As the industry develops, large-scale poultry farming is becoming increasingly mature. This means farming businesses must improve their ability to withstand risks more quickly.
This is especially true of disease prevention and control: it must be precise, accurate, and fast. Otherwise, one or two major outbreaks, or a series of incorrect diagnoses, can cause a business huge losses.
This is not like raising a few thousand chickens as a small household operation, where, if it does not work out, you can simply give up and go find a job. Businesses have different responsibilities to bear.
Therefore, we need to diagnose chicken diseases accurately. We should prevent diseases that have not yet occurred or are likely to occur, and treat those that have already occurred. Based on the author’s many years of experience in diagnosing and treating chicken diseases, I would like to share some insights with everyone.
Diagnosing chicken diseases requires considering various factors comprehensively and from all angles. We should not draw a simple, rough conclusion based solely on an autopsy or visible symptoms.
Many diseases have similar features. If you take the wrong direction, the treatment results can be very different. In my work, I have met many impatient people who, after just a few words—or as soon as they see you make the first cut into a chicken—urgently demand to know what disease it has. When I say I need to analyze it, they become impatient and assume I cannot tell. It is a very frustrating situation.
I. Consider the flock as a whole.
For example, feed intake, droppings, general condition, changes in egg production, and whether there are any respiratory signs. Sometimes the symptoms shown by dead chickens differ from those in the flock, or are not representative.
If you make a hasty decision to medicate the whole flock based solely on the post-mortem examination of one or two chickens, a lot of money will be wasted on medication. A judgment based on both the flock’s overall signs and those of sick or dead chickens is relatively more accurate.
II. Consider the course of the disease.
For example, respiratory signs in a flock can involve many diseases (Newcastle disease, infectious bronchitis, infectious laryngotracheitis, mycoplasmosis, infectious coryza, etc.), as well as respiratory signs caused by poor ventilation or poor air quality.
Some diseases develop rapidly and spread quickly, while others develop more slowly and last longer. Different problems require different plans: whether to use antibacterial or antiviral medication, whether to vaccinate or improve ventilation, whether to improve air quality or move the flock, and so on. You cannot simply use two or three, or even four or five, medications all at once and expect everything to be fine.
III. Consider disease trends.
Some diseases are seasonal, such as fowlpox, leucocytozoonosis, and heat stress. Some diseases are associated with environmental conditions, such as coccidiosis and persistent enteritis, as well as respiratory disease outbreaks caused by strong winds or uneven temperatures.
If chickens die from heat, their internal organs may show lesions similar to those of Newcastle disease. Failure to distinguish between them could mean missing the opportunity to save them.
If infectious laryngotracheitis is prevalent in a particular region, then as soon as respiratory signs appear in a flock, infectious laryngotracheitis should be considered first, with other types of respiratory disease ranked lower. The final decision should be made after careful consideration and investigation.
IV. Consider farm management and the statements of the attendants.
Some problems are caused by improper handling or overlooked details during rearing. For example, impurities or blockages in drinkers, water lines, or nipples may leave some chickens without enough water. Feed may spoil or become moldy because it has been stored for too long, old feed has accumulated in the troughs and has not been cleared, or bulk ingredients were not thoroughly inspected on arrival. This can lead to mycotoxicosis, fungal pneumonia, and other conditions.
In addition, occasional respiratory problems may be caused by colds resulting from excessive ventilation or by dry conditions in the chicken house. If these problems occur but are not identified during the investigation, and infectious diseases are assumed to be the cause, treatment will become much more difficult and economic losses will increase.
V. Consider differential diagnosis of diseases.
Many diseases have extremely similar visible symptoms. Making a hasty judgment without distinguishing between them can lead to many errors and very serious consequences.
For example, white watery droppings (also called lime-water-like or cream-like droppings) can occur with infectious bursal disease, Escherichia coli infection, and Salmonella infection.
Infectious bursal disease often causes acute deaths, and the dead birds are often well-fleshed and large. Deaths from Escherichia coli infection are more often associated with wasting, and the dead birds often have shrunken legs and feet. Birds with Salmonella infection are often extremely emaciated (there are, of course, other lesions, which are not described here one by one).
For example, difficulty breathing and gasping with the mouth open can occur with Newcastle disease, infectious laryngotracheitis, and infectious bronchitis.
Newcastle disease may also be accompanied by pale eggs and a drop in egg production; infectious laryngotracheitis may cause coughing up blood and unusual cries; infectious bronchitis, in contrast, produces a metallic sound deep in the trachea. Likewise, yellow-green droppings can occur in several different conditions.
If you administer medication without thinking it through, getting the diagnosis wrong can have irreversible consequences.
VI. Medication history should also be considered.
If a poultry house has already been treated with medication, or has used certain medications in the past, we should take that into account.
On the one hand, choose medications from different classes for treatment to avoid drug resistance and limitations in bacterial susceptibility (farms with the necessary resources can conduct a drug susceptibility test first). Where possible, avoid reusing medications within a short period. On the other hand, previously used treatment regimens can help us investigate and analyze the disease.
If a medication used recently was effective or kept the condition stable, that indicates the diagnosis was on the right track, so continue treatment with a medication from the same class to consolidate the results. Otherwise, the diagnosis may be incorrect, and other possibilities should be reconsidered and changes made promptly.
In addition to the above, there are sudden and random situations, as well as newly emerging diseases, which require us to keep learning and drawing conclusions through practice.
Traditional Chinese medicine emphasizes inspection, listening and smelling, inquiry, and palpation; these methods can also be applied in the livestock farming industry:
Inspection — observing the environment and the flock;
Listening and smelling — learning about trends and developments in poultry diseases;
Inquiry — communicating with farm workers and business managers;
The “cut” approach—namely, dissection and laboratory diagnosis.
In short, by approaching the flock and disease prevention and control with a rigorous attitude, thorough consideration, careful investigation, and a steady work style, even if success cannot be guaranteed, losses can be minimized and risks reduced, allowing us to move forward steadily and sail far in the livestock industry.