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.
Antemortem findings :
In septic fever the other signs may include
Postmortem findings :
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 re-examined. 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 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 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.
Antemortem findings :
Postmortem findings :
One or more lesions may be absent. However if one significant lesion is present, such as, generalized acute lymphadenitis, the carcass must be condemned. All gross lesions in the carcass and organs must be considered before the animal is judged septicemic.
Septicemia is found in many infectious diseases including acute forms of salmonellosis, leptospirosis, swine erysipelas, hog cholera and in anthrax in cattle.
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.
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 :
Postmortem findings :
Toxaemia is frequently associated with:
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.
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.
In anthracosis, the carbon particles are found as a black pigment in tissues. This condition is seen as black pigment of the lungs and corresponding lymph nodes in animals raised in urban areas. The lungs affected with anthracosis are condemned and the carcass is approved.
The carotenoid pigments are exogenous pigments, greenish-yellow in colour which consist of carotene A, carotene B, and xanthophyll. They are important in meat inspection because they cause yellowish discoloration in the fat and muscles of (Jersey and Guernsey) cattle. Carotenoid pigments should be differentiated from bile pigments in icterus. The bovine liver affected with this condition is enlarged and shows a bright yellow colour. Such a liver is condemned with the rationale that the affected liver demonstrates some toxic changes, as damaged liver cells cannot metabolize carotene. Liver carotenosis must be differentiated from pale livers in advanced pregnancy.
The endogenous pigments, except for melanin and lipofuscin are derivates of haemoglobin.
Melanosis is an accumulation of melanin in various organs including the kidneys, heart, lungs and liver (Fig. 19), 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)
Xanthosis (“Wear-and-Tear”) pigment is a brown pigmentation of skeletal and heart muscles of cattle (Fig. 20). 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.
Fig. 19: Melanin deposits in the sheep viscera.
Fig. 20: Myocardial lipofuscinosis.
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 (Fig. 21), 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.
Fig. 21 : Osteohemo- chromatosis showing brown pigmentation of ribs and vertebrae in a 6 months old calf.
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 (Fig. 22, 23), 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 (Fig. 24).
Fig. 22: Jaundice of an aged cow caused by liver disease. Note yellow discoloration of body fat, lungs, heart and kidneys.
Fig. 23: Yellow discoloration of pig viscera and carcass caused by cirrhosis of the liver.
Fig. 24: Classification of jaundice
Prehepatic jaundice occurs following excessive destruction of red blood cells. Tick-borne diseases such as Babesia ovis and Anaplasmosis cause this type of icterus, which is one of the main causes of carcass condemnation in Southern Africa due to prevalence of these parasites. Overproduced blood pigment, which cannot be metabolized in the liver, builds up in the blood (haemoglobinemia). It is excreted by the kidneys into the urine (haemoglobinuria). Normal urine colour changes and becomes bright red to dark red.
Hepatic jaundice occurs due to direct damage to liver cells as seen in liver cirrhosis (Fig. 23), systemic infections, and in chemical and plant poisoning. In sheep, jaundice may have been caused by phytogenic chronic copper poisoning.
Liver function is impaired and the liver is unable to secrete bile pigments. Obstructive jaundice occurs when the drainage of the bile pigment bilirubin is blocked from entry into the intestine. This usually occurs due to the obstruction of the hepatic ducts by a tumour, by parasites such as flukes or by gall stones. Obstruction may also occur due to an inflammation of the bile ducts. In hogs, mature ascarides may occlude the bile ducts.
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.
Icterus should not be confused with yellow fat disease in hogs fed predominantly on fish by-products or by the yellowish appearance of tissue caused by breed characteristics or nutritional factors.
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 pigs muscles haemorrhage is frequently associated with fractures (Fig. 25). Petechial haemorrhage is noted as tiny foci 1 – 2 mm in diameter. Ecchymotic haemorrhage (Fig. 26) is larger being up to 2 - 3 cm in size. Paint brush haemorrhage includes extensive streaking with haemorrhage. Haemorrhage is also associated with vitamin C deficiencies, a sudden increase in blood pressure with weakened blood vessels, and improper electric current stunning in pigs and sheep. Lengthy transportation, exposure to stress before slaughter, hot weather and excitement are some of the other factors which contribute to muscle haemorrhage.
Fig. 25: Fractured bone and muscle haemorrhage in a market hog.
Fig. 26: Ecchymotic haemorrhage in the tongue muscle of a cow.
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 (Fig. 27). They are associated with trauma or a clotting defect. Haematoma of the spleen (Fig. 28) 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.
Fig. 27 : Haematoma in the abdominal wall of an ewe.
Fig. 28: Haematoma of the bovine spleen.
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 (Fig. 29). A slightly or moderately bruised carcass is approved if no systemic changes are present. Affected tissues are condemned.
Fig. 29: Extensive bruises of a beef carcass.
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 (Fig. 30) 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.
Fig. 30:Liver abscesses caused by Fusobacterium necrophorum.
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 (Fig. 31) 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 (Fig. 32). 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”, Fig. 33). 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.
Fig. 31: Secondary abscesses in the spleen of an aged cow.
Fig. 32: Tail necrosis caused by biting and secondary spine abscesses.
Fig.33: Multiple abscesses in the calf liver as a result of an umbilical infection; carcass with such condition should be condemned.
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.
Antemortem findings :
Postmortem findings :
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.
Leanness (Poorness) is often observed in range bulls on poor quality pasture, high milking cows and young growing animals which have had protein deficient diet. The animals are physiologically normal and the reduced fat deposits of the animal carcass are normal in colour and consistency. The reduced muscle tissue is firm and of a normal consistency. The muscle colour is darker than normal, and fat tissue may still be present in the orbit of the eye.
Fig. 34: Emaciated cow showing marked reduction of muscle mass.
Fig. 35: Serous atrophy of renal fat. Note petechial haemorrhages, seen frequently in septicemic diseases.
Fig. 36: Hanging gelatinous fat between the spinal process.
Edema is the accumulation of excess fluid in the intercellular (interstitial) tissue compartments, including body cavities.
There are two types of edema:
Inflammatory edema shows yellow, white or greenish clear or cloudy fluid in the area of inflammation. Non-inflammatory edema is an accumulation of fluid in subcutaneous tissue, submucosae, lungs and brain.
Localized edema is noted after:
The swelling of a leg of a cow in prolonged decubitus. This swelling is caused by obstruction of the venous outflow
Interference with the lymph circulation of an organ or area by proliferation of tumours in or around bile ducts.
Inflammation or an allergic reaction
Systemic or generalized edema may occur secondary to congestive heart failure or is caused by low protein levels in the blood. The latter may be associated with:
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.
Antemortem findings :
Postmortem findings :
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 re-examination 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.
Fig.37: Abdominal edema caused by liver disease.
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 (Fig. 38) 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.
Fig. 38: Interstitial emphysema in the cow's lungs.
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.
Tumours are usually divided according to tissue of origin i.e. epithelial, mesenchymal (connective tissue), haemopoietic, nervous etc. Tumour behavioral classification include their mode of growth and the degree of invasiveness. Slow growing non invasive circumscribed tumours are considered benign and fast growing, infiltrative and frequently metastatic are malignant tumours. The spread of neoplasm is by direct expansion and infiltration, via lymphatics and blood circulation and by implantation. Carcinoma are tumours of the epithelial tissue. They are usually spread via the lymphatic system. Sarcoma are connective tissue tumours, commonly spread via haematogenous route. Implantation to surrounding parietal cavities is observed in ovarian carcinoma. The spread of malignant tumours via lymphatics or 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.
Fig. 39: Squamous cell carcinoma affecting cow's eye and parotic lymph node. In this case, tumour lesions were also observed in the lungs. Carcass was condemned.
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 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. In cattle mineralization of the aorta and brachiocephalic trunk (Fig. 40) is sometimes seen. Calcification is also seen in parasitic infections (Fig. 41) and in many chronic infections such as tuberculosis, botryomycosis etc. The presternal pressure necrosis of fat (putty brisket) seen in cattle and rarely in sheep may also eventually mineralize. Inflammatory metaplasia leading to ossification is an incidental finding during post-mortem examination of food animals. It is most commonly found in peritoneal scars of hogs.
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.
Fig. 40: Calcification of the aorta and brachiocephalic trunk in a young heifer.
Fig. 41: Parasitic lesions undergoing mineralization in a sheep liver.
Degeneration implies the change of tissue to a lower or less functionally active form or deterioration (impairment) of an organ or cell due to changes in its size. If chemical change of the tissue occur this is regarded as a true degeneration. Cloudy swelling (parenchymatous degeneration, albuminous degeneration or granular degeneration, acute cellular swelling) in the cell is a response to cell insults including trauma, anoxia, immune mechanisms, toxins, viral, and bacterial agents. In cloudy swelling, cell proteinaceous substances become cloudy and the cell increases in size. It is observed in the heart, kidneys, liver, glands and muscles.
Cloudy swelling is often associated with fatty degeneration. Affected organs are pale, lustrous and softer than normal, slightly enlarged and have the appearance of having been boiled (Fig. 42). In slight insults, the animal may recover and in severe cases cloudy swelling is succeeded by fatty degeneration.
Fatty infiltration is an accumulation of fat in the heart, liver, kidneys, pancreas, etc. The liver is yellow, soft in consistency, has round edges, dimples on pressure, is enlarged and has a greasy texture on cut surfaces. Fatty infiltration may disappear from the tissues if the causative agent is removed. The extensive accumulation of fat in the liver is caused by an increased dietary intake of fat, increased mobilization of fat during lactation or starvation. It is also seen in healthy animals slaughtered shortly after parturition and often accompanies advanced pregnancy in cows and ewes.
Fatty degeneration is an irreversible process and occurs when fat accumulates in the damaged cell. The liver capsule is dull and has a turgid appearance. This condition is associated with acute febrile and toxic conditions and with chemical poisoning by arsenic, phosphorus, chloroform etc. The liver and kidneys affected are a pale, clay-red colour and greasy on touch. They have a patchy or spotted appearance.
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.
Fig. 42: Degeneration, Cloudy swelling and associated fatty change of the pig liver.
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.
Telangiectasis. Bovine liver affected with telangiectasis.
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 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:
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.
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.
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.
Grassland in many parts of Africa contains scattered grasses with spear-like seeds. These seeds may penetrate through the wool and skin to the subcutis, and further through to the abdominal wall into the abdominal cavity.
Antemortem and postmortem findings:
Judgement: If an acute generalized inflammation is associated with haemorrhages and abscesses, the carcass should be condemned, otherwise the carcass is approved.
Fig. 44: Spear grass penetration of sheep. Numerous spear like seeds in the sheep carcass.