The lipid peroxidation and antioxidant defense system is a balanced system responsible for the processing and utilization of lipids in the body’s cells. It plays an important role in lipid metabolism, cell protection and overall health of the body. Its proper functioning is necessary to ensure optimal functioning of cells and organs throughout the body. The article clinically and experimentally substantiates the pathogenetic role of lipid peroxidation products and the level of antioxidant protection in cows with endometritis and purulent-necrotic processes in the finger area, as well as with the comorbid course of endometritis and orthopedic pathology. It has been shown that multimorbid manifestation is accompanied by a more severe course than individual diseases. It has been established that the development of postpartum endometritis and purulent-necrotic lesions of the limbs in cows is accompanied by a highly significant increase in lipid peroxidation products in the blood serum against the background of a decrease in the amount of antioxidant enzymes, with the exception of ceruloplasmin. Moreover, these changes are accompanied by a sharp jump in the comorbid course of endometritis and orthopedic pathology in highly productive animals.

The purpose of the study is to conduct intravital diagnostics of calves with acute catarrhal bronchopneumonia using bronchoalveolar lavage samples and a detailed study of microbiocenoses from the collected contents. Objectives: development of a technique for intravital collection of bronchoalveolar lavage in calves with bronchopneumonia; study of the microbial landscape in calves with bronchopneumonia, characteristics of isolated microorganisms and their associations. The object of the study is calves aged 1–3 months, sick with acute catarrhal bronchopneumonia (n = 37). Pathological bronchoalveolar lavage was collected transnasally from the tracheal bifurcation area using sterile silicone catheters into sterile test tubes. Bacteriological studies were conducted using generally accepted methods at the Scientific and Educational Resource Center (SERC) Pharmacy of the People's Friendship University of Russia. As a result of the studies, 115 microorganisms of 13 species, classified into 9 genera, were isolated. The majority of isolates – 71 (61.7 %) were classified as gram-negative microorganisms. Staphylococcus aureus, Mannheimia haemolytica, Escherichia coli, Pasteurella multocida, Klebsiella pneumoniae, Streptococcus pyogenes and Klebsiella ozaenae were most often isolated from pathological material in cases of bronchopneumonia in calves. Isolates of E. coli were most often represented by O8, O26 and O111 serotypes. Of the 115 microorganisms that initiated bronchopneumonia in calves, the majority – 75 (65.2 %) cultures – had pathogenic properties. Retrospective analysis of microbial associations showed that most often the development of acute catarrhal bronchopneumonia in calves is caused by associations of opportunistic microorganisms, which included from 2 to 5 pathogens. Moreover, associations that included three members were most often isolated – 21 (56.8 %) and two members – 8 (21.6 %). Thus, in acute catarrhal bronchopneumonia of calves, microbiocenoses are formed in the inflammation focus, which can include various variations of opportunistic microorganisms.

In veterinary medicine, there is a problem of the comorbid course of reproductive function disorders and purulent-necrotic lesions in the toe area of cows. The research was carried out on the basis of Voskresenskoye JSC, Voskresensky district, Moscow region, with a total population of 1,450 heads of cattle, including 830 cows. The material for the study was cows with endometritis (n=28), animals with orthopedic pathology (n=25) and with a comorbid course of postpartum endometritis and purulentinflammatory processes in the toe area (n=27). Indicators obtained from clinically healthy animals (n=23) were used as control. From animals in the control and experimental groups, blood was taken in the morning before feeding from the jugular vein for morphofunctional studies. In experienced cows that had lesions in the limbs before or after birth, the likelihood of gynecological diseases associated with morphological disorders in the ovaries increased. The significant spread of these types of pathology is the direct cause of prolonged anaphrodisia of cows and a decrease in the level of reproduction of the herd with a high incidence of limb diseases. It has been established that the clinical manifestation of the comorbid course of orthopedic and obstetric-gynecological pathology has a more severe clinical manifestation than in the course of individual diseases. The study was supported by the grant from the Russian Science Foundation No 24-26-00172, https://rscf.ru/project/24-26-00172/.

Recently, due to the intensification of dairy cattle breeding, there has been an increase in the concentration of cattle, while unfavorable conditions are being created for the mother herd, helping to reduce their resistance to various unfavorable factors. Therefore, the study of clinical manifestations in the comorbid course of endometritis with purulentnecrotic diseases in the area of the hooves of highly productive cows, as well as a detailed comparison of the obtained indicators with clinically healthy animals and animals with a separate manifestation of endometritis and orthopedic pathology, in our opinion, is a very relevant area for scientific research. The research was supported by the Russian Science Foundation Grant No. 24-26-00172, https://rscf.ru/project/24-26-00172/. The experiment was approved by the bioethical commission of the Department of Veterinary Medicine of the Russian Biotechnological University, regarding the humane treatment of experimental animals. The research was carried out on the basis of Voskresenskoye JSC, Voskresensky district, Moscow region, with a total population of 1,450 heads of cattle, including 830 cows. The material for the study was cows with endometritis (n=28), animals with orthopedic pathology (n=25) and with a comorbid course of postpartum endometritis and purulent-inflammatory processes in the toes (n=27). Indicators obtained from clinically healthy animals (n=23) were used as control. Using the method of one-way analysis of variance (ANOVA), we established significant changes in the indicators of rumen contractions (F = 12.44; p<0.001), respiratory movements (F = 19.28; p<0.001), pulse (F = 8.21; p<0.001) and body temperature (F = 41.13; p<0.001).

A serious problem for the health of cattle, especially in highly productive animals, is infectious bronchopneumonia, which occurs when exposed to numerous adverse environmental factors and opportunistic microorganisms. Infectious bronchopneumonia is an important problem in the livestock industry and remains a major cause of significant economic losses in dairy herds and feedlots due to high morbidity and mortality rates, in addition to negatively affecting growth, reproductive performance and life expectancy. Therefore, the development of a new method for intravital minimally invasive diagnosis of calves with acute catarrhal bronchopneumonia using bronchoalveolar lavage sampling for subsequent microbiological studies is relevant. The invention relates to veterinary medicine and can be used in intravital diagnostics of bronchopneumonia in calves by isolating microorganisms that initiate the purulent-inflammatory process from samples of bronchoalveolar contents taken in the area of the tracheal bifurcation. A method for intravital diagnosis of bronchopneumonia in calves includes transnasal introduction to a sick animal of a sterile silicone medical tube with a diameter of 4 mm (the internal diameter of the hole is 3 mm), a wall thickness of 1.0 mm and a length of 150 cm, until slight resistance and a repeated cough reflex appear, upon reaching in the area of the tracheal bifurcation, the nasogastric tube is moved back 1 cm, a disposable syringe with a volume of 50 ml is attached to the free end, and with its help, 30-40 ml of sterile isotonic saline solution (0.9% NaCl solution, 37° C) is injected into the trachea, and then immediately aspirate up to 10 ml of bronchoalveolar contents.

Antimicrobial activity of antibacterial agents (benzylpenicillin, methicillin, amoxicillin, cefazolin, ceftriaxone, cefquinome, cefepime, gentamicin, tylosin, lincomycin, enrofloxacin, marbofloxacin) and herbal medicines (extracts ofEleutherococcus,Echinacea purpureaandHypericum perforatum) was studied. The purpose of the research was to determine sensitivity to antibiotics and phytobiotics in microorganisms isolated from bronchoalveolar lavage fluid collected from calves with acute catarrhal bronchopneumonia. Calves with acute catarrhal bronchopneumonia (n= 37) aged 13 months were studied in the research. Bronchoalveolar lavage was collected into sterile test tubes from sick calves using silicone sterile catheter. Bacteriological studies were carried out in LLC Vettest, using generally accepted methods. Determining the sensitivity of isolated opportunistic microorganisms to antibacterial drugs showed that the vast majority of them have rather low efficiency. It was found that all 115 isolated microorganisms were sensitive only to three antibacterial drugs: fourth-generation cephalosporin antibiotics cefquinome and cephepime, and third-generation fluoroquinolone antibiotic marbofloxacin. Of the phytobiotics studied,Hypericum perforatumextract had the most pronounced antimicrobial properties against the main initiators of acute catarrhal bronchopneumonia in the calves. Moreover, it showeda more powerful antimicrobial effect against gram-positive bacteria. This makes it possible to use it widely in complex therapy in calves.

The treatment of intestinal dysbiosis in animals remains one of the most complex and urgent problems in veterinary medicine to this day. Recently, a steady increase in pathologies has been recorded, accompanied by the development of disorders of the gastrointestinal tract of various etiologies in animals. Despite the constant improvement of methods for correcting the intestinal microbiota, the occurrence of dysbacteriosis in various pathological processes not only does not decrease, but, on the contrary, increases. This study revealed definite pathogenetic features of intestinal dysbiosis in cats of varying severity. It has been established that substantial changes occur in the blood of cats with dysbiosis, and with the decompensated third degree of severity, profound hematological shifts occur. The differences found may have significant clinical and laboratory importance since they complement the available data on intestinal dysbiosis in cats, which, in our opinion, will improve diagnostic and prognostic approaches, as well as therapeutic and preventive measures. Keywords: dysbiosis, cats, pathogenesis, compensated, subcompensated, decompensated.

The intestinal barrier is one of the most important components that maintain gastrointestinal homeostasis, therefore changes in bacterial composition can lead to increased intestinal permeability and the development of intestinal translocation of opportunistic microorganisms, with the subsequent development or complication of various infectious diseases. A comparative description of the microbiota of the intestinal tract of calves with compensated, subcompensated and decompensated acute catarrhal bronchopneumonia of calves was carried out in the conditions of livestock farms of Vladimir and Moscow Oblasts. Calves aged 1–3 months with acute catarrhal bronchopneumonia (n = 37) were used for the study. The severity of the disease was assessed based on clinical and laboratory tests. The samples taken from clinically healthy animals (n = 8) were used as controls. It has been shown that in calves with compensated acute catarrhal bronchopneumonia, the qualitative and quantitative composition of the intestinal microbiome does not differ from clinically healthy animals. During the clinical manifestation of subcompensated and decompensated acute catarrhal bronchopneumonia in calves, a significant quantitative and qualitative shift in the microbiome occurs in the intestines, which indicates the occurrence of dysbiosis. We believe that this area is quite relevant and requires further scrupulous research.

A special place among environmental factors affecting the body of animals is occupied by microorganisms— pathogens of infectious diseases. In this regard, the problem of circulation of associations of conditionally pathogenic microorganisms capable of causing a fairly wide range of pathologies in cattle in cattle is acute. The article provides a study of the microbial background of the vaginal-luminous contents selected in the acute purulent-catarrhal postpartum endomethry in cows. It was shown that 58 strains of opportunistic microorganisms of 13 species, classified into 6 genera, were isolated from 20 cows suffering from acute purulent catarrhal endometritis. The most frequently isolated cultures were St. aureus, E. coli (serotypes O4, O9 and O83), Str. pyogenes, Str. agalactiae, P. aeruginosa, Str. uberis and Str. faecalis. Moreover, the development of acute purulent-catarrhal endometritis in cows was more often caused by grampositive bacteria. Of the 58 isolated strains of microorganisms, 22 (37.9%) cultures caused the death of white mice when administered intraperitoneally. At the same time, gram-positive cocci were more likely to have pathogenic properties, namely representatives of the genera Streptococcus spp. (11 — 50.0%) and Staphylococcus spp. (6 — 27.3%) isolates, respectively. It was found that endometritis more often causes associations of opportunistic microorganisms, which included three joints in 14 (50.0%) cases, less often four joints in 7 (25.0%) cases. The isolated microorganisms were sensitive to only three antibacterial drugs: cefkin, cefepime and marbofloxacin.

The aim of the study was to search for, isolate and characterize new bacteriolytic enzymes that show promising potential for their use in medicine, agriculture and veterinary. Using a transcriptomic analysis, we annotated in Lysobacter capsici VKM B-2533T the genes of known bacteriolytic and antifungal enzymes, as well as of antibiotics, whose expression levels increased when cultivated on media conducive to the production of antimicrobial agents. The genes of the secreted putative bacteriolytic proteases were also annotated. Two new bacteriolytic proteases, Serp and Serp3, were isolated and characterized. The maximum bacteriolytic activities of Serp and Serp3 were exhibited at low ionic strength of 10 mM Tris-HCl, and high temperatures of, respectively, 80 °C and 70 °C. The pH optimum for Serp was 8.0; for Serp3, it was slightly acidic, at 6.0. Both enzymes hydrolyzed autoclaved cells of Micrococcus luteus Ac-2230T, Proteus vulgaris H-19, Pseudomonas aeruginosa and Staphylococcus aureus 209P. Serp also digested cells of Bacillus cereus 217. Both enzymes hydrolyzed casein and azofibrin. The newly discovered enzymes are promising for developing proteolytic antimicrobial drugs on their basis.

The aim of the study was to study the effect of diets using the potentially probiotic drug Bacillus amyloliquefaciens KB54 as part of compound feed (the rate of administration is 0.1% of the total diet, the content of viable spores in the final product is 106CFU/g) in the diets of laying hens of the Dekalb cross. In the course of the study, it was established that the viability indicators of laying hens were at a high level and the safety of livestock in the studied groups during the period of the experiment was 100%; egg production in the experimental group was 96.7%, which is 2.3% more than in the control group of laying hens; chickens in the experimental group exceeded the control in growth intensity, which affected an increase in live weight by 12.5%, or 188.5 grams, which is 1.7 percentage points or 25.2 grams more than in the control group; feed costs for 10 eggs and 1 kg of egg mass in the experimental group were 1.43 and 2.36 kg, respectively, which is 11.7 and 14.5% lower than the control values. In this regard, we recommend using the probiotic preparation Bacillus amyloliquefaciens KB54 in the diets of laying hens, introduced into the compound feed in the amount of 0.1% of the total diet with the content of viable spores in the final product 106CFU/g.

There is a lack of scientifically proved data about change of specious composition and quantitative ratio of microbiota in digestive tract when panleukopenia progresses. So, analysis of these indicators can help to find out mechanics of development and processing of dysbiotic statements, make a prognosis of it's course and develop methods of efficiency evaluation of preventive and treatment measures dealing with cats' panleukopenia. In course of virus illnesses including panleukopenia good conditions for activation of opportunistic microorganisms appear in cats macroorganism. The multiplication of accompanying can considerably complicate the main illness course. Also, opportunistic microorganisms that frequently figure as representatives of resident and transit organism microflora can affect it detrimentally in while the ecological balance of major and minor microbiote is broken. Analysis of these indicators will allow to find out the mechanics of dysbiotic statements development and progressing, prognose the difficulty of their courses and understand methods of efficiency evaluation of preventive and treatment measures dealing with cats' panleukopenia. Accompanying microflora during cats panleukopenia isolated from different seek animals' biotopes. It was found that during cats panleukopenia in different biotopes of the organism dysbacteriosis appear and it's accompanied by sharp decrease of normoflora representatives and their replacing with opportunistic microorganisms.

The aim of the work is to study the effectiveness of complex treatment of cats with acute bacterial cholangiohepatitis. According to inclusion and exclusion criteria, the study included a cohort of cats (n = 14) with acute bacterial cholangiohepatitis. For all sick cats the pathology was confirmed by isolation of biliary culture of microorganisms by means of cholecystocentesis under ultrasonic control. Clinical, hematological, ultrasonographic, statistical methods of investigation were used in this work. Sick cats with light form of cholangiohepatitis, prescription of combinations of marbofloxacin, metronidazole, ursodeoxycholic acid, cyanocobalamin, tocopherol acetate as therapy leads to complete recovery of animals, is accompanied by a decrease in the rate of erythrocyte sedimentation, normalization of erythrocytopoiesis indices, a decrease in the activity of alanine aminotransferase and alkaline phosphatase in serum.

Despite the creation of more and more new generations of antibacterial agents, the correction of intestinal dysbiosis in animals currently remains one of the most complex and urgent problems in clinical veterinary medicine. The article presents an analysis of the pathogenetic manifestation (microbial background, hematological analytes) in decompensated intestinal dysbacteriosis in domestic cats in the dynamics of its correction. The aim of the study was to study the comparative effectiveness of various pharmacotherapy regimens for decompensated intestinal dysbacteriosis in cats. The data shows that when correcting decompensated intestinal dysbacteriosis in domestic cats, the most rational treatment regimen is the complex use of Lactobifadol probiotic (contains at least 1.0 106 CFU/g of lactic acid bacteria Lactobacillus acidophilus LG1-DEP-VGIKI and 8.0 107 CFU/g of bifidobacteria Bifidobacterium adolescentis B-1-DEP-VGNKI), Vetelact prebiotic (contains lactulose - not less than 50 %), Azoksivet immunomodulator (contains 1.5 mg of azoximer bromide in 1 ml), as well as infusion therapy (intravenous drip injection of 10 ml/kg of 0.9 % sodium chloride solution; 10 ml/kg of 5 % glucose solution; 5 ml/kg of rheosorbelact and 2.5 ml/kg of refortan). This was confirmed by the results of pathogenetic picture (analysis of the microbial background and individual hematological analytes), in the dynamics of pharmacotherapy, namely before the start of correction, as well as on days 7 and 14. The improvement of diagnostic approaches and methods for correcting the most severe degree of intestinal dysbacteriosis (the stage of decompensation) creates prerequisites for the future study of dysbiotic disorders of the intestinal tract in other animal species, considering the severity of its manifestation.

The treatment of intestinal dysbiosis in animals remains one of the most complex and urgent problems in veterinary medicine to this day. Recently, a steady increase in pathologies has been recorded, accompanied by the development of disorders of the gastrointestinal tract of various etiologies in animals. Despite the constant improvement of methods for correcting the intestinal microbiota, the occurrence of dysbacteriosis in various pathological processes not only does not decrease, but, on the contrary, increases. Therefore, the choice of the optimal therapeutic regimen for the correction of the most severe decompensated degree of intestinal dysbacteriosis in cats is an important area of scientific research. The article shows that in case of decompensated intestinal dysbacteriosis in cats, the administration of the probiotic "Lactobifadol" in combination with the prebiotic "Vetelact" and the immunomodulator "Azoksivet" against the background of infusion therapy is the most effective, as evidenced by the registration of an overall clinical improvement of 1.28 times (p < 0.001) faster, when compared with animals of the group C1. At the same time, normalization of appetite, unpleasant odor from the oral cavity and the nature of fecal matter occurs in cats of group C3 1.40 days (p < 0.05), 1.60 days (p < 0.01) and 1.80 days (p < 0.01) earlier, according to compared with animals that were corrected according to scheme C1.

The development of new herbal preparations for the treatment of urolithiasis is an urgent task of medical science. Ficus have attracted the attention of pharmacologists due to a wide range of biological properties, including antioxidant, anti-inflammatory, antibacterial and antifungal activity. We studied the effectiveness of Ficus tikoua Bur. in SD rats in which urolithiasis was induced by 6 weeks of oral administration of ethylene glycol 0.5% ad libitum instead of drinking water. Administration of the extract of Ficus tikoua Bur., as well as comparative drug Cystone® after modeling of urolithiasis lead to the restoration of diuresis and the concentration of inorganic phosphates starting from the 6th week of the experiment. The use of the Ficus tikoua Bur. extract for 6 weeks, both during the modeling of urolithiasis and during the recovery period, led to the restoration of the percentage of lymphocytes in the blood, content of sodium, chlorine and inorganic phosphates in the blood to the control level. Thus, the extract of Ficus tikoua Bur. seems to be a promising drug for effective treatment of the initial stages of the development of urolithiasis.

A model of a chronic lung inflammation in SPF Sprague-Dawley rats was developed by repeated intratracheal administration of LPS in a dose of 0.4 mg/kg. On day 22 of the study, male rats treated with LPS have relative monocytopenia and reduced mean concentration of hemoglobin in the erythrocyte and the mean platelet volume in comparison with the control animals (saline). Intratracheal administration of LPS induced an inflammatory process in the lungs characterized by focal atelectasis, compensatory emphysematous expansion of subpleural pulmonary acini, focal mononuclear and neutrophilic perivascular and peribronchial infiltration, and minor focal mononuclear and neutrophilic infiltration of the alveolar walls. Against the background of LPS administration, germinal centers appeared in the lymphoid follicles of the white pulp of the spleen, and focal mononuclear infiltration of the tracheal mucosa and/or submucosa was observed in some animals.

Research on the study of parasitocenoses in endometritis and mastitis in cows, as well as gastrointestinal and respiratory diseases of newborn calves, were carried out in 12 farms in the Moscow region with a total number of 4,445 cows and 12,254 cattle. It was found that parasitocenosis in cattle in the farms of Moscow region are vulnerable to factor of infections composed of S. agalactiae, S. dysgalactiae, S. uberis, S. pyogenes, S. pneumoniae, S. faecalis, S. aureus, S. albus, S. saprophyticus, S. epidermidis, S. intermedius, S. enterica (S. enteritidis, S. typhimurium, S. dublin), E. coli (O1, O2, O4, O8, O9, O18, O22, O26, O33, O78, O101, O111, O126, O137), P. aeruginosa, P. multocida, K. pneumoniae, K. oxytoca, P. vulgaris, P. mirabilis, B. subtilis, B. cereus, C. freundii, L. plantarum, L. rhamnosus, L. acidophilus, L. xylosus, L. lactis and C. albicans. This research found that mastitis and endometritis in cows, as well as gastrointestinal and respiratory diseases in newborn calves, are caused by almost similar associations of microorganisms (parasitocenoses) that circulate in the farm (intra-farm infection). The results of the experiment indicate that the association of conditionally pathogenic microorganisms that circulate among cattle of farms in the Moscow region are parasitocenoses, and are independently regulated under the influence of macroorganism and environmental factors; it is a complex, multicomponent, strictly balanced ecosystem, each of which is an important link in the etiological factor of cattle infections.

The stresses that arise during routine animal husbandry procedures, such as milking, shearing, weighing, loading and hoof care, are an actual problem in animal husbandry. The components of economic damage under stress are a decrease in overall resistance and productivity, deterioration in product quality, an increase in labor costs and funds per unit of production, an increase in animal morbidity and mortality. The studies were carried out on the basis of Belozernoe farm in the Salsky district, the Rostov region. A complex of clinical and laboratory studies was performed on 18 sheep (10 Romanov and 8 Tsigay breeds) aged 2 to 3 years, before and after a planned routine shearing. Stress in sheep caused by planned shearing was clinically manifested by general depression, in some cases, subfebrile fever, moderate tachypnea and tachycardia. It was shown that stress was accompanied by anemia, the development of erythropenia and leukopenia. Immunocompetent cells in the blood of experimental animals during stress development were analyzed. Severe lymphocytopenia was found to occur after a haircut. In addition, in the blood of experimental animals under stress, a tendency to a decrease in T-total cells was noted, which was accompanied by an increase in 0-cells, which was significant in sheep of the Tsigay breed (p0.05). When analyzing the main immunoregulatory T cells in sheep under stress, a significant increase in T-suppressors was revealed with a relatively stable level of T-helpers in the blood studied. Thus, a significant (p0.05) increase in the level of T-suppressors in sheep of Romanov and Tsigay breeds was recorded; it was by 1.15 and 1.19 times higher compared with the initial data. It should be noted that we did not find any significant differences between animals of Romanov and Tsigay breeds in stress development after shearing. The obtained data should be taken into account in the further search for methods of stress correction in sheep.

In this study, two experiments were performed to investigate the anesthetic efficiency, hematological and biochemical effects of thymol on Nile tilapia, Oreochromis niloticus. In the first experiment, in order to estimate thymol anesthetic efficacy, tilapia juveniles were exposed to anesthetic baths at six different concentrations of thymol (10, 20, 40, 60, 80, and 100 mg L-1) and the induction and recovery times were recorded. The second experiment was performed with five treatments: CON (non-anesthetized fish), TH1 (anesthesia with 80 mg L-1 thymol within 1 min), TH5 (anesthesia with 30 mg L-1 thymol within 5 min), EU1 (anesthesia with 80 mg L(-1 )eugenol within 1 min), and EU5 (anesthesia with 30 mg L-1 eugenol within 5 min). The results showed that thymol at 10 mg L-1 concentration failed to induce anesthesia; however 20-100 mg L-1 concentrations induced anesthesia within 491-56.3 s. A strong negative relationship was detected between thymol concentrations and induction times (R-2 = 0.906). Anesthesia had no significant effects on plasma albumin, triglyceride, cholesterol, alanine aminotransferase, and the blood mean corpuscular hemoglobin levels. The anesthetized fish exhibited significant elevations in plasma cortisol, glucose, lactate, and the blood hematocrit and mean corpuscular volume; these parameters exhibited significant elevations in the fish anesthetized by 30 mg L-1 anesthetics, compared to the 80 mg L-1 . Plasma globulin, total protein, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, catalase, superoxide dismutase, and the blood hemoglobin and red blood cell significantly increased, as mean corpuscular hemoglobin concentration decreased, in the fish anesthetized by 30 mg L-1 anesthetics, compared to the CON fish. The anesthetized fish showed similar plasma glutathione levels, all significantly lower than the CON fish. The EU5 fish exhibited significant elevation in the plasma malondialdehyde levels, compared to the CON fish. In conclusion, thymol anesthetic efficacy was similar to eugenol in Nile tilapia weighing similar to 40 g at water temperature of 26 degrees C. Considering the physiological responses, slight but significant elevations in plasma proteins, lactate, lactate dehydrogenase, and malondialdehyde levels attest that thymol may induce less stress, hypoxia, and oxidative stress in the fish than eugenol, but further studies are needed to provide robust and clinically applicable data to support this hypothesis.