Before conducting a physical examination, the bird’s appearance and behavior should be observed from a distance and within the flock. The behavior of a flock can be assessed by how they interact as a group (eg, huddling when cold). A healthy bird should be bright, alert, and interacting with the flock, with good appetite and free of abnormal behavior. Any increased respiratory effort or tail bobbing, abnormal postures, and awareness of the birds (check for drooping wings, head tilts, etc.) should be noted. Immediate emergency care should be provided to a bird before a complete physical examination if any of the following are seen:
seizures or other neurologic signs
extreme respiratory difficulty
Chickens and other domestic fowl can be restrained for examination by reaching over the back and holding the wings down. Then, the bird should be picked up and the fingers inserted between the legs while supporting the breast with the other hand. Restraining the bird upside down is not ideal, because it may increase its stress level and also cause regurgitation, as well as result in broken bones if bones are brittle from low calcium. Restraining a bird by squeezing the breast area is also not ideal, because thoracic compression of the chest will compromise breathing. The bird should be kept as calm as possible to prevent injury to both the bird and the handler. A chicken hook, which is a wire hook used to grab birds by the shanks, can also be used to catch or restrain birds outdoors.
For larger birds such as turkeys, the handler can fold his or her arms and upper body over the wings and back of the bird, hug firmly, and lift. When lifting a bird, a handler can restrain it using both hands by grabbing either both legs, both wings, or a leg and a wing of opposing sides. It is important to remain low to the ground when handling bigger birds; grabbing these birds by their wings or legs can be dangerous and easily cause injury during struggling. For waterfowl such as ducks and geese, it is easiest to use the neck as a catching handle; however, once the bird is caught, it should be picked up by grabbing the wings together behind the back and using the other hand to support the abdomen. Smaller flight birds, such as quail, chukar partridges, and pheasants, can first be restrained by careful use of a net or towel and then holding the wings or legs. Catching birds on the first attempt minimizes stress.
Physical examinations should be performed using a systematic approach:
Examine the head and neck. The comb should be bright red, slightly warm, turgid, and free of scabs and lesions. The bird should hold its head high and have good muscle tone.
Observe the eyes, and check for any discharge or cloudiness that may indicate illness. The eyes of a healthy adult bird should be clear and bright and have a copper-red iris and a round pupil with well-defined margins. Young chicks generally have a blue-gray iris. The eyelids should be free of swelling and opened wide.
Check external nares for discharge, crusts, and scratches. The beak should be smooth and free of cracks, and the tips should come to a point.
Open the mouth and check for ulcers and mucosal lesions on the tongue and mucosal membranes at the commissures of the beak.
Check the color of the earlobes to predict the color of the eggs the hens will produce. Hens that have white earlobes generally produce white eggs, and hens that have red earlobes generally produce brown or other pigmented eggs.
Evaluate the feathers to check for feather loss and how they are distributed. Loss of feathers around the back and back of the neck may indicate mating behavior by roosters. Check feathers at the base of the feather shaft to look for parasites such as lice, mites, and nits (lice egg packets). Feathers around the vent should be clear and free of blood or feces. Pasting of the vent with loose feces may indicate enteric disease. Check for scabs and blood around the vent, which are evidence of vent pecking and cannibalism.
The two small bones at the sides of the vent are the pubic bones. They should be flexible and have space in between. If hens are in lay, this distance should be 5–6 cm. When the hen is not laying, the pubic bones are usually stiff and close together (1.5 cm or less).
Venipuncture and Blood Collection
Blood can be safely collected from multiple sites in a bird to obtain baseline measurements. This can include PCV, total solids, and estimated WBC count +/- serum biochemistry. The most common site of venipuncture is the brachial (wing) vein. The chicken vein is much more superficial compared with that in mammals, and hematomas are easily formed. Clotting of blood (even serum) occurs rapidly and abundantly due to large amounts of tissue thromboplastin present in avian species. In a healthy bird, blood volume that equates to 1%−2% of the body weight can be safely obtained, but this may be 0.5% in a compromised or high-risk patient. Other sites of venipuncture include the medial metatarsal vein (located in the medial aspect of the shanks) and the jugular vein (the right side is more prominent in chickens).