Animal anatomy, histology, pathological anatomy

OPTION TECHNIQUE
Given the economic importance of ruminant animals, autopsies are usually carried out in the presence of interested parties (veterinary and zootechnical specialists, livestock workers, animal owners), and sometimes representatives of administrative authorities.
Avamnesis.Before autopsy, anamnesis is collected, the epizootic situation on the farm, and the clinical condition of animals, especially those with similar signs of the disease, are clarified. Blood smears are examined to rule out anthrax. Suspicion of anthrax is caused by cases of ruminant disease with an unclear symptom complex, sudden death, especially in the summer when animals are kept on pasture.
External inspectionThe corpse begins with identifying identifying features. Specify the type and breed of the animal, color and special features, gender and age, body build (anatomically correct; if incorrect, then indicate its changes, for example, sagging back in a cow with osteomalacia), fatness category (average, above average, fat, below average, emaciated) and economically useful qualities of the animal. Determine the size (length and height) and approximately body weight (weigh if necessary). The average live weight of cows varies depending on the breed from 320 to 650 kg, of bulls - from 450 to 1050 kg.
Age.In adult cattle, it is determined by its teeth and horns. In newborns, the umbilical cord is wet, the hooves are not worn out; in 2-week-olds, the umbilical cord fell off; In 2-month olds, the crust on the navel wound fell off.
Determining age by teeth.The toes, internal middle incisors, external middle incisors appear before or a few days after birth, and the posterior incisors appear 3–8 days after birth. The first signs of wear of baby teeth become noticeable on the toes at 1–1/2 months of age, and on the internal middle incisors at 2 months. At 10 months, the grinding surface of the toes covers the entire lingual surface of these teeth; at 12 months the incisors do not touch each other; at 15 months, the grinding surface of the toes and internal middle incisors covers their entire surface; at 17 months, the incisors sit freely, the corollas are short and the roots become visible. The change of incisors begins: hooks at 1 year and 9 months, internal middle incisors at 2 years, external middle incisors at 3 years, rear incisors at 4 years. After six months, all the teeth grow in. After 4 years, due to abrasion of the incisors (especially the hooks), the grinding surface appears in the form of a narrow strip, then it gradually expands and after 7–8 years it covers half the surface of the teeth, and after 9–10 years it covers the lingual surface. Animals over ten years old are labeled “old”. By this age, their teeth have worn down significantly.
In sheep and goats from the age of six, it is quite difficult to determine age. After replacing all the primary incisors with permanent ones, the animals are considered “old.” By the age of 10–12, all incisors fall out.
Determining age by horns.For the first month, a distinct thickening of the epithelium can be felt in place of the horns: soft thickening for 2 weeks, hard thickening for 1 month. Temporary horns fall off – 9 months, permanent horns – 1 year. From 1 to 2 years, a mobile horny core is felt, and in 3 months the bone base of the horns appears. At 5 months, the horns are 3 cm long, at 12 months – 10–16 cm.
In subsequent years, age is determined by the number of rings on the horns, since each pregnancy causes the appearance of one ring-shaped depression on the horn. Depending on the timing of the first (in the 2nd or 3rd year of life), 1 or 2 years are added to the number of rings.
Determination of cadaveric changes.In cattle, especially well-fed ones, cooling occurs more slowly than in sheep and goats. In the latter, rapid cooling is prevented by thick fur. In some diseases (for example, in cows with postpartum eclampsia, jaundice, etc.), body temperature during life may be several degrees below normal.
Rigor mortis. As a rule, rigor mortis develops faster and is more severe in beef cattle than in dairy cattle. In large, muscular animals it occurs more quickly than in small ones, and during slaughter by bleeding. In emaciated animals and hypotrophic newborns, rigor mortis is weakly affected or does not occur at all.
Cadaveric spots (hypostasis and imbibition). In large and small cattle with a well-developed coat and pigmented skin, carcass spots can be detected only after skinning, i.e. from the subcutaneous tissue. In internal organs, their appearance is accompanied by transudate effusion into the serous cavities.
Cadaveric decomposition in ruminants is usually rapid. As a result of autolytic processes, the mucous membrane of the proventriculus peels off in layers and remains on the feed masses. In the organs of the abdominal cavity, putrefactive decomposition can be detected within a few hours after the death of the animal just by external examination and putrefactive odor. By the end of the first day after death, the abdominal wall acquires a greenish color. The formation of gases may be accompanied by a change in the appearance of the corpse and post-mortem swelling, which differs from intravital swelling (rumen tympany) in the absence of a corresponding redistribution of blood in the organs.
When examining the corolla, crumbs and hooves, pay attention to the swelling in the redness of the corolla, the correct shape and growth of the hoof horn, its shine or dullness, evenness or the presence of cracks, creases, etc. (necrobacteriosis, jashur, hoof rot, metabolic disorders, Rustenholtz's ulcers, etc.). If necessary, the horn shoe is cleared and cut.
Of the superficial lymphatic nodes in ruminants, the submandibular, retropharyngeal, prescapular and superficial inguinal nodes are examined.
When examining the mammary gland, attention is paid to the size (well-, moderately or underdeveloped; large, medium, small udder), filling and nature of the contents in the milk tanks, condition of the nipples and skin. Determine the shape of the udder (round, bath-shaped, cup-shaped, “goat” in cows, primitive); supraglavicular lymph nodes are opened; after separating the mammary gland from the corpse, parallel sagittal incisions are made of each lobe through the nipples, milk tanks to the base of the gland with a layer thickness of 1–2 cm. At the same time, the cutability of the udder tissue is determined (a normal udder is difficult to cut, while in acute, purulent and necrotizing In mastitis, it is easy to cut, the cut surface is unevenly colored and moist), color, shine, moisture, structure and pattern of tissue (the ratio of glandular and connective tissue, and in dry and obese cows, adipose tissue).
In males, the external genitalia are examined after they are separated from the abdominal wall to the posterior sciatic notch. If there are changes in the external genitalia (hypoplasia or atrophy of the testes, inflammation and necrosis of tuberculosis, brucellosis, fungi and other origins), they are removed and examined together with other organs of the genitourinary system.
When examining skeletal muscles, an incision is made along the muscle fibers (masticatory, scapula, croup), paying attention to possible pathological processes (hemorrhages, edema, necrosis, white blisters, abscesses, etc.) characteristic of white muscle disease, foot-and-mouth disease, cysticercosis and other diseases.
In dairy cows, attention is paid to possible changes in bone tissue (changes in configuration, softening and resorption of the caudal vertebrae, the last ribs, the cortical layer of tubular bones with its replacement by fibrous and fatty tissues, thickening of the epiphyses, osteochoidrosis with the presence of necrosis, urticaria, detachments of articular cartilage), characteristic of osteodystrophy. In newborn calves, the bones are less dense, their joints can be easily cut with a knife, but one should keep in mind the possibility of developing rachitic changes in bone tissue (softening, deformation, etc.). In newborn calves, the medullary space of the long bones is filled with bone marrow.