Agriculture Reference
In-Depth Information
Thinness may be an expression of physiological normal-
ity, but the more serious emaciation is usually associated
with other signs of disease.
Both conditions may involve aphagia (decreased food
intake) in the form of inappetence (reduced appetite),
anorexia (complete absence of appetite), pica (depraved
appetite) or complete starvation.
Decreased food intake ( aphagia ) has a variety of differ-
ent causes; many, however, are unknown. They include
all the febrile diseases, stomatitis, pharyngitis, metabolic
toxaemia, gastrointestinal parasitism and cobalt defi-
ciency in ruminants, nutritional deficiencies (thiamin in
pigs, protein, energy, copper, phosphorus, salt, iron, zinc,
manganese, iodine, etc.), thirst, severe pain, stress and
inadequate level of feeding.
Pica or depraved appetite ( allotriophagia ) involves eat-
ing, licking or drinking of foreign materials. The materi-
als consumed on occasions are hair, wool, wood, faeces,
litter (by all species including poultry), soil, bark, bones,
cloth, poisons such as lead and foreign bodies (especially
by cattle) and cannibalism (foetuses, tails and ears of
pigs, etc.). The drinking of urine occasionally observed
in dairy cattle is a form of pica but can also be seen in
cows deprived of adequate drinking facilities.
Malnutrition ( inanition ) is the state in which the diet
contains all the essential nutrients but in reduced
amounts - a stage on the way to complete starvation. It is
more common than starvation and is associated with
some loss of body weight, ketosis, reduced metabolic res-
piratory and heart rates, hypothermia and sexual activ-
ity. Malnutrition commonly occurs during inclement
weather in horses, cattle and sheep, in particular where
supplementary feeding is absent.
Starvation involves complete cessation of food intake
(proteins, carbohydrates, fats, vitamins, minerals and trace
elements) and quickly leads to a great loss of weight with
exhaustion of glycogen stores, breakdown of muscle pro-
tein to amino acids and increase in urinary urea, increased
fat catabolism with release of fatty acids and formation of
ketones and hypoglycaemia and decrease in insulin pro-
duction. Starvation does not commonly occur today in
developed countries, only being observed in cruelty cases.
In pica, malnutrition and starvation, there is an
increased susceptibility to infection with higher morbid-
ity and mortality rates.
Emaciation is a wasted condition of the animal body
that may be pathological, occurring during the course of
a disease such as TB and Johne's disease in cattle and par-
asitic gastroenteritis, chronic fascioliasis and caseous
lymphadenitis in sheep. In old ewes, the teeth may be lost
and the animal unable to eat. Erysipelas, swine fever and
paratyphoid in pigs can produce great loss of condition in
pigs. It may also be the result of prolonged starvation.
chondroma from cartilage, leiomyoma from smooth
muscle and so on. Polyp is a benign adenoma arising as a
projection from a mucous surface. However, the suffix
- oma can be deceptive since lymphomas and sarcomas
are malignant collections of lymphocytes and melano-
mas, mesotheliomas and seminomas are also malignant.
Some gliomas (tumours of CNS astrocytes and oligoden-
drocytes), myelomas (plasma cell collections) and
teratomas (tumours containing different cell types found
in the ovary and testis) are benign and some malignant.
Malignant tumours arising from mesenchymal tissues
(connective tissue, muscle, cartilage, bone, blood and
blood vessels, lymphoid tissues, kidneys and gonads) are
termed sarcomas , for example, fibrosarcoma, chondro-
sarcoma and adenosarcoma. Those arising from epithe-
lial tissues are called carcinomas . The carcinomas can be
further differentiated, for example, squamous cell carci-
noma which is a cancer with cells resembling stratified
squamous (scaly or plate-like) epithelium.
Leukaemias are malignancies in which the normal
white blood cells (WBC) are replaced by large numbers
of lymphocytes, monocytes or myelocytes.
Judgement of neoplasia
Careful examination of the lesions as to shape, size,
colour, consistency, location, number, distribution, etc.,
along with general carcase signs, may give some idea as
to identification, whether benign or malignant, to
provide a basis for provisional judgement.
However, it is difficult visually to distinguish many
tumours, for example, between fibromas and equine sar-
coids, between fibropapillomas and fibrosarcomas and
between the latter and myxosarcomas and undifferenti-
ated carcinomas. Judgement is usually simpler in poultry,
in which poor condition is a common accompaniment.
An accurate diagnosis can only be made by detailed
histopathological examination of samples of suspect
lesions, a procedure which should always be resorted to
when suspect neoplastic lesions are encountered.
Enzootic bovine leukosis is a notifiable disease in the United
Kingdom, and all suspect cases, including those in meat
plants, must be notified to the state veterinary service.
A single or a few localised benign tumours require con-
demnation of the affected part or organ , provided there are
no other adverse signs. Numerous benign tumours in dif-
ferent organs and multiple malignant growths warrant
total condemnation . While poor carcase condition,
oedema, etc. may exist to assist in this judgement, it should
be remembered that this support is not always present.
Poor condition/emaciation
The difference between leanness and emaciation is one of
degree, but both may possess the same basic causes.
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