A-Z of chicken diseases

[TIckingThymeBomb]

i beg your finest parden? aren't chickens just wonderful...

 

[OrpingtonManiac]

23. Avian Mycoplasmosis
This is the collective term for both Mycoplasma gallisepticum and Mycoplasma synoviae.
Males and younger birds are affected more severely.

M. Gallisepticum: Can cause chronic respiratory disease (CRD) in chickens and infectious sinusitis in turkeys.
M. Synoviae: Is largely associated with subclinical infections, confined to the air sacs. When stressed the infection can affect the synovial membrane of the
joints. It can cause Airsacculitis.

Symptoms:
Coughing, nasal/eye discharge, tracheal rales, weight loss, reduced appetite, reduced egg production, lameness, swollen and warm hocks and footpads.

Prevention:
Prevent wild birds accessing feeders and waterers, minimise stress, quarantine new birds.

 

[OrpingtonManiac]

24. Avian nephritis viral infection
ANV infection is caused by a highly infectious astrovirus. It predominantly affects the birds kidneys, causing renal damage and visceral urate deposits due to gout. Sometimes, it affects the intestines. Chickens can become infected from an infected birds faeces. It mainly occurs in chicks of less than 7 days

Symptoms:
Gout, diarrhoea, weight loss, stunted growth.

Prevention:
Biosecurity

 

[OrpingtonManiac]

25. Avian osteoporosis
This is a metabolic bone disease which occurs commonly in commercial layers. The formation of eggshells requires large amounts of calcium which, if the hen does not get enough from her diet, will be depleted from their bones instead. Inadequate amounts of vitamin D or phosphorus can worsen the condition.
This occurs more frequently in summer, as heat stress has a negative effect on circulating ionic calcium. They are at a higher risk of fractures

Symptoms:
Weakness, inability to stand, paralysis, deformed legs, not laying eggs, soft, thin or shell-less eggs.

Prevention:
Feed a balanced diet, provide free access to oyster shell, allow plenty of exercise, reduce heat stress.

 

[OrpingtonManiac]

Chicken anatomy
Digestive system part 1: The mouth and oesophagus

This starts at the mouth and ends at the cloaca.

The mouth:
They take in food into the beak, where digestion starts. Glands in the mouth release enzymes, mainly amylase, and saliva. The saliva softens the food, and contains the enzymes. Amylase digests starch into maltose. Chickens do not have teeth. The tongue pushes the food to the back of the throat, into the oesophagus.

The oesophagus:
The oesophagus connects the mouth to the crop, and the crop to the proventriculus. Its function is to allow passage of food in the first part of the digestive system.

 

[OrpingtonManiac]

Chicken anatomy
Digestive system, part 2:
The crop is located in the neck region, and is where food and water is stored. When the crop is nearly empty, it sends signals to the brain to encourage them to eat more. Very little digestion occurs here. The food mixes with small numbers of bacteria and lactic acid, which lowers the crops pH. The bacteria are mainly lactobacilii, which can bind to the crop epithelium, creating a thin biofilm layer. Bacterial colonisation is initiated around hatching time. Withdrawing feed before slaughter can cause a decrease in lactobacilii numbers, and an increase in pH. This encourages pathogens like salmonella to colonise the crop. This also occurs when withdrawing feed to induce moulting in laying hens. It has been found that, in hens that are induced to moult by starvation, and sometimes restricted access to water, that their eggs contain a higher proportion of salmonella bacteria than those that are not induced to moult.
The proventricularus is the glandular stomach where digestion primarily begins. Hydrochloric acid lowers the pH, providing an optimum pH for enzyme activity, like pepsin, and killing most unwanted, pathogenic bacteria. Food is moved between this and the ventriculus, or gizzard. This is made up of two, thick, muscles that grind food, with a protective lining protecting sed muscles, which also aids digestion due to its sand-paper like surface. This contraction cycle takes place 4 times a minute. The Chickens often pick up small stones which, after being softened by the proventriculus, are ground into smaller pieces in the gizzard. The stones remain in the gizzard until they are ground into small enough pieces to pass into the rest of the system.

 

[OrpingtonManiac]

Chicken anatomy:
Digestive system, part 3:
The small intestine is composed of the duodenum (often called the duodenal loop), and the lower small intestine. The remainder of digestion occurs in the duodenum, and nutrients are absorbed in the lower small intestine. Enzymes and bicarbonate (to counter the hydrochloric acid) are received from the pancreas, and bile from the liver.
The lower small intestine is made up of the jejunum and ilium. The meckels diverticulum marks the end of the jejunum and start of the ileum. It is formed during the embryonic stage, and is a remnant of the yolk sac, which after hatching relocates to the small intestine. It shrinks as the chicken ages.

 

[OrpingtonManiac]

Chicken anatomy
Digestive system part 4 (final part)
The ceca are two pouches located where the small and large intestines join. Some water remaining in the digested material is absorbed here. It also is ferments any remaining materials. It produces several fatty acids and all 8 B vitimans. It also plays a role in the transportation of sodium, water, potassium and chloride.
It harbours a large microbial community and may enlarge if a high fibre diet is given.
The large intestine is where the last water reabsorption occurs. It is shorter than the small intestine.
In the cloaca, digestive waste mixes with wastes from the urinary system (urates). This is chickens form of urine. The end of the reproductive tract also exits through here. When laying an egg, the egg does not come into contact with faeces or urates.

 

[OrpingtonManiac]

26. Avian philophthalmiasis
Philophtalmus gralli is a zoonotic trematode which infects the orbital and conjunctival tissue. It occasionally infects humans.
It causes conjunctivitis and keratitis (inflammation of the cornea). It is transferred to the water, where the eggs hatch and seek out a host (frogs, fish, snails etc.)
Chickens will become infected by contact with the water, or ingesting the host. The red rim melania and quilted melanie are frequent hosts.

Symptoms:
Conjunctival redness, ocular discharge, blesopharospasm, frequent eye scratching, swollen eyelid, corneal opacity, blindness.

Prevention:
Restrict access to freshwater areas.

 

[OrpingtonManiac]

27. Avian tuberculosis
This is a contagious, slow-developing, chronicgranulomatous disease caused mainly by mycobacterium spp. It occurs in all avian species, and sporadically in mammals.
The disease primarily affects the liver and intestine.
The most common form, the intestinal form, causes progressive loss of condition. A loss of body fat causes the face to appear smaller, and muscle atrophy will cause the keel bone to become more prominent. If granulomas occur in the bone marrow, it can cause paralysis. This is known as tuberculosis arthritis. The most common transmission is orally. Once inside the chickens body, it replicates inside macrophages.

Symptoms:
Loss in feather quality; low body condition; diarrhoea and soiling of vent feathers (pasty butt); pale, dry, thin wattles and comb; weakness; abdominal enlargement; abnormal gait; lethargy; difficulty breathing; subcutaneous masses.

Prevention:
Minimise stress
Minimise contact with wild birds and pigs
Don't house your flock in an area with a previously high concentrations of birds
Maintain good sanitary conditions
Expose ground to sunlight
Provide vitamins and probiotics.