Aspectos anatômicos, fisiológicos e semiológicos do sistema urinário e relato de caso de insuficiência renal em bovino.

Abstract

When compared to other organic systems, the urinary system is little affected by diseases, and difficulties in caring for animals with diseases in this system, ineffective treatments and deaths are common. This work presents a theoretical framework on anatomical, physiological and semiological aspects of the urinary system and, later, it is reported a case of renal failure with the aim of contributing to the clinical study and knowledge of pathologies of the urinary system of ruminants. Each kidney is made up of millions of tiny functional units, the nephron. The right kidney has a dorsal retroperitoneal attachment to the sublumbar musculature and the left kidney has a variable location, when the rumen is distended it is pressed to the medial plane and rests below and caudal to the right kidney. The kidney is lined with a fibrous capsule that restricts ability to expand renal tissue. Cortical and medullary regions are distinguishable in macroscopic sections by the much lighter color of the former. The vascularization of the kidney is much more extensive than the size of the organ would suggest. The kidneys are innervated by the sympathetic nerves of the renal plexus and branches of the vagus nerve. The adrenal glands are located close to the kidneys. The right is heart-shaped and located against the medial border of the cranial end of the corresponding kidney. The left is usually found within the perirenal fat. Making up the lower urinary system are the ureters that are responsible for transporting urine from the kidneys to the urinary bladder and urethra. The kidneys, through processes such as filtration, reabsorption and tubular secretion, excrete metabolic waste and recover filtered substances needed by the body. Other important functions of the kidneys are the maintenance of the body's water content, plasma tonicity and blood pH. In the anamnesis of patients suspected of renal disorders, specific items should be added, including volume of urine in each urination, appearance, presence of solid or semi-solid material, viscosity and presence of blood cells. The frequency, interval, posture, and signs of urination pain or discomfort need to be evaluated, as well as water intake and previous urinary disease. Specific examination of the urinary system should include evaluation of the kidneys by rectal palpation and location, size, shape, consistency, wall thickness, and presence of bladder stones. Urination should be evaluated for frequency, dysuria, retention, or incontinence. Among the complementary exams are urinalysis, renal function tests, diagnostic imaging and biopsy. The Volhard concentration test also provides information on kidney function by evaluating the density of the urine produced. The inability of the kidneys to perform their normal metabolic and endocrine functions, either partially or completely, is known as renal failure and renal failure. The case of renal failure described refers to a female bovine with a history of weight loss, reduced appetite and milk production. On physical examination, dehydration, pollakiuria and polyuria were identified. Rectal palpation was performed where it was observed that the left kidney was increased in size and the caudal aspect of the right kidney was easily identified. Serum biochemistry identified azotemia and hypophosphatemia. In the evaluation of urinary density, isosthenuria was characterized. After the diagnosis of renal failure, the animal returned to the property and died after 4 months. At necropsy there were 20 liters of fluid in the abdominal cavity, swollen kidneys with pale color and the presence of white striations distributed diffusely over the entire surface of the organ. On histological examination there was a marked change in tissue architecture. In the interstitium of the cortical and medullary portions, there was intense proliferation of fibrous connective tissue and focal areas of lymphoplasmacytic inflammatory infiltrate. The histopathological findings characterized renal failure due to chronic tubulointerstitial nephritis. Based on the clinical signs, complementary exams and necropsy findings, associated with the histopathological examination, a definitive diagnosis of chronic renal failure due to nonspecific tubulo-intesticial nephritis was established, demonstrating the need for multidisciplinary knowledge to establish the diagnosis.