CHAPTER V
Post-mortem Examinations
1. Making the Examination
A post-mortem examination should always be undertaken if there is any doubt as to the cause of death. Poultry rearers who are not already familiar with the normal appearance of the internal organs of a fowl should take the first opportunity of studying them.
Post-mortem examinations should be done in a systematic manner; but, if desired, a very speedy examination may be made by rapidly removing, or bending back, the breast bone of the unplucked bird.
It will be more generally satisfactory, however, to devote time to the operation, and it is suggested that the work be carried out on the following lines:
1. Nail the body of the dead fowl on a board in the position shown in Fig. 30, having first partly or wholly plucked the bird.
Fowl nailed on board; lines A B, A C and B D show where to cut.
2. With a sharp knife cut along lines AC, BD (Fig. 30), and bend the breast bone backwards, exposing the internal organs. (Fig. 31.) As the breast bone is raised it will be necessary to cut through the mesentery and other connecting tissues. Break it back at D, cutting through the flesh and the muscle with sharp scissors.
3. Remove heart, liver, gall-bladder and spleen, making neat severances and without injury to any of the other organs. If the heart or large blood vessels be injured in the operation, blood will flow out and interfere with the work.
Breast bone removed; internal organs in situ.
4. Cut through the œsophagus, below or above the crop, as most convenient, and also cut through the large intestine near the cloaca. Without disconnecting the parts, lift out the gizzard, intestines, and other portions of the alimentary canal, carefully tearing away the membranous tissues of the mesentery.
5. Spread the organs out and examine each one carefully and critically, making sections if necessary. (Fig. 32.)
6. Cut open gullet, crop, stomach, gizzard, intestines, and cæca and examine the contents.
7. Examine the lungs, cutting off a portion and throwing it into water, when it will float if healthy, but sink if congested.
8. Cut through the skin of the neck. Sever the windpipe near the head, and also where the bronchi enter the lungs. With scissors cut it open, and examine for molds or gapes or for exudates indicative of various forms of cold or lung congestion.
Internal organs removed for examination.
9. Examine the brain (Fig. 34) for blood clots. Some care will be necessary in cutting through the skull so as not to injure the brain tissue, which should be a milky white. A sharp and strong pair of scissors or a small, fine saw (e. g., tenon saw) will be useful for older birds. Remove the skin and cut from behind, raising the bones and exposing the brain.
2. The Normal Condition of the Internal Organs
(See Fig. 32.)
The œsophagus carries the food from the mouth and passing down the neck beside the windpipe opens into—
The crop, where the food is macerated. Thence it gradually passes into—
The true stomach (or proventriculus), which is lined with small gastric-secreting glands that may be seen with the naked eye. This organ is hidden by the liver, and opens directly into—
Lungs, kidneys, etc., in situ.
The gizzard, situated on the left side of the abdomen. It rests on the coiled-up mass of intestines. It is dark red and is partly hidden by the left lobe of the liver. The walls are strong and muscular. Here the food is ground against small bits of stone, etc. The partially digested food passes out through an aperture near the entrance of the true stomach into—
The duodenum or upper portion of the small intestine. It forms a loop that incloses—
The pancreas, a compact, flattened organ, pinkish in color, that discharges its secretion by three ducts into the intestines.
The small intestine, after forming the loop (duodenum), continues its course. It first passes toward the left and is disposed in many folds connected by the mesentery; toward the end it passes up behind the true stomach. Connected to the intestines are the blind bodies known as—
The cæca, connected to the small intestines for several inches and which, after becoming considerably smaller in diameter, enter the alimentary tract where—
The large intestine (rectum) starts. This portion of the intestines is short and enters—
The cloaca, into which the urinary and reproductive ducts discharge. The external opening is known as the vent or anus.
The brain, situated in the back of the head, is protected by the cranial bones. It is milky white except where the blood vessels may be seen.
The windpipe connects the larynx at the throat with the lungs branching into the two bronchi.
The lungs, situated in the upper portion of the thoracic abdominal cavity, are firmly attached to the ribs, in the interspaces between which they fit. They are flattened and oval in shape, bright red in color, and loose and spongy in texture.
The heart is cone-shaped. The lower portion rests between the lobes of the liver. The heart is red and is inclosed in a sac (the pericardium) that is easily removed.
The liver, situated a little lower down than the heart, consists of two lobes. The right lobe is often larger than the left which may be cleft at the lower end. The left lobe covers the true stomach and part of the gizzard. If there is some delay in holding a post-mortem examination the edges of the lobes of the liver become discolored. Normally the color is a purplish red.
The gall bladder fits into a shallow depression on the underside of the right lobe of the liver and appears green in color. A duct conveys the bile from the liver into the gall bladder, whence it passes by another duct into the intestine.
The spleen, a nearly round, reddish body, with a purplish tinge, is attached by a ligament to the right side of the true stomach and is hidden by the liver.
The kidneys extend along the sides of the spine from immediately below the lungs to near the termination of the abdominal cavity. The general color is a chocolate red, but a small portion at the upper end (known as the adrenal), is yellow. There is no urinary bladder. The urates are carried direct through the ureters to the cloaca.
The testes (of the male bird) are attached to the upper portion of the kidneys. They are white or very light-colored, and may be of different sizes.
The ovary (of the female bird), situated on the left side, covers the kidney on that side. It consists of numerous ova of various sizes each of which may develop into an egg. As an ovum passes through the oviduct it is first coated with an albuminous covering (the white of egg); lower down it is coated with a calcareous deposit that forms the shell of the egg. (Fig. 18.)
Examination of brain and of portions of intestines and windpipe.
3. Diagnosis of Disease by Post-Mortem Symptoms
For purposes of diagnosis each organ must be examined. Note in each case if it is enlarged, spotted, ruptured, inflamed or engorged with blood. Observe if it is an unusual color or if it possesses any other symptom of an abnormal character.
A single symptom in a single organ, unless very pronounced and characteristic, will not be sufficient evidence for forming an accurate opinion as to the cause of death. But if the condition of the other organs and the symptoms before and attending death are taken into consideration, there will seldom be any difficulty, from a practical standpoint, in deciding upon the nature of the disease. Many points can be decided only by a pathologist with the aid of a microscope, such, for example, as the difference between coccidial and bacterial diarrhea, but it is quite enough for the poultryman to realize that one of his fowls has died of an attack of an acute form of diarrhea and that the rest of his birds may become infected.
The following notes draw attention to the main diagnostic symptoms observable on post-mortem examination, arranged under the heading of the organs affected. Other symptoms are put in parentheses.
Post-Mortem Symptoms
BRAIN
Apoplexy.—Shown by congestion of blood vessels of brain. (Staggering gait and sudden death.)
HEART
Cholera.—Punctiform hemorrhages are generally found in the heart in cases of cholera. (Yellow feces; diarrhea; sudden death of several or many fowls; inflammation of upper portion of intestines.)
LIVER
Tuberculosis.—Yellowish-white spots on liver varying in size, somewhat raised and convex; the spots or nodules may be readily separated from the rest of the liver. The liver itself is often very much enlarged. (Fowl gradually loses weight and may go lame; mesentery and spleen affected with nodules.)
Cholera.—Liver enlarged, dark green and softened, sometimes showing whitish spots.
Coccidial diarrhea.—More or less circular patches, depressed in the centre, associated with plugged cæca, the linings of which have sores.
Congested liver.—Much enlarged and engorged with blood, may be readily torn.
Fatty degeneration or fatty liver.—In the first case the liver is rather shrunken and hardened, and in the latter excessive deposits of fat may be noticed.
Liver trouble.—(Indigestion.) An enlarged liver without any of the special symptoms noted among the other diseases of the liver.
Gout.—Needle-like crystals (urate of soda) give the liver the appearance of having been covered with chalk. (Other organs in abdominal cavity covered with same powder-like crystals.)
Aspergillosis.—Necrotic areas with mold. (Fowls go light and move about in a depressed manner, resting on their breast bones.)
STOMACH
Gastritis.—The mucous membrane lining of the stomach is reddened and inflamed.
INTESTINES
Diarrhea.—Acute forms of intestinal troubles give rise to inflammation of the mucous membrane lining the walls of the intestines.
Cholera.—The upper portion of the intestines may be reddened and the contents show streaks or clots of blood.
Worms.—Round or tape worms present in intestines.
CÆCA
These blind ducts are of importance in showing the presence of coccidiosis in fowls or blackhead in turkeys.
Coccidial diarrhea.—The cæca are enlarged and show ulcers developing from the inside.
WINDPIPE
The linings of this organ should be clean and free of obstruction or mucous exudations.
Gapes.—Small worms about three-quarters of an inch long are found attached to the trachea.
Aspergillosis.—A whitish mold will be seen along the inside of the windpipe.
Pneumonia.—The bronchial tubes contain a thick mucous exudate.
Congestion of lungs.—Blood escaped from congested lungs is found in the bronchi.
LUNGS
These should be a bright red and spongy in texture.
Congestion.—One or both lungs are distended with blood and dark in color.
Pneumonia.—A condition that follows on congestion, the whole lung affected losing its spongy texture, the air spaces being filled with a semi-solid substance.
Brooder pneumonia.—Spots due to an Aspergillus fungus on lungs. (Chickens attacked.)
MESENTERY
Cholera.—Congestion of blood vessels of mesentery often seen.
Tuberculosis.—The mesentery may be studded with nodules.
SPLEEN
Tuberculosis.—A greatly enlarged spleen.
Enteritis.—(Bacterial.) Spleen enlarged but paler in color.
URETERS
Cholera.—Ureters distended with yellow urates.