Poultry anatomy and necropsy

Introduction to Poultry Anatomy and Necropsy

Overview of the Webinar

• Jackie Jacob introduces herself as a poultry extension worker at the University of Kentucky, coordinating the small and backyard flocks community of practice.

• Dr. David Frame from Utah State University is introduced as the presenter for this month's webinar focused on avian anatomy and necropsy.

Purpose of the Presentation

• The presentation aims to provide insights into avian anatomy and how to perform a necropsy, particularly for those with small flocks who may need to assess their birds' health.

• Dr. Frame acknowledges that some attendees may have limited anatomical knowledge, setting a foundational understanding for all participants.

Dr. David Frame's Background

Professional Experience

• Dr. Frame shares his background in veterinary medicine, having attended Oregon State University and completed residency work at UC Davis.

• He has extensive experience working with turkeys before joining Utah State University’s faculty in 1998, focusing on extension services and diagnostic laboratory work.

Understanding Avian Anatomy

Key Learning Objectives

• The primary goal is to familiarize participants with normal chicken anatomy, emphasizing differences from mammals.

• Understanding what constitutes "normal" is crucial; recognizing abnormalities will prompt seeking veterinary assistance when necessary.

Limitations of Visual Diagnosis

• Dr. Frame emphasizes that not all diseases can be diagnosed visually; many look similar upon examination.

• Diagnostic laboratories play an essential role in identifying specific diseases through various tests beyond visual inspection.

Bird Bone Structure

Unique Features of Avian Skeleton

• The presentation begins discussing bird bone structure using pigeons as examples to illustrate key points about avian anatomy.

• Birds have fused bones which contribute to their lightweight structure necessary for flight; this rigidity is compared to aircraft fuselages.

Respiratory System Insights

• Birds lack teeth which lightens their load; they also possess a bony orbit around their eyes—a feature absent in mammals.

Understanding Bird Anatomy and Care

Proper Handling of Birds

• When holding birds, such as chickens or parakeets, avoid constricting their sternum to allow for proper breathing.

• It's important to support the bird's breast with your hands without restricting both the back and breast simultaneously.

Unique Skeletal Features of Birds

• The furcula, commonly known as the wishbone, is a unique bone in birds that is detached from others; its exact function remains uncertain but may provide stability to the thoracic cavity.

• Different bird species exhibit variations in skeletal structure; for example, geese have more vertebrae in their neck compared to chickens.

Distinguishing Characteristics of Chickens

• Anatomical features like comb types (single comb, rose comb), earlobes (varying colors), and wattles are key identifiers among chicken breeds.

• Chickens possess skin covered with feathers rather than hair; feathers serve multiple purposes including mobility and protection from elements.

Feather Structure and Functionality

• Feathers are essential for insulation; they trap air which provides warmth rather than relying solely on the feather material itself.

• Oil slick exposure can compromise a bird's ability to insulate due to damage to feather structure.

Molting Process in Birds

• Molting is a natural process where birds renew their feathers annually; it typically follows a specific sequence starting from the head downwards.

Understanding Chicken Molting and Necropsy Techniques

Chicken Molting Process

• The molting process in chickens involves wearing down of feathers, leading to ragged appearances before they eventually fall out.

• Chickens typically molt in the fall to prepare for egg-laying in spring; this high-energy process is essential for their reproductive cycle.

• While fall is the ideal time for molting, stress factors can cause chickens to molt at any time throughout the year.

Preparing for Necropsy

• Always perform necropsies away from the flock to prevent aerosolizing pathogens or transferring infections back to them.

• Personal protective equipment (PPE) is crucial; minimum requirements include coveralls, disposable gloves, and footwear not used around birds. A face mask may also be advisable if dust or dander is present.

Essential Equipment for Necropsy

• Basic necropsy tools include forceps, surgical scissors (preferably tissue scissors), and a sharp knife. These can be sourced from surgical supply companies.

• Keeping tools sharp is vital; wet stones are recommended for sharpening knives and scissors effectively.

Safety Precautions During Necropsy

• Always wear exam gloves or waterproof gear during necropsies to avoid contact with fluids that may contain disease agents.

• Using dish soap and water helps control dust and feathers during the procedure, while disinfectants like quaternary ammonium can also be effective.

Conducting the Necropsy

• Utilize a cutting board when performing necropsies to protect your knife's edge and maintain cleanliness during dissection.

Understanding Chicken Anatomy and Health

Observing Signs of Health Issues

• Chickens may exhibit signs of health issues such as starvation due to impaction or intestinal problems, leading to a lack of muscle development.

• Dehydration can cause chickens to appear rened; skin should be carefully peeled back for examination.

Examining the Crop

• The crop is an organ that moistens feed before digestion; care must be taken not to cut into it prematurely, especially if filled with feed.

• A normal crop appears thin-walled; fungal infections can occur but this particular crop looks healthy.

Respiratory System Inspection

• Begin examining the respiratory system by cutting on the right side of the chicken's mouth, avoiding the trachea for diagnostic purposes.

• Infraorbital sinuses may swell with mucus in respiratory diseases; they should contain minimal fluid when healthy.

Trachea and Esophagus Analysis

• The esophagus transports food while the trachea remains open due to cartilaginous rings; both should be clear without excessive mucus or debris.

• A clean trachea is crucial for proper airflow; any abnormal findings like blood or excess mucus indicate potential health issues.

Opening the Body Cavity

• To access internal organs, cut along each side of the breast and retract it carefully to reveal underlying structures like the liver and heart.

• Breaking air sacs helps in accessing organs efficiently, ensuring consistent placement during examinations.

Understanding Avian Respiratory System

• Chicken lungs are non-expansive and work alongside air sacs which facilitate breathing through a bellows effect rather than expansion like mammalian lungs.

Understanding Avian Anatomy and Physiology

Importance of Air Sacs in Birds

• Air sacs play a crucial role in avian respiration, although they are nonvascular and have limited ability to expel contents.

• In dusty or ammonia-rich environments, air sacs can become inflamed quickly, leading to health issues for birds.

Characteristics of the Avian Heart

• The avian heart is larger relative to body mass compared to mammals and has the same number of chambers.

• Chickens exhibit high blood pressure and pulse rates (200-400 beats per minute), necessitating significant cardiac effort.

Observations on the Spleen

• The spleen serves as a blood storage organ; an abnormally large spleen may indicate underlying health problems.

Egg Production Insights

• All egg yolks that a hen will produce throughout her life are present at hatching, highlighting the unique reproductive biology of chickens.

Excretory Adaptations in Birds

• Avian kidneys excrete uric acid instead of urine, which is lighter and aids in flight efficiency by reducing body weight.

Digestive System Overview

Structure and Function of the Digestive Organs

• The gizzard functions as a grinding organ for food, similar to teeth in mammals; it often contains small stones to aid in this process.

Pathway Through the Digestive Tract

• Food travels from the esophagus into the proventriculus before entering the rest of the digestive system.

• The gallbladder's size can indicate feeding status; if full, it suggests that bile hasn't been properly released into the digestive tract.

Role of Pancreas and Intestinal Structures

• The pancreas is located within the duodenal loop and plays a vital role in digestion by releasing necessary enzymes.

Mid-Small Intestine Anatomy

Meckel's Diverticulum Significance

• Meckel's diverticulum marks where the yolk sac attaches during development; its presence is useful for diagnostic purposes when examining intestinal health.

Large Intestine Functions

• The short large intestine includes ceca that reabsorb water; dysfunction here can lead to diarrhea, complicating diagnosis due to various potential diseases affecting these organs.

Common Digestive Issues

Crop Impaction Causes

Understanding Chicken Digestive and Reproductive Systems

Digestive Issues in Chickens

• The impact of water consumption on chicken digestion is significant; if a chicken consumes excessive feed without adequate water, it can lead to an impacted crop, causing swelling and blockage.

• Genetic predisposition plays a role in the likelihood of developing a dropped crop, which can occur due to indigestible materials or overconsumption.

• The cecum connects to the iliocecal junction, where lymphoid tissues known as cecal tonsils are located; enlargement of these tonsils can indicate serious diseases.

• Chickens can experience issues similar to hardware disease in ruminants if they ingest sharp objects like wire or nails, leading to punctures and potential peritonitis.

• The cloaca serves as the common outlet for the urinary, digestive, and reproductive systems; it is associated with the bursa of Fabricius, an important lymphoid organ.

Immune Function and Reproductive Anatomy

• The bursa of Fabricius produces lymphocytes that help fight infections; B cells derive their name from this organ's function in birds.

• In hens, the spleen's appearance changes during egg production; granular structures represent developing ova that will eventually form egg yolks.

• The left ovary is typically functional in chickens; fluid accumulation may occur in non-functional right ovarian ducts, often unnoticed but relatively common.

• Egg-laying allows hens to raise young while maintaining mobility for survival; this evolutionary adaptation supports their ability to escape predators while nurturing offspring.

• Hens ovulate approximately 20 minutes after laying an egg; however, some ova may miss their target and cause inflammatory reactions if they enter the abdominal cavity.

Fertilization Process

• After ovulation, eggs drop into the infundibulum—a funnel-shaped structure—where fertilization must occur within three minutes for successful reproduction.

• If ova do not reach the infundibulum correctly, they may be reabsorbed or lead to complications such as egg yolk peritonitis due to inflammation from misplaced yolks.

Understanding Egg Formation in Chickens

The Role of Albumin in Egg Development

• Albumin, the egg white, consists of two types: thin and thick. It spends approximately 3 hours in the Magnum area for proper layering.

• After the Magnum, the egg moves to the infundibulum for about 1.5 hours where plumping occurs and membranes are added before entering the shell gland.

Shell Formation Process

• The shell gland is crucial as it houses the egg for 20 to 21 hours, during which up to 2 grams of calcium are deposited into the eggshell.

• Hens typically lay eggs early in the morning, with laying times gradually shifting later each day; this can lead to missed days if they lay too late.

Anatomy Insights on Ova and Laying Rates

• A close-up view reveals an ovum that hasn't yet entered the infundibulum; a lack of capillaries indicates where blood specks may occur when membranes break.

• Different chicken breeds exhibit varying laying rates; Mediterranean breeds like Leghorns can achieve peak production rates of 90% to 95%.

Understanding Chicken Reproductive Systems

• The cloaca serves as a common outlet for urinary, digestive systems, and egg-laying; its condition can indicate hen health and laying status.

• Familiarity with chicken anatomy is essential; understanding organ placement aids in recognizing normal versus abnormal conditions.

Impact of Freezing on Necropsy Results

• Freezing carcasses may alter organ appearance but generally allows for necropsy examination despite some limitations in histopathology.

• Abnormal nerve appearances near kidneys can indicate disease; familiarity with anatomy is crucial for accurate diagnosis.

Conclusion on Home Necropsies

• Home necropsies should not replace professional veterinary advice but can provide insights into poultry health issues.

Upcoming Webinars on Poultry Care and Management

Overview of Future Webinars

• Participants are encouraged to suggest topics for future webinars via the chat box.

• Upcoming sessions include:

• September: Focus on winter care for backyard poultry flocks, preparing for potentially harsh conditions.

• October: Processing poultry, particularly relevant for Thanksgiving preparations.

• November: Starting a small commercial operation in poultry management. Details are still being finalized.

• December: Coaching a 4-H team, aimed at those working with children in agricultural settings.

• January: A specialist from the CDC will discuss salmonella outbreaks related to backyard poultry, addressing public health concerns from recent incidents.

Resources and Recordings

• The webinar is being recorded; past and upcoming webinars can be accessed at extension.org/poultry. This resource provides valuable information on various topics discussed in previous sessions.

• For updates and additional resources, participants can follow the Poultry Extension on Facebook at facebook.org/poultryextension. This platform offers insights into ongoing activities related to small and backyard flocks.

Discussion Points on Poultry Health

• There was an inquiry about kidney health in poultry; it was noted that kidneys can vary in size due to factors like dehydration or other health issues such as gout, which may cause enlargement rather than reduction in size.

• Egg binding is highlighted as a significant issue among chickens, often caused by an imbalance of calcium and phosphorus levels in the blood rather than physical obstruction during egg-laying processes. Understanding this condition is crucial for effective flock management and health monitoring.

Conclusion of Webinar