Download Common Poultry Diseases For the Practicing Veterinarian

Common Poultry Diseases
For the Practicing Veterinarian
Carey P. Laster, DVM, MS
The purpose of this presentation is to review some of the most commonly encountered poultry
diseases the practicing veterinarian may observed in a backyard or small flock environment. The
diseases presented are not all inclusive, but represent conditions most commonly submitted to the
diagnostic laboratory, presented in a systemic approach.
Respiratory diseases
Mycoplasma gallisepticum infection (MG; Chronic Respiratory Disease; CRD)
MG occurs primarily in chickens and turkeys but also has been reported in partridge, pheasants,
peafowl, quail, guinea fowl, ducks, and pigeons. All ages of chickens and turkeys can have the
disease although usually occurring in older birds. M. gallisepticum seldom survives for more
than a few days outside of the host and carrier birds are essential for its survival. The organism
may be present and cause no disease until triggered by stress, such as changes in housing,
management, nutrition, or weather. MG is transmitted in some hatching eggs (transovarian
transmission) laid by inapparent carriers. Infected progeny then transmit the agent laterally
through infectious aerosols in air and through contamination of feed, water, and environment.
The agent probably can be transmitted by other species of birds, domestic or wild. In addition
the agent can be transmitted mechanically on shoes, feed sacks, equipment, etc. Clinical signs
usually develop slowly in the flock. They vary in severity with changes in the weather and may
persist for weeks or months. Signs include coughing, sneezing, rales, ocular and nasal discharge,
and swelling of the infraorbital sinuses. Lesions include catarrhal inflammation of the nasal
passages, sinuses, trachea, and bronchi. Air sacs are often thickened and opaque. Ancillary
diagnostic tests include serology and PCR. Positive MG cases are reportable to the Office of
State Veterinarian. To control the infection, depopulation of infected premises should precede
establishment of a clean flock. Thoroughly clean and disinfect the houses and leave them vacant
for a few weeks. Prevention is based largely on obtaining chicks hatched from eggs from MGfree breeder flocks. Many broad-spectrum antibiotics have been used for treatment and will
suppress losses, but will not completely eliminate infection from the flock. Relapses often occur
when treatment is discontinued. Most antibiotic are given in feed or water, preferably in water.
Tylosin and tetracyclines have been used for treatment.
Digestive diseases
Coccidiosis
Avian coccidiosis is a common protozoal disease of poultry and many other birds characterized
by diarrhea and enteritis, caused by a variety of species of Eimeria. Coccidia are host specific,
hence do not pass among various classes of poultry. Infection is by the fecal-oral route.
Ingestion of infected feed, water, litter and soil results in infection. When a sporulated
(infective) oocyst is ingested, sporozoites are released to initiate asexual and sexual cycles that
lead to development of thousands of new oocysts in the intestine. Oocysts are shed in the feces
and soon sporulate and become infectious for other birds. Coccidia need moisture to sporulate;
therefore, outbreaks occur when susceptible birds are put into infected pens or when litter
becomes wet and the temperature is warm. Coccidia produce lesions in the gut by destruction of
the epithelial cells in which they develop and multiply, and by trauma to the intestinal mucosa
and submucosa.
Clinical signs include weakness, paleness, ruffled feathers, general
unthriftiness, diarrhea, and death. Droppings may be bloody but are more often whitish and
semisolid in texture. Primary coccidial lesions are ballooning of the intestine or ceca with fetid
odor, enteritis, intestinal or cecal cores, catarrhal or hemorrhagic intestinal content, speckled
appearance of the serosal surface of the intestine, and pin-point hemorrhages on the serosal
surface. A diagnosis of coccidiosis can be based on flock history, signs, and intestinal lesions.
Microscopic demonstration of oocysts in feces or intestinal scrapings confirms the diagnosis.
Sanitation, plus a coccidiostat in the feed, is the best method of preventing coccidiosis.
Management factors include good dry litter at all times and changing litter after each flock.
Proper ventilation helps to keep litter dry. Outbreak treatment must be fast and effective, and
thus requires medication by drinking water. Sulfadimethoxine and Amprolium are effective
treatments.
Ulcerative Enteritis (Quail Disease)
Ulcerative enteritis is an acute bacterial infection of game birds, primarily quail, characterized by
ulcerations of the intestinal tract and by multifocal hepatic necrosis. UE occurs frequently in
young, captive game birds and occasionally in turkey poults and young chickens. Young birds
are affected more frequently than adults although the disease occurs frequently in adult quail. It
frequently occurs in association with other diseases such as coccidiosis. The etiology agent is
Clostridium colinum, a very resistant organism that can be difficult to isolate. The etiologic
agent is spread primarily through the droppings of acutely affected or recovered carriers birds
and persists in the soil for many months. Infection can be spread by flies that feed on infectious
droppings. The disease is highly contagious, especially among quail. In most species, clinical
signs are similar to those seen with coccidiosis, including listlessness, humped appearance,
retracted neck, drooping wings, partially closed eyes, ruffled feathers, diarrhea, and perhaps
bloody feces. In quail, white watery droppings are distinctive. Sudden death may occur without
signs being apparent, especially during onset. Mortality may be very high in quail, up to 100%
within a few days. Affected birds have deep ulcers scattered throughout the intestine, including
the ceca, and the ulcers may be numerous enough to coalesce. Ulcers may be round or lenticular.
Deep ulcers often can be detected through the serosa of the unopened intestine and may penetrate
it to induce peritonitis. The affected liver usually contains multiple, yellow or tan necrotic foci.
To control the infection, raise the flock in facilities and on ground where the disease has never
occurred. Do not add birds. Prevent contact with all other bird species. Keep old birds and
young birds separated. If possible, not have both age groups on the same premises. Practice
careful sanitation including frequent cleaning and disinfection. Promptly remove and destroy all
sick birds. UE is so difficult to prevent in quail that most growers ultimately maintain the birds
on wire-bottom cages or pens. When quail have access to their droppings, UE eventually occurs.
The causative organism is susceptible to many antibiotic, especially those the work against gram
positive bacteria. Bacitracin, neomycin, streptomycin, penicillin, lincomycin, and tetracylines
are effective. Bacitracin and neomycin work together for initial medication; bacitracin in the
feed and neomycin in the drinking water. When mortality stops, discontinue water treatment.
Bacitracin dosage is 100 to 200 g/ton of feed and neomycin dosage in 200 mg/gal water.
Capillariasis
Cropworms of the Capillaria sp. are nematodes that infest the crop and esophagus. They burrow
into the mucosa, causing inflammation and thickening. The parasites are thin and thread-like and
difficult to see grossly, but are easily demonstrated in mucosal scrapings. Ova are oval-shaped
and operculated on both ends. Life cycles of Capillaria species can be direct or indirect, that is
by ingesting embryonated eggs directly or by eating earthworms (intermediate host) that has
ingested embryonated eggs. Capillaria nematode eggs pass in the droppings of the bird.
Embryonation requires 24 to 30 days and the egg becomes infective only in the embryonated
form. Chickens, turkeys, geese, ducks, guineas and many wild or captive game birds, especially
quail, are susceptible. Birds heavily parasitized tend to huddle in isolated areas, are unthrifty,
have ruffled feathers, are emaciated, and may have diarrhea. Infected crops will have thickened
walls and be void of feed but will have an excessive amount of white, mucoid material on the
surface. Fendbendazole and levamisole are effective anthelmintics; however, the use of these
drugs is off-label since there are no readily available approved treatments for meat or egg
producing birds except piperizine, which is only effective against ascarids.
Histomoniasis (Blackhead)
Histomoniasis is a protozoal disease caused by Histomonas meleagridis affecting turkeys,
peafowl, chukars, grouse, partridges, pheasants, quail and sometimes chickens, characterized by
necrotizing lesions involving the ceca and liver. Transmission of H. meleagridis is possible via
three routes: 1) Ingestion of fresh feces. 2) Ingestion of embryonated cecal worm ova
containing the protozoan. 3) Ingestion of earthworms containing cecal worm larvae within their
tissues. Earthworms serve as transport host for the cecal worm and the cecal worm acts as a
transport host for the histomonad. Diagnosis can be made on the basis of clinical signs and
characteristic lesions. Initially there is listlessness, anorexia, drooping wings and yellow feces.
Head parts may be cyanotic, thus the common name “blackhead”. Emaciation is common in
chronic cases, usually in older birds. Gross lesions are distinctive. There is bilateral
enlargement of the ceca with thickening the cecal walls. The mucosa is usually ulcerated. The
ceca often contain caseous cores which are yellow, gray or green and may be laminated.
Peritonitis occurs when the cecal wall becomes perforated. The liver contains irregularly round,
depressed, target-like lesions that vary in color. They vary in diameter but often are 1-2 cm and
may coalesce to produce larger lesions. There is currently no approved medication for treatment
of histomoniasis in food animals. Small groups of birds not being raised for consumption can be
effectively treated with metronidazole at a dose of 30 mg/kg orally SID for 5 days or 1.5 g/gal in
the drinking water for 5-15 days. Anthelmintic treatment may help suppress the population of
cecal worms.
Neurologic disorders
Marek’s Disease
Marek’s disease is a herpesvirus-induced neoplastic disease of chickens characterized by
infiltration of various nerve trunks and/or organs with pleomorphic lymphoid cells. Marek’s
disease is important primarily in chickens, to a much lesser degree in quail, and has been rarely
observed in other species. The disease most commonly occurs in sexually immature chickens 27 months old, but can occur at virtually any age beyond 3 weeks. The disease occurs worldwide
and virtually all flocks are exposed to the causative virus. Infected chickens shed viruscontaining feather follicle dander, which is a source of infection for other chickens by the
respiratory route. Infected carriers may or may not be clinically ill, and carrier birds can
sporadically shed virus throughout their lifetimes. The disease is very contagious and infectious
dander can be disseminated over long distances. Birds with lymphoid infiltration of the
peripheral nerves may demonstrate partial paralysis. A particularly characteristic clinical
presentation is a bird with one leg stretched forward and the other back as a result of unilateral
paresis or paralysis of the leg (fowl paralysis). However, chickens with visceral lymphomas may
exhibit few signs and, instead, become depressed and comatose prior to death. Blindness may
occur associated with lymphoid infiltration of the iris. At least four different lesion patterns are
recognized: gross enlargement and/or yellowing and loss of cross-striations of peripheral nerves;
discoloration of the iris; enlargement of feather follicles with reddening (skin leucosis); and
visceral tumors involving the liver, heart, spleen, gonad, kidney, proventriculus, and other organs
and tissues. There is no effective treatment for Marek’s disease. The disease can be prevented
by obtaining chicks that have been vaccinated for Marek’s disease at hatch. Because immunity
from vaccination is not fully developed for 7-10 days, it is necessary to minimize early exposure.
This requires careful sanitation and disinfection, particularly because the virus survives well for
months in poultry facilities. Revaccination is not necessary and immunity is usually life-long.
Musculoskeletal disease
Staphylococcosis
Staphylococcosis is a systemic disease characterized most frequently by purulent arthritis and
tenosynovitis. Staph infections of poultry occur worldwide and affect all classes of birds. The
causative agent is Staphylococcus aureus, an opportunistic pathogen, and disease is usually
associated with a break in the skin or beak (trauma, beak trimming, toe trimming, etc.) The
organism is ubiquitous and persists in the environment. It moves slowly through the flock
because it does not spread from bird to bird. Any injury or break of epithelial surfaces, skin, or
mucous membranes can be an entry site for infection. There are various manifestations of the
disease, namely, septicemia, arthritis, synovitis, osteomyelitis, and bumblefoot. Clinical signs
are unthriftiness, inappetence, swollen joints, lameness, emaciation, ruffled feathers, and
diarrhea. In septicemic form, signs are usually limited to depression, fever, and loss of appetite.
The arthritic form usually follows the septicemic phase and lame birds develop swollen joints
and breast blisters. Birds with bumblefoot have swollen, abscessed footpads, a result of puncture
wounds of the foot. With the septicemic form, lesions include a swollen, congested, greenish
liver, engorged abdominal vessels, and petechial hemorrhages on the heart, fat, and serosal
surfaces. In the arthritic forms, the joints become swollen and filled with creamy purulent
exudate.
Foot lesions have thickened, abscessed foot pads with caseous material.
Staphylococcus aureus is sensitive to several antibiotics. Erythromycin, penicillin, and
tetracyclines are the most frequently used medications.
Suggested Poultry Medications
I.
Antiparasitics
a) Roundworms
i)
Piperazine (Wazine-34), in water, 1-4 g/gal for 1-4 days
ii)
Levamasole (Tramisol Soluble Drench powder, Levasole Drench powder)
 Using 13.65% injectable, 5-15 ml/gal of water for 1-3 days, repeat in
10 days
 2.25 mg/gal of water for 4-5 days, repeat in 10-14 days
b) Capillaria
i)
Levamasole
 15-30 mg/kg orally as a single bolus
 2.25 mg/gal water for 4-5 days, repeat in 10-14 days
ii)
Fendbendazole (Panacur), not FDA approved for birds, in feed
 10-50 mg/kg PO once daily for 5 days, also affective for
roundworms
c) Coccidiosis
i)
Amprolium (Amprol, Corid)
 1/3 oz powder (20% soluble powder)/gal water for 10-14 days
 9.5 ml/gal water (9.6% oral solution) for 5-7 days
ii)
Sulfadimethoxine (Albon)
 Soluble powder 94.6 g/packet for addition to drinking water
 12.5% concentrated solution for addition to drinking water
d) Histomonas
i)
Metronidazole (Flagyl)
 Not approved, off-label
 250 mg daily or 1.5 g/gal water for 5-15 days
II.
Antibiotics
a) Oxytetracycline (Terramycin powder)
 200-800 mg/gal water
 2-4 tsp/gal for 7-10 days
b) Tylosin (Tylan Soluble powder)
 2-3 g/gal water 3-5 days
 50 mg/lb BW per day for 3-5 days