostridium perfringens type B (see Clostridial Diseases: Enterotoxemia Caused by Clostridium perfringens Types B and C) is a distinct intestinal disease of lambs in the first week of life. It is seen principally in hill breeds of sheep in the UK and is characterized by sudden death or diarrhea, dysentery, and toxemia. In the USA, C perfringens type C causes a similar syndrome. Watery mouth or rattle belly (see Intestinal Diseases in Ruminants: Watery Mouth Disease in Lambs), a disease of uncertain etiology associated with low concentrations of circulating immunoglobulins, is seen predominantly in the UK. It also affects young lambs but is manifest by GI stasis. Coccidiosis (see Coccidiosis: Coccidiosis of Sheep and see Coccidiosis: Coccidiosis of Goats) and GI helminthiasis (see Gastrointestinal Parasites of Ruminants: Gastrointestinal Parasites of Sheep and Goats) except for haemonchosis, are important causes of diarrhea in older nursing and weaned sheep. Terminal ileitis and villous atrophy, both of unknown etiology, are often present in the intestine of lambs culled because of poor growth.
GI helminthiasis is the most common cause of diarrhea in pastured sheep. Coccidiosis develops in association with overstocking or intensive indoor housing and poor sanitation. Salmonellosis (see Salmonellosis) can cause diarrhea in all ages; the circumstances in young lambs are similar to those in calves. It also can cause outbreaks of diarrhea late in pregnancy and is frequently accompanied by abortion. Salmonellosis is more common when sheep or goats are congregated intensively or stressed, particularly by shipping. Yersinia pseudotuberculosis and Y enterocolitica have both been associated with enterocolitis and diarrhea in young sheep at pasture that are debilitated from factors such as starvation and cold weather. Diarrhea may be present in bluetongue in sheep (see Bluetongue) and is accompanied by typical mucosal lesions. In goats, diarrhea is often prominent in enterotoxemia associated with C perfringens type D (see Clostridial Diseases: Type D Enterotoxemia). This is not a feature of the clinical disease in sheep but may be present in flockmates of affected sheep. In feedlot sheep, diarrhea most commonly is associated with grain overload, salmonellosis, or coccidiosis.
Other intestinal diseases of adult sheep may manifest with diarrhea. Infection with C perfringens type C (struck, see Clostridial Diseases: Enterotoxemia Caused by Clostridium perfringens Types B and C) manifests with abdominal pain, tenesmus, and rapid death. Intestinal obstruction due to intestinal accidents occur sporadically but are usually not seen clinically. Sheep with paratuberculosis (see Paratuberculosis) usually show progressive emaciation without diarrhea. Progressive emaciation also is the primary sign in adult sheep with intestinal adenocarcinoma, which can be prevalent in certain areas, associated with ingestion of bracken fern (see Bracken Fern Poisoning).
Watery Mouth Disease in Lambs
(Slavery mouth, Slavers, Rattle belly)
Watery mouth disease is not seen in extensively managed flocks but accounts for ~25% of UK newborn lamb deaths in indoor intensive lambing systems. Morbidity in a flock can be as high as 30% and, if untreated, most affected lambs die. A similar syndrome has been reported in lambs in Spain and goat kids in France and Canada.
Etiology and Pathogenesis
Lambs 12–72 hr old with inadequate or delayed access to colostrum because of sibling competition, weakness, early castration, or low maternal care or yield are at greatest risk. Low transfer of maternal antibodies and the unique digestive physiology of the newborn lamb allow gram-negative bacteria, particularly Escherichia coli ingested accidentally from contaminated fleece or bedding, to survive and translocate from the gut to the bloodstream. The strains involved are K99 antigen negative and regarded normally as nonenteropathogenic and nonenterotoxigenic. The resultant bacteremia may be tolerated by the lamb but >104 colony-forming units/mL are associated with the release of free endotoxin, and endotoxic shock develops rapidly.
Affected lambs are hypothermic, dull, stop feeding and, classically, have long strings of saliva drooling from the mouth. Less obvious cases may have a wet muzzle; others may show no external signs of excess salivation, but the mouth may be cold to the touch and contain frothy saliva. Lacrimation may also be seen. The abomasum may become distended with gas and liquid, giving the deceptive appearance of a well-fed lamb, but if these lambs are lifted and shaken gently, a noise associated with the alternative name of “rattle belly” may be heard. Scour occurs infrequently.
Necropsy may reveal a bloated and inflamed GI tract, retained meconium, pale kidneys and muscle, dehydration, and enlarged and reactive mesenteric lymph nodes.
Biochemical and hematologic changes and necropsy findings in affected lambs are consistent with endotoxemia and the clinical diagnosis of endotoxic shock. Terminally, lambs develop endotoxemia, leukopenia, severe hypoglycemia, lactic acidemia, and metabolic acidosis. Differential diagnoses include joint ill or navel ill, hypothermia, primary starvation, and infectious enteritis.
There is no specific treatment. Parenteral antibiotics, NSAID, and 50–200 mL of an electrolyte and 10% glucose solution containing a water-soluble antibiotic (neomycin and/or streptomycin) given tid by stomach tube may help, but antibiotic treatment should be given before lambs become bacteremic at 4–8 hr after birth to reduce the possibility of lysing bloodborne bacteria and precipitating endotoxic shock. Purgatives or enemas may help overcome gut stasis and expel the infecting bacteria. Treatment should be continued until signs resolve and the lamb is sucking again. Boosting body temperature by external warming may also be required. However, such care is time-consuming and expensive and carries no guarantee of success.
Prevention is the best option. Ewes should be well nourished to ensure a plentiful supply of colostrum. Yards, pens, ewes, and equipment should be kept as clean as possible throughout lambing to help control the buildup of E coli and keep the incidence of disease low. Supplementary feeding of lambs using stored colostrum (ewe, cow, or goat) or commercial colostrum substitute should provide a minimum of 50 mL/kg within 6 hr of birth. Lambs should not be castrated in the first 24 hr because this depresses colostrum intake.
In controlled experiments, a single dose of oral antibiotic given within 2 hr of birth to colostrum-deprived lambs delivered into a contaminated indoor environment was as effective as ewe colostrum in preventing neonatal disease and death in all lambs up to 3 days old, despite the absence of maternal antibodies. Thus, antibiotic treatment can provide simple, quick, and inexpensive protection against watery mouth disease and is an attractive option for the busy sheep farmer. However, it is important that such treatment be targeted to lambs in the high-risk categories specified above because indiscriminate dosing may encourage antibiotic resistance.
Last full review/revision May 2012 by Clive C. Gay, DVM, MVSc, DVSc (Hons), FACVSc, DACIM (Hons); J. Christopher Hodgson, BSc, PhD, MBA; Jeanne Lofstedt, BVSc, MS, DACVIM (Large Animal); Steven R. Bolin, DVM, MS, PhD