COMMON DISEASES OF FARM ANIMALS
COMMON DISEASES OF FARM ANIMALS
R. A. CRAIG
By R. A. Craig D.V.M.
[Illustration: Frontispiece--INSANITARY DAIRY STABLE AND YARDS. DISEASE AND
FINANCIAL LOSS ARE TO BE EXPECTED WHEN FARM ANIMALS ARE KEPT IN FILTHY
In preparing the material for this book the author has endeavored to
arrange and discuss the subject matter in a way to be of the greatest
service and help to the agricultural student and stockman and place at
their disposal a text and reference book.
The general discussions at the beginning of the different sections and
chapters and the discussions of the different diseases are naturally
brief. An effort has been made to conveniently arrange the topics for both
practical and class-room work. The chapters have been grouped under the
necessary heads with review questions at the end of each chapter and the
book divided into seven parts.
The chapters on diseases of the locomotory organs the teeth surgical
diseases and castration although not commonly discussed in books of this
class the writer believes will be of value for reference and instructional
When used as a text-book it will be well for the instructor to supplement
the text with class-room discussions.
The writer has given special emphasis to the cause and prevention of
disease and not so much to the medicinal treatment. Stockmen are not
expected to practise the medicinal treatment but rather the preventive
treatment of disease. For this reason it is not deemed advisable to give a
large number of formulas for the preparation of medicinal mixtures to be
used for the treatment of disease but such treatment is suggested in the
most necessary cases.
R. A. CRAIG.
PURDUE UNIVERSITY LaFayette Ind. August 1915.
I. GENERAL DISCUSSION OF DISEASE
II. DIAGNOSIS AND SYMPTOMS OF DISEASE
PART II.--NON-SPECIFIC OR GENERAL DISEASES.
IV. DISEASES OF THE DIGESTIVE SYSTEM
V. DISEASES OF THE LIVER
VI. DISEASES OF THE URINARY ORGANS
VII. DISEASES OF THE GENERATIVE ORGANS
VIII. DISEASES OF THE RESPIRATORY APPARATUS
IX. DISEASES OF THE CIRCULATORY ORGANS
X. DISEASES OF THE NERVOUS SYSTEM
XI. DISEASES OF THE SKIN
XII. DISEASES OF THE EYE
XIII. GENERAL DISEASES OF THE LOCOMOTORY APPARATUS
XIV. STRUCTURE OF THE LIMBS OF THE HORSE
XV. UNSOUNDNESSES AND BLEMISHES
XVI. DISEASES OF THE FORE-LIMB
XVII. DISEASES OF THE FOOT
XVIII. DISEASES OF THE HIND LIMB
PART III.--THE TEETH.
XIX. DETERMINING THE AGE OF ANIMALS
XX. IRREGULARITIES OF THE TEETH
PART IV.--SURGICAL DISEASES.
XXI. INFLAMMATION AND WOUNDS
XXII. FRACTURES AND HARNESS INJURIES
XXIII. COMMON SURGICAL OPERATIONS
PART V.--PARASITIC DISEASES.
XXIV. PARASITIC INSECTS AND MITES
XXV. ANIMAL PARASITES
PART VI.--INFECTIOUS DISEASES.
XXVIII. INFECTIOUS DISEASES COMMON TO THE DIFFERENT SPECIES OF DOMESTIC
XXIX. INFECTIOUS DISEASES OF THE HORSE
XXX. INFECTIOUS DISEASES OF CATTLE
XXXI. INFECTIOUS DISEASES OF POULTRY
(Frontispiece) Insanitary dairy stable and yards.
1. Side and posterior view of bull showing conformation favorable to the
development of disease.
2. Insanitary yards.
3. Showing where pulse of horse is taken.
4. Auscultation of the lungs.
5. Fever thermometer.
6. Dose syringe.
7. Hypodermic syringes.
8. Photograph of model of horse's stomach.
9. Photograph of model of stomach of ruminant.
10. Oesophageal groove.
11. Dilated stomach of horse.
12. Rupture of stomach of horse.
13. Showing the point where the wall of flank and rumen are punctured
with trocar and cannula in "bloat".
14. Photograph of model of digestive tract of horse.
15. Photograph of model of digestive tract of ruminant.
16. A yearling colt that died of aneurism colic.
17. Photograph of model of udder of cow.
18. Photograph of model of uterus of cow containing foetus.
19. Placenta of cow.
20. A case of milk-fever.
21. Milk-fever apparatus.
22. A case of catarrhal cold.
23. Photograph of model of horse's heart.
24. Elephantiasis in horse.
25. Photograph of model of horse's brain.
26. Unilateral facial paralysis.
27. Bilateral facial paralysis.
28. Skeleton of horse.
29. Photograph of model of stifle joint.
30. Atrophy of the muscles of the thigh.
31. Shoulder lameness.
33. Sprung knees.
35. Bones of digit.
36. Photograph of a model of the foot.
37. Foot showing neglect in trimming wall.
38. A very large side bone.
39. A case of navicular disease.
40. An improperly shod foot.
42. Quarter-crack caused by barb-wire cut.
43. Changes occurring in chronic laminitis.
44. Atrophy of the muscles of the quarter.
46. A large bone spavin.
47. Normal cannon bone and cannon bone showing bony enlargement.
48. Bog spavins.
49. Thorough pin.
51. Head of young horse showing position and size of teeth.
52. Longitudinal section of incisor tooth.
53. Cross-section of head of young horse showing replacement of molar
54. Transverse section of incisor tooth
55. Transverse sections of incisor tooth showing changes at different
56. Teeth showing uneven wear occurring in old horses.
57. Fistula of jaw.
58. A large hock caused by a punctured wound of the joint.
59. A large inflammatory growth following injury.
60. Fistula of the withers.
61. Shoulder abscess caused by loose-fitting harness.
62. A piece of the wall of the horse's stomach showing bot-fly larvae
63. Biting louse.
64. Sucking louse.
65. Nits attached to hair.
67. Sheep scab mite.
68. Sheep scab.
69. A severe case of mange.
70. Liver flukes.
71. Tapeworm larvae in liver.
73. Tapeworm larvae in the peritoneum.
74. Thorn-headed worms.
75. Large round-worm in intestine of hog.
76. Lamb affected with stomach worm disease.
77. Whip-worms attached to wall of intestine.
78. Pin-worms in intestine.
79. A hog yard where disease-producing germs may be carried over
from year to year.
80. Carcass of a cholera hog.
81. Kidneys from hog that died of acute hog-cholera.
82. Lungs from hog that died of acute hog-cholera.
83. A piece of intestine showing intestinal ulcers.
84. Cleaning up a hog lot.
85. Hyperimmune hogs used for the production of anti-hog-cholera serum.
86. Preparing the hog for vaccination.
87. Vaccinating a hog.
88. Koch's _Bacillus tuberculosis_.
89. A tubercular cow.
90. Tubercular spleens.
91. The carcass of a tubercular cow.
92. A section of the chest wall of a tubercular cow.
93. A very large tubercular gland.
94. A tubercular gland that is split open.
95. Caul showing tuberculosis.
96. Foot of hog showing tuberculosis of joint.
97. _Staphylococcus pyogenes_.
98. _Streptococcus pyogenes_.
99. Bacillus of malignant oedema showing spores.
100. Bacillus of malignant oedema.
101. _Bacillus bovisepticus_.
102. A yearling steer affected with septicaemia haemorrhagica.
103. _Bacillus anthracis_.
104. _Bacillus necrophorus_.
105. Negri bodies in nerve-tissue.
106. A cow affected with foot-and-mouth disease.
107. Slaughtering a herd of cattle affected with foot-and-mouth disease.
108. Disinfecting boots and coats before leaving a farm where cattle have
been inspected for foot-and-mouth disease.
109. Cleaning up and disinfecting premises.
110. _Bacillus tetani_.
111. Head of horse affected with tetanus.
112. A subacute case of tetanus.
113. Streptococcus of strangles.
114. _Bacillus mallei_.
115. Nasal septum showing nodules and ulcers.
116. _Streptococcus pyogenes equi_.
117. A case of "lumpy jaw".
118. The ray fungus.
119. Bacillus of emphysematous anthrax.
120. Cattle tick (male).
121. Cattle tick (female).
122. Blood-cells with _Piroplasma bigeminum_ in them.
123. _Bacillus avisepticus_.
GENERAL DISCUSSION OF DISEASE
Disease is the general term for any deviation from the normal or healthy
condition of the body. The morbid processes that result in either slight or
marked modifications of the normal condition are recognized by the
injurious changes in the structure or function of the organ or group of
body organs involved. The increase in the secretion of urine noticeable in
horses in the late fall and winter is caused by the cool weather and the
decrease in the perspiration. If however the increase in the quantity of
urine secreted occurs independently of any normal cause and is accompanied
by an unthrifty and weakened condition of the animal it would then
characterize disease. Tissues may undergo changes in order to adapt
themselves to different environments or as a means of protecting
themselves against injuries. The coat of a horse becomes heavy and appears
rough if the animal is exposed to severe cold. A rough staring coat is
very common in horses affected by disease. The outer layer of the skin
becomes thickened when subject to pressure or friction from the harness.
This change in structure is purely protective and normal. In disease the
deviation from normal must be more permanent in character than it is in the
examples mentioned above and in some way prove injurious to the body
CLASSIFICATION.--We may divide diseases into three classes: _non-specific
specific_ and _parasitic_.
_Non-specific diseases_ have no constant cause. A variety of causes may
produce the same disease. For example acute indigestion may be caused by a
change of diet watering the animal after feeding grain by exhaustion and
intestinal worms. Usually but one of the animals in the stable or herd is
affected. If several are affected it is because all have been subject to
the same condition and not because the disease has spread from one animal
_Specific Diseases._--The terms infectious and contagious are used in
speaking of specific diseases. Much confusion exists in the popular use of
these terms. A _contagious_ disease is one that may be transmitted by
personal contact as for example influenza glanders and hog-cholera. As
these diseases may be produced by indirect contact with the diseased animal
as well as by direct they are also _infectious_. There are a few germ
diseases that are not spread by the healthy animals coming in direct
contact with the diseased animal as for example black leg and southern
cattle fever. These are purely infectious diseases. Infection is a more
comprehensive term than contagion as it may be used in alluding to all
germ diseases while the use of the term contagion is rightly limited to
such diseases as are produced principally through individual contact.
_Parasitic diseases_ are very common among domestic animals. This class of
disease is caused by insects and worms as for example lice mites ticks
flies and round and flat worms that live at the expense of their hosts.
They may invade any of the organs of the body but most commonly inhabit
the digestive tract and skin. Some of the parasitic insects mosquitoes
flies and ticks act as secondary hosts for certain animal microorganisms
that they transmit to healthy individuals through the punctures or the
bites that they are capable of producing in the skin.
CAUSES.--For convenience we may divide the causes of disease into the
predisposing or indirect and the exciting or direct.
_The predisposing causes_ are such factors as tend to render the body more
susceptible to disease or favor the presence of the exciting cause. For
example an animal that is narrow chested and lacking in the development of
the vital organs lodged in the thoracic cavity when exposed to the same
condition as the other members of the herd may contract disease while the
animals having better conformation do not (Fig. 1). Hogs confined in
well-drained yards and pastures that are free from filth and fed in pens
and on feeding floors that are clean do not become hosts for large numbers
of parasites. Hogs confined in filthy pens are frequently so badly infested
with lice and intestinal worms that their health and thriftiness are
seriously interfered with. In the first case mentioned the predisposition
to disease is in the individual and in the second case it is in the
surroundings (Fig. 2).
[Illustration: FIG. 1.--Side and posterior view of bull showing
conformation favorable to the development of disease.]
_The exciting causes_ are the immediate causes of the particular disease.
Exciting causes usually operate through the environment. With the exception
of the special disease-producing germs the most common exciting causes are
faulty food and faulty methods of feeding. The following predisposing
causes of disease may be mentioned:
_Age_ is an important factor in the production of disease. Young and
immature animals are more prone to attacks of infectious diseases than are
old and mature animals. Hog-cholera usually affects the young hogs in the
herd first while scours suppurative joint disease and infectious sore
mouth are diseases that occur during the first few days or few weeks of the
animal's life. Lung and intestinal parasites are more commonly found in the
young growing animals. Old animals are prone to fractures of bones and
degenerative changes of the body tissues. As a general rule the young are
more subject to acute diseases and the old to chronic diseases.
[Illustration: FIG. 2.--Insanitary yards.]
_The surroundings or environments_ are important predisposing factors. A
dark crowded poorly ventilated stable lowers the animal's vitality and
renders it more susceptible to the disease. A few rods difference in the
location of stables and yards may make a marked difference in the health of
the herd. A dry protected site is always preferable to one in the open or
on low poorly drained soil. The majority of domestic animals need but
little shelter but they do need dry comfortable quarters during wet cold
_Faulty feed and faulty methods of feeding_ are very common causes of
diseases of the digestive tract and the nervous system. A change from dry
feed to a green succulent ration is a common cause of acute indigestion in
both horses and cattle. The feeding of a heavy ration of grain to horses
that are accustomed to exercise during enforced rest may cause liver and
kidney disorders. The feeding of spoiled decomposed feeds may cause
serious nervous and intestinal disorders.
_One attack of a certain disease_ may influence the development of
subsequent attacks of the same or a different disease. An individual may
suffer from an attack of pneumonia that so weakens the disease-resisting
powers of the lungs as to result in a tubercular infection of these organs.
In the horse one attack of azoturia predisposes it to a second attack. One
attack of an infectious disease usually confers immunity against that
particular disease. _Heredity_ does not play as important a part in the
development of diseases in domestic animals as in the human race. A certain
family may inherit a predisposition to disease through the faulty or
insufficient development of an organ or group of organs. The different
species of animals are affected by diseases peculiar to that particular
species. The horse is the only species that is affected with azoturia.
Glanders affects solipeds while black leg is a disease peculiar to cattle.
1. What is disease?
2. How are diseases classified? Give an example of the different classes.
3. What is a predisposing cause? Exciting cause?
4. Name the different predisposing and exciting causes of disease.
DIAGNOSIS AND SYMPTOMS OF DISEASE
The importance of recognizing or diagnosing the seat and nature of the
morbid change occurring in an organ or group of organs cannot be
overestimated. Laymen do not comprehend the difficulty or importance of
correctly grouping the signs or symptoms of disease in such a way as to
enable them to recognize the nature of the disease. In order to be able to
understand the meaning of the many symptoms or signs of disease we must
possess knowledge of the structure and physiological functions of the
different organs of the body. We must be familiar with the animal when it
is in good health in order to be able to recognize any deviation from the
normal due to disease and we must learn from personal observation the
different symptoms that characterize the different diseases. Stockmen
should be able to tell when any of the animals in their care are sick as
soon as the first symptom of disease manifests itself by changes in the
general appearance and behavior. But in order to ascertain the exact
condition a general and systematic examination is necessary. The examiner
whether he be a layman or a veterinarian must observe the animal
carefully noting the behavior appearance surroundings and general and
Before making a _general examination_ of the animal it is well if the
examiner is not already acquainted with the history of the case (care feed
and surroundings) to learn as much about this from the attendant as is
possible. Inquiry should be made as to the feeding the conditions under
which the animal has been kept the length of time it has been sick its
actions or any other information that may be of assistance in forming the
diagnosis and outlining the treatment.
The _general symptoms_ inform us regarding the condition of the different
groups of body organs. A careful study of this group of symptoms enables us
correctly to diagnose disease and inform ourselves as to the progress of
long severe affections. These symptoms occur in connection with the pulse
respirations body temperature skin and coat visible mucous membranes
secretions and excretions and behavior of the animal.
_The local symptoms_ are confined to a definite part or organ. Swelling
pain tenderness and loss of function are common local symptoms. A _direct_
symptom may also be considered under this head because of its direct
relation to the seat of disease. It aids greatly in forming the diagnosis.
Other terms used in describing symptoms of disease are _objective_ which
includes all that can be recognized by the person making the examination;
_indirect_ which are observed at a distance from the seat of the disease;
and _premonitory_ which precede the direct or characteristic symptoms.
The _subjective_ symptoms include such as are felt and described by the
patient. These symptoms are available from the human patient only.
Pulse.--The character of the intermittent expansion of the arteries called
the pulse informs us as to the condition of the heart and blood-vessels.
The frequency of the pulse beat varies in the different species of animals.
The smaller the animal the more frequent the pulse. In young animals the
number of beats per minute is greater than in adults. Excitement or fear
especially if the animal possesses a nervous temperament increases the
frequency of the pulse. During and for a short time after feeding and
exercise the pulse rate is higher than when the animal is standing at
The following table gives the normal rate of the pulse beats per minute: