Animal anatomy, histology, pathological anatomy

Examination of internal organs.The study of organs begins with the spleen, taking into account its role in the septic process. In healthy animals, the spleen pulp is red-brown in color. Trabeculae have the appearance of gray-white stripes and dots. They appear especially clearly in cases of anemia and organ atrophy; with a decrease in hemosiderin, the color of the pulp is crimson-red. The pattern of follicles (in newborns they are small and macroscopically invisible) and trabeculae and the degree of pulp softening are determined. A smooth cut surface indicates compaction of the follicles, an uneven and granular surface indicates organ hyperplasia. The pulp is scraped with the blunt side of the knife blade. It can be small, significant and abundant (in septic diseases). With anthrax, the spleen can be so softened that its parenchyma, along with blood, drains from the cut surface in the form of a semi-liquid tar-like mass. In leukemia, the spleen is dense, with large white follicles and can reach a length of 1 m and a width of 20–30 cm.
Determine the shape of the heart. In healthy animals it is cone-shaped. With expansion and hypertrophy, the apex of the heart is blunted. If necessary, measure the height of the heart (in a cow - 18.6 cm, in a calf 1-2 months old - 9 cm, in an adult sheep - 10-11 cm), circumference, dimensions of the atria and ventricles.
Determine the size, weight and shape of the liver, the condition of the edges (blunted with enlargement, sharp with atrophy), the type of surface (smooth or granular-nodular with cirrhosis), consistency (dense or flabby - when pressed with a finger, a hole remains), color (brown is normal , red-brown with hyperemia, gray-brown or yellow with granular or fatty degeneration). The blood supply, color, shine or dullness of the cut surface, the pattern of the lobular structure (mosaic or nutmeg in case of blood stagnation in combination with parenchyma degeneration), the consistency and scraping of the parenchyma, and the condition of the bile ducts are determined. With fascioliasis and dicroceliosis, as well as cholelithiasis, the bile ducts are strongly angular and appear in the form of tortuous yellow-white strands, and with severe damage, parasites are found in them with the presence of parasitic or biliary cirrhosis.
Reproductive organs. In females, the vaginal vestibule, vagina, cervix, body and uterine horns are opened. The thickness and type of their wall, the condition (are there any tears!) of the mucous membrane, caruncles, the quantity and properties of the contents, especially in post-abortion and postpartum complications are determined. Pay attention to color, consistency, smell, presence of exudate, dead tissue, gas bubbles, etc. In pregnant cows, determine the age of the fetus by size (length, weight), presence of hair, etc., check for any anomalies in the development of the fetus and membranes (increased amount of amniotic fluid, swelling of the membranes, placental abnormalities, etc.); open and examine the fetus.
When examining the ovaries, pay attention to their size, shape, consistency and color (reduced and denser with an erased bean-shaped shape during hypofunction). Longitudinal incisions are made on the convex surface of the ovaries, the degree of development of the follicles, the color and ratio of the cortical and medulla layers, the presence and condition of the corpus luteum, cysts and other changes are noted, their connection with the oviducts and the condition of the latter are assessed.
Stomach. During an external examination, the volume and configuration of the multichamber stomach is determined. When the rumen is swollen, the degree of blood filling of the vessels is noted (with tympania, the vessels are anemic, and if the swelling occurred after the death of the animal, they are filled with blood).
Before opening, the multi-chambered stomach of ruminants is straightened in one plane, for which purpose the connective tissue ligaments between the book, mesh, rumen and abomasum are dissected (Fig. 313).



Fig. 313. Cut line of the walls of the complex stomach of ruminants.

Examine the gastric lymph nodes and vessels. Then the scar, mesh, and book are sequentially opened from the esophagus along the greater curvature, and the abomasum along the lesser curvature to preserve the folds of the mucous membrane and feed masses. The contents of the proventriculus and abomasum are determined: the amount of feed, composition (the nature and degree of its fermentation, color, smell, presence of gases), and foreign bodies in the mesh (nails, wire, needles, pins, sand, etc.). Overfilling of the rumen with dryish feed masses and their compaction in the book is observed with atony of the proventriculus; mushy foamy contents are characteristic of tympani.

The condition of the mucous membranes is examined taking into account the peculiarities of their structure in different parts of the stomach (their integrity, color, swelling, presence of mucus, etc.), as well as the muscular and serous layers. Damage to the walls of the mesh by foreign objects occurs in traumatic reticulitis, catarrhal-hemorrhagic inflammation of the abomasum occurs in infectious diseases, mycotoxicosis and poisoning. Severe thickening of the abomasal wall, folds of the mucous membrane and its ulceration are observed in cows with leukemia.
In young calves, especially considering the frequent cases of gastrointestinal diseases, the condition of the digestive gutter and abomasum is carefully examined (the proventriculus in the stomach of ruminants is poorly developed). Particular attention is paid to the composition and properties of the contents and the condition of the mucous membrane.
Intestines. Examine the condition of the intestines and mesentery, determine the amount and properties of fat in it, the blood supply to the vessels; mesenteric lymph nodes are examined (size, shape, consistency, color, pattern, development of follicles, their possible changes).
When opening the intestine, the intestine is cut at the site of attachment of the mesentery, then a small transverse incision is made in the wall, a blunt jaw of intestinal or button scissors is inserted into it, and an incision is made along the line of attachment of the mesentery. When examining the duodenum, jejunum and ileum, intestinal patency, wall thickness, its appearance, quantity and properties of the contents, the condition of the mucous membrane and mucus, lymphatic follicles and Peyer's patches are determined. Next, the intestines are cleaned of the contents, placing it on the palm of the hand between the index and middle fingers, and the hand is advanced with the back of the hand, the contents are removed and the mucous membrane is examined more carefully, its thickness and folds are determined (with chronic catarrh, folds are not straightened, post-mortem folds are easily eliminated) , color, moisture, possible hemorrhages, hyperemia, overlays, ulcerations, strings, scars, etc.
Then the cecum, the initial loop, the spiral labyrinth and the final loop of the colon, the rectum are opened, the quantity and properties of the contents, the condition of the intestinal wall, mucous membrane and solitary follicles are determined. If helminths are detected, scatological studies are carried out. If there are appropriate indications (infectious diseases, poisoning), pathological material and contents are taken for additional laboratory tests.
The autopsy and examination of organs is completed by drawing up an autopsy report and drawing up a pathological diagnosis. Overalls, instruments and the autopsy site are thoroughly disinfected, and the remains of the corpse and organs are disposed of.