Special Poultry Diseases

By Edward T. Mallinson and Jim A. Stunkard.

This chapter provides brief descriptions of diseases that 1) more commonly are found in small, backyard poultry flocks, or 2) are more significant economically or personally when they do occur. Further reading on these and many other diseases is recommended.

All Poultry Types.

Two important diseases shared by chickens, turkeys, guinea fowl, partridges, pheasants, quail, and domestic waterfowl (ducks and geese) are pullorum disease and fowl typhoid.

These salmonella infections, transmitted via breeder flocks and hatching eggs, are capable of producing severe, rapidly spreading disease especially in young chickens and turkeys. They also can cause havoc in guinea fowl and upland game birds. Infection and losses have been reported as well in waterfowl and occasionally other avian and mammalian species.

In most states, testing of breeder flocks now is mandatory for detecting and controlling pullorum-typhoid. However, some untested flocks do exist. To be sure you avoid the risk of these diseases, always insist on purchasing U.S. (NPIP) Pullorum-Typhoid Clean stock.

Small, local dealers and custom or home-type hatcheries because of their small size or more remote location may escape detection and testing by State poultry health agencies. It is to the benefit of all concerned that such operations participate in NPIP programs and become tested.

Chicken Diseases

Coccidiosis.

At least five distinctly different species of intestinal coccidial protozoans infect chickens. All can produce considerable inflammation in different sections of the digestive tract below the gizzard.

Two of these coccidial species, Eimeria (E.) necatrix and E. tenella, cause massive and often fatal hemorrhages. With E. necatrix these hemorrhages result in severe distention of the middle of the intestine. With E. tenella, the two, blind cecal pouches become swollen with dark blood-filled debris. Numerous preventive and therapeutic anticoccidials are available from feed stores and livestock suppliers.

Fowl Coryza.

This disease, caused by the bacteria Hemophilus gallinarum, often is involved in respiratory diseases of multiple-age flocks where periodic cleanout and cleanup is not practiced.

Affected chickens generally develop very watery eyes, and severe reddening and swelling of the sinuses surrounding one or both eyes. Discharges coming from the eyes and nostrils of affected birds typically have a very offensive odor much more so than in other respiratory infections of chickens.

Several antibiotics and other chemotherapeutic agents are effective in suppressing the infection. Dramatic improvements have been reported with the use of erythromycin preparations via the drinking water.

Laryngotracheitis, a respiratory virus infection of chickens and occasionally other species of fowl, often results from failure to maintain tight flock security and isolation.

The disease typically produces marked hemorrhage of the windpipe (trachea) of chickens, and flock death losses of 5 to 20 percent. It is readily introduced through purchase of recovered virus carriers at auctions, fairs, or poultry shows.

Poultry catching crates and hauling trucks that are not cleaned and disinfected between hauls have frequently been associated with outbreaks in new flocks or new distant locations.

The movement of people and animals between farms also is involved. Clothing and fur easily can be contaminated with virus-laden dust particles.

If you own a flock of show chickens, are located in an area where this disease is prevalent, or make replacement purchases at live poultry auctions, you should seriously consider vaccination against laryngotracheitis. Excellent, easily administered products are available at very modest cost.

Liver Ailments

Lymphoid Leukosis, a virus-caused disease, also is called "big liver disease." It causes large tumors in many internal organs, especially the liver, and needs to be distinguished from avian tuberculosis and Marek's disease. Unlike Marek's disease, which also produces liver and other internal tumors, lymphoid leukosis is breeder flock transmitted, whereas Marek's is not.

Infected females usually transmit the infection through the egg to some or all of their offspring. There is no preventive medication or vaccination.

As an aid in preventing lymphoid leukosis, which can kill 25 percent or more of a flock of mature chickens in 12 months' time, you should obtain all chicks at one time from the same parent stock and place them in fully-depopulated clean and disinfected quarters. Avoid further additions until the next cleanout.

Marek's Disease is a very common liver tumor and paralysis-producing virus disease of chickens, now fortunately under reasonable control through vaccination. Novice poultrymen failing to obtain chicks vaccinated at one day of age with one of several types of Marek's vaccine will often be severely disappointed when high Marek's death losses begin at about 8 to 10 weeks of age and persist to 20 to 25 weeks of age or longer.

Day-old vaccination almost is a must for preventing this disease. Excellent protection is obtained from vaccination, especially if vaccinated chicks are placed in dust-free clean and disinfected pens.

Small hatcheries usually can get veterinary assistance locally or from vaccine sup-Pliers on a good day-old Marek's disease vaccination program for their customers. Marek's disease and vaccination for this disease are not considered hazardous to human health.

Mites and Ticks

Scaly leg mites, caused by the mite Knemidocoptes mutans, produce slow-spreading but eventually very severe thickening of the skin of the shank, and raising and discoloration of the shank scales. It usually is encountered on old poultry premises and on aged chickens.

Direct miticide treatment of affected shanks and eventual flock depopulation and cleanup generally eliminates scaly leg mite problems.

Fowl ticks, Argas persicus, are sometimes called blue-bugs. Besides causing anemia, they may cause tick paralysis in growing or adult hens. They also transmit spirochetosis, a serious bacterial disease not only of chickens but also of turkeys, game birds, waterfowl, and other birds.

Tick control requires removal of breeding and hiding areas in and around the chicken house as already discussed and application of sprays specifically labeled effective against ticks.