A-Z of chicken diseases

[OrpingtonManiac]

35. Blindness
Occasionally , chicks can hatch blind or without eyes, or can go blind as a result of disease.

Signs of blindness:
Cloudy, discoloured eye; misshaped pupils; little reaction to external stimuli; inability to recognise food and water; consistent chirping in newly hatched chicks; bumping into objects; reduced activity; clumsiness; pecking at air.

Supportive care:
Do not let chickens free-range when at risk of predator attacks, or unsupervised.
Keep birds in confined areas, with no access from predators
Ensure they are not bullied by others
Ensure they are getting sufficient food and water, and monitor weight gain and loss.

Prevention:
Promptly treat respiratory infections.

 

[OrpingtonManiac]

36. Blister beetle toxicity
Blister beetles are insects that contain the toxin cantaridin. This is highly toxic, and if consumed by a chicken, may be fatal. Cantaridin causes irritation through direct contact. When ingested, it affects the chickens gastrointestinal tract, kidneys and heart. Lesions are often found in the crop and gizzard

Symptoms:
Loss of appetite; depression; tachycardia (accelerated heart rate); Tachypnea (accelerated respiratory rate); sudden death; ataxia: vomiting beetles.

 

[Wyorp Rock]

Up next will be:

Botulism, Brain Tumor, Breast Blister....

 

[OrpingtonManiac]

𝟯𝟳. 𝗕𝗼𝘁𝘂𝗹𝗶𝘀𝗺
This is a disease caused by a toxin produced by clostridium botulinum. The toxin binds to the nerve endings, interfering with muscle movements. Symptoms usually develop between 24 hours and 17 days after ingestion, depending on the amount of toxin digested. Activated charcoal can be given to treat the bird. Most deaths occur due to respiratory and cardiac failure.

Transmission:
Botulism spores are found in dust, soil, water, spoiled feed, decaying matter and in the digestive tracts of animals and fish. Maggots also harbour C. Botulinum.

Symptoms:
Limp neck, flaccid paralysis, muscle weakness, drooping eyelids, difficulty swallowing, weakness, drooping wings, difficulty breathing.

Prevention:
Do not feed spoiled chicken feed or maggots
Clean up spilled feed regularly
Do not allow chickens access to standing water
Do not allow access to composts
Properly dispose of dead animals
Do not feed chickens rotting vegetables, particularly cabbage
Be careful when feeding chickens fermented feed

 

[OrpingtonManiac]

𝗖𝗵𝗶𝗰𝗸𝗲𝗻 𝗮𝗻𝗮𝘁𝗼𝗺𝘆: 𝗙𝗲𝗺𝗮𝗹𝗲 𝗿𝗲𝗽𝗿𝗼𝗱𝘂𝗰𝘁𝗶𝘃𝗲 𝘀𝘆𝘀𝘁𝗲𝗺 (𝗲𝗴𝗴 𝗹𝗮𝘆𝗶𝗻𝗴).

The whole process of egg formation takes 25-26 hours, therefore each day the hen will lay later and later, until she skips a day.

Ovary:
The chicken reproductive system consists of the ovary and oviduct. Although female chickens have two ovaries, only the left is functional.
The ovary is a cluster of developing ova, and is located midway between the neck and tail. The ovary is fully formed when the pullet hatches, so the maximum number of eggs the chickens will lay is determined when the chick hatches. Both ovaries start to grow at around 72 hours into incubation.

Oviduct:
When ovulation occurs, the ovum enters the oviduct. The oviduct is divided into 5 sections:

The infundibulum: The muscular infundibulum engulfs the ovum, moving to surround it. The ovum stays here for 15 to 17 minutes. Fertilisation occurs here.

The magnum: This is the largest section of the oviduct, and the thick albumen forms (the egg white). The ovum remains for 3 hours. The chalaza is formed (these are two white strands that suspend the yolk in the white).

The Isthmus: This is where the inner and outer shell membranes form. The developing egg remains here for 75 minutes.

The shell gland: Also known as the uterus, this is where shell formation occurs. The shell is largely made of calcium carbonate, which is pulled from the birds bones. Pigment deposition occurs here. The egg remains for 20+ hours.

The vagina: This is the last part of the oviduct, and helps in egg laying. The bloom, or cuticle forms here prior to oviposition . The egg turns here, so is layed large end first

The ova: These start out as a single cell, surrounded by a vitelline membrane (This is a transparent membrane that separates the yolk from the white) . As the ovum develops, yolk is added. The colour of the yolk comes from fat soluble pigments called xanthophylls contained in the hens diet.
Ovulation: This is the release of the mature ovum into the oviduct. During ovulation, the ovum, which is enclosed in a sack, ruptures along the suture line, or stigma. Occasionally, the vitelline membrane is damaged in this process, resulting in pale spots on the yolk (mottling).

Light and ovulation: The female’s reproductive system is sensitive to the number of light hours in a day. The release of the next ova occurs 30-37 minutes after the egg was layed. If the egg was layed too late, ovulation will wait until the next day.

 

[Sally PB]

The egg turns here, so is layed large end first

So, at some point, the egg is sideways. Think about that the next time you see a jumbo sized egg...

 

[Wyorp Rock]

So, at some point, the egg is sideways. Think about that the next time you see a jumbo sized egg...

Amazing isn't it!

 

[OrpingtonManiac]

𝟯𝟳. 𝗕𝗿𝗮𝗶𝗻 𝘁𝘂𝗺𝗼𝘂𝗿𝘀
Types of Brain tumours that have been identified in birds are:

Astrocytomas:
These are frequently multiple, unincapsulated small nodules, usually located at the base of the cerebellum or underlying rostral brain stem. They must be differentiated from reactive gliosis caused by migrating parasites.

Medulloblastomas:
These are a type of primitive neuroectodermal tumour which develops in the cerebellum.

Pineoblastoma:
This is an aggressive type of maligned tumour which develops in the pineal gland .

Symptoms:
Wry neck; walking backwards; incoordination; ataxia; difficulty perching; head pressing; tremors; head tilting; poor weight gain despite a good appetite; microphthalmia.

 

[OrpingtonManiac]

𝗖𝗵𝗶𝗰𝗸𝗲𝗻 𝗮𝗻𝗮𝘁𝗼𝗺𝘆: 𝗧𝗵𝗲 𝗵𝗲𝗮𝗿𝘁, 𝗮𝗿𝘁𝗲𝗿𝗶𝗲𝘀 𝗮𝗻𝗱 𝘃𝗲𝗶𝗻𝘀
Birds have very efficient cardiovascular system, to allow flight.
There are many blood vessels which transport oxygen, nutrients, carbon dioxide, hormones, heat and waste products.

The heart is located in the thoracic cavity, between the two lobes of the liver. It is surrounded by a membrane called the pericardium. It is conical in shape, with the pointed end directed towards the rear of the bird.

The veins bringing deoxygenated blood from the body into the heart enter the right atrium.
The opening connecting the right atrium to the ventricle is crescent-shaped, and instead of the tricuspid valve found in mammals, there is a strong, muscular plate. The opening between the left atrium and ventricle is circular in shape, with membraneous flaps instead of the bicuspid valve found in mammals. The septum is thin, and there is an even thinner section in the middle, called the fossa ovalis.

The external wall of the right ventricle is much thinner than that of the left. At its base is the opening for the pulmonary artery, with three, pocket-like, semi-lunar valves. The wall of the left ventricle is much thicker, apart from at the apex (pointed end). This provides the strength to pump blood all around the body, through the aorta. The aorta leave the heart from the left ventricle through an opening with semi-lunar valves, similar to that of the pulmonary artery. Tendinous cords prevent the valves from moving too much (e.g turning inside out) due to the high pressure of the blood. The cords are called chordae tendonae.

The heart has its own blood supply: The coronary arteries, which branch off from the aorta.

The pulmonary system starts with the pulmonary artery, that, after leaving the right ventricle, divides into right and left branches. Each enters the lungs, ultimately to be involved with gas exchange. Shortly after the aorta divides to form the two coronary arteries, it divides again -the first of many divisions. Blood from the aorta supplies the head, thoracic region and abdominal region.
As arteries divide, they become smaller and smaller, until they form arterioles. Upon entering the target organ, they divide into thin-walled capillaries which deliver oxygen and nutrients to the cells.

The capillaries rejoin once they leave the organ, forming venules that carry deoxygenated blood to the heart. They enter the heart as three main veins: The caudal vena cava, the right cranial vena cava, and the left cranial vena cava. The caudal vena cava drains the abdominal region, whereas the two cranial vena cavas drain the head and upper body (excluding the lungs).

 

[OrpingtonManiac]

𝗖𝗵𝗶𝗰𝗸𝗲𝗻 𝗮𝗻𝗮𝘁𝗼𝗺𝘆: 𝗕𝗹𝗼𝗼𝗱 𝗰𝗼𝗺𝗽𝗼𝘀𝗶𝘁𝗶𝗼𝗻
Blood is the transport vehicle for the body. It carries, among other things: Products of metabolism, Hormones, enzymes, antibodies, effete products of tissues and organs and many other inorganic and organic substances.

Erythrocytes:
These are large, flat, oval, nucleated cells. The nucleus is positioned in the centre of the cell, and are typically elongated. Occasionally, they will not contain a nucleus (like mammalian erythrocytes), but these are atypical. The red colouring is caused by the presence of haemoglobin, which binds to oxygen. Their function is to transport oxygen to tissues and organs. They are formed in the red bone marrow.

Leucocytes:
They are nucleated cells with a colourless cytoplasm. Some have fine granules in their cytoplasms, while others have coarse granules, and others have no granules. Granulocytes are a type of leucocytes. Most are phagocytic. Their shape is therefore variable, but they are circular in normal conditions. They are mono-nuclear and the nucleus is often multi-lobed. They are formed in the spleen, lymphoid tissue and bone marrow. Types of leucocytes are:
Heterophils are spherical in shape, and their nuclei are distinctly lobed, with thick strands of nuclear material (nucleoplasm) joining them. They are important for protection against bacterial infections, as they have a bactericide function, and ingest protein.
Eosinophils have bi-lobed nuclei. There contain fewer, rounder granules than in heterophils. The function is unknown, but their numbers increase in cases of internal parasitic infections. It has also been suggested they have a detoxification function.
Basophils have a generally oval shaped nucleus that is not lobed. There are fewer of these, and their function is unknown.
Lymphocytes are the most common heterophils. Their size varies, though older cells tend to be smaller. The nucleus size is the same, and may be kidney-shaped. The mobility of these cells is reduced, and they likely have zero phagocytic action. Their function is to regulate toxic materials. They also release enzymes that assist in the synthesis of the nucleoplasm.
Monocytes are the largest leucocytes and are sometimes difficult to distinguish from lymphocytes. The nucleus varies in shape. They are very mobile and phagocytic. Their function is to remove, by ingestion, bacteria, protozoan and tissue debris.
Thrombocytes are similar to platelets (found in mammals), but are less involved in blood clotting. They are numerous, and the smallest of all blood cells, and group together in clumps. They are formed in the bone marrow.

Plasma:
Plasma is the liquid, non-cellular part of the blood. It contains: Glucose, non-protein nitrogen substances, plasma proteins, plasma liquids, plasma enzymes, metallic elements, water.

Blood glucose:
As in mammals, it is in the form of D-glucose, although it is usually at higher levels. Hormones like glucagon, insulin, corticoids and glucocorticoids affect the level. Plane of nutrition also affects levels. The average level is about 10mmol/litre (compared to around 4.5mmol/ litre in humans).

Non-protein nitrogen:
After the removal of plasma proteins, the remaining fluid contains a number of nitrogenous substances including: Uric acid, urea, creatine, free amino acids, free ammonia.
Uric acid represent the bulk of waste nitrogen. They are the end product of protein metabolism. The level is influenced by sex and reproductive state (non-layers have higher levels). Urea is eliminated by the kidney, and is influenced by age and sex.
Creatine is an amino acid present in animal tissues. It combines with phosphate (making phosphocreatine) which is important in the anaerobic phase of muscle contraction. The ammonium ions are found in very small quantities. Around 22 amino acids have been found in small quantities in avian blood (although not all at the same time).
Plasma proteins:
Albumins transport calcium and other minerals, fatty acids and hormones.
Immunoglobins are produced by lymphocytes as a result of antigenic demand.
Transferrin transports iron across the intestinal wall. This is part of the secondary immune response, as it makes iron unavailable to viruses and bacteria.
Ceruloplasmin is for copper transport.
Phosvitin carries calcium, iron and phosphate to the yolk and calcium to the shell gland.
Lipoproteins carry fat-soluble vitamins, hormones and some minerals in the blood.
Fibrinogen is important for blood-clotting.