Ventral Abdomen Research Articles

Chrysosporium articulatum mimicking Trichophyton spp. infection in a cat: a case presentation and literature review

BackgroundDermatophytosis is a common skin infection of cats and many other animals. A reliable diagnosis is crucial because of the zoonotic potential of dermatophytes. The routine mycological diagnostic procedures for dermatophytosis are widely known, but in the case of some isolates, identification based on phenotypic characteristics may be incorrect. Infections caused by Chrysosporium spp. are usually described in reptiles, but in other animals they are uncommon.Case presentationThis study presents a description of a cat with dermatological lesions, that was mistakenly diagnosed with Trichophyton spp. dermatophytosis. Clinical material for mycological examination was collected from alopecic areas on the back of the neck, the ventral abdomen, and the hindlimbs. The initial identification based on phenotypic properties indicated Trichophyton spp. The result of the MALDI-ToF MS allowed the exclusion of the Trichophyton genus. Ultimately, the correct identification as Chrysosporium articulatum was obtained based on the sequencing of ribosomal genes.ConclusionsInterpretation of the results of the mycological examination of samples collected from animals’ skin or hair shafts is always challenging. Thus, careful consideration of the primary cause of the clinical lesions observed on the skin is mandatory, and the culture results are worth supporting by molecular methods.

Neoplastic and non-neoplastic lesions in biopsy samples from pet rabbits in Hong Kong: a retrospective analysis, 2019-2022.

Rabbits are popular pets in the urban environment of Hong Kong, ranking third behind cats and dogs. Here we describe the frequency of neoplastic and non-neoplastic lesions in biopsies from pet rabbits submitted to the CityU Veterinary Diagnostic Laboratory between 2019 and 2022, comprising 247 tissue samples from 243 rabbits collected by veterinarians in 19 veterinary clinics. Among the 243 rabbits, there were 128 females (65 spayed), 114 males (54 castrated); sex information was not provided for 1 rabbit. The rabbit breeds included 45 Lionhead, 35 Dwarf, 14 Lop, 11 Dwarf Lop, 5 French Lop, 3 Angora, 2 Dutch, 2 Holland Lop, and 1 each of Netherland Dwarf, Velveteen, Mini Lop, and New Zealand White. The mean ages of rabbits with neoplastic and non-neoplastic lesions were 7.1 and 5.7 y, respectively. The most common neoplastic lesions were adenocarcinoma (26.4%), trichoblastoma (21.4%), sarcoma (9.4%), and thymoma (8.2%). The most common non-neoplastic lesion was uterine cystic endometrial hyperplasia (14.8%), followed by dermal abscess formation in the ventral abdomen or skin of the head (12.5%). Although a broad spectrum of other lesions was described, our findings in biopsies from pet rabbits in Hong Kong are consistent with those in other jurisdictions.

Use of a modified SCORFAD scale to define localised reaction patterns associated with a flea burden in cats.

The SCORing Feline Allergic Dermatitis scale (SCORFAD) is a validated dermatological scale assessing reaction patterns associated with allergic dermatitis in cats. While no pathognomonic reaction pattern is recognised with flea allergy dermatitis (FAD), miliary dermatitis is more common. This study aimed to document regional cutaneous reaction patterns of cats with fleas using a modified SCORFAD (mSCORFAD). In total, 142 owned cats from West Central Florida enrolled over three study periods. To be included, each cat and household environment had five or more fleas on Day (D)0. Cats were examined on D0, D7, D14, D21, D28, D44, D56 and D80. On D0 they were treated with an isoxazoline and treatment continued through the study. Ten body regions were assessed using mSCORFAD to give a regional score for each of four reaction patterns. These were compared using the Wilcoxon rank sum test. At D80 there was an 80% reduction in total mSCORFAD representing clinical response to ectoparasite control only. The most commonly affected region was the ventral abdomen with a mean mSCORFAD score of 1.8 (95% confidence interval = 1.5-2.1) compared with other body regions (p < 0.01). The most common reaction patterns were self-induced alopecia on the ventral abdomen and miliary dermatitis in the cervical region (p < 0.0001). The mSCORFAD suggests that self-induced alopecia on the ventral abdomen and miliary dermatitis in the cervical region is more strongly associated with a flea burden in cats.

How frequently are insects wounded in the wild? A case study using Drosophila melanogaster.

Wounding occurs across multicellular organisms. Wounds can affect host mobility and reproduction, with ecological consequences for competitive interactions and predator-prey dynamics. Wounds are also entry points for pathogens. An immune response is activated upon injury, resulting in the deposition of the brown-black pigment melanin in insects. Despite the abundance of immunity studies in the laboratory and the potential ecological and evolutionary implications of wounding, the prevalence of wounding in wild-collected insects is rarely systematically explored. We investigated the prevalence and potential causes of wounds in wild-collected Drosophilidae flies. We found that 31% of Drosophila melanogaster were wounded or damaged. The abdomen was the most frequently wounded body part, and females were more likely to have melanized patches on the ventral abdomen, compared with males. Encapsulated parasitoid egg frequency was approximately 10%, and just under 1% of Drosophilidae species had attached mites, which also caused wounds. Wounding is prevalent in D. melanogaster, likely exerting selection pressure on host immunity for two reasons: on a rapid and efficient wound repair and on responding efficiently to opportunistic infections. Wounding is thus expected to be an important driver of immune system evolution and to affect individual fitness and population dynamics.

Findings of an Extraluminal Leiomyosarcoma of the Urinary Bladder in a Dog.

A 9 yr old male miniature poodle presented with acute diarrhea, vomiting, and a distended abdomen. A large and firm mass was palpated in the caudal abdomen. Radiography showed a large soft-tissue mass in the mid ventral abdomen. The mass was mildly contrast-enhancing and in contact with the right cranial aspect of the bladder on computed tomography. The mass was heterogeneous with minimal blood flow on Doppler examination. Surgery confirmed its origin of the urinary bladder, and it was diagnosed leiomyosarcoma on pathology. This is the first report of extraluminal leiomyosarcoma of the bladder wall with imaging characteristics using various modalities.

Pathology Anatomy and Hemolymph Profile of Spiny Lobster (Panulirus homarus) Infested by Octolasmis sp. on Bottom Cage

Spiny lobster, a fishery commodity with important economic value, is often infested by Octolasmis sp. on their bodies, which causes stress conditions that lead to death. This study aimed to determine the anatomical pathology and hemolymph profile of spiny lobster infested with Octolasmis sp. in bottom cages. The method used was an observation, where 30 lobsters (weight 112.44 ± 24.63 g) were carried out in June–July 2022 at the Pesona Bahari Wongsorejo, Banyuwangi. Hemolymph profile and anatomical pathology data were analyzed, respectively, using the Independent T-Test and Kruskal-Wallis test (α = 95%). The results based on scoring data showed a very significant difference between infected and healthy lobsters (p &lt; 0.01), characterized by the occurrence of tail flakes, lesions on the carapace, gill melanization, and the appearance of ulcers on the ventral abdomen. A very significant change occurred in the hemolymph profile of infected lobsters compared to healthy lobsters (p &lt; 0.01). Total hemocyte count increased with high concentrations of granular cells, respectively 22.1–37.8 ´x 106 cells/mL and 63.75–64.5%, along with lobster damage, while hyaline cells decreased. This study showed that there was a change in anatomic pathology and hemolymph profile between infected and healthy lobsters.

Evan’s Syndrome Hemolytic Anemia with Thrombocytopenia in a Labrador Dog: A Case Report

A seven-year-old Labrador retriever intact male dog was presented to the Referral Veterinary Polyclinic, Indian Veterinary Research Institute, Izatanagar with a history of inappetance, melena, and petechial hemorrhages on the ventral abdomen and treated by a local veterinarian for a prolonged period of time. Clinical examination showed pale mucous membranes, peripheral lymphadenopathy, and mild hepatomegaly. A Complete blood count revealed anemia, leukopenia, and thrombocytopenia and serum biochemistry showed hypoalbuminemia and hypoproteinemia. The dog was suspected of having a haemoprotozoan infection, and a thin peripheral blood smear was submitted to the Division of Parasitology, Indian Veterinary Research Institute, Izatanagar, Bareilly, for examination. A blood smear was screened for haemoprotozoan examination using Giemsa’s stain, which showed positivity for Babesia vogeli. An abdominal ultrasound confirmed hepatic enlargement. The blood clotting profile reveals an increase in activated partial thromboplastin time and prothrombin time. The dog's blood sample tested negative for Babesia vogeli, B. gibsoni, E. canis, and H. canis by multiplex PCR; this could be because of prior initiation of antibiotics. A periheral blood smear showed elevated spherocytes count and saline agglutination test was positive. Based on history, clinical examinations, laboratory findings and cytological examinations the case was tentatively diagnosed as chronic case of tick fever with concomitant Evans syndrome. A blood transfusion was performed and around 300 ml of whole blood was infused. Treatment was initiated with triple antibiotic therapy and an immunosuppressive dose of steroids, but after 4 weeks, the dog succumbed to the condition. Further research is required to optimize treatment regimens for dogs with Evan's syndrome, as the prognosis is uncertain.

Co-Occurrence of Pseudopregnancy, Pyometra, and Bacterial Parasitic Anaplasmosis in a Persian Cat

An intact female tabby Persian cat, 26-month-old, was brought to IPB University Veterinary Teaching Hospital on the 21st of February, 2023, due to vaginal discharge, inappetence, and lethargy. Physical examination revealed a distended abdomen, mammary gland enlargement, and fever (40.1 °C). The heart and respiratory rates were 128 beats per minute and 32 times per minute, respectively. The patient body weight was 3.87 kg. The veterinarian palpated masses inside the abdominal cavity and observed obvious purulent and haemorrhagic vaginal discharge. Haematology showed leukopenia and thrombocytopenia, and the eosinophil percentage of white blood cells was increased (eosinophilia). Blood chemistry analysis showed hyperglycaemia. Ultrasonography showed two hyperechoic masses inside two hypoechoic pouches in the queen’s uterus, suspected as two dead foetuses (no heartbeat). Roentgen revealed abnormalities in the vena cava caudalis, bronchial pattern in the lung, radioopaque masses in the ventral abdomen, radio-opacity changes in the small and large intestines, and abnormalities in the spleen. The patient’s diagnosis was pyometra, and ovariohysterectomy surgery was performed on the patient. The patient was treated with additional medicines (antibiotics and others) according to the symptoms. The patient’s symptoms disappeared, except for the fluctuating febrile and pale mucous membrane. A blood smear performed on the 1st of March 2023 revealed Anaplasma phagocytophilum (A. phagocytophilum) in the white blood cells, and immediately doxycycline treatment (10 mg/kg body weight, twice daily) was given. The patient was discharged from the hospital on the 14th of March, 2023, with no febrile or other symptoms reported. This case is the first report of open cervix-type pyometra and anaplasmosis co-occurrence in a Persian cat from IPB University Veterinary Teaching Hospital in Indonesia.

Epidemiology of horse pythiosis in the Pantanal of Mato Grosso: Exploring the host-parasite-vector relationship

Horse pythiosis is considered an endemic disease in the Brazilian Pantanal region, causing devastating health and economic losses. This study aimed to enhance the understanding of pythiosis epidemiology, map the distribution of horse body lesions, and investigate the correlation between these lesions and warm body surface areas, potentially implicating hematophagous vectors in the disease's transmission. A prospective study was conducted on equids in the Pantanal Mato-grossense and adjacent areas from 2012 to 2022, with 112 horses and three mules diagnosed with pythiosis. Clinical and epidemiological data, lesions' photographic records, and healthy equids' thermal imaging were collected. Most pythiosis cases occurred between January and March, correlating with regional flood cycles. Most lesions were found on limbs and the ventral abdomen, with dark-colored horses exhibiting a higher frequency of lesions. Interestingly, the thermal mapping revealed that warm areas on a healthy horse's body overlapped significantly with lesion distribution – blood-sucking insects also prefer these areas. The results suggest that pythiosis lesions in horses correlate with warmer areas of the animal body, reinforcing the hypothesis of vector involvement in disease transmission. This study underscores the need for further observational research to fully understand the complex epidemiological dynamics of pythiosis in horses.

Microstructural characterization of the skin in the African straw-coloured fruit bat, Eidolon helvum (Pteropodidae).

The African straw-coloured fruit Bat, Eidolon helvum, is a Yinpterochiroptera bat that is of public health and ecological importance. This study investigated the light microscopic morphology, morphometry and histochemistry of the skin and its glands across the cheek, withers, croup, ventral abdomen, perianal region, wing membrane, intercrural membrane and foot pad of the species. Sweat glands were absent and hypodermis was observed only in the withers, croup and ventral abdomen. The croup had the highest density of hair follicles while the perianal region had the highest density of sebaceous gland acini. The thicknesses of the dermis and epidermis were significantly high in the withers and foot pad respectively. Hair follicles and sebaceous glands were absent in the wing membrane. The sebaceous glands had melanin pigmentation at the periphery and stained positive to Alcian Blue-periodic acid Schiff at the withers and ventral abdomen. Epidermal and dermal thicknesses reported in this study were generally higher than those of Yangochiroptera bats and the presence of sebaceous glands and hair follicles in the wing membrane were variable in different bat species. This study has provided baseline information on the light microscopic morphology and morphometry of the skin and its glands across the various body regions in the African straw-coloured fruit bat. This information would be helpful in the understanding, handling, skin disease treatment and management of the bat in captivity for biomedical research purposes.

Quantification of the bacterial flora and its major constituents on the abdominal skin of clinically healthy dogs.

To report the density, and the major constituents, of the bacteria on the skin surface of healthy dogs and to assess if scraping the skin before sampling was necessary. 20 healthy dogs were recruited for the study, with informed consent in all cases. Flocked swabs were used to sample the skin surface and to sample the skin surface after superficial scraping with a blunted spatula. Both samples were taken within a brass guide of 3.5 cm-2 area. Next-generation 16S rRNA sequencing was used to identify and quantify components of the bacterial microbiome. The median density of the bacterial microbiome on the ventral abdomen of 20 healthy dogs was approximately 1.1 X 105 cm-2 (IQR 1.22 X 104, 1.6 X 105 cm-2). Sphingomonas species were isolated on 17 of the 20 dogs and Corynebacterium kroppstedtii from 15. This is the first study to report the density of the canine skin microbiome. Superficial scraping of the skin before swabbing does not affect the result of sampling the microbiome in healthy dogs. These results will increase our understanding of the biology of canine skin.

Clinical Features and Histopathologic Examination of Lentiginosis Profusa in a Dog

An 5-year-old Yorkshire Terrier dog was presented due to a gradually developing hyperpigmented spot at the ventral abdomen, around lips, interdigital space and paws. The skin lesions appeared 2 years ago and gradually increased the numbers. The skin condition was generally dry on presentation, and several hyperpigmented macules and patches were detected. Except for the hyperpigmented skin lesions, other physical examinations and dermatological examination results were non-remarkable. Based on the history and clinical examination results, the genetic dermatological disease, lentigo was highly suspected. Skin biopsy and histopathologic examination were performed to rule out other pigmentary skin disease including tumor. The histopathologic examination revealed epidermal hyperplasia, melanocytic hyperplasia and hyperkeratosis. The dermatologic signs and histopathologic results were compatible with lentiginosis profusa. Canine lentiginosis profusa predominantly occurs in mature dogs and is generally considered a benign condition. While it is primarily a cosmetic concern, it is essential to distinguish it from other hyperpigmentation-related diseases.

Evaluation of multifactorial digestive disorders in a dairy herd at different stages of lactation.

The manager of a large dairy herd (total confinement, total mixed ration feeding, 10130 kg milk sold per cow and year) requested a workup of a digestive disorder problem that had been ongoing for several years. The cows were at all stages of lactation, and the incidence proportion (events/100 cows at risk) of digestive disorders was approximately 5 to 10%. The clinical picture included an abnormal demeanor of varying severity and signs that differed among the cows. The latter included decreased milk production and physical activity, low body condition score, abnormal rumen motility and stratification, small intestinal dilatation, diarrhea, undigested fiber particles in the feces, fever and abdominal pain.The following approach was used to investigate the digestive disorder problem:1. The herd was assessed for production levels, housing requirements, feeding protocols and animal health management. The latter comprised evaluation of different animal scores, metabolic profile analysis, diagnosis of disease, culling records and slaughter data. The results revealed risk factors concerning the feeding and animal health monitoring, (e. g. in dry matter intake and silage quality management, disease detection and diagnosis in fresh cows). The assessment also identified a high occurrence of digestive disorders of unknown origin.2. Fifteen cows that represented the ongoing digestive disorder problem were selected to undergo clinical examination, hematological analysis, urinalysis, and ultrasonography of the ventral abdomen. The clinical examinations revealed different digestive disorders, which were mainly inflammatory in nature, in all the cows. Eight cows had localized reticuloperitonitis and 13 had left displaced abomasum with different degrees of displacement and adhesions between the abomasum and reticulum attributable to reticuloperitonitis.Our results revealed a multifactorial problem caused by several risk factors relating to animal health and feeding management protocols that resulted in different types of digestive disorders. The wires from damaged tires used to hold the pit silo tarps in place were identified as a possible traumatic cause of the reticuloperitonitis. Treatment, prevention and follow-up of the different conditions were discussed.

Outbreaks of dermatopathy caused by Tephrosia noctiflora intoxication in Brazilian cattle

This study aims to update the knowledge concerning the intoxication by Tephrosia noctiflora in Brazilian cattle herds by reporting new cases of intoxication in lactating cows, their calves and bulls and highlight the epidemiology, clinical signs, pathogenesis, gross, and microscopic lesions. The morbidity and mortality of this intoxication in the farms studied was low. Gross lesions in all affected cattle consisted of dermatitis with hyperpigmentation, crusts, ulceration, erythema, and lichenification in the skin of limbs, ventral abdomen, perianal and perineal areas of lactating calves and adult cattle. Microscopically, the main lesion observed consisted of severe dermatitis with parakeratotic hyperkeratosis, papillated proliferation, and diffuse, accentuated lymphoplasmacytic inflammatory infiltrate in the epidermis and dermis. The presence of skin lesions mainly in the limbs and ventral abdomen of cattle implies the pathogenesis of intoxication is related to a primary contact dermatitis, and the occurrence of similar lesions on the skin of nursing calves reinforces this hypothesis. The putative toxins of T. noctiflora have been thought to be rotenoids. Additional work is needed to define better if these compounds are the main toxin responsible for the dermatopathy observed in these herds.

Effect of Bedding Systems on Hygiene and Milk Yield of Crossbred Dairy Cows

In dairy cattle, bedding and its management contribute predominantly to the comfort of the cow, udder health and milk quality. The aim of the study is to assess the effect of different bedding materials such as concrete floor, rubber mats, coir pith and dried solid manure on hygiene and milk yield and in crossbred dairy cows. Twenty-four crossbred cows with six animals in each group were selected for the study for one lactation period spread over three different seasons. The control group (T1) was maintained in concrete floor without any bedding material. In (T2) rubber mats of 1.2 m × 1.8 m × 0.025m area were provided on concrete floor. In (T3) coir pith and (T4) dried solid manure (DSM) on concrete floor was the bedding. The mean tail head, upper rear limb, ventral abdomen, udder and lower rear limb hygiene score of the T1 group were higher than other groups, which indicated that the cows became ‘dirty’ and the T3 group had lower score than others which denoted cows were ‘very clean’ with significant difference (P&lt;0.01) between them. The range of hygiene score in cows of T2 group revealed that the cows were ‘average to dirty’ whereas in T4 ‘clean to average’. The hygiene score of cows improved during summer season and reduced in monsoon. The cows of T1 group had the lowest overall daily milk yield (8.66 ± 0.22 kg) while the cows of T3 group had the highest yield (9.98 ± 0.30 kg).

Symptoms: Abdominal Pain, Diaphoresis, Fever, Nausea, and Constipation

Symptoms: Abdominal Pain, Diaphoresis, Fever, Nausea, and Constipation

Aspectos da morfologia e morfometria da pele do tamanduá bandeira (Myrmecophaga tridactyla, LINNAEUS, 1758)

The aim of the present study is to describe the skin morphology and morphometry of the giant anteater (M. tridactyla), based on comparative analysis applied to skin segments from central metacarpal torus (palmar pad), dorsal thorax, ventral cervical, ventral abdomen, medial carpal and nasal regions. In order to do so, eight adult specimens of M. tridactyla were used for macroscopic studies and four for microscopic assessments. Microscopy was used to assess fur general features that were macroscopically assessed through visual analysis. Fragments (2.0cm²) were collected from the selected regions for microscopic studies. Samples were fixed on McDowell solution, processed through routine histology techniques and subjected to semi-serial cuts (5 μm). The cuts were stained in HE, Alcian blue and periodic acid Schiff. General morphology of different skin layers was described, as well as their architecture and composition; mesoscopy of the epidermis, dermis and stratum corneum was also carried out. There was difference in skin morphometry between males and females, and between different skin regions in the same animal, based on the statistical evaluation of the recorded values. All epidermis layers were assessed for the selected regions. Dermis encompassed surface and deep layers; it presented sweat and sebaceous glands, as well as hair follicles. Findings also allowed reporting that epidermis components are easily identified given its thickness, and the large amount of sweat glands in it – it contrasts its physiological features.

English

Myiasis is the infestation of living tissues of human and animals with larvae of flies in the Order Diptera. This study determined the gross and histopathological lesions due to Cordylobia anthropophaga infestations of Dogs in Kitui County, Kenya. Four dogs identified and confirmed to have canine cutaneous myiasis (CCM) infestation were purchased for the study. All the study animals were clinically examined for skin lesions characteristic of CCM and euthanized for complete necropsy examination and histopathological sample collection. Tissue sections were collected from areas with lesions of CCM namely; skin, skeletal muscles and regional draining lymph nodes. They were preserved in 10% buffered formalin and were processed and analyzed using standard methods. Grossly, all dogs had poor body condition, patches of alopecia, emaciated and had the pathognomonic lesions for canine cutaneous myiasis (CCM) characterized by multifocal coalescent nodular lesions (harboring Cordylobia anthropophaga larvae) with 3 mm diameter central pore (furuncles) and erythematous base. Some had serous, hemorrhagic or purulent discharges from the furuncles that matted surrounding hairs. Lesions were distributed mainly on the ventral abdomen, axilla, flanks, legs, perineum and external reproductive organs. Examination of the skin revealed that the furuncular lesions extended throughout the skin thickness from epidermis to the sub-cutis and underlying pale skeletal muscles. There was regional lymphadenopathy in affected body regions. Histopathology confirmed the main lesions in all the dogs were parasitic granulomas, congested blood vessels in the surrounding tissues and eosinophilic lymphadenitis. The granulomas were located in the skin and the underlying skeletal muscles. The lesions were characterized by centrally located parasite, surrounded by connective tissue and heavy infiltration with inflammatory cells predominantly eosinophils. Draining lymph nodes had eosinophilic lymphadenitis. The reported pathological lesions resulted in unthriftiness, alopecia, lethargy and anorexia due to pain and stress resulting to emaciation and possible death. There is need to eradicate the etiological agent as it affects the wellbeing of dogs in the study area. Key words: Canine, Cordylobia anthropophaga, Myiasis, gross pathology, histopathology, Kitui County.

Septicemia caused by an emerging pathogen, Elizabethkingia miricola, in a laboratory colony of African dwarf frogs (Hymenochirus curtipes).

An outbreak of morbidity and mortality in an African dwarf frog (Hymenochirus curtipes) colony was reported following arrival at an animal research facility. Animals were found dead on arrival or became moribund shortly thereafter, and additional animals showed clinical signs of lethargy, weight loss, and anorexia over the following 3 weeks. Externally, some affected animals presented with multifocal areas of hyperemia in the inguinal and axillary areas and on the limbs, and mottled tan discoloration along the ventral abdomen. Histologically, lesions were consistent with generalized septicemia, characterized by granulomatous meningitis, otitis media, peritonitis (coelomitis), myocarditis and pericarditis, nephritis, pneumonia, and arthritis. Gram staining identified gram-negative rod-shaped bacteria free within tissues and within macrophages. Culture results of coelomic swabs identified moderate to numerous Elizabethkingia miricola. Testing of water from tanks housing affected animals showed elevated levels of nitrites and ammonia, and the presence of Citrobacter, Aeromonas, Pseudomonas, and Staphylococcus spp. cultured from several tank biofilters. E miricola is a newly recognized and rapidly emerging opportunistic pathogen in anurans and has been reported as a cause of septicemia in humans. This report documents the first occurrence of E. miricola septicemia in African dwarf frogs and illustrates the importance of this potential pathogen in the laboratory setting for amphibian research colonies, as well as those individuals directly working with them.

Clinical efficacy of an ultrasound-guided bilateral rectus sheath block for umbilical hernia repair in calves: A prospective randomized trial.

Surgical umbilical hernia repair is a frequent procedure in newborn calves, requiring mandatory pain management. This study aimed to develop an ultrasound-guided rectus sheath block (RSB) and to evaluate its clinical efficacy in calves undergoing umbilical herniorrhaphy under general field anesthesia. Gross and ultrasound anatomy of the ventral abdomen and the diffusion of a new methylene blue solution after injection within the rectus sheath were described in seven fresh calf cadavers. Then, fourteen calves undergoing elective herniorrhaphy were randomly assigned to receive either bilateral ultrasound-guided RSB with 0.3 mL/kg of bupivacaine 0.25% and 0.15 µg/kg of dexmedetomidine or 0.3 mL/kg of 0.9% NaCl (control). Intraoperative data included cardiopulmonary variables and anesthetic requirements. Postoperative data included pain scores, sedation scores and peri-incisional mechanical threshold assessed by force algometry at specific time points after anesthetic recovery. Treatments were compared using Wilcoxon rank-sum, Student's t-test, and Cox proportional hazard model as appropriate. Mixed effect linear models on rank, with random effect calf; fixed effects time, treatment, and their interaction were used to compare pain scores and mechanical thresholds over time. Significance was set at p = 0.05. Calves receiving RSB recorded lower pain scores between 45 - 120 minutes (p < 0.05) and at 240 min after recovery (p = 0.02). And they recorded higher mechanical thresholds between 45 and 120 min after surgery (p < 0.05). Ultrasound-guided RSB provided effective perioperative analgesia in calves undergoing herniorrhaphy under field conditions.