Tirath S. Sandhu, DVM, Ph.D.
Keeping ducks healthy requires taking the necessary steps to prevent disease outbreaks from occurring in the first place, and in cases where ducks do become infected, administering appropriate treatment to minimize mortality and morbidity. The following guidelines were developed with large flocks of ducks in mind, but they also apply to small flocks.
Disease prevention in ducks, and in poultry in general, is discussed in more detail in standard textbooks on poultry diseases and in other related publications, some of which are referenced on this site (Duck Publications). Caretakers must be diligent in three main areas to prevent ducks from becoming infected with disease.
Common Diseases of Ducks
Duck Virus hepatitis
Duck virus hepatitis is a highly fatal contagious disease of young ducklings, 1-28 days of age. Ducklings are most susceptible at the younger ages and gradually become more resistant as they grow older. The disease is rarely seen in ducklings over 4 weeks of age. The onset of the disease is very rapid, it spreads quickly through the flock and may cause up to 90% mortality. Sick ducklings develop spasmodic contractions of their legs and die within an hour in a typical "arched-backward" position. The liver is enlarged and shows hemorrhagic spots. To prevent this disease, keep age groups isolated and vaccinate breeder ducks with an attenuated live virus duck hepatitis vaccine (to produce maternally immune ducklings).
Duck Plague (Duck Virus Enteritis)
Duck virus enteritis is an acute, contagious, highly fatal disease of waterfowl caused by a herpes virus. This disease is most likely to affect mature ducks, but is also seen in young ducks. Affected birds show sluggishness, ruffled feathers, greenish-yellow diarrhea that is sometime blood-stained. Dead birds often have blood-stained feathers around the vent and blood dripping from the nostrils. Hemorrhages may be found in tissues throughout the body. Eruptive lesions of the mucous lining of the esophagus and intestine are characteristic signs of the disease. Necrotic plaques may be observed in the cloaca. Regular immunization of breeder ducks with an attenuated live duck virus enteritis vaccine provides adequate protection.
Riemerella anatipestifer Infection
This bacterial disease of ducks is also known as Pasteurella anatipestifer infection, infectious serositis and New Duck disease. Anatipestifer infection causes high mortality, weight loss and condemnation. In the acute form, listlessness, eye discharge and diarrhea are commonly seen. Ducks show incoordination, shaking of the head and twisted neck. Birds are commonly found on their backs, paddling their legs. Typical lesions found in dead birds are infected air sacs, membranes covering the heart and liver, and meningitis. Preventive management and vaccination are effective means of control. Penicillin, enrofloxacin and sulfadimethoxine-ormetoprim (0.04-0.08% in feed) are effective in reducing mortality.
Avian cholera, also called fowl cholera, caused by the bacterium Pasteurella multocida is an important disease of domestic ducks, and is an especially troublesome disease of ducks in some parts of Asia. This disease is associated with poor sanitation, and standing water in duck pens. Symptoms include loss of appetite, mucous discharge from the mouth, diarrhea, and in breeder ducks, labored breathing. Lesions found in dead birds include hemorrhages on heart muscle, mesentery and abdominal fat. The liver is enlarged, copper colored and friable (easily crumbled). Pinpoint whitish spots may be seen on the liver. Good sanitation practices go a long way toward preventing this disease. Sulfadimethoxine-ormetoprim (0.02-0.04%) and Chlortetracycline (0.044%). given in feed are effective treatments.
This common infection of poultry caused by Escherichia coli., causes reduced hatchability, infection of the yolk sac (omphalitis), a septicemia (bacterial invasion of bloodstream) in ducks 2-8 weeks of age and salpingitis and peritonitis in breeder ducks. In market ducks, E. coli. infection produces lesions very similar to those seen in Riemerella anatipestifer infection (see above). Good sanitation and management are important preventive measures. Sulfadimethoxine-ormetoprim (0.04-0.08%) and chlorotetracycline (0.044%) in feed are helpful in controlling this disease.
This condition occurs when ducks inhale spores produced by the mold (fungi) Aspergillus (Aspergillus fumigatus is the common species) that grows on damp straw or feed. These inhaled spores cause multiple nodules or plaques in the lungs and air sacs. Common signs include gasping, listlessness and dehydration. This disease is not to be confused with aflatoxin poisoning described below. The best solution to prevent aspergillosis is to avoid using moldy straw and preventing feed from getting wet.
Ducks are particularly susceptible to certain toxins, and in some cases strikingly more than chickens or turkeys. Therefore, duck caretakers must be especially diligent in preventing ducks from consuming or being exposed to these toxins.
Molds (fungi) that grow on cereal grains and oilseeds before and after harvest produce a number of toxins that are particularly harmful to ducks. By far the most toxic of these substance is a group of toxins called aflatoxins. Aflatoxins are produced by the molds Aspergillus flavus and Aspergillus parasiticus. Ducks are highly susceptible to these toxins. Very small amounts will cause high mortality. Wet harvest conditions encourage the growth of this mold.
Ducks that have access to stagnant ponds or other areas where decaying organic matter (animal carcasses, in particular) is found may consume toxins produced by the bacterium Clostridium botulinum. This happens when temperature and other conditions are right for the growth of this anaerobic spore-forming bacterium. Botulism causes a progressive flaccid (limp) paralysis of the neck (limberneck), legs and wings. Affected ducks usually die in a coma within 24-48 hours.
Castor bean poisoning
Incidents of high death losses in wild ducks, due to consuming castor beans (Ricinus communis) have been reported in Texas. Castor beans contain ricin, a toxalbumin known to cause toxicity in humans and domestic animals.
Some older varieties of rapeseed meal contain erucic acid and goitrogens at levels high enough to be harmful to poultry. Ducks are much more sensitive to erucic acid than are chickens and turkeys. Genetically improved varieties of rapeseed (Canola) contain much lower levels of these toxins. However even Canola meals should first be tested in ducks before their use in duck feeds on a large scale.
Duck keepers should take care not to use insect sprays or rodent poisons, that are known to be harmful to ducks, in areas accessible to ducks. Some insect sprays are highly toxic to ducks, such as parathion and diazinon. Always read the directions on the insecticide container carefully before using around ducks. Rat poisons that contain Warfarin, an anticoagulant, if consumed by ducks, can cause them to bleed to death.