by Douglas R. Kuney, Howard L. Enos, William W. Brown and Charles E. Whiteman* (10/18)
Quick Facts…
- Infectious organisms can transfer to birds from sources, such as droppings, the respiratory tract, mucus discharges, other animals, tools/equipment, handling by people, insects, water, soil and passed to offspring.
- It is very important to keep and maintain current flock health records. These records should include documenting feed consumption, production and mortality. These records are critical to helping identify the cause of health problems.
- It is important to note the rate of disease spread throughout the flock in preliminary respiratory ailment diagnosis.
- If a disease problem is suspected in the flock, a veterinarian should be consulted as soon as possible before any corrective action is taken. The following diseases are reportable to the Colorado State Veterinarian’s office: Highly and Low Pathogenic Avian Influenza, Newcastle disease and All Foreign Animal Diseases*.
| Infectious ailments | Diagnostic aid/signs symptoms | Prevention/Treatment | Age affected |
| Air sac disease | Coughing, nasal discharge, breathing difficulties, depressed appetite, watery eyes, stunted growth. | Provide good ventilation, keep birds healthy, warm and provide a good diet. | Young birds |
| Avian encephalomyelitis | Failure of muscle coordination, irregularity of muscle action. progressive paralysis, dull eye expression, sitting on hocks, head and neck tremors. Many times symptoms are not apparent in older birds. | Vaccinate at least 4 weeks before egg laying, survivors are immune. | Young birds most seriously affected. |
| Avian influenza | Low pathogenic version: respiratory problems listlessness, appetite loss, breathing difficulty, lower egg production. Highly pathogenic version: facial swelling, blue comb and wattles, dehydration, respiratory problems, may have blood tinged discharge from nostrils, may also die before any symptoms. | Protect flock from wild birds. No treatment. | All ages |
| Fowl cholera “cholera pasteurellosis” |
Fairly fast spreading with high mortality; loss of appetite, darkening of the head parts (may be swollen), green discharge, coughing and nasal discharge; the course of the illness is short. | Obtain disease-free stock and maintain a clean premises; keep other birds and mammals from flock, rodent management Sulfaquinoxaline and other sulfa drugs. | All ages |
| Coryza | Foul smelling discharge from nose, swollen face, eyes sinuses, labored or noisy breathing, sneezing, watery eyes, drop in egg production. | Avoid combining birds from different flocks, antibiotics can treat symptoms but affected birds should be culled. | All ages (mostly adults) |
| Chronic respiratory disease | Rattling sound in lungs, coughing, sneezing and nasal discharges. Slow spreading with a prolonged course in the flock. May show no signs. | Vaccinate, No treatment is effective, erythromycin, tetracycline or tylosin may reduce deaths. | All ages |
| Fowl pox (transmitted by mosquitos) |
There are two forms: wet pox and dry pox. The wet pox form is characterized by pustules in the mouth, sinuses, and larynx. It can plug the trachea and cause suffocation. The dry form is characterized by scabs or wart like lesions on the skin of wattles, comb and face. They may also be lethargic, causing a drop in egg production. Young will grow slow. | Control flies, mites and mosquitos, vaccinate when disease is detected, isolate affected birds. | All ages |
| Infectious bronchitis | Noticeable drop in egg production by 20-50% with variable mortality. Respiratory symptoms (sneezing, gasping, nasal discharge). Rapid spreading usually within 1-2 weeks. Often there are soft-shelled or misshapen eggs. Feed and water consumption is lower. | Avoid mixing of various aged birds, no vaccines effective, provide electrolytes and keep birds warm. | All ages |
| Infectious laryngotracheitis | Respiratory symptoms are very pronounced sometimes with with bloody mucus discharge from nose and mouth. Necks are sometimes extended during inhale, may be wheezy or gurgly. May also have watery eyes. Symptoms appear 1-2 weeks after exposure and persists for 1 – 4 weeks. Generally lower egg production is observed. | Do not introduce mature birds to flock, no treatments effective, vaccinate. | Usually adults |
| Marek’s disease | Lameness, paralysis (inability to raise wings), gasping, blindness or combinations of these. Tumors will form on the inside or outside of the chick. The iris of the eye will turn a grayish color and won’t react to light. Excessive loss of weight is sometimes observed. Mortality up to 60% and usually peaks within six weeks but then continues at a low rate. Chick should be put down as they will carry the disease for life. | Vaccinate, no treatment available. | 3 weeks to 6 months |
| Newcastle disease | Symptoms occur in layers, characterized by a sudden drop in egg production to near 0%. Low to no mortality. respiratory symptoms are usually seen but are mild. Soft-shelled and deformed eggs are common. This disease spreads rapidly through the flock. Nervous signs are partial to complete paralysis, facial swelling paralysis, twisting of neck, watery discharge from the nostril, trembling. There are 3 forms of the disease – lentogenic (mildly pathogenic), mesogenic (moderately pathogenic) and velogenic (highly pathogenic). | Prevent infection from other flocks or wild birds. | All ages |
| Rickets | Young birds develop a lame stiff-legged gait. Laying birds produce fewer eggs that are thin or soft-shelled. This is due to a nutritional imbalance of calcium, phosphorus or vitamin D3. | Provide sunlight, calcium and phosphorus. | All ages |
| Thrush (sour crop) | Lethargy, rough feathers, distended crop, loss of appetite, slow growth, weight loss, sour mouth odor. | Keep feed fresh and dry, sanitize waterers frequently, Copper sulfate make sure not to overdose. | Young birds |
| Vitamin E deficiency | Lack of motor coordination, e.g. loss of balance, falling over backwards. A reddish black swelling along the abdomen is sometimes seen. | Supplements or dark, leafy greens. | Young birds |
| Vitamin A deficiency | In young birds, cessation of growth, drowsiness and poor coordination are observed. In laying flocks, decreased egg production occurs, inflammation of the eyes and sinuses may occur in a few birds. Respiratory symptoms often present. | Vitamin A, D & E supplements or dark leafy greens. | Usually young birds |
Ailments of chickens can manifest themselves in many ways and there usually are no clear-cut set of symptoms present because of secondary complications.
Many nutritional deficiencies can express symptoms that are very similar to those caused by an infectious organism; therefore the feed should be carefully examined.
Good sanitation practiced by all individuals coupled with good nutrition and a good vaccination program are keys to a healthy and thrifty flock.
* World Organization for Animal Health (WOAH) list of Reportable Diseases: https://www.woah.org/en/what-we-do/animal-health-and-welfare/animal-diseases/ , Colorado Department of Agriculture Reportable Disease List https://www.colorado.gov/pacific/aganimals/livestock-health
