Avian anatomy Flashcards
Integument - שכבה מגינה
The largest organ system of the body is the integument. The integument protects the underlying structures and organs. The integument is also a physical barrier between the body and the outside world. The bird’s external anatomy is made up of the skin, the beak, claws, and feathers.
The skin of companion birds is delicate, dry, and slightly wrinkled. The area around the nostrils is known as the cere. Many passerine birds do not have a cere. Birds do not have sweat glands. Some birds possess one major skin gland known as the uropygial gland. The uropygial gland empties into a papilla located at the dorsal base of the tail. A fatty sebaceous material secretes from this gland and is spread over feathers during preening, helping to waterproof the feathers. The uropygial gland is absent in the ostrich, emu, woodpecker, and Amazon parrot.
Feathers
have many functions. They are essential for flight, and they keep the skin safe from trauma and exposure. Feathers also play a role in thermoregulation, camouflage, and communication. Birds have several types of feathers:
contour feathers – flight feathers or body feathers covering the body and wings
remiges or primary flight feathers – located on the outer end of the wing
secondary flight feathers – located on the wing between the body and the primaries
coverts or body feathers – provide surface coverage over the remainder of the body
down feathers – soft and fluffy feathers that provide insulation; powder down feathers break down and produce a white dusty powder in some species.
blood feathers – new, growing feather with a vascular supply.
blood feather shafts are dark and bleed profusely if broken
broken blood feathers may result in death of the animal if not treated.
Musculoskeletal system
Avian skeletons are highly adapted. Many avian bones are pneumatized, meaning they contain air, resulting in a lighter skeleton. Although these bones are lighter, they have thin walls that make them relatively fragile. The beak is strengthened through the fusion of the bones in the skull. The neck of the bird is long and flexible. The keel (sternum) supports the pectoral muscles used in flight. Birds have a fused caudal vertebra called the synsacrum. The synsacrum stabilizes the bird’s back during flight.
The pectoral muscles constitute 20 percent of a bird’s weight. The pectorals are the largest muscle mass in the body of an avian patient. The pectorals are often used by the health-care team to determine the bird’s body condition.
Respiratory system
The respiratory system found in avians is unlike the respiratory system in other companion animals. Air enters through the nares, which are located on either side of the beak. The operculum is located immediately behind the nares in the nasal cavity. After entering the nares, air passes over the operculum, through the sinus cavities, and enters the oral cavity through the choana. The choana is a V-shaped notch in the roof of the bird’s mouth that directs air from the mouth and nasal cavities to the glottis. Birds differ from other companion animals in that the glottis fits snugly into the choanal slit when the bird closes its mouth, thus establishing a closed connection from the nostrils to the windpipe.
Air then travels through the glottis and down the trachea. The trachea in a bird is found on the left side of the cervical area. The internal anatomy can be viewed in Figure 16.2. The avian trachea runs along the entire length of the neck and consists of complete cartilaginous rings that cannot expand. The syrinx, or the avian voice box, is found at the end of the trachea. Although birds do not talk as well as humans, they can produce vocalizations. Vocalizations in birds occur when air is forced over the syrinx, vibrating membranes during the expiratory phase of respiration. The complexity of a bird’s vocalizations depends on the species and number of muscles in the syrinx.
As the air continues, it enters the small lungs, which are located near the dorsal spine. Air exchange takes place here. Birds’ lungs do not inflate as they lack alveoli and lung lobes. Birds also lack a diaphragm. Inspiration of air occurs by the action of the intracostal joints and movement of the sternum/keel, which draws in inspired air with a bellows-like action into the caudal air sacs due to the action of the abdominal musculature. This bellows-like action takes place in the coelom. Active muscle contraction is needed for both inspiration and expiration in avians.
There are nine air sacs into which air flows. The air sacs are hollow spaces that have thin walls and are highly vascularized. The air sacs can be located as follows:
Four paired air sacs: cranial thoracic caudal thoracic cervical abdominal
One unpaired air sac:
interclavicular – thoracic inlet between the clavicle
Gas exchange does not occur in the air sacs in avians. In order to move a breath completely through the respiratory system, the bird must complete two breath cycles. It is important to remember that normal breathing in birds should not be noticeable and the beak should remain closed. After exercise, especially if the caged bird “escapes” and flies around the house before returning to its cage, there may be increased head and tail movement and increased abdominal effort. However, after a minute or two the bird’s respiratory pattern should return to normal.
Digestive system
The avian species have a high metabolic rate requiring ingestion of large amounts of food. The beak anatomy will differ with the foraging strategies and diet makeup of the particular bird. In most birds, the beak is responsible for grasping food and pulverizing it. The tongue helps in this grasping and crushing process. The mouth of a bird includes the following:
hard, upper palate soft, lower palate unique tongue taste buds scattered through the mouth salivary glands As a bird swallows, the food enters and travels though the esophagus. In many species, the esophagus expands in the interclavicular space, creating the crop. The anatomy of the crop varies among birds, but is typically a dilation of the esophagus into either a single pouch or a double pouch. The crop is responsible for softening food and passing small portions of food into the true stomach, known as the proventriculus, where digestive acids and enzymes begin breaking down the food. Next the food is passed into a thickly muscled organ that grinds the food into smaller particles known as the gizzard or ventriculus. The small intestine is the major organ responsible for digestion and absorption of nutrients. Following the small intestine is the large intestine which terminates at the cloaca. The vent is the external opening of the cloaca, from which the droppings exit the body. Bird excrement, or droppings, consists of three components; 1) liquid urine, 2) cream consistency urates, and 3) feces. The consistency of the droppings is variable depending upon the diet.
Circulatory system
The avian heart is approximately one-and-a-half times larger, relatively speaking, than the heart in mammals. The heart rate of birds is 250 to 350 beats per minute in large parrots and up to 1,400 beats per minute in small avian species. Blood pressure also runs higher than in other companion animals. It is important to note that birds do not have lymph nodes, and the lymphatic system is less extensive that that of mammals. Red blood cells differ from those of mammals as well. In birds, red blood cells appear oval in shape and contain a nucleus.
Restraint
As with all animals, proper restraint techniques are important for the safety of the handler and the person performing examinations or treatments as well as the safety and well being of the patient. Restraint is a large stressor for avian patients, so knowing the avain patient and proper restraint and capture techniques will help to decrease pain and stress in your patient.
All escape routes should be closed, and the room should be sealed. Hiding places to which the bird may flee should be identified and closed off. Towels are recommended to capture and restrain the avian patient. Towels of different sizes relative to the size of the bird are indicated. Using a towel to capture a bird helps to reduce fear of hands in the future. Gloves are not recommended, as this may cause the bird to develop a fear of hands, and the wearer loses significant tactile sensation which is extremely important when handling birds (Figure 16.3). A slow approach with the towel in hand is best. Do not try to capture a bird that is sitting on the owner, as this may result in behavioral issues of the bird toward the owner such as the bird biting or attacking the owner. Remember to use a calm and soothing tone when approaching a bird, similar to our restraint discussion of other species. Display confidence, especially when trying to capture and restrain a large bird—they can detect fear and hesitation. The hand (in the towel) should grasp the head of the bird toward the cervical (lower) end of the head, but do not choke around the neck. Hold the sides of the head firmly, but ensure the bird is able to breathe. Oftentimes, letting the bird bite the excess towel offers a distraction. However, care must be taken at all times to ensure the bird does not explore the restrainer’s fingers and bite, thus causing injury. For small birds use the remainder of the hand to control the body and make sure the towel is wrapped around the bird to control the wings and feet. Larger birds should remain controlled with the opposite hand holding the towel that is wrapped around the body. The person restraining the bird should be monitoring the bird’s respirations and stress level the entire time it is restrained. The patient should be observed closely for signs of stress, hypoxia, and hyperthermia. Hands should be moved accordingly to allow the examiner to examine the bird at a faster pace.
Remember, restraint is a very stressful experience for a bird. Allow the examiner to move as quickly as possible to ensure the bird is restrained for as short a time as possible. It is typical for a bird to show signs of stress when the restraint is released and the bird is placed back in its carrier. Open beak breathing, holding wings away from body, and fluffing of feathers may be exhibited by the bird. However the bird should recover quickly, so be alert if the bird exhibits these behaviors for more than a few minutes after returning to its cage.
Restraint
As with all animals, proper restraint techniques are important for the safety of the handler and the person performing examinations or treatments as well as the safety and well being of the patient. Restraint is a large stressor for avian patients, so knowing the avain patient and proper restraint and capture techniques will help to decrease pain and stress in your patient.
All escape routes should be closed, and the room should be sealed. Hiding places to which the bird may flee should be identified and closed off. Towels are recommended to capture and restrain the avian patient. Towels of different sizes relative to the size of the bird are indicated. Using a towel to capture a bird helps to reduce fear of hands in the future. Gloves are not recommended, as this may cause the bird to develop a fear of hands, and the wearer loses significant tactile sensation which is extremely important when handling birds (Figure 16.3). A slow approach with the towel in hand is best. Do not try to capture a bird that is sitting on the owner, as this may result in behavioral issues of the bird toward the owner such as the bird biting or attacking the owner. Remember to use a calm and soothing tone when approaching a bird, similar to our restraint discussion of other species. Display confidence, especially when trying to capture and restrain a large bird—they can detect fear and hesitation. The hand (in the towel) should grasp the head of the bird toward the cervical (lower) end of the head, but do not choke around the neck. Hold the sides of the head firmly, but ensure the bird is able to breathe. Oftentimes, letting the bird bite the excess towel offers a distraction. However, care must be taken at all times to ensure the bird does not explore the restrainer’s fingers and bite, thus causing injury. For small birds use the remainder of the hand to control the body and make sure the towel is wrapped around the bird to control the wings and feet. Larger birds should remain controlled with the opposite hand holding the towel that is wrapped around the body. The person restraining the bird should be monitoring the bird’s respirations and stress level the entire time it is restrained. The patient should be observed closely for signs of stress, hypoxia, and hyperthermia. Hands should be moved accordingly to allow the examiner to examine the bird at a faster pace.
Remember, restraint is a very stressful experience for a bird. Allow the examiner to move as quickly as possible to ensure the bird is restrained for as short a time as possible. It is typical for a bird to show signs of stress when the restraint is released and the bird is placed back in its carrier. Open beak breathing, holding wings away from body, and fluffing of feathers may be exhibited by the bird. However the bird should recover quickly, so be alert if the bird exhibits these behaviors for more than a few minutes after returning to its cage.
Nutrition
Problems associated with nutrition are very common in birds kept as pets. Psittacine and passerine species have unique nutritional requirements, and if owners are not familiar with the proper care and feeding of the particular species, the bird is at risk for disease or malnutrition. Each avian species has differing nutritional demands, so it is important to review the needs of the particular breed of bird with the owner.
Smaller birds have a higher metabolic rate and higher energy requirements than larger birds. Small birds should have continuous access to food. Seed diets are popular, but most are deficient in certain nutrients, and seed is not the natural diet of birds kept as pets. Seed diets are mainly comprised of sunflower seeds, which are low in calcium and vitamin A and high in fat. This type of diet leads to obesity and specific deficiencies in birds. Birds in captivity may also select specific foods from a variety offered by the owner. This also leads to nutritional deficiencies. Birds will select items to eat on the basis of water content, texture, color, and taste as opposed to nutrient content. This results in the potential for severe nutrient imbalance.
Pelleted diets are formulated diets that include the nutrients recommended for specific species of companion birds. These diets are also formulated along the life stage/lifestyle philosophy and are available not only for specific species, but also specific ages, lifestyles, and reproductive statuses. Commercial pelleted diets include vitamins, so vitamin supplementation is contraindicated. If the owner is feeding a seed diet, the recommendation to transition to pelleted foods should be discussed. Veterinary health-care team members play a huge role in educating and offering support to bird owners transitioning from a seed diet to a pelleted diet. Proper nutrition in all species leads to a longer, healthier life of the bird.
Fresh water should be available at all times. The owner should be educated to place the water dish above the perches. This will decrease fecal contamination. Birds, like other companion animals, should have clean, fresh water available to them at all times.
integument - שיכבה חיצונית
The integument protects the underlying structures and organs. The integument is also a physical barrier between the body and the outside world. The bird’s external anatomy is made up of the skin, the beak, claws, and feathers.
The skin
delicate, dry, and slightly wrinkled.
The area around the nostrils- האיזור מסביב לנחיר
is known as the cere
passerine birds don’t have cere
sweat glands.
Birds do not have sweat glands.
uropygial gland - בלוטת הזנב, מצויה בבסיס של רוב הציפורים. היא מפרישה שמן לתחזוק הנוצות
The uropygial gland empties into a papilla located at the dorsal base of the tail. A fatty sebaceous material secretes from this gland and is spread over feathers during preening, helping to waterproof the feathers.
The uropygial gland is absent in the ostrich, emu, woodpecker, and Amazon parrot.
Feathers
have many functions. They are essential for flight, and they keep the skin safe from trauma and exposure. Feathers also play a role in thermoregulation, camouflage, and communication. Birds have several types of feathers:
contour feathers – flight feathers or body feathers covering the body and wings
remiges or primary flight feathers – located on the outer end of the wing
secondary flight feathers – located on the wing between the body and the primaries
coverts or body feathers – provide surface coverage over the remainder of the body
down feathers – soft and fluffy feathers that provide insulation; powder down feathers break down and produce a white dusty powder in some species.
blood feathers – new, growing feather with a vascular supply.
blood feather shafts are dark and bleed profusely if broken
broken blood feathers may result in death of the animal if not treated
