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Keys to the Successful Identification, Treatment and Control of Crop Dysfunction
This paper is intended as a basic guide to understanding and dealing with crop dysfunction. Emphasis will be on prevention, early identification and treatment of this all too common condition. It will stress continuing education and learning through experience, while advocating strict hygiene and promoting established husbandry practices as effective deterrents to crop related illness. My goal is to help the reader understand crop dysfunction and to help him become familiar with diagnostic tools and the remedies and treatments available.
Chick mortality due to illness involving crop dysfunction is a common and serious problem in many nurseries. One of the greatest challenges to successful hand-feeding involves recognizing the conditions related to or leading to crop dysfunction. Birds are unique in the way they mask signs of illness until they are close to critical. This instinctive cover-up makes it difficult, particularly for the inexperienced bird keeper, to successfully identify, diagnose and treat crop-related illness. Dealing with circumstance involving crop dysfunction does require a certain amount of experience, and a basic knowledge of avian pediatrics and neonatal anatomy as well as a keen eye.
Learn all you can
It is paramount that breeders and avian caretakers alike continually educate themselves and experience all aspects of baby bird care. It is not only important to study the principles of nursery management and technique but to be aware of resources available. These resources can range from a magazine borrowed from a friend to a consultation with your avian veterinarian. Material dealing with avian anatomy, pediatrics, basic husbandry and nursery management practices is readily attainable. In the interest of aviculture, personal enrichment and a better understanding of birds in general you must read current articles and books. Bird related periodicals (Bird Talk, Bird Breeder, Bird Times, etc.) are quite informative and are filled with information. Join a bird club/organization and routinely attend seminars; stay abreast of prevalent avian research and developments in the field of avian pediatrics and diligently seek the guidance of knowledgeable and experienced veterinarians, breeders and aviculturists. Finally, start your own avian reference library and consult it often.
An avian reference library should include at least one book in each of these categories (included are highly rated, must have books):
A General ReferenceDavid Alderton's Atlas of Parrots and/or The Complete Parrot by Arthur Freud.
Bird Care or Husbandry/ManagementThe Complete Bird Owner's Handbook by Gary Gallerstein, DVM and/or Dr. Joel Murphy's Parrot Care, A Guide to Basic Understanding of Parrot Care.
Training And BehaviorMy Parrot, My Friend by Bonnie Munro Doane and Thomas Qualkinbush.
Health and MedicineClinical Avian Medicine and Surgery by Greg Harrison DVM and Linda Harrison, Avian Medicine: Principles and Application by Branson Ritchie, DVM, PhD, Greg Harrison, DVM, Linda Harrison.
Breeding, Species or Genus Specific Parrots of the World by Joseph M. Forshaw and The Atlas of Parrots by David Alderton.
Avian Pediatrics, Nursery Management and IncubationHandfeeding and Raising Baby Birds by Matthew Vriends, Parrots, Handfeeding & Nursery Management by Rick Jordan, Parrot Incubation Procedures by Rick Jordan and Psittacine Aviculture: Perspectives, Techniques and Research by Richard Schubot, Kevin and Susan Clubb.
LegislationA Birdkeepers Legislative Handbook by Kelly Tucker and On Wings, A Monthly Publication Serving the Avicultural Community, published monthly by MacDhui Enterprises, Inc, Bill Franklin, editor and Judy Franklin Legislative editor.
If well informed and properly prepared, it is possible to deal with pediatric difficulties with confidence and success. Experienced breeders and veterinarians are easily approached and filled with knowledge and wisdom. Breeders, veterinarians and of course books are in fact learning tools and sources of unlimited information and guidance. Knowledge, whether reached through personal experience, apprenticeship or through books, will supply tools needed to develop skills and instill confidence. Being well informed is the first step to positive identification, accurate diagnosis and successful treatment of avian digestive disorders. Be prepared, be informed and use the resources available.
Harrison and Harrison's Clinical Avian Medicine and Surgery is an excellent reference book and an invaluable resource. Linda and Greg Harrison describe it as a reference/textbook for veterinarians and students, designed to introduce the reader to new philosophies, concepts, and trends in captive bird care with much information of value to aviculturists, zoologists, wildlife biologists, avian pathologists, pet shop owners, and ultimately the pet bird owner. (Harrison). The chapters on "Selected Physiology for The Avian Practitioner", "Pediatric Medicine" and of course "Clinical Anatomy", are very informative. Clinical Avian Medicine and Surgery will give you a better understanding of avian anatomy and the avian digestive system .
The avian digestive system, which includes the crop, is a highly complex and important part of avian anatomy. Only by becoming familiar with normal avian anatomy and physiology are we better able to recognize the abnormal. Gaining a better understanding of avian anatomy, particularly the upper GI tract, will prove helpful in dealing with digestive disorders particularly those disorders involving the crop. In order to recognize the subtle signs of crop dysfunction, the normal avian digestive system must be studied.
The crop, a significant part of the upper GI tract, is a continuation of the esophagus, extending from just below the jaw to just above the breastbone. Partially digested food moves from the crop down through the digestive tract. A healthy, normal crop contains natural enzymes and beneficial bacteria, which breaks down food and slowly moves it down through the stomach, into the gizzard and finally down lower GI tract. It is when this system does not function normally that digestive disorders and crop dysfunction occur.
What is Crop Dysfunction?
An actual crop disorder directly affects and relates to the crop. Crop dysfunction can be defined as a condition in which food does not move normally from the crop down into the digestive system. This condition may or may not be disease related. Numerous environmental, congenital, acquired, infectious and nutritional problems can affect chicks and cause crop dysfunction and stasis. Crop stasis, which is crop dysfunction, is commonly referred to by several names: slow crop, "sour crop" and impaction. These terms are often used interchangeably. Clinically speaking the terms describe varying degrees or conditions of crop dysfunction.
Crop stasis, or slow crop, is a general term used to describe a condition when the crop is extremely slow to empty or in severe cases (usually when neglected and secondary infections are established) completely shuts down. Crop stasis can be the result of impaction, sour crop, disease, trauma and/or stress. Impaction is a serious form of crop stasis usually caused by ingestion of foreign materials such as bedding or unhulled seeds, or when hand-feeding formula liquid and solids separate. Crop stasis resulting form formula separation occurs when food is poorly mixed or if formula or environmental temperature is too cold. Furthermore, the formula liquid will dehydrate from the crop. If undetected and left untreated crop mobility will slow, resulting in crop stasis and finally blockage and/or impaction. Consequently, there will be little or no digestion or mobility taking place. This condition does not always mean a bacterial or fungal problem exists in the digestive system; however, when diagnosed early, is indicative of a simple digestive upset that can be easily treated with fluid and enzyme therapy. Unfortunately, undigested food remaining in a crop over a extended period can "stagnate" or sour, eventually resulting in stasis and a condition often referred to as "sour crop". Any form of crop stasis, including sour crop, can lead to or be a result of dangerous yeast, fungal or bacterial infection. If symptoms of crop dysfunction are ignored and left untreated or improperly treated, they will progressively get worse, finally leading to secondary infections, complications and eventually death.
Clearly, any sign of crop abnormality should be considered a serious sign of a potentially dangerous condition. Undigested food remaining in the crop over a 24 hour period provides an excellent growth medium for opportunist bacteria, and yeast or fungi. The secondary infections caused by these pathogens are potentially dangerous, prove more difficult to treat and often need veterinary intervention. Therefore, quick and accurate diagnosis and treatment of slow crop is the key to preventing severe and complicated secondary crop infections.
Various diagnostic procedures must be performed in order to identify, determine the degree of crop dysfunction and decide on a plan of treatment. Any evaluation of a crop stasis should begin with a through history and physical. This requires a practical knowledge of avian anatomy and normal neonatal development for the species. History taking and physical examination are helpful in identifying digestive problems, but they are also necessary in reaching a diagnosis and deciding on proper treatment.
To diagnose is to identify and determine the cause and nature of a disease by the use of skillful and scientific methods. Established methods may include evaluating the history of the disease process; physical examination and observation of the signs and symptoms present; laboratory data and special tests. A medical diagnosis is the entire process of determining the cause of the patient's illness or discomfort. The chosen method of arriving at a diagnosis will depend on a number of factors including the type of illness or injury in question. Diagnostics involve clinical skills (such as history and physical examination) and may or may not include sophisticated laboratory investigations such as gram stains, bacterial culture, CBC and sensitivity. A clinical diagnosis is determined by history, observation, laboratory studies, and symptoms. The value of establishing a diagnosis is to provide a logical basis for treatment and prognosis (Tabors 535). An accurate diagnosis may be made by a veterinarian or well-informed layman using available clinical skills and scientific methods. Of particular significance to diagnosis is patient history and routine physical examinations.
Medically speaking, history is defined as a systematic record of past events as they relate to the patient. Specifically, medical history is a record of past illnesses and conditions, including prior treatment or medications, that could affect the health of the patient" (Tabors 906). An accurate and detailed hand-feeding log including routine physical examinations can be invaluable diagnostic tools useful in identifying a problem, establishing the cause, predicting what will happen and ultimately deciding on a treatment plan. When monitoring a chick's progress it is crucial to have on hand as much information as possible. Often with very small, sick chicks the numbers of possible diagnostic tests are few, therefore, a complete and accurate history in combination with a through physical exam is of paramount importance. Always assess the physical condition of each chick, palpate the crop to detect thickening or foreign bodies, examine chest and abdomen, eyes, nostrils, beak and oral cavity. Always check skin color, crop condition and monitor respiratory noises. Daily weighing is recommended and can effectively provide early clues to illness. Consequently, record any and all data in a detailed hand-feeding log.
The Hand-feeding Log
Carefully kept records can supply much of the vital information needed in providing complete histories for chicks being hand-fed. Dr. Robert Clipsham in his series of articles dealing with prenatal medical management describes record keeping as being "of prime importance for accurate hand care of psittacine offspring." (Clipsham 44). Keeping detailed hand-feeding logs is not only responsible aviculture, it is and can be vital to the successful hand-raising of baby parrots. Logs should contain up-to-date notes of all aspects of the birds' care including medical history and observations noted during the physical examination. Pertinent data should include relevant notes and remarks, hatch date, date pulled, crop empty rate, food volume and consistency, formula used and daily weights. The brooder, bedding materials, ambient humidity and temperature, thermometer placement, sanitation protocol, clutchmates, etc. are all relevant therefore should be recorded. It is not only applicable to keep detailed records of each baby but also to compare recorded data to published species' weight and development charts and tables. These charts and tables are found in various books and articles dealing with hand-feeding and avian pediatric development.
Hand-feeders should familiarize themselves or have access to the charts and tables of normal weight ranges, weight gains, weaning weight loss, developmental parameters, and maximum food amounts for various species. Any sign of weight gain or loss can be one of the first indications of a pediatric digestive problem. A baby should gain weight every day until weaning begins.
Any weight loss generally indicates improper feeding or disease. Dr. Kim Joyner agrees that it is important that records of daily-recorded weights be kept on each hand-fed baby. Any failure to gain or a loss of weight is one of the first indications of a problem (Joyner 22). By the time the visual signs of disease, as poor droppings, lethargy, or crop stasis, are pronounced, treatment can be more difficult. Other telltale symptoms of a digestive disorder are decreased food intake, increased time between feedings and change in frequency or consistency of droppings. A good history coupled with a through daily physical examination will provide invaluable clues and up to date information essential to accurate diagnosis and treatment.
The following is a list of questions pertinent to the diagnosis and treatment of crop dysfunction. These are questions a veterinarian may ask as part of his clinical work up. Answers will provide useful diagnostic clues. Answers to these questions should be found in a well-documented hand-feeding log.
When did you notice the problem? How long has this problem been going on?
Has this happened before?
Is there a history of previous illnesses? Treatment? Did the treatment work?
Was the chick fed from day one and at what age did you begin to hand-feed?
How old is the chick?
How much does he weigh?
What hand-feeding implements and technique are you using?
What hand-feeding formula are you feeding? Com mercial or homemade?
How many times a day is he being fed?
Amount fed at each feeding?
What is the normal time it takes for the crop to empty? How long does it take now?
Are you using any supplements or additives in the formula?
What is the consistency of the formula?
Have you changed his formula recently?
Has there been any change in the bird's environment? What type of brooder are using? Heat source?
Brooder temperature? Humidity?
What bedding are you using?
How many babies are in the brooder? Is this the only baby that has problems?
What are the condition and frequency of the drop pings?
What are your sanitation practices?
A proper physical examination is a critical step in detecting disease and with practice can be successfully accomplished by most hand-feeders. A trained eye can mean the difference between detecting illness early enough to provide appropriate treatment and an unfortunate death. With preparation and persistence, physical examinations can be deliberately performed and early warning signs of illness identified and dealt with. A physical examination including weigh-in and complete body check is recommended at least once a day. The examination should be preformed when the crop is empty, as aspiration is a concern. Routinely palpate the crop to check the contents for volume, consistency and abnormalities. Subtle symptoms or clues noted when performing an examination can be early indications of minor problems that if left untreated can often lead to more complicated difficulties in the future (See Physical Examination Chart). Knowing what is normal and healthy is important to early detection and diagnosis.
A healthy crop extends slightly backwards to the right side of the neck, parallel to the trachea. The crop "should reveal a rounded structure dependent in size on the volume of food present. The tone should always be firm and never droopy" (Clipsham 45). Babies have very large crops compared to older birds. A chick's crop will hold about twice as much food as the crop of an adult of the same species. Crop shapes and capacities differ between species and sometimes between individuals of the same species. Capacity also is dependent on age and stage of development. Be aware of these differences and become familiar with the norms of each species. For example: Macaw crops are typically more pendulous than tighter Eclectus and Lovebird crops.
Below is a list of approximate maximum crop capacity for some popular species. These numbers are not to be interpreted as the rule. Remember all babies are individuals and proper changes should be made. These numbers are valid for babies over two weeks old.
Maximum crop capacity of selected species
Macaws 100 to 140cc
Cockatoos 75 to 120cc
Mini Macaws 40 to 60cc
Smaller Cockatoos 50 to 75cc
Amazons 50 to 70cc
Smaller Amazons 35 to 50cc
Eclectus 35 to 50cc
Pionus 25 to 40cc
African Grey 25 to 60cc
Large Conures 35 to 60cc
Smaller Conures 15 to 30cc
Alexandrines 25 to 35cc
Caique 25 to 35cc
Indian Ring-necks 12 to 25cc
Quaker Parakeets 12 to 20cc
Cockatiels 10 to 15cc
Brotogeris Parakeets 8 to 12cc
Lovebirds 5 to 10cc
Parakeets 4 to 10cc
A healthy crop will show subtle signs of contractions. These contractions are a normal part of the digestion process. The smooth muscle in the crop wall periodically contracts, causing waves of movement that can be seen from the crop's exterior. Most species' crops will contract downward from the throat toward the crop helping the food move down the digestive tract. Either crop hyper- or hypo-motility (movements too rapid or slow) can occur. Definite rates have not been established for each species but 1 to 2 contractions should be seen per minute in a partially filled crop (Psittacine 65 ). Changes in motility rates can indicate digestive difficulties. Unusual rates and force of these contractions are often present in cases of crop dysfunction. Always note any unusual physical changes. Any deviation from the norm as in size, volume, motility rates or condition should warrant a closer look and further interpretation.
There are a number of clinical conditions that can effect the digestive
system. It is important to interpret the signs of these conditions correctly.
Information obtained from the history and through physical examinations
of neonates will provide valuable clues necessary to accurately diagnose
crop-related problems. Diagnostic techniques are helpful in determining
if veterinary intervention is necessary. Many breeders are experienced
in avian pediatrics and familiar with neonatal problems and often diagnose
and treat on their own. These breeders are experienced enough to know
when to seek veterinary help. However, if you feel confident enough to
diagnose and treat the illness yourself, do so judicially KNOW
WHAT YOU ARE DOING. Inaccurately diagnosing and treating pediatric problems
can prove harmful, even deadly. Use your valuable re
The chances of crop stasis can be minimized with careful environmental management, good nutrition, and hygiene. Poor environmental conditions usually brought about by shoddy management practices are probably the most common non-medical cause of slow crop. Stress brought on by poor management practices has the potential to cause disease and particularly crop dysfunction. Infections caused by yeast, bacteria and fungi are common examples of digestive disorders associated with environment and the stress brought on by its mismanagement. Kevin Flammer lists important sources of pathogenic bacteria as being food, water supply, other birds in the nursery, [feeding utensils, brooding containers, bedding] and contamination by the nursery feeder (Harrison 643). In addition, crop burn, malnutrition, overfeeding, and stretching of the crop can also be traced to improper husbandry/management practices.
Obviously, many of the digestive disorders occurring in the avian nursery are indeed related to environmental management practices and hygiene and are indeed preventable. Preventive care and immediate attention to stressful environmental conditions is the key to keeping management related disease to a minimum. The early identification of a problem and correction of the adverse environmental condition, including supportive care will often amend a minor medical difficulty and restore crop function to normal. For instance, simple crop stasis resulting from environmental conditions involving brooders that are too hot, too cold, too humid or too dry can be easily remedied. This can be accomplished by simply adjusting a thermostat and providing appropriate therapy until crop function returns to normal.
In order to prevent and treat crop stasis it is important to watch for and eliminate potential causes:
Primary Causes of Crop Stasis
· Traumacrop burn or injury
· Infection of the crop lining
· Over-stretching of the crop
· Incorrect brooder temperature or humidity levels
· Foreign bodies (improper bedding, seed hulls)
· Food impaction
Secondary Causes of Crop Stasis
· Environmental temperature and humidity too high or too low
· Gram negative bacteria, generalized infection causing slow crop
· Formula inconsistencies and improper handling; formula temperatures;improper feeding and feed ing schedule inconsistencies
· Malnutrition, nutritional deficiencies
· Blockage of the alimentary tract distal to the crop (Harrison 647)
Veterinarians, who are educated in medical science and trained in avian medicine, are able to expertly employ all manners of diagnostic procedures in order to arrive at a satisfactory treatment plan, whereas laymen, even an experienced layman, are limited in medical knowledge and resources. Experience and a good library does go a long way providing information useful in the diagnosis and treatment of avian pediatric problems dealing with crop dysfunction. Basic diagnostic procedures and treatment plans can be learned. Many breeders are experienced enough with neonatal problems to diagnose and treat on their own. Nevertheless, they will often consult with an avian veterinarian who will help with diagnosis and treatment.
In order to arrive at a successful treatment plan a series of elected treatment procedures must be followed. Medically speaking, treatment is defined as any elected procedure used for the cure of a disease or pathological condition. An elected treatment may be active, causal, supportive or surgical. An active treatment is directed specifically toward the cure of a disease. An example would be antibiotic therapy prescribed after appropriate lab tests are preformed. Whereas a causal treatment is directed toward the cause of the disease. Once the cause is corrected, an appropriate treatment plan can be initiated. For example: too low a brooder temperature can cause crop stasis. By raising the brooder temperature and providing supportive therapy, normal crop function will return. That is, stop feeding formula and orally administer small amounts of electrolyte or saline until crop returns to normal. Treatment may be supportive. Supportive treatments can be important to active, causal and surgical treatments. They supplement and employ special measures to support a specific therapy. In the example of a causal treatment, fluid and heat therapy are supportive treatments. A surgical treatment is where the patient must be operated on in order for a cure to be realized. (Tabor 2031). Surgery is often necessary in cases of crop burn. Surgery almost always involves supportive therapy of one type or another.
Some digestive disorders require actively treating the disease with antibiotics. The use of antibiotics can often mean the difference between life and death. Birds with advanced symptoms of crop stasis are particularly susceptible to bacterial infections because of their weakened state. These secondary infections, often found in the intestines, multiply and eventually gain entrance into the bloodstream. This is a life threatening condition. If a bacterial infection is suspect it is important to see your veterinarian as improper diagnosis and treatment can be dangerous. It is extremely important to be sure a bacterial infection is present before treating with antibiotics.
Be aware that many diseases, particularly those involving early stages of crop stasis, are not caused by bacteria. Not to say that the problem won't eventually develop into a bacterial infection . However, treatment with antibiotics will not always help a bird that is ill: antibiotics have no effect whatsoever on infections caused by viruses or fungus. In cases of severe crop stasis and when babies are visibly weak, a reduced feeding response and signs of anemia, depression and weight loss can indicate bacterial infection. Birds who whine and beg excessively or make no effort to eat may have a low-grade bacterial infection. Bacterial infection can often lead to a yeast or fungal infection. Using antibiotics indiscriminately can cause yeast overgrowth resulting in candida.
When should a bird be treated with antibiotics?
Dr. Barbera L Oglesbee in her article "Are Wonder Drugs Wonderful" recommends we know the answers to the following questions before using antibiotics:
1) Is there a bacterial infection present, and if so, where is the infection? 2) What particular bacterial species is present? 3) Which antibiotic will treat the infection, and will it be effective at blood concentrations attainable to birds? and 4) What effect will the antibiotic have on the bird's normal flora? If these questions can't be answered, see your veterinarian before administering antibiotics.
It is extremely important that a bacterial infection is accurately diagnosed before using antibiotics. Your avian veterinarian will prove invaluable. He is able to accurately diagnose a bacterial infection based on sound diagnostic procedures, including history, physical examination, bloodwork, tissue analysis, gram stains, and other relevant lab tests. He will then prescribe appropriate antibiotic treatment and therapy.
While this paper doesn't begin to cover all aspects of dealing with crop dysfunction, it has attempted to establish basic guidelines when dealing with crop stasis. It points out ignorance and inexperience as major causes of crop related illness and addresses the problem of identification, treatment and control. Diagnosis and treatment of crop dysfunction is difficult and does require expertise. Only by learning from personal experience and continued education can we hope to acquire the proficiency to prevent, identify and successfully treat cases of crop dysfunction in the nursery.
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