Úlceras do abomaso: estudo epidemiológico e anatomopatológico em bovinos com comorbidades

Abstract

There are still many questions about the etiopathogenesis of abomasum ulcers that affect cattle and that impact on animal production, causing significant economic losses. In the last ten years, there has been greater interest from the scientific community in clarifying the possible cause and effect relationships of this disease. Therefore, the aim of this study was to conduct an epidemiological and anatomopathological study in cattle with abomasal ulcers and carriers the comorbidities. A total of 201 cattle were used, 40/201 (20%) young animals under the age of two years and 161/201 (80%) adults, aged over two and a half years, and diagnosed with type 1 or 2 ulcers in the pathological examination and 25 cattle, young (n=8, less than two years old) and adults (n=17, older than two and a half years), diagnosed with perforated abomasal ulcers of the type 3, 4 or 5, in clinical, ultrasonographic, exploratory laparotomy, abdominal centesis or pathological examination. Epidemiological risk indicators such as; sex, race, age, type of rearing, feeding, time of year, health practices and stage of lactation, as well as clinical, pathological diagnostic data were collected through medical records. At necropsy, the ulcers were analyzed for the degree of penetration into the mucosa, bleeding and topographic distribution by affected region, cardia, fundus and pylorus, as well as the abdominal cavity was evaluated for the presence of peritonitis. For histopathological examination, the ulcers were fixed in 10% buffered formalin, processed by routine protocol and stained with hematoxylin-eosin (HE). There was a higher occurrence of cases of abomasum ulcers in females, in the dry period (October to March). In the macroscopic examination of the abomasum, focal ulcers subtype 1b and multifocal ulcers subtype 1a and 1b were the most common, respectively. Ulcers abomasum type 1 and 2 were characterized by focal inflammatory process, focally extensive multifocal or diffuse, particularly by mononuclear cells. Abomasitis associated with ulcerated mucosa was found in 160/201 (79.60%), with lymphoid follicle hyperplasia in 104/201 (51.74%). On 26/201 (12.93%), abomasitis had diffuse foci of multifocal lymphocytic proliferation by atypical lymphocytes. In the histopathology of perforated ulcers, lymphocytic and neutrophilic abomasitis was found in most cases, associated with fibrosis with thrombosis of vessels. The main clinical findings in animals with perforated ulcer were: apathy, dehydration, intestinal hypomotility, diarrheal stools, hypomotile or atonic rumen, tachycardia, tachypnea, abdominal distension with bilateral bulging and increased abdominal tension. The most frequent abnormal hematological findings were hypoproteinemia and leukocytosis due to neutrophilia with a left shift. Peritoneal fluid (LP) from animals with perforated ulcers showed an inflammatory reaction in cytology, characteristic of exudate. The diagnosis of perforated ulcer was possible in three cases on ultrasound and in two cases on exploratory laparotomy. In the postmortem examination, all cases of type 3, 4 or 5 ulcers presented focal peritonitis, diffuse peritonitis or omental bursitis, respectively. Comorbidities were present in 68% and 100% of cases in animals with perforated ulcers and type 1 and 2, respectively, the most frequent being related to the digestive system. Thus, the results of this study emphasize the occurrence of type 1 abomasal ulcers in dairy cattle carriers the primary comorbidities. Although type 1 ulcers do not cause characteristic clinical signs, it is possible that they are an important cause of abdominal pain and decreased production in dairy cattle, on the other hand, perforated ulcers cause clinical signs suggestive of pertitonitis, and thus ultrasonography with abdominal centesis and exploratory laparotomy are necessary tools to predict them, and a diagnosis is always possible when these tests are combined, helping the veterinarian in making decisions to avoid further animal suffering and unnecessary treatment costs. Once, the cases of type 4 or 5 ulcers present unfavorable clinical evolution.