Nematodes

Carcass judgment for safe and healthy meat

GENERAL PATHOLOGICAL CONDITIONS 

Fever (Pyrexia)
 
Fever is an abnormal elevated body temperature. It may be classified as septic and aseptic according to the presence or non presence of an infection. In septic fever the infection is caused by viruses, bacteria, bacterial toxins, protozoa and fungi. Aseptic fever may be caused by a) tissue necrosis as seen in muscle degradation due to intermuscular injection of necrotizing substances, in rapidly growing tumours undergoing necrosis or lysis of burned tissue; b) by chemicals or surgery. In former by an administration of drugs and in latter by breakdown of tissue and blood. c) during anaphylactic reaction of antibodies to the foreign antigens.
 
Judgement : Carcass is condemned if fever syndrome is associated with presence of bacteria or bacterial toxins in the blood and/or findings of drugs and antimicrobial substances.
 
If typical signs of fevered carcass are not seen carcass should be held for 24 hours after slaughter and reexamined. In case of mild fevered syndrome detected first on postmortem inspection, the carcass may be conditionally approved with heat treatment providing that bacteriological and chemical test are negative.
 
Differential diagnosis : Hyperthermia and septicemia. In hyperthermia the elevation of body temperature is caused by physical factors such as high environmental temperature or prolonged muscular exertion, particularly in humid weather.

Inflammation in viral diseases

Inflammation associated with viral diseases is usually secondary to primary cellular change. Secondary bacterial infections frequently accompany and complicate viral diseases particularly respiratory and skin diseases. Viral infection associated with fever, malaise, anorexia or incoordination is attributed to absorption of injured cell products, viral toxicity and viral abnormalities which cause circulatory disturbances. Vascular shock together with viral toxicity and failure of one or more vital organs, is thought to be associated with death in viral diseases.
 
Septicemia
 
Septicemia is a morbid condition caused by the presence of pathogenic bacteria and their associated toxins in the blood. The positive diagnosis of septicemia can only be made by isolation of the causative organism from the blood stream. This is not practised on routine antemortem examination of animals in abattoirs; however, the evidence of septicemia is determined by the antemortem and postmortem findings.
 
Judgement : The animals, animal carcasses, offal and other detached portions of animals affected with septicemia are condemned. In borderline cases bacteriological examination should be done wherever possible.
 
Toxaemia
 
The identification of toxaemia presents some difficulties on routine antemortem and postmortem examination. The gross lesions differ depending on the specific organisms and toxins involved. Also the clinical signs of toxaemia simulate a variety of other pathologic conditions.
Toxaemia is defined as the presence and rapid proliferation of exotoxin and endotoxin derived from microorganisms or produced by body cells in the blood-stream. Clinical signs and postmortem findings are similar to those of septicemia.

Antemortem findings :
 
Toxaemia is frequently associated with: 

1. Gangrenous mastitis
2. Metritis
3. Aspiration pneumonia
4. Old wounds and injuries
5. Diffuse peritonitis due to perforation of the reticulum or uterus.

All these signs may not be seen in every animal affected with toxaemia.
 
Judgement : If there is evidence of septicemia or toxaemia the carcass and the viscera should be condemned and the implements used during inspection and the hands and arms of the inspector should be washed and disinfected. The primary lesions causing septicemia or toxaemia including metritis, mastitis, pericarditis, enteritis and others, should be observed and recorded as causes of condemnation. Comatose or moribund animals should be condemned on antemortem examination. 

Pigmentation

Pigments are classified as exogenous and endogenous. Exogenous pigments are synthesized outside of the body and endogenous within the body itself.
Pigments are coloured substances which accumulate in the body cells during the normal physiological process and abnormally in certain tumours and conditions. They have a different origins, biological significance, and chemical composition.
The endogenous pigments, except for melanin and lipofuscin are derivates of haemoglobin.
 
(A) Melanosis
 
Melanosis is an accumulation of melanin in various organs including the kidneys, heart, lungs and liver, and other locations such as brain membranes, spinal cord, connective tissue, periosteum etc. Melanin is an endogenous brown-black pigment randomly distributed in tissue. In grey and white horses, this pigment is found under the shoulder, axillary area and ligamentum nuchae. Melanin is also found in lymph nodes, pig skin and belly fat or mammary tissue in female pigs. This condition is called “seedy belly” or “seedy cut” since the black colour in the mammary tissue resembles round, black seeds. The melanotic tissue in pigs shows a tendency towards neoplasia. Melanin deposits in the oesophagus and adrenal glands in older sheep are a common finding on postmortem examination. Multifocal deposits of melanin in the liver of a calf is known as “Melanosis maculosa”. It is common in calves and it usually disappears after the first year of age.
 
Judgement : Carcasses showing extensive melanosis are condemned. If the condition is localized, only the affected organ or part of the carcass needs to be condemned.
 
Differential diagnosis : Haemorrhage, Melanoma, Distomatosis (liver flukes)
 
(B) Myocardial lipofuscinosis (Brown atrophy of the heart, Xanthosis)
 
Xanthosis (“Wear-and-Tear”) pigment is a brown pigmentation of skeletal and heart muscles of cattle. The condition is seen in old animals such as “cull dairy cows” and in some chronic wasting diseases. It is prevalent in Ayrshire cows and approximately 28 % of normal Ayrshire cows have this pigment in skeletal and heart muscles. Xanthosis is not dependent on the age of animals in this breed. 

(C) Congenital porphyria (osteohemochromatosis, pink tooth)
 
Porphyria is the accumulation of plant or endogenous porphyrins in the blood resulting in tissue pigmentation and photosensitization. This is a hereditary disease and is observed in cattle, swine and sheep. In porphyric cattle, exposure to light will initiate the development of photodynamic dermatitis. In swine, photodynamic dermatitis does not occur.
 
The disease is also known as osteohemochromatosis, due to a reddish brown bone pigmentation and “pink tooth” because of a brownish-pink discoloration of teeth.
Judgement : Carcass showing extensive xanthosis is condemned. If the condition is localized, only the affected organ or part of the carcass needs to be condemned. Head and bones of a carcass affected with osteohemochromatosis are condemned. The bones are “boned out” and remaining muscles are approved. If the condition is generalized the carcass is condemned.
 
 (D) Icterus(Jaundice)
 
Icterus is the result of an abnormal accumulation of bile pigment, bilirubin, or of haemoglobin in the blood. Yellow pigmentation is observed in the skin, internal organs, sclerae (the white of the eye), tendons, cartilage, arteries, joint surfaces etc. Icterus is a clinical sign of a faulty liver or bile duct malfunction, but it may be also caused by diseases in which the liver is not impaired. Jaundice is divided into three main categories.
 

1. Prehepatic jaundice (haemolytic icterus)
2. Hepatic jaundice (toxic icterus)
3. Posthepatic jaundice (obstructive icterus)

Judgement : Animals suspected to have icterus should be treated as “suspects” on antemortem examination. On postmortem examination, the carcass and viscera with haemolytic, toxic icterus and obstructive icterus are condemned. Less severe cases are kept in the chiller for 24 hours. Upon re-examination, the carcass may be approved or condemned depending on the absence or presence of pigment in the tissue. If the obstructive icterus disappears after 24 hours, the carcass and viscera can be passed for human food.
 
A simple laboratory test will help to make an objective test for bile pigment icterus. Two drops of serum are mixed on a white tile with two drops of Fouchets agent.2 A blue/green precipitate is positive for bile icterus.
 
2 Fouchets Reagent Trichloroacetic acid.                                            25 gm 
FeCl3 (10 % solution)                                                                          10 ml 
Distilled water                                                                                      100 ml
 
Differential diagnosis : Yellow fat in animals with heavy corn rations, nutritional panniculitis (yellow fat disease, steatitis) and yellow fat seen in extensive bruises. In yellow fat disease, the fat has a rancid odour and flavour upon cooking.
 
To differentiate icterus from the normal colour of fat of certain breeds, the sclera, intima of the blood vessels, bone cartilage, liver, connective tissue and renal pelvis should be examined. If yellow discoloration is not noted in these tissues, icterus is not present.

Haemorrhage and Haematoma
 
Haemorrhage is seen at slaughter in various organs, mucous and serous membranes, skin, subcutaneous tissue and muscles. It may be caused by trauma, acute infectious diseases or septicemia.
 
In haemorrhage caused by improper stunning, there may be a delay between stunning and sticking of the animal. The electrical current used in stunning causes cardiac muscle stimulation and vasoconstriction of blood vessels. This might induce a rapid rise in blood pressure leading to haemorrhages in the organs and muscle (so called “blood splashing”).
 
The stunning of animals by a mechanical blow to the head is still practised with sheep and is a significant cause of haemorrhage in organs particularly the lungs and heart. The blow to the head will initiate a rise in blood pressure. The normal arterial blood pressure in sheep is 120 – 145 mm/Hg. This may rise to 260 mm/Hg or over in a stunned animal. The heart rate will be increased. Immediate bleeding with the fast blood flow from the cut vessels could prevent this type of haemorrhage in sheep.
 
Agonal haemorrhage (due to rupture of capillaries) is caused by laboured breathing and contraction of musculature during violent death.
 
A lump formed from a blood clot in tissues or organs is called a haematoma. Haematoma varies in size and may be over one meter in diameter. They are associated with trauma or a clotting defect. Haematoma of the spleen may be associated by head butting by horned animals.
 
Judgement : A carcass is approved if the haemorrhage is minor in extent and is due to physical causes. The affected tissue is condemned. A carcass affected with extensive haemorrhage where salvaging is impractical, or a haemorrhagic carcass associated with septicemia is condemned.
 
Differential diagnosis : Haemorrhage resulting from blackleg, and sweet clover poisoning

Bruises
 
Bruises are frequently found on antemortem and post-mortem examination in food producing animals and poultry. In cattle bruises caused by transportation or handling are commonly found in the hip, chest and shoulder areas; in pigs within the ham and in sheep in the hind leg. Bruises and haemorrhage in the hip joint are caused by rough handling of animals during shackling. Bruises in poultry can be localized or generalized and are frequently associated with bone fractures or ruptured ligament tendons.
 
Judgement : Bruised animals should be treated as suspects on ante mortem examination. On postmortem examination, carcasses affected with local bruising are approved after being trimmed. Carcasses affected with bruises or injuries associated with inflammatory lesions are also approved if tissue reaction does not extend beyond the regional lymph nodes. The affected area should be condemned. When bruises or injuries are associated with systemic change and the wholesomeness of the musculature is lost, the carcass will be condemned.
 
On postmortem examination of bird carcasses affected with bruises and fractures, the following judgement should be observed: 
    (a) the fractures associated with bruises are removed and affected tissue is condemned, 
    (b) in compound fractures with damaged skin, the fractured site and surrounding tissue are condemned; 
    (c) in simple fractured without bruises and damaged skin, the affected portion may be approved for mechanical and manual boning operations. If the lower part of bone is fractured, the bone may be removed by cutting above the fracture. A carcass affected with extensive bruises is condemned on postmortem examination. A slightly or moderately bruised carcass is approved if no systemic changes are present. Affected tissues are condemned. 

Abscess
 
An abscess is a localized collection of pus separated from the surrounding tissue by a fibrous capsule.
The most common bacteria in liver abscesses include Actinomyces (Corynebacterium) pyogenes, Streptococcus spp. and Staphylococcus spp. In the lungs the most common bacteria are Pasteurella spp. and Actinomyces pyogenes. Fusobacterium (Sphaerophorus) necrophorum causes liver abscesses as a complication of rumen inflammation (rumenitis) in adult cattle. This condition is common in feedlots where cattle are fed a high grain diet which produces acidity in the rumen and ulcerative rumenitis. The rumen lesion is invaded by F. necrophorum which pass further via the veins to the liver and stimulate abscess formation.

Judgement : The judgement of animals and carcasses affected with abscesses depends on findings of primary or secondary abscesses in the animal. The portal of entry of pyogenic organisms into the system is also of importance. The primary abscess is usually situated in tissue which has contact with the digestive tract, respiratory tract, subcutaneous tissue, liver etc. The secondary abscess is found in tissue where contact with these body systems and organs is via the blood stream. The brain, bone marrow, spinal cord, renal cortex, ovary and spleen may be affected with secondary abscesses. In judgement of the carcass, the inflammation of the renal medulla and contact infection in the spleen and ovaries must be ruled out. A single huge abscess found in one of the sites of secondary abscesses may cause the condemnation of a carcass if toxaemia is present. In pigs an abscess is frequently observed in the jaw and in the spine. Spinal abscesses in pigs are commonly caused by tail biting. The bacterial agent from the tail penetrating the spinal canal could be arrested in the lumbo-sacral and cervical spinal enlargements, initiating an abscess formation.

Inspectors should differentiate the abscesses in the active and growing state from the older calcified or healed abscesses. In domestic animals, the primary sites of purulent infections are post-partum uterus, umbilicus or reticulum in “hardware disease”. Secondary abscesses are frequently observed in distant organs. Small multiple abscesses may develop in the liver of calves as a result of infection of the umbilicus (“sawdust liver”). Carcasses with such condition should be condemned.
 
The animals affected with abscesses spread through the blood stream (pyemia) are condemned on antemortem if the findings of abscesses are over most areas of the body and systemic involvement is evident as shown in elevated temperature and cachexia.
 
On postmortem examination, the carcasses are condemned for abscesses, if the abscesses resulted from entry of pyogenic organisms into the blood stream and into the abdominal organs, spine or musculature. An abscess in the lungs may require condemnation of the lungs and an passing the carcass if no other lesions are noted. Liver abscesses associated with umbilical infection require condemnation of the carcass. If no other infection is present the abscess is trimmed off and the liver may be utilized for human or animal food depending on the regulations of the respective country. Multiple abscesses in the liver require condemnation of the organ. 

Emaciation

Emaciation is a common condition of food animals and is characterized by a loss of fat and flesh following the loss of appetite, starvation and cachexia. It is associated with gradual diminution in the size of organs and muscular tissue as well as edema in many cases. The organs and muscular tissue appears thinner, moist and glossy. Cachexia is a clinical term for a chronic debilitating condition or general physical wasting caused by chronic disease.

Emaciation may be associated with chronic diseases and parasitic conditions such as round worms in pigs and fascioliasis in cattle and sheep, swine erysipelas, neoplasms, tuberculosis, John's disease, caseous lymphadenitis, and poor teeth and lack of nutrition. Emaciation is a postmortem descriptive term which should be differentiated from thinness.
 
Judgement : Animals affected with emaciation should be treated as “suspects” on antemortem inspection. On postmortem examination it is important to assess and differentiate emaciation from leanness. In case of doubt, the carcass may be held in the refrigerated room and the general setting of the carcass should be examined the following day. If the body cavities are relatively dry, edema of muscle tissue is not present and fat is of an acceptable consistency i.e. has “set”, the carcass may be passed for food.
 
Well nourished carcasses with serous atrophy of the heart and kidneys and mere leanness may also be fit for human consumption. A carcass with any amount of normal fat may be approved if everything else appears normal. The carcasses from animals being in transport for a long period of time may show extensive serous atrophy of fat (mucoid degeneration of fat tissue) without any changes in organs and muscles. If after being in the cooler for 24–48 hours, the fat resumes its normal consistency, the carcass is approved. Otherwise, the carcass is condemned.
 
The carcass and viscera must be condemned if emaciation is due to chronic infectious disease. An objective judgement of emaciation with edema may be made using a 47 % ethanol/methanol in water solution. A clear, pea-sized piece of bone marrow, taken from the distal radius, is put carefully into the solution. If it sinks, the marrow which reflect the water content of the carcass as a whole, has approximately 45 % water content. The carcass should be condemned.
 
Differential diagnosis : Thinness-leanness, edema and uraemia

Edema
 
Edema is the accumulation of excess fluid in the intercellular (interstitial) tissue compartments, including body cavities.
There are two types of edema: 

1. Inflammatory edema (exudate)
2. Non-inflammatory (transudate)

Anasarca is a form of edema of the subcutaneous tissues. Ascites is an accumulation of fluid in the peritoneal cavity. Hydrothorax is an accumulation of fluid in the pleural cavity. Hydrothorax may accompany traumatic pericarditis, ascites, cirrhosis of the liver and round worm infestation in sheep. Anasarca may be caused by toxaemic infection.
 
Judgement: Animals affected with generalized edema may be condemned on antemortem inspection. In less severe non-generalized cases, animals are treated as “suspects”. When making a judgement of a carcass affected with edema, it is important to know the underlying cause of the edema and also to know the significance of all other lesions found in the carcass.
 
The carcass may be totally or partially condemned depending on the extent and cause of the condition. The presence of localized edema necessitates removal of the affected area. The carcass is then approved. Edema associated with diseased conditions such as traumatic pericarditis, malignant neoplasm or septicemia requires condemnation of the carcass because of the primary condition. Edema observed in the mesentery is commonly related to circulation interference in the caudal vena cava due to  liver abscess or chronic liver disease. Such a carcass may be held in the cooler for re-examination. Dry serous membranes of the abdominal and thoracic walls and a carcass appearing normal after reexamination can be passed for human consumption. Carcasses which have been condemned for edema associated with malnutrition only may be salvaged for animal food (except in case of edema associated with septicemia).
 
Differential diagnosis : Pericarditis, peritonitis, pleuritis, renal amyloidosis, liver disease, grain overload and vagal indigestion, high altitude disease, uraemia and absorption of a large bruised area.

Emphysema
 
Emphysema in animals is associated with some disease conditions and is caused by an obstruction to the outflow of a air or by extensive gasping respiration during slaughter procedures.
All species may be affected with alveolar emphysema. However interstitial emphysema occurs mostly in cattle. In the latter, the lack of collateral ventilation forces the rupture of alveoli and the migration of air into the interstitium. The lobules of the lungs become separated by the distended interstitial tissue and marked lobulation of lungs is observed.
 
Alveolar emphysema appears as small air bubbles due to air trapped in dilated alveoli. Large accumulations of air, a few centimetres in diameter, are called “bullae or bullous emphysema”.
Postmortem findings: Postmortem findings of the emphysematous lungs include a pale, enlarged greyish-yellow, pearl like shiny lesion. Upon palpation, the affected area feels puffy and crepitant.
Two diseases of food animals associated with emphysema are chronic obstructive pulmonary disease (COPD) in horses, and interstitial pneumonia in cattle. COPD is also called heaves and frequently described under chronic bronchitis or bronchiolitis in horses. Interstitial pneumonia in cattle is also described under fog fever or acute chronic pulmonary edema and emphysema.
 
Judgement: Affected lungs are condemned.  

Tumours or neoplasms

A tumour is an abnormal mass of tissue which grows without control and uncoordinated with the tissue or organs of origin or those nearby. Its presence if often cumbersome to the tissue or organ it arose either by pressure or by replacement of normal functional tissue. Tumour cells resemble healthy cells however serve no useful purpose. The term tumour in current medical lexicon is presently limited to neoplastic growths.
haematogenous spread to another area not directly connected with the original site is called metastasia.
 
Some of the common tumours found during beef inspection are squamous cell carcinoma, lymphosarcoma, pheochromocytoma, mesothelioma etc.

Judgement: Carcass affected with metastatic neoplasms is condemned. Multiple benign tumours in different organs also require condemnation of carcass. Carcass affected with circumscribed benign tumours is approved.

Calcification
 
Calcification is the deposition of calcium salts in dead and degenerating tissue. It may be regarded as a body reaction to immobilize some foreign agents. It may occur in any tissue or organ. In dairy cows, calcification is noted in the heart (endocardium) and is caused by excessive dietary supplementation with Vitamin D. if calcium particles are removed from the surrounding tissue, they appear white or grey, irregularly rounded and frequently honeycombed. Calcification is detected on postmortem examination by a gritty sound upon incision with a knife.
 
Judgement: Carcass and viscera affected with presternal calcification are approved. Affected brisket is condemned. Calcified parasitic organs and heart in dairy cows are also condemned. 

Degeneration
 

• Degeneration 
• Cloudy swelling 
• Fatty infiltration 
• Fatty degeneration 

Judgement: Organs and muscles affected with cloudy swelling are condemned. Detailed examination of the carcass is necessary since systemic changes are usually present and the carcass is therefore condemned. A liver affected with fatty infiltration is approved. 

Telangiectasis (“Plum pudding”)

This liver condition is found in cattle, sheep and horses. It is more frequent in older cows. The liver lesions are bluish black and irregular with depressed surfaces and dilated blood filled hepatic sinusoids. A cause of hepatic telangiectasis in cattle is thought to be local ischemia.
 
Judgement: Slightly affected liver is approved after appropriate trimmings. Extensively affected liver requires condemnation. Condemned material can be used for animal food.

Abnormal odours

Abnormal odours may result from the ingestion of certain feedstuff, drugs, various pathological conditions, absorption of odours from strong smelling substances and sexual odour from some male animals. Pig carcasses may have a fishy odour if the pig was consuming excessive fish meal in the diet or was fed cod fish oil. Drugs which may cause absorption of odours include turpentine, linseed oil, carbolic acid, chloroform, ether, aromatic spirits of ammonia etc.
 
In cows affected with ketosis, the sweetish odour of acetone may be present in the muscles. If treatment was not successful in dairy cows affected with milk fever, the odour of acetone may be noted in the connective tissue, kidney fat and musculature. The flesh of bloated and constipated animals may give off a faecal odour. If the meat is kept in a room which was recently painted, the odour may pass on to the carcass. The odour is most noted in a carcass right after slaughter.
 
Judgement: The carcass having fish meal odour has inferior meat. Viscera and organs are also inferior. Generalized drug treatment requires condemnation of the carcass. If local treatment and withholding periods are observed, the carcass and viscera are approved. Sexual odour in a carcass can have a limited distribution according to the consumers taste. Extremely strong sexual odour requires condemnation of the carcass.

A carcass which gives off a pronounced odour of medicinal, chemical or other foreign substances shall be condemned. If the odour can be removed by trimming or chilling, the carcass may be passed for human food after the removal of affected parts or dissipation of the condition.

Carcasses affected with sexual odour should be held in the cooler and re-tested periodically. If the odour disappears the carcass is approved. If the sexual odour is present after 48 hours, the carcass shall be condemned. Young boars and ridglings are treated as suspects and held pending a heat test.
 
If abnormal odour is suspected the smell will be enhanced by placing a piece of muscle or tissue in cold water and bringing to the boil.

Immaturity 

Immaturity occurs mainly in calves. In many countries, the slaughter of calves younger than two weeks of age is prohibited. The muscle of immature animals is moist, pale, flabby and poorly developed. It is low in protein, high in water content and contains a high proportion of bone. Immature animals should not be slaughtered for human consumption.
Antemortem and postmortem findings: 

1. Presence of the umbilical cord
2. Bluish and not completely retracted gums
3. Greyish muscles are flabby, tear easily and are not well developed
4. Dark red kidney and edematous kidney capsule

Judgement : Carcass and offal of immature animals are condemned.
 
Remarks: A presence or non presence of fat around the kidneys (“caul fat”) should not be used as a guide for judgement of immature animals.

Plant poisoning

In developing countries, slaughter animals, particularly cattle are often trekked some hundreds of kilometres on the hoof to the abattoirs. During this journey, animals may suffer from various plant poisoning. In addition cattle living in areas where pasture has poisonous plants may suffer from the effects of chronic plant poisoning. Different body systems may be affected and various lesions may be seen at meat inspection.
 
Clinical signs and gross lesions observed in animals that have ingested certain poisonous plants: Tulip (slangkop) causes diarrhoea, bloated abdomen and heart failure. Lantana camara causes photosensitization. Senecio causes necrosis and cirrhosis of liver. Crololaria causes laminitis. Dicapetalum cymosum causes heart failure and sudden death.
 
Judgement: Judgement of the animal or animal carcass will depend on the clinical signs and the extent and severity of the lesions.
 
Chemical poisoning
 
Dipping of cattle in acaricide on a regular basis is practised in many parts in order to control thick borne diseases. Chemicals used for this purpose include arsenic, chlorinated hydrocarbons and organophosphates. Dipping may lead to clinical cases of poisoning, which may be manifested with the following clinical signs: nervous system disturbances, acute abdominal pain, diarrhoea and skin lesions. Gross lesions may include gastro-enteritis, fatty degeneration of the liver and inadequate bleeding.
 
Judgement: The carcass, offal and intestine should be condemned if clinical signs of poisoning are associated with postmortem lesions.