List of eighteen major diseases of chicken:- 1. Pulmonary Hypertension (Ascitis) Syndrome in Broiler Chickens 2. Amyloidosis 3. Deep Pectoral Myopathy 4. Rupture of the Gastrocnemius Tendon in Broiler Breeders 5. Cage Layer Fatigue 6. Hyperkeratosis 7. Gout 8. Hyperandrogenism in Broiler Chickens and Others.
Disease # 1. Pulmonary Hypertension (Ascitis) Syndrome in Broiler Chickens:
The pulmonary hypertension syndrome (PHS) or ascitis is related to the rapid growth and enhanced metabolic processes in broilers. Affected chickens are with a strongly distended abdomen, reluctance to move, respiratory troubles and cyanosis. The pleuroperitoneal cavity of affected chickens is filled with straw-yellow fluid.
The rapid growth in contemporary broilers is related to higher needs for oxygen, and the lung remains relatively small in comparison to body dimensions. The main factor for PHS is hypoxaemia that results in enhanced cardiac activity.
The consequences are pulmonary hypertension, right cardiac failure and ascitis. Immediate causes for hypoxaemia are the inadequate ventilation, the high ammonia or dust levels in premises, low temperatures, stimulating the metabolic processes.
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Generalised passive venous hyperaemia and stasis in the liver and other viscera are observed. The right ventricle at an early stage is hyper-trophied whereas at a later-dilated with extremely thinned wall. The diagnosis is based on gross lesions. The reduction of oxygen requirements by slowing down the metabolism protects from and decreases the incidence of ascitis. Restriction of forage consumption and various light patterns are recommended.
Disease # 2. Amyloidosis:
Amyloidosis is seen mainly in adult birds. It is characterized by extracellular buildup of the protein amyloid in different viscera and the joints. Amyloid arthropathy is primarily associated with Enterococcus faecalis and Mycoplasma synoviae. Brown layers are particularly susceptible. Some genetic factors could be involved in the incidence of amyloidosis too.
The affected joints are enlarged, swollen and contain orange-yellowish matter. Amyloidosis of the liver, the spleen and the kidneys are observed. The affected organ is multifold enlarged with stretched capsule, rounded margins and pale colour. The state is usually seen following severe disturbances in protein metabolisms, prolonged and exhausting diseases (tuberculosis, etc.).
The cannibalism in birds is usually consequence of feather pecking or pulling out, or vent pecking, that are behavioural reactions. Feather pecking or pulling out are observed in birds, reared in closed, often overcrowded premises. This happens frequently in growing broiler breeder flocks during the period of restricted feeding.
Disease # 3. Deep Pectoral Myopathy:
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The deep pectoral myopathy (DPM), called also green muscle disease or Oregon disease, is observed in heavy meat types of turkeys or chickens. The disease occurs because of ischaemic necrosis due to inadequate blood supply of variously sized deep pectoral muscle groups. The lesion is uni- or bilateral and is detected as a slaughterhouse finding. Affected muscles have an unusual green colour.
Disease # 4. Rupture of the Gastrocnemius Tendon in Broiler Breeders:
This state could cause significant economical losses in broiler breeder flocks. It is usually seen in birds older than 12 weeks but is also observed in breeders at the age of 7 weeks or older than 24 weeks. The rupture could be uni- or bilateral.
Clinically, lameness is observed. In affected birds, swelling of the posterior surface of the leg, just above the tibiotarsal joint could be palpated. In acute lesions, haemorrhages are visible through the skin.
In older lesions, a blue-greenish discolouration is present whereas in chronic lesions, very hard masses as abnormal subcutaneous tissue are palpated. In part of birds, the muscles of affected legs undergo a various degree of atrophy. In acute lesions, swellings and haematomas under the skin of the posterior surface of the leg are detected.
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In older or chronic lesions, the blood is partially or completely reabsorbed. The end of ruptured tendon and the adjacent tissue are involved at a various extent by a newly grown fibrous tissue. RGT should be differentiated from reovirus-and MS infections, where the gross and histological lesions are with a marked inflammatory character.
Disease # 5. Cage Layer Fatigue:
Cage layer fatigue syndrome in birds is characterized by an inability to stand on their feet and fragile bones. It is mainly observed in young layer hens reared in batteries in the period of maximum egg-laying. Affected birds lie down and stopped eating. Egg shells become thin.
The calcium deficiency in layer hens results in initial removal of calcium from bones, to complete depletion of the medullary bone and thereafter, of the bone wall. The bones are strongly thinned and spontaneous fractures, especially of the tibia and the femur could occur.
Although the severe calcium deficiency is often a triggering factor, the aetiology of the syndrome seems to involve other, yet unknown factors.
The supplementation of calcium, phosphate and multivitamin preparations in the diet and drinking water, the regulation of avian population density into cages and ensuring adequate nutritional and drinking fronts are also contributing for the favourable outcome of the condition.
Disease # 6. Hyperkeratosis:
A local form of hyperkeratosis in an ostrich. Increased amount of keratin in the horny tissues — down feathers and beak — is present, resulting in their coarse appearance. The state is linked to impaired metabolism of sulfur- containing amino acids, vitamin A deficiency, etc.
Disease # 7. Gout:
The gout is characterized by retention and build-up of urates in tissues. It is seen as two separate syndromes: visceral gout and articular gout. The visceral gout is manifested with deposition of urates in renal tubules and the serous coats of the heart, the liver, the mesentery, the air sacs or the peritoneum.
The urate deposits on serous coats resemble a chalky white dust. Visceral urate deposits are generally due to renal failure. Possible causes for this could be obstruction of ureters, renal damage or dehydration. Most commonly, visceral gout following dehydration is observed in newly hatched chickens after overheating or a more prolonged stay in the hatchery.
Visceral gout outbreaks are related to vitamin A deficiency, treatment with sodium bicarbonate, mycotoxicoses, etc. Urolithiasis is an aetiologically unknown state, occurring primarily in cage layer hens, characterized by obstruction of one or both ureters with urates, atrophy of one or more renal lobes and a various degree of renal and visceral gout.
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A number of aetiological factors are related to this condition protein excess, calcium excess (3% or more), sodium bicarbonate toxicity, mycotoxins (ochretoxin, etc.), vitamin A deficiency and nephrotropic strains of the infectious bronchitis virus.
The lower phosphorus levels (under 0.6%) are probably helping the manifestation of the disease. There are no specific clinical signs except for the depression and the weight loss. The death rate could increase and persist around 2-4% monthly during the productive period. The total mortality is heavily affected flocks could reach 50%.
Disease # 8. Hyperandrogenism in Broiler Chickens:
Hyperandrogenism in broilers is a condition, manifested with marked signs of masculinization in chickens from both genders. The first signs could start very early after the age of 10-12 days. A very noticeable reddening of the comb and wattles, coarse feathering of the face, strong growth of nails and a highly aggressive behaviour in about 100% of birds are observed.
The peak of clinically manifested masculinization traits is between the age of 20 and 30 weeks in all chickens. The serum testosterone is manifold higher. In 23-day-old broilers, average testosterone concentrations were 709 ng/dl vs. 36 ng/dl in intact chickens at the same age.
The mycotoxins following contamination of some of forage components with moulds are assumed to be a possible cause for this state, but yet, it is not clear if this or another factor is causing hyperandrogenism.
Disease # 9. Effect of Cleavers (Galiumaparine) Seeds on Healthy Status and Production Traits in Broiler Chickens:
Galiumaparine, cleavers or sticky-willy, is an annual weed in cereals and earthed-up crops, and an herbal plant belonging to the Galium genus (herbarium). The seeds (fruit) are dry, round or kidney-shaped, with smooth, corrugated or granular surface, sometimes covered with hooked prickles, brown or grey colour and are notched on one side (nuts).
On the left — seeds with coat, on the right — without coat. In the gizzard of chickens, the seeds become white with a contrasting black-coloured unipolar groove, similar to an eye. Most probably, that is why they are called “snake eye”.
Purulent necrotic processes in the gizzard of a chicken. The health is influenced by consequences of mechanical obstruction because of seeds’ accumulation in the gizzard. A direct toxic effect of Galiumaparine is also supposed (primarily hepato- and nephrotoxic), due to release of toxic glycosides and other toxic substances from the seeds.
Disease # 10. Gizzard Impaction in Turkey:
The gizzard impaction could result in high mortality in turkey poults during the first three weeks of life. Affected turkey poults are dehydrated with empty gut, but the gizzard is filled with hard fibrous masses.
In some cases, the fibrous masses enter the first part of the duodernum or the lower parts of the small intestines. The impaction is resulting from eating litter that gizzards cannot ingest. The prevention is aimed at control of litter eating.
Disease # 11. Roundheart in Turkeys (Dilated Cardiomyopathy):
The aetiology is not known, but genetic factors or early viral myocarditis is supposed. The state is lethal in turkeys at the age of 1-4 weeks. Pathoanatomically, a severe dilated cardiomyopathy, often accompanied with ascitis, hydropericardium and congestion of other organs is detected.
Disease # 12. Acute Selenium Intoxication:
Acute selenium intoxication in birds is usually seen after multifold overdosing of preparations containing inorganic selenium with the aim of prevention or therapy.
In the early hours after intake of toxic doses of selenium, a high death rate (up to 100%) and massive haemorrhages in the liver are seen. In birds that survived the later stage of the selenium toxicosis, liver haemorrhages are outlined on the background of dystrophic necrobiotic changes.
Disease # 13. Acute Propane-Butane Intoxication:
In cases of acute intoxication with propane butane (due to damage in heating appliances where propane-butane is used as energy source for heating), asphyxia, cyanosis of the featherless skin, pulmonary edema and sub-capsular haemorrhages in the liver are observed.
Pasted vent is usually observed in diarrhoea, when the rectal masses are sticked to adjacent feathers. The observed plugs prevent the evacuation of the next faecal masses. This results in dilatation and obstipation of the rectum.
Disease # 14. Spontaneous Rupture of the Caudal Renal Artery in Turkeys:
A case of spontaneous rupture of the caudal renal artery in broiler turkeys is observed at the age of 8-12 weeks. Some birds in an excellent body condition die. The carcasses are anaemic.
The necropsy shows that in some birds, the entire body cavity is filled with clotted blood and in others — massive sub-capsular coagula from the side of the affected kidney are detected. In all cases, unilateral rupture was observed, primarily of the left renal artery.
Disease # 15. Subcutaneous Emphysema:
Subcutaneous emphysema in the right inguinal region occurs after penetration of air or gases in the subcutaneous connective tissue. Usually, it results after air-sac tearing or skin injury. Subcutaneous emphysema also occurs in the region of the head.
Disease # 16. Gastrointestinal Impaction:
A sacciform blind pouch occurs after attachment of the intestinal wall to an unabsorbed yolk sac causing impaction.
Disease # 17. Intestinal Invagination:
Involvement of anterior parts of the small intestine, the mesentery and the tops of the caecum into the ileum. Usually, it occurs with a strong intestinal peristalsis, often following ingestion of feed after a restrictive feeding regimen. Rotation of the small intestine on the longitudinal axis of the mesentery resulting in venous stasis and necrosis of the intestinal wall.
Disease # 18. Crop Impaction:
It is caused by hard, fibrous feed or litter, whose accumulation results in impaction. The retained content into the crop sometimes causes putrefactive necrotic processes, affecting the crop wall and the covering skin.