Coccidia

Coccidia are microscopic protozoan parasites that infect the intestinal tract of birds, causing a disease known as coccidiosis. These single-celled organisms belong primarily to the genera Eimeria and Isospora in avian species and represent one of the most common parasitic infections in both wild and captive birds. Coccidiosis affects a wide range of bird species including poultry, psittacines, finches, canaries, pigeons, and many others, with different coccidia species showing varying degrees of host specificity. While many birds carry low levels of coccidia without apparent illness, clinical coccidiosis can cause serious gastrointestinal disease ranging from mild diarrhea to life-threatening hemorrhagic enteritis, particularly in young or immunocompromised birds.

Coccidia transmission occurs through the fecal-oral route when birds ingest oocysts, the environmental stage of the parasite, from contaminated food, water, or surfaces. Oocysts are shed in the droppings of infected birds and require a period of development in the environment, called sporulation, before becoming infective. Under favorable conditions of warmth and moisture, sporulation occurs within one to three days. Once ingested by a susceptible bird, the sporulated oocysts release parasites that invade the intestinal lining, where they undergo complex reproductive cycles that amplify parasite numbers dramatically. This multiplication causes damage to intestinal cells and triggers the clinical signs of coccidiosis.

The impact of coccidiosis on bird health depends on multiple factors including the coccidia species involved, the number of oocysts ingested, the bird's age and immune status, and the presence of stressors that compromise immunity. Light infections in healthy adult birds may cause no apparent illness and may even provide some immunity against future exposure. However, heavy infections, particularly in young birds or those stressed by other factors, can cause severe intestinal damage with bloody diarrhea, dehydration, and death. The economic impact of coccidiosis in poultry is significant, while in pet birds, the disease represents an important cause of morbidity and mortality, especially in breeding facilities and multi-bird households.

Treatment of coccidiosis involves anticoccidial medications combined with supportive care to address dehydration and secondary complications. Prevention focuses on good hygiene practices to reduce environmental oocyst contamination and, in some cases, prophylactic medication or vaccination in high-risk situations. Bird owners should work with avian veterinarians to diagnose and treat coccidiosis appropriately, as misdiagnosis or inappropriate treatment can worsen outcomes. With proper veterinary care and management, most birds recover from coccidiosis, though prevention remains preferable to treatment.

The primary cause of coccidiosis is ingestion of sporulated oocysts from a contaminated environment. Coccidia oocysts are shed in the droppings of infected birds and must undergo sporulation in the environment to become infective. This process requires appropriate temperature, moisture, and oxygen, and typically takes one to three days under optimal conditions. Once sporulated, oocysts can remain viable in the environment for months, particularly in moist, shaded areas protected from direct sunlight. Birds become infected when they ingest these sporulated oocysts while eating, drinking, or preening. Oocysts are remarkably resistant to environmental conditions and many disinfectants, making environmental contamination difficult to eliminate.

Environmental and husbandry factors significantly influence coccidiosis risk. Moist, warm environments favor oocyst sporulation and survival, increasing infection pressure. Overcrowded conditions concentrate oocysts in smaller areas and increase stress on birds, compromising their ability to resist infection. Poor sanitation allowing fecal accumulation provides more opportunities for oocyst exposure. Dirty water and food sources contaminated with droppings serve as vehicles for transmission. Stress from any source including environmental factors, nutritional deficiencies, or concurrent disease suppresses immune function and allows coccidia to multiply to pathogenic levels. New birds introduced without quarantine can bring different coccidia species to established populations.

The coccidia life cycle involves complex reproductive stages within the host that amplify parasite numbers dramatically. After ingestion of sporulated oocysts, parasites are released in the intestine and invade the cells lining the intestinal wall. Within these cells, coccidia undergo multiple rounds of asexual reproduction called schizogony, with each generation producing many daughter cells that go on to infect additional intestinal cells. This exponential multiplication causes progressive destruction of the intestinal lining. Eventually, sexual reproduction occurs, producing oocysts that are shed in the droppings to continue the cycle. The entire cycle within the host typically takes five to seven days depending on the coccidia species.

Risk factors for clinical coccidiosis include young age, as birds under one year and particularly those under several months are most susceptible to severe disease. Stress from weaning, transport, environmental changes, or concurrent illness increases vulnerability. High environmental contamination from poor hygiene or overcrowding increases the dose of oocysts ingested. Immunosuppression from any cause allows uncontrolled parasite multiplication. Introduction to new environments exposes birds to coccidia species they have not previously encountered. Some bird species appear more susceptible than others, with finches, canaries, and young psittacines commonly affected.

The mechanism of disease involves destruction of intestinal epithelial cells during coccidia reproduction. As parasites multiply within intestinal cells, those cells are destroyed when daughter parasites are released. The cumulative loss of intestinal lining cells disrupts normal absorption of nutrients and fluids. Damage to blood vessels in the intestinal wall causes hemorrhage in severe cases, producing the bloody diarrhea characteristic of acute coccidiosis. Inflammation in response to tissue damage further impairs intestinal function. Secondary bacterial infections may develop when the intestinal barrier is compromised. The combined effects of malabsorption, fluid loss, hemorrhage, and secondary infection can rapidly lead to deterioration and death in severe cases.

Early warning signs of coccidiosis can be subtle and easily overlooked. Mild changes in dropping consistency, with slightly looser stools than normal, may be the first indication of intestinal involvement. Decreased appetite or changes in eating patterns can occur before more obvious symptoms develop. Slight lethargy with reduced activity compared to normal may be noticed by observant owners. Young birds may show slowed growth or failure to gain weight appropriately. The feathers around the vent may become soiled if droppings are loose. Because these early signs are nonspecific and many birds maintain apparent normal health with low-level coccidia infections, early coccidiosis often goes unrecognized.

As coccidiosis progresses, more characteristic symptoms develop. Diarrhea becomes increasingly obvious, with watery, loose, or mucoid droppings. In severe cases, droppings may contain blood, appearing red or dark brown, indicating intestinal hemorrhage. Weight loss becomes apparent despite normal or increased food offering. The bird may appear hunched or fluffed, indicating discomfort and illness. Decreased water intake compounds the dehydration caused by fluid loss through diarrhea. The vent area typically becomes soiled and may appear irritated. Overall condition deteriorates progressively as the intestinal damage accumulates.

Behavioral changes accompany the physical symptoms of coccidiosis. Affected birds become progressively lethargic, spending more time resting and showing decreased interest in activities and surroundings. Reduced vocalization and social interaction are common. Appetite typically decreases as the disease progresses, though birds may still attempt to eat. Sleep patterns may be disturbed. Birds may show signs of abdominal discomfort, including reluctance to move or hunched posture. Young birds may appear depressed and fail to develop normal social and foraging behaviors compared to healthy age-matched individuals.

Physical signs of coccidiosis include poor body condition with progressive weight loss. The keel bone becomes more prominent as muscle mass decreases. Feather condition may deteriorate, with plumage appearing dull or ruffled. Pale coloration of the cere and skin may indicate anemia in cases with significant intestinal hemorrhage. Dehydration signs include sunken eyes, prolonged skin tent, and dry mucous membranes. Droppings characteristically show increased water content, may contain mucus, and may be blood-tinged or frankly bloody in severe cases. The vent area is typically soiled and may show signs of irritation from contact with abnormal droppings.

Symptom progression in coccidiosis follows the parasite's reproductive cycle, with clinical signs often peaking around five to seven days after initial infection when parasite numbers are highest and tissue damage is most severe. Mild cases may stabilize and improve as the bird's immune response develops. However, severe infections or those in young or immunocompromised birds can progress rapidly to life-threatening disease. Dehydration from fluid loss compounds the effects of nutrient malabsorption. Secondary bacterial infections may develop as the intestinal barrier is damaged. Without treatment, severely affected birds may die within days of developing obvious symptoms.

Emergency symptoms requiring immediate avian veterinary care include bloody diarrhea, which indicates severe intestinal hemorrhage and potential life-threatening blood loss. Severe weakness, inability to perch, or collapse warrants urgent attention. Complete refusal to eat or drink for more than 24 hours in a symptomatic bird indicates serious illness. Signs of severe dehydration including sunken eyes, cold extremities, and extreme lethargy suggest shock requiring emergency intervention. Rapid deterioration over hours rather than days indicates acute, severe disease. Young birds with coccidiosis can deteriorate extremely quickly and should be treated as emergencies when symptomatic. Any bird with suspected coccidiosis showing serious symptoms should receive prompt veterinary care.

Diagnosis of coccidiosis begins with a thorough history and physical examination by an avian veterinarian. The veterinarian will inquire about the bird's housing, diet, exposure to other birds, age, and any symptoms observed. Physical examination in birds with coccidiosis often reveals poor body condition, dehydration, and soiling around the vent. Palpation of the abdomen may reveal thickened intestinal loops in some cases. The veterinarian will assess the overall condition of the bird and look for signs of secondary complications. Compatible history and clinical signs raise suspicion for coccidiosis, but laboratory confirmation is needed to confirm the diagnosis and assess severity.

Fecal examination is the primary diagnostic method for detecting coccidia. A fresh fecal sample is examined using flotation techniques that concentrate oocysts for microscopic identification. Coccidia oocysts have characteristic appearances allowing identification, appearing as oval to round structures with distinct internal features when sporulated. Quantitative oocyst counts help assess infection severity, though the relationship between oocyst numbers and clinical disease is complex. High oocyst counts typically indicate active infection, while low counts may represent light infection, early or late stages of infection, or recovered carriers. Because oocyst shedding varies during the infection cycle, multiple samples may be needed for detection in early or light infections.

Additional diagnostic tests help assess the bird's overall health and detect complications. Complete blood count may reveal anemia if significant intestinal hemorrhage has occurred. Dehydration is reflected in elevated packed cell volume and total protein concentration. Blood chemistry panels assess electrolyte imbalances from fluid loss and evaluate organ function. Fecal cytology may reveal inflammatory cells, blood cells, and bacteria indicating intestinal damage and secondary infection. In deceased birds, necropsy with examination of the intestinal tract can reveal characteristic lesions and allow identification of the coccidia species involved through histopathology.

Differential diagnosis for coccidiosis includes other causes of diarrhea and gastrointestinal disease in birds. Other intestinal parasites including giardia, cryptosporidium, and worms can produce overlapping symptoms. Bacterial enteritis from organisms such as Salmonella, Campylobacter, or Clostridium causes similar gastrointestinal signs. Viral infections affecting the digestive system produce comparable symptoms. Dietary causes of diarrhea should be considered. Stress-induced gastrointestinal disturbances may resemble mild coccidiosis. Heavy metal toxicity can cause gastrointestinal symptoms. Accurate diagnosis through fecal examination combined with clinical evaluation ensures appropriate treatment is provided. Because coccidiosis can progress rapidly in susceptible birds, treatment may be initiated based on clinical suspicion while awaiting confirmatory testing.

Emergency and immediate treatment for birds severely affected by coccidiosis focuses on stabilization. Birds presenting in critical condition require aggressive fluid therapy to combat the severe dehydration that results from diarrhea. Subcutaneous or intravenous fluids restore circulating volume and correct electrolyte imbalances. Supplemental heat is essential for birds that have become hypothermic due to weakness and shock. Nutritional support through tube feeding provides calories for birds too weak to eat independently. Severe anemia from intestinal hemorrhage may require blood transfusion in extreme cases. Once stabilized, anticoccidial treatment is initiated. In less severe cases, treatment can begin immediately upon diagnosis with supportive care provided concurrently as needed based on the bird's condition.

Medical management of coccidiosis involves administration of effective anticoccidial medications. Sulfadimethoxine and other sulfonamide antibiotics are commonly used and effective against most avian coccidia species. Trimethoprim-sulfamethoxazole provides an alternative sulfonamide option. Amprolium acts through a different mechanism by interfering with thiamine metabolism in the parasite and is commonly used in poultry. Toltrazuril and ponazuril represent newer anticoccidial agents that may be effective when other treatments fail. Treatment typically continues for five to fourteen days depending on the medication and severity of infection. The veterinarian selects appropriate medication and duration based on the bird species, severity, and any concurrent health issues.

Surgical intervention is not applicable for coccidiosis treatment. However, complications such as severe intestinal damage may rarely require supportive surgical intervention. The focus of treatment remains medical management with anticoccidial medications and supportive care.

Supportive care addresses the consequences of intestinal damage and promotes recovery. Fluid therapy corrects dehydration and electrolyte imbalances from diarrhea. Nutritional support with easily digestible foods helps maintain the bird's condition during treatment. Probiotics may help restore normal intestinal flora once treatment is complete, though their use during active treatment is debated. Vitamins, particularly B vitamins that may be depleted during sulfonamide treatment, can be supplemented. Maintaining appropriate environmental temperature and humidity supports recovery. Reducing stress through quiet housing allows the bird to direct energy toward healing. Secondary bacterial infections may require antibiotic treatment in addition to anticoccidial medication.

Environmental treatment is critical for preventing reinfection and breaking the cycle of transmission. Thorough cleaning of enclosures removes fecal material containing oocysts. While coccidia oocysts are resistant to many disinfectants, physical removal through cleaning is effective at reducing environmental contamination. Some products containing quaternary ammonium compounds or ammonia may have activity against oocysts when used at appropriate concentrations and contact times. Moisture control helps prevent oocyst sporulation. Substrate should be replaced and kept dry. Food and water containers require daily cleaning to prevent contamination. Treatment of all birds in the environment may be necessary if coccidiosis is detected in group-housed birds.

Treatment decisions balance multiple factors including disease severity, bird species, and practical considerations. Young birds and those with severe symptoms require more aggressive treatment including hospitalization and intensive supportive care. The choice of anticoccidial medication considers effectiveness, bird species sensitivity, and potential side effects. Sulfonamides require adequate hydration and can cause kidney damage in dehydrated birds if fluids are not provided. Cost considerations include medication, supportive care, follow-up testing, and potential hospitalization. Expected outcomes with appropriate treatment are generally good for birds diagnosed and treated before severe dehydration and intestinal damage develop. Follow-up fecal examinations typically two to three weeks after treatment assess whether coccidia have been eliminated or controlled.

The recovery timeline for birds treated for coccidiosis varies based on disease severity and the bird's condition at treatment initiation. Birds with mild infections may show improvement within two to three days and recover fully within one to two weeks. More severely affected birds with significant dehydration, weight loss, or intestinal damage may require two to four weeks for full recovery. The intestinal lining must regenerate after damage from the parasite, which takes time even after coccidia are eliminated. Initial improvement in dropping consistency and appetite is typically seen within the first three to five days of treatment. Weight regain and return to full activity occur more gradually over the following weeks.

Post-treatment care requirements include completion of the full prescribed course of anticoccidial medication even if the bird appears improved. Stopping treatment early can allow resistant parasites to survive and multiply, causing relapse. Follow-up fecal examinations should be performed two to three weeks after treatment completion to confirm elimination or reduction of oocysts to acceptable levels. Continued nutritional support with high-quality, easily digestible foods promotes intestinal healing and weight restoration. Environmental cleaning must continue to reduce reinfection risk from persistent oocysts. Gradual return to normal activities is appropriate as the bird regains strength.

Prognosis factors for birds recovering from coccidiosis include the severity of infection at diagnosis, the bird's age and baseline health, response to treatment, and success of environmental management. Birds diagnosed and treated early before severe intestinal damage develops have excellent prognoses. Young birds are more susceptible to severe disease but can recover fully with appropriate treatment. Those with severe dehydration, significant weight loss, or complications have more guarded prognoses. Quality of life during recovery is maintained through supportive care, appropriate nutrition, and minimizing stress while the intestinal tract heals.

Long-term outlook following recovery from coccidiosis depends on several factors. Many birds develop some degree of immunity after infection, which helps protect against future clinical disease. However, immunity may be species-specific, and exposure to different coccidia species can cause new infections. Continued exposure to low levels of coccidia can actually help maintain immunity in recovered birds, though overwhelming exposure can still cause disease. Some birds become asymptomatic carriers, shedding oocysts without showing clinical signs and serving as sources of infection for susceptible birds. With good hygiene and management practices, most birds remain healthy after recovering from coccidiosis. Regular fecal monitoring helps detect any recurrence early.

Environmental prevention is the cornerstone of coccidiosis control. Maintaining clean, dry housing reduces oocyst survival and sporulation. Moist environments favor oocyst development, so controlling humidity and ensuring good drainage is important. Regular removal of droppings prevents accumulation of oocysts. Solid flooring that can be thoroughly cleaned is preferable to substrates that retain moisture and organic material. Elevated feeding and watering stations reduce contamination of food and water with droppings. Feed and water containers should be cleaned daily. While oocysts are resistant to many disinfectants, physical removal through cleaning combined with drying and sunlight exposure helps reduce environmental contamination.

Quarantine protocols help prevent introduction of new coccidia species to established bird populations. New birds should be quarantined separately for at least 30 days, with fecal examinations performed to detect parasitic infections. Birds from different sources may carry different coccidia species, and introducing new species can cause disease outbreaks in previously healthy populations. Prophylactic anticoccidial treatment of new arrivals may be considered in some situations. The quarantine area should be completely separate from other birds. Thorough cleaning between quarantine occupants prevents coccidia transmission from one bird to the next.

Dietary prevention supports immune function and intestinal health. A complete, balanced diet provides nutrients needed for optimal immune response to coccidial challenges. Vitamin A is particularly important for maintaining healthy intestinal epithelium that resists parasite invasion. Adequate protein supports immune cell production and tissue repair. Probiotics may help maintain a healthy intestinal microbial population that competes with coccidia. Avoiding stress from nutritional deficiencies helps the bird mount effective immune responses to coccidia exposure. While good nutrition cannot prevent infection, well-nourished birds are better able to control coccidia multiplication and limit clinical disease.

Health maintenance through regular avian veterinary care facilitates early detection of coccidiosis. Routine wellness examinations include discussion of parasite risks and prevention strategies. Regular fecal screening detects infections before clinical signs develop, allowing early treatment. For high-risk situations such as breeding facilities with young birds, prophylactic anticoccidial medication in feed or water may be recommended by the veterinarian. Vaccines are available for some coccidia species in poultry but are not commonly used in pet birds. Managing stress from any source helps maintain immune function and resistance to clinical coccidiosis.

Early intervention when coccidiosis is suspected prevents progression to severe disease. Bird owners should become familiar with normal droppings for their birds to recognize early changes that might indicate intestinal problems. Any suspicion of coccidiosis warrants prompt veterinary evaluation, particularly in young birds or those showing obvious symptoms. When coccidiosis is diagnosed in one bird of a group, all birds should be tested and treatment considered for the group. Immediate environmental cleaning and disinfection limits ongoing transmission. Working proactively with an avian veterinarian to assess risk factors and implement appropriate prevention measures provides the best protection against clinical coccidiosis.

Daily management for birds recovering from or at ongoing risk for coccidiosis requires consistent attention to hygiene and monitoring. Daily cleaning of enclosures removes droppings before oocysts have time to sporulate to infectious stages. Moisture control through good drainage and appropriate ventilation helps prevent oocyst development. Food and water containers should be cleaned daily and positioned to prevent fecal contamination. Monitoring dropping character helps detect any changes that might indicate recurrence or new infection. Weight monitoring tracks recovery progress or provides early warning of problems. Medication administration during treatment must follow the prescribed schedule exactly. Detailed records of treatments, weights, and observations provide valuable information for veterinary consultations.

Home environment modifications support coccidiosis prevention and treatment success. Enclosures should facilitate thorough daily cleaning with smooth surfaces that can be sanitized effectively. Substrate should be easy to replace and should not retain moisture. Avoiding overcrowding reduces stress and decreases environmental contamination density. Good ventilation helps control humidity while maintaining appropriate temperature. Separating young birds from adults may reduce exposure to coccidia before immunity develops. Creating clean feeding and watering areas that can be maintained separate from soiled areas reduces transmission opportunity.

Maintaining quality of life during coccidiosis management balances hygiene requirements with the bird's behavioral needs. While cleanliness is essential, providing appropriate enrichment maintains mental health. Foraging opportunities using clean food sources keep birds mentally engaged. Social interaction continues to meet the bird's social needs, though separation may be necessary during treatment of actively shedding birds. As birds recover, gradually expanding their environment and activities supports physical and psychological wellbeing. The goal is maintaining a clean environment without eliminating the environmental complexity birds need for mental stimulation.

Ongoing monitoring and care become routine for birds that have experienced coccidiosis. Regular fecal examinations, typically every three to six months for high-risk birds, confirm controlled parasite levels and provide early warning of any increase. Weight monitoring detects subtle changes that might indicate emerging problems. Annual wellness examinations allow professional assessment and adjustment of prevention protocols as needed. Maintaining awareness of stress factors that might trigger clinical disease helps prevent recurrence. For birds in multi-bird environments or breeding situations, ongoing vigilance for coccidiosis is particularly important.

Caregiver support helps bird owners manage the challenges of coccidiosis prevention and control. Understanding that low-level coccidia presence is common and that clinical disease results from the interaction of exposure level, immunity, and stress helps set realistic expectations. Avian veterinarians provide guidance on prevention strategies appropriate for individual situations. Bird clubs and online communities offer opportunities to learn from others' experiences. Educational resources about avian parasites help owners understand the conditions they are managing. With proper management, coccidiosis is preventable and treatable, and most birds live healthy lives with appropriate care.

Birds at highest risk for clinical coccidiosis include young birds of most species, particularly those under three to six months of age. Young birds have not yet developed immunity from previous exposure and are more susceptible to severe disease from coccidia multiplication. Poultry including chickens, turkeys, and game birds are commonly affected, with coccidiosis representing a major disease concern in commercial and backyard flocks. Finches and canaries are frequently affected by Isospora species adapted to these hosts. Pigeons harbor their own coccidia species and clinical disease is common, particularly in young birds. Lovebirds and budgerigars commonly experience coccidiosis in breeding situations where young birds are exposed to environmental contamination.

Psittacines of various species can develop coccidiosis, though susceptibility and disease severity vary. Cockatiels, particularly young birds in breeding facilities, commonly experience coccidia infections. Larger psittacines including amazons, african greys, cockatoos, and macaws can be affected, especially when stressed or immunocompromised. Wild-caught or wild-rescued birds may carry coccidia species from their natural environments. Birds in multi-bird environments including pet stores, breeding facilities, and rescue organizations face increased exposure risk from environmental contamination. Any bird experiencing stress from transport, environmental changes, or concurrent disease has increased susceptibility to clinical coccidiosis.

Screening recommendations for coccidia depend on the bird's age, housing situation, and risk factors. Young birds should be tested during their first veterinary examinations and at regular intervals during their first year. All new birds entering a collection should be tested during quarantine. Regular screening every three to six months is appropriate for birds in high-risk situations including breeding facilities, multi-bird households, and outdoor aviaries. Annual fecal examination as part of routine wellness care is recommended for lower-risk indoor pet birds. Any bird showing gastrointestinal symptoms should be tested promptly. Working with an avian veterinarian to develop appropriate screening protocols based on individual risk assessment provides optimal protection against undetected infections and clinical disease.

Conditions commonly co-occurring with coccidiosis include other gastrointestinal parasites, as environments supporting coccidia often harbor additional parasite species. Giardia, cryptosporidium, and intestinal worms may be present simultaneously, requiring comprehensive fecal examination and appropriate treatments. Secondary bacterial enteritis frequently complicates coccidiosis as the damaged intestinal lining allows bacterial invasion. Clostridial overgrowth is particularly common and may require specific antibiotic treatment in addition to anticoccidial medication. Nutritional deficiencies from malabsorption during active infection may persist into recovery and require correction. Stress from any source predisposes birds to clinical coccidiosis, so addressing underlying stressors is part of comprehensive management.

Conditions with symptoms similar to coccidiosis require differentiation through appropriate diagnostic testing. Other intestinal parasites including giardia and cryptosporidium cause overlapping symptoms of diarrhea and weight loss. Bacterial enteritis from various pathogens produces comparable gastrointestinal signs. Viral infections affecting the digestive system cause similar symptoms. Dietary issues including sudden diet changes or inappropriate foods can cause diarrhea. Stress-induced gastrointestinal disturbance may resemble mild coccidiosis. Heavy metal toxicity causes gastrointestinal symptoms. Accurate differentiation through fecal examination and additional testing as needed ensures appropriate treatment is provided.

Potential complications of coccidiosis include severe dehydration from fluid loss through diarrhea, which can be life-threatening if not corrected promptly. Intestinal hemorrhage in severe cases causes anemia that may require supportive treatment or, rarely, blood transfusion. Secondary bacterial infections including clostridial overgrowth can cause additional intestinal damage and systemic illness. Chronic intestinal damage may result in persistent malabsorption in some birds. Immunosuppression from severe infection increases susceptibility to other opportunistic infections. Young birds may experience growth retardation from nutrient losses during active infection. Prevention of complications relies on early detection through routine screening, prompt treatment of clinical infections, and comprehensive supportive care including appropriate fluid therapy for dehydrated birds.