• Acute: Having a short or relatively severe course
• Carrier: Apparently health animal that harbors disease organism and is capable of transmitting them to other animals
• Chronic: Of long duration
• Contagious: Infectious disease that may be transmitted from one individual to another
• Diagnosis: Art of distinguishing one disease from another
• Disease: Any departure form normal state of health
• Infectious: Capable of causing disease
• Immunity: Ability to resist infections from normal exposure to disease agents
  • Active immunity: Acquired by recovery from the disease or by vaccination
  • Passive immunity: Achieved by passing of antibodies from the hen to the chick through the egg
• Lesion: Abnormality of some aspect of an organ or tissue (usually size, shape, color or structure)
• Morbidity: Incidence of a disease in a flock
• Mortality: Death rate; % of individuals that die
• Prevention: Not letting the disease occur
• Sign: Evidence of a disease
• Symptom: Subjective evidence of the disease being present
• Treatment: Promoting recovery or preventing the spread of the disease once it has occurred
• Vector: Mechanical transmission of a disease

In order to be able to identify signs of disease it is important to be familiar with the characteristics of a healthy bird.

• Erect stance with head and tail elevated
• Bright red comb and wattles
• Filled-out face parts
• Bright and alert eyes
• Clean nostrils
• Smooth, neat, clean feathers
• Filled-out legs
• Joints that are smooth and cool to the touch
• Weight that is typical for the type and age of the bird
• Powerful movements when struggling
• Scales on the legs and feet that are clean and waxy in appearance
• Color of the skin that is characteristic for the breed and strain of bird, as well as the age and state of production 

In addition, a healthy bird eats and drinks frequently with the usually accompanying waste products (fecal material with white uric acid crystals) and displays no signs of respiratory distress.

Signs of Respiratory Infection

A disease-causing organism can affect more than one system, leading to a variety of different clinical signs. There is considerable overlap in the commons signs of respiratory diseases, making diagnosis difficult without a necropsy.

Common signs of respiratory infection include the following:

• Coughing
• Sneezing
• Rales (abnormal breathing sounds)
• Gasping
• Shaking head
• Discharge from the eyes
• Conjunctivitis (inflammation of the conjunctiva of the eye)
• Discharge from the nose
• Swelling of the face and/or wattles
• Bluish-purple discoloration of the face
• Retarded growth
• Inactivity
• Dirty wings (birds tend to wipe their nostrils on their wings)

Less common signs of respiratory infection include the following:

• Twisting of the head and neck (torticollis)
• Paralysis
• Diarrhea, which might be green and watery
• Swollen joints
• Lameness
• Red or white spots on the legs and comb
• Warts or scabs

Signs of Nonrespiratory Infection

Common signs of nonrespiratory infection include the following:

• Labored breathing
• Reduced water consumption
• Dehydration
• Reduced feed consumption
• Weight loss or stunted growth
• Emaciation
• Bluish-purple discoloration of the face
• Pale comb
• Small comb
• Abscessed wattles
• Discharge from the mouth
• Blindness
• Enlarged abdomen
• Navel infection
• Swollen joints
• Swollen foot pads
• Lameness
• Tremors
• Paralysis
• Twisting of the head and neck (torticollis)
• Weakness
• Diarrhea, which might be greenish
• White feces
• Bloody feces
• Pasted vent
• Watery droppings
• Thin-shelled eggs
• Shell-less eggs
• Reduced egg production
• Increased mortality
• Helicopter wings (that is, broken or twisted feathers)
• Ruffled feathers
• Foul odor
• Inactivity

NOTE: It is not unusual for poultry to die suddenly without showing any signs of disease.

Prevention is the most effective method for dealing with the disease. The National Poultry Improvement Plan was established to eliminate Pullorum Disease caused by Salmonella pullorum. The disease is transmitted from hen to chick through the egg. Breeder flocks are tested and any positive individuals are removed from the breeding flock. The NPIP program has since been extended to include testing and monitoring for Salmonella typhoid, Salmonella enteritis, Mycoplasma gallisepticum, and Avian Influenza. The NPIP currently involves commercial poultry, turkeys, waterfowl, exhibition poultry, backyard poultry, and game birds.

It is important to start your flock using NPIP-certified birds. A list of NPIP participants can be found on the NPIP home page.

National Poultry Improvement Plan (NPIP - USDA)

NPIP participants by state

Kentucky Representative:
Dr. Katie Flynn, State Veterinarian, Kentucky Department of Agriculture, Division of Animal Health
100 Fair Oaks Lane, Suite 252
Frankfort, KY 40601
Phone: (502) 782-5903
Email: katie.flynn@ky.gov

Additional contact: Dr. Kerry Barling, Deputy State Veterinarian - 502-782-5913 kerry.barling@ky.gov 
Additional contact: Megan Zinner, Poultry Programs - 502-572-5903 megan.zinner@ky.gov

Biosecurity refers to management practices put in place on your farm to prevent the introduction to and/or spread of disease in your poultry flock. Biosecurity is the cheapest, most effective means of disease control.

It is important to be able to identify signs of a health problem in your flock and take immediate action. It is important to keep your poultry house and equipment clean. If you borrow equipment from others it is very important that you clean and disinfect the equipment before using them with your flock. The other flock may look healthy but could be carriers of a disease, which can occur if they have been sick and recovered.

Defend the Flock program (USDA/APHIS)

The role of humans in poultry disease outbreaks (University of Florida)

Vaccines can be a very important tool for preventing poultry diseases. Unfortunately, most poultry vaccines are only available in 1,000 or more doses, and once mixed must be used within 24 hours. It is important, therefore, to consider the price of the vial and calculate the cost per bird.

The avian immune system (University of Kentucky)

The interrelationship of nutrition and immunity (University of Florida)

Understanding vaccines (University of Nebraska)

Vaccination of small flocks (University of Florida)

Investigating vaccination failure in poultry flocks (University of Florida)

Many of the same signs of illness occur in flocks with a variety of different diseases. It is important for small flock producers to get an accurate diagnosis in order to be able to treat the remaining birds. Submission to a diagnostic laboratory is recommended. Typically each state has one or more veterinary diagnostic laboratory. Both diagnostic labs in Kentucky require that submissions go through a referring veterinarian.

University of Kentucky's Veterinary Diagnostic Laboratory

Shipping address: 1490 Bull Lea Rd., Lexington, KY 40511
Mailing address: P.O. Box 14125, Lexington, KY 40512-4125
Phone: (859) 257-8283
Fax: (859) 255-1624
Office Hours: Monday - Friday 8:00 a.m. to 4:30 p.m.
Receiving Hours: Monday - Friday 8:00 a.m. to 6:00 p.m.; Saturday 9:00 a.m. to 5:00 p.m.; Sunday 1:00 p.m. to 5:00 p.m.
Diagnostic Services Coordinator: Dr. Deborah Maples, (859) 257-7112, deborah.maples@uky.edu
After-hours emergency: Dr. Alan Lynachan, Interim Director, (859) 257-6570, alan.loynachan@uky.edu

Breathitt Veterinary Center, Murray State University

Form for submitting birds for necropsy
Shipping address: 101 MSU Drive, Hopkinsville, KY 42241
Mailing address: P.O. Box 2000, Hopkinsville, KY 42241
Phone: (270) 886-3959
Fax: (270) 886-4295
Avian Pathologist: Dr. Carey Laster

If a disease gets past your biosecurity program it may be necessary to treat them with medications. There are a variety of medications available that are labeled for use with poultry. It is very important to read the label - medications can only be used as indicated on the label. If your species of poultry is not listed it is not cleared for use with those birds. Off-label use is only allowed under a veterinarian's supervision.

Compendium of veterinary products

Poultry diseases and medications for small flocks (University of Connecticut)

Preventive medicine for backyard poultry flocks (Western University)

It is important to keep poultry facilities clean. A good biosecurity program will help to keep disease exposure to a minimum. If a problem occurs, clean and disinfect when there is a disease outbreak.

Bleach is a relatively inexpensive and effective disinfectant. It is good for cleaning up and getting rid of many dangerous bacteria, viruses. Unfortunately bleach is also harmful to humans, wildlife and the environment. Disinfectant wipes and cleaning sprays may not be as effective as bleach at

Characteristics of selected disinfectants (Center for Disease Control)

Water sanitation (Animalsites.blogspot.com)

For profitable poultry production (as well as a 'happy' flock) it is important to maintain a healthy flock. The well-known quote "The best defense is a great offense" holds true when keeping poultry. A strong biosecurity program is important to keep disease-causing organisms (bacteria, viruses, fungi, etc) away from your flock.

To understand the effects of disease-causing organisms (and management problems) on the health of your flock it is important to have a good understanding of the anatomy and physiology of poultry and what the inside of a healthy bird looks like.

Avian necropsy techniques (University of Florida)

The most popularly known poultry disease is Avian Influenza.

• Bird Flu - Information for Hunters and Taxidermists
• Bird Flu - Identification and Reporting
• Bird Flu - Considerations for Pets and Non-Farm Animals
• Bird Flu - Cleaning and Disinfection
• Bird Flu - Biosecurity and Prevention

Sticky droppings: A feed-related problem (Washington State University)

Common poultry diseases (University of Florida)

A variety of leg disorders are possible in poultry flocks. They can be the result of improper nutrition and/or management. Some problems are genetic. Leg problems can be a problem in chicken flocks raising Cornish-based chicks for meat production (i.e., broilers) because of the potential for them to put on weight faster than they can develop the bone structure to support the weight. Waterfowl, turkeys, and game birds are prone to leg and foot problems

Eye disorders (not related to disease) are not very common in poultry flocks. Birds rely on their sight in order to find food and water so any problems with their vision will adversely affect flock performance.

Poultry flocks can pick up a variety of different parasites, both external and internal. Small infestations may not cause any health problems, but a heavy infestation can reduce performance, and animal welfare and can sometimes lead to death. It is important to monitor your flock for any signs of parasites

External

A number of different external parasites can infect a flock, typically from wild birds. Most live on the host and should be relatively easy to identify. The red chicken mite, however, does not live on the birds. Instead, they hide in crevices during the day and come out to feed on the birds at night. To check for red mites you would need to examine the birds at night.

ASC-206: Common External Parasites of Poultry

Internal

Coccidia are single-cell protozoa that damage the lining of the small intestine. They are host-specific, meaning the species that affects cattle, swine, and poultry do not affect sheep and vice versa.

Blackhead is another single-celled parasite of poultry, Histomonas meleagridis, which typically affects the cecal wall of the infected bird. It can be carried by chickens without doing any damage but turkeys are very susceptible.

Intestinal parasites in backyard poultry flocks (University of Florida)

Parasite management for natural and organic poultry: Blackhead in turkeys (ATTRA) - Note: The drugs mentioned for the treatment of blackhead in this publication have been removed from the market and are no longer legal for treating poultry in the USA.

Preventing blackhead disease in turkeys and game birds (Kansas State University)

Poultry and Sheep

Using multi-species grazing, including poultry, can play an important role in controlling sheep worms. Ruminants (other than sheep) serve as dead-end hosts to the sheep worm preventing the spread of larvae. Having poultry follow sheep in the rotation is another way to eliminate a lot of larvae.

Mycotoxins

Mycotoxins are becoming a serious problem in the feed industry. Mycotoxins are toxic compounds produced by molds in animal feeds. Even if the mold is destroyed, the mycotoxin usually remains. The Veterinary Diagnostic Laboratory at the Iowa State University College of Veterinary Medicine monitors the levels of mycotoxins in corn in the Midwest area. The December 2009 report indicated that there is a higher than normal incidence of the corn affected by mycotoxins across Iowa and in samples submitted from six states including Illinois, Kentucky, Michigan, Oklahoma, Texas, and Wisconsin.

• Introduction to mycotoxins (Alltech) - A website dedicated to helping you better understand the growing mycotoxin problem in the feed industry.
• How delayed harvest might affect ear rots and mycotoxin contamination (Iowa State University)

Nutritional Deficiencies

For the health and productivity of your birds, it is important that they are fed diets that meet their nutritional requirements. Complete feeds can be purchased that are formulated to meet all the nutritional requirements (energy, protein, and amino acids, fat, vitamins, macro- and micro-minerals, etc.) of a particular class of poultry.

Vitamins

Fat-soluble vitamins

Vitamin A is required for the health of the membranes of the digestive, urinary, reproductive and respiratory systems. A vitamin A deficiency can result when the level in the diet is inadequate or the vitamin added to the diet is oxidized by rancid fat in the diet. Additionally, neomycin, a common antibiotic, decreases the absorption of vitamin A. Vitamin A is a fat-soluble vitamin and an inadequate level of fat in the diet could also limit its absorption, even if in the diet at adequate levels.

Symptoms of a vitamin A deficiency include:

• Cheese-like, but odorless, discharge from one or more eye;
• Extremely thin birds (i.e., emaciation);
• Weak and/or uncoordinated birds;
• Ruffled feathers;
• Eyelids stuck together (referred to as sicca);
• Water discharge from the throat (referred to as roup), nostrils or eyes in young birds; and
• Egg production and hatchability decrease in adults

A vitamin D deficiency in poultry results in an inadequate level of vitamin D3 in the diet. Vitamin D3 is needed for proper calcium and phosphorus metabolism and thus the formation of a normal skeleton, beak and claws, and eggshells. Rickets occurs in young birds while cage layer fatigue (osteomalacia) occurs in mature females. It can be mistaken for other causes of deforming leg weakness in poultry.

A vitamin E deficiency results in a condition known as 'crazy chick disease' or encephalomalacia (softening of the brain). In chicks, it usually occurs between 15-30 days of age. Vitamin E is required for reproduction as well as the normal integrity of the central nervous and muscular systems. Vitamin E is also an effective antioxidant and is an important protector of essential fatty acids (e.g. linolenic acid), vitamin A, and vitamin D3.

A vitamin E deficiency is typically caused by an inadequate level of vitamin E in the diet. In addition, vitamin E is readily destroyed by heat (a term referred to as heat-labile). A deficiency of selenium will also result in a deficiency of vitamin E. Selenium levels are low in some areas of the country resulting in lower levels in cereal grains.

Symptoms of a vitamin E deficiency include:

• Uncoordination
• Tremors
• Rapid contractions and relaxation of the legs resulting in what is known as 'crazy chick disease'
• Testicular degeneration in adult males resulting to decreased fertility
• Increased embryonic mortality

A vitamin E deficiency resembles Avian Encephalomyelitis (AE), Newcastle Disease (AE), and a vitamin B1 deficiency.

Vitamin K is required for the production of prothrombin which is essential in blood clotting. So a deficiency of vitamin K results in an increase in hemorrhaging. It can cause increased embryonic mortality, with the dead embryos having hemorrhaging conditions.

A vitamin K deficiency can be caused by a deficiency of vitamin K in the diet. High levels of sulfaquinoxaline, a medication for prevention or treating coccidiosis in chickens and turkeys.

Water-soluble vitamins

Vitamin B1 deficiencies result from an inadequate level in the diet. Other causes of a deficiency include excess Amprol (used to treat or control coccidiosis) in the diet; moldy feed; or by rancid fat oxidation. A deficiency typically takes three weeks to develop. Vitamin B1 is needed for the formation of a coenzyme involved in the function of the nervous system. A vitamin B1 deficiency resembles Avian Encephalomacia (AE), vitamin E deficiency and Newcastle disease.

Symptoms of a vitamin B1 deficiency in young birds include:

• Nervousness
• Ruffled feathers
• Leg weakness
• Unsteady gait
• Paralysis (convulsions with head retraction) called polyneuritis
• Star-gazing (head retracted due to paralysis of the anterior muscles of the neck)

Symptoms of a vitamin B1 deficiency in adults include:

• Blue comb
• Decrease in respiration rate
• Lowered body temperature

Vitamin B2 is a cofactor in many enzyme systems. Most are associated in oxidation-reduction reactions that are involved in respiration. A vitamin B2 deficiency can be mistaken for Marek's disease since both have enlarged peripheral nerves.

Symptoms of a vitamin B2 deficiency include:

• Curled toes
• Poor growth
• Weak and emaciation in young birds
• Decrease in size of leg muscles (i.e., atrophy)
• Skin is dry and harsh
• Poor hatchability and egg production in adults
• Dead embryos with 'clubbed' down feathers.
• Turkeys have severe dermatitis (i.e., inflammation of the skin) in the feet and shanks as well as incrustations on the corners on the mouth.

Feather Pecking & Cannibalism

Regardless of the housing system, feather pecking and cannibalism can be a problem, especially with chickens and pheasants. Prevention is always the key. Make sure that you are following best management practices (BMPs) on housing and nutrition for the species of poultry you keep.

Cannibalism in small poultry flocks (Kansas State University)

Cannibalism by poultry (University of Nebraska)

Egg Eating

A bad habit egg production flocks can pick up is egg eating. Once it starts it is a hard habit to break. Proper housing, nest design, and nutrition are important factors to consider.

Egg-eating by chickens in small and backyard poultry flocks (eXtension.org/poultry)

Preventing hens from eating eggs (Kansas State University)