Radiographic, ultrasonographic, and computed tomographic characteristics of an accessory liver lobe in a cat.

A 5-year-old male Norwegian Forest cat presented with increased hepatic serum biochemical parameters. Abdominal radiography showed an oval cranioventral mass and ultrasound revealed a mobile mass attached to one hepatic lobe. Computed tomography (CT) confirmed that the mass was attached to the right medial liver lobe. Differential diagnoses were an accessory liver lobe, benign neoplasia, and focal nodular hyperplasia. The mass was removed and histopathology confirmed the mass to be normal liver tissue. Accessory liver lobe should be included in the differential diagnosis of a mobile cranial abdominal mass with a similar ultrasonographic or CT appearance to the liver.

Effects of midazolam before or after alfaxalone for co-induction of anaesthesia in healthy dogs.

OBJECTIVE: To study the effect of alternating the order of midazolam and alfaxalone administration on the incidence of behavioural changes, alfaxalone induction dose and some cardiorespiratory variables in healthy dogs. STUDY DESIGN: Prospective, randomized, controlled, clinical trial. ANIMALS: A total of 33 client-owned dogs undergoing elective procedures. METHODS: Following intramuscular acepromazine (0.02 mg kg-1) and morphine (0.4 mg kg-1) premedication, anaesthesia was induced intravenously (IV) with a co-induction of either midazolam (0.25 mg kg-1) prior to alfaxalone (0.5 mg kg-1; group MA), or alfaxalone followed by midazolam at identical doses (group AM). The control group (CA) was administered normal saline IV prior to alfaxalone administration. Additional alfaxalone (0.25 mg kg-1 increments) was administered as required in all groups until orotracheal intubation was possible. Changes in behaviour, quality of induction, ease of intubation and incidence of adverse events at induction were recorded. Heart rate (HR), respiratory rate (fR) and systolic arterial blood pressure (SAP) were measured before treatments (baseline values), 30 minutes after premedication and at 0, 2, 5 and 10 minutes postintubation. RESULTS: The incidence of excitement was higher in group MA compared with groups CA (p=0.005) and AM (p=0.013). The mean induction dose of alfaxalone was lower in group AM compared with group CA (p=0.003). Quality of induction and ease of intubation were similar among groups. Mean HR values decreased after premedication and increased after alfaxalone administration in all groups. Mean SAP values were similar between groups. The number of animals that required manual ventilation was higher in the MA group. CONCLUSIONS AND CLINICAL RELEVANCE: Despite a lower occurrence of adverse events at induction in group AM compared with group MA and a reduction of alfaxalone dose requirement in group AM compared with group CA, the use of an alfaxalone-midazolam co-induction does not seem to produce any cardiovascular or respiratory benefits in healthy dogs.

IMAGING DIAGNOSIS-COMPUTED TOMOGRAPHY FINDINGS IN A DOG WITH SPONTANEOUS TRANSMURAL MIGRATION OF A TEXTILOMA INTO THE CECUM.

A 3-year-old spayed female dog was presented with 3-month history of severe bilateral uveitis subsequent to previous ovariohysterectomy. Physical examination revealed moderate abdominal pain. Computed tomography showed a nonobstructive heterogeneous mass-like lesion with a speckled gas pattern (spongiform pattern) within the cecum. Exploratory laparotomy revealed a surgical swab in the lumen of the cecum with severe adhesions. Histopathological examination demonstrated a chronic inflammatory pyogranulomatous reaction to the retained swab embedded within the intestinal wall, consistent with transmural migration of the swab from the peritoneal cavity into the cecum.

IMAGING DIAGNOSIS-RADIOGRAPHIC, ULTRASONOGRAPHIC, AND COMPUTED TOMOGRAPHIC CHARACTERISTICS OF A DUODENAL DUPLICATION CYST IN A YOUNG CAT.

A 7-month-old, 2.8 kg, intact female Siamese cat was evaluated for repetitive and intermittent episodes of vomiting and anorexia. Abdominal palpation revealed a round, firm, nonpainful mass in the right cranial abdomen. Ultrasonography findings were consistent with a cystic structure adjacent to the descending duodenum. The structure exhibited a "muscular rim sign." A duodenal duplication cyst was confirmed by histopathological analysis. Computed tomography ruled out concurrent vertebral anomalies and clarified anatomic relationships for surgical planning. To the authors' knowledge, this is the first description of an ultrasound "muscular rim sign" in a duodenal duplication cyst in a cat.

IMAGING DIAGNOSIS-URETHROVAGINAL FISTULA CAUSED BY A MIGRATING GRASS AWN IN THE VAGINA.

A young intact female dog was presented with urinary incontinence. Abdominal ultrasound revealed the presence of hyperechoic linear structures within the cranial vagina suggestive of foreign material. A computed tomography (CT) retrograde vaginourethrogram demonstrated the presence of a fistulous tract between the urethra and vagina. A presumptive diagnosis of urethrovaginal fistula due to migration of foreign material was made. The grass awn was removed with vaginoscopic-guided retrieval. Fourteen days later, surgical repair of the fistula and an ovariohysterectomy were done. This case report emphasizes the usefulness of CT for diagnosis and precise anatomical localization of genitourinary tract fistulas.

Ultrasonographic and anatomic study of the canine elbow joint.

OBJECTIVE: To (1) assess the canine elbow joint using a high frequency transducer (18 MHz); (2) describe the echogenicity and echo texture of the joint; and (3) correlate the ultrasonographic images with transparent plastinated anatomic sections. DESIGN: Descriptive study. SAMPLE POPULATION: German Shepherd cross-breed dogs (cadavers, n = 10; live dogs, n = 5). METHODS: Elbow joints of 10 adult German Shepherd cross-breed dog cadavers were examined by ultrasonography and then 5 cadavers were selected for use in an anatomic study, in which 2 mm thick sections were obtained in the same planes as in the ultrasonographic protocol. Sections were plastinated using the E-12 plastination method and correlated to the corresponding ultrasonographic images. The elbow joints of 5 German Shepherd adult dogs were assessed by ultrasonography for comparison with cadaver images. RESULTS: Good correspondence of soft tissue and bone structures was obtained between ultrasound images and anatomic sections. There was no difference in the ultrasonographic appearance of elbows of cadavers and live dogs in which the muscular, ligamentous, and bone components of the joints were evaluated. CONCLUSION: This study presents a descriptive comparison of anatomic and ultrasonographic images, which will offer clinicians a more comprehensive understanding of the anatomic structures of the canine elbow joint and serve as reference for further imaging diagnostic studies because of the precise correspondence between anatomic plastinated sections and ultrasonographic images.

IMAGING DIAGNOSIS-SPONTANEOUS PNEUMOMEDIASTINUM SECONDARY TO PRIMARY PULMONARY PATHOLOGY IN A DALMATIAN DOG.

A 1.5-year-old, 23 kg intact male Dalmatian dog was evaluated for acute respiratory insufficiency without a previous history of trauma or toxic exposition. Imaging revealed pneumomediastinum, pneumothorax, diffuse unstructured interstitial pulmonary pattern, pulmonary interstitial emphysema, and pneumoretroperitoneum. Histopathological evaluation of the lungs revealed perivascular and peribronchial emphysema, mild lymphocytic interstitial pneumonia with atypical proliferation of type II pneumocytes in bronchioles and alveoli. A lung disease resembling fibrosing interstitial pneumonia in man and cats has been previously reported in Dalmatians and should be included as a differential diagnosis for Dalmatians with this combination of clinical and imaging characteristics.

Description and Evaluation of Dye and Contrast Media Distribution of Ultrasound-Guided Rectus Sheath Block in Cat Cadavers.

The rectus sheath block is an ultrasound-guided anaesthetic technique which aims to provide analgesia to the abdominal midline. This study aimed to assess the distribution of 0.4 mL kg-1 of a mixture of methylene blue and iopromide injected into each hemiabdomen in the internal rectus sheath in cat cadavers. We hypothesise that this technique would be feasible and would cover the rami ventrales of the last thoracic and the first lumbar spinal nerves. The study was divided into two phases. Phase 1 aimed to study the anatomical structures of the ventral abdominal wall (four cats were dissected). Phase 2 (ten cadavers) consisted of an ultrasound-guided injection of the mixture mentioned above and the assessment of its distribution by computed tomography and anatomical dissection. The results showed the staining of the cranioventral abdominal wall with a craniocaudal spread of four (three to eight) vertebral bodies. Methylene blue stained three (one to four) rami ventrales, affecting T10 (60%), T11 (100%), T12 (90%), T13 (50%) and L1 (5%). Based on these results, it could be stated that this technique could supply anaesthesia to the midline of the abdominal midline cranial to the umbilicus in clinical patients, but it may not be able to provide anaesthesia to the middle and caudal midline abdominal region.

Effects of altering the sequence of midazolam and propofol during co-induction of anaesthesia.

OBJECTIVE: To assess the effects of varying the sequence of midazolam and propofol administration on the quality of induction, cardiorespiratory parameters and propofol requirements in dogs. STUDY DESIGN: Randomized, controlled, clinical study. ANIMALS: Thirty-three client owned dogs (ASA I-III, 0.5-10 years, 5-30 kg). METHODS: Dogs were premedicated with acepromazine (0.02 mg kg(-1) ) and morphine (0.4 mg kg(-1) ) intramuscularly. After 30 minutes, group midazolam-propofol (MP) received midazolam (0.25 mg kg(-1) ) intravenously (IV) before propofol (1 mg kg(-1) ) IV, group propofol-midazolam (PM) received propofol before midazolam IV at the same doses, and control group (CP) received saline IV, instead of midazolam, before propofol. Supplementary boluses of propofol (0.5 mg kg(-1) ) were administered to effect to all groups until orotracheal intubation was completed. Behaviour after midazolam administration, quality of sedation and induction, and ease of intubation were scored. Heart rate (HR), respiratory rate, and systolic arterial blood pressure were recorded before premedication, post-premedication, after midazolam or saline administration, and at 0, 2, 5, and 10 minutes post-intubation. End-tidal CO2 and arterial oxygen haemoglobin saturation were recorded at 2, 5 and 10 minutes post-intubation. RESULTS: Quality of sedation and induction, and ease of intubation were similar in all groups. Incidence of excitement was higher in the MP compared to CP (p = 0.014) and PM (p = 0.026) groups. Propofol requirements were decreased in MP and PM groups with respect to CP (p < 0.001), and in PM compared to MP (p = 0.022). The HR decreased after premedication in all groups, and increased after midazolam and subsequent times in MP (p = 0.019) and PM (p = 0.001) groups. Incidence of apnoea and paddling was higher in CP (p = 0.005) and MP (p = 0.031) groups than in PM. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of midazolam before propofol reduced propofol requirements although caused mild excitement in some dogs. Administration of propofol before midazolam resulted in less excitatory phenomena and greater reduction of propofol requirements.

Imaging diagnosis-infiltrative lipoma causing spinal cord and lumbar nerve root compression in a dog.

A 12-year-old, male, fox terrier dog presented with an abnormal gait of the left pelvic limb. Computed tomography revealed a large, homogeneous, hypoattenuating, noncontrast enhancing mass within the left epaxial muscles that invaded the L5-6 vertebral canal and caused spinal cord compression. Imaging findings were consistent with an infiltrative lipoma. The mass was removed and a left hemilaminectomy was performed in the affected area. Histopathology confirmed the mass to be an infiltrative lipoma. The dog recovered and regained neurologic function within 2 weeks. Computed tomography assisted preoperative planning by characterizing the shape, size, and location of the mass.

Modified Ultrasound-Guided Dorsal Quadratus Lumborum Block in Cat Cadavers.

The quadratus lumborum (QL) block is an ultrasound-guided locoregional anesthesia technique which aims to provide analgesia to the abdomen. The main objective of this study was to assess a modified ultrasound-guided dorsal QL block in cat cadavers. For this purpose, a volume of 0.4 mL kg-1 of a mixture of iopromide and methylene blue was administered between the psoas minor muscle and the vertebral body (VB) of the first lumbar vertebra, and its distribution was assessed in thirteen cat cadavers. We hypothesized that this injection point would be feasible, offering a more cranial distribution of the injectate and a more consistent staining of the truncus sympathicus. The study was divided into two phases. Phase 1 consisted of an anatomical study (three cadavers were dissected). Phase 2 consisted of the ultrasound-guided administration of the injectate and the assessment of its distribution by computed tomography and anatomical dissection. The results showed a consistent distribution of contrast media within five (4-8) VBs from T10 to L5. Methylene blue stained three (2-6) rami ventrales, affecting T11 (10%), T12 (20%), T13 (60%), L1 (85%), L2 (95%) and L3 (65%). The truncus sympathicus was dyed in all cadavers with a spread of five (3-7) VBs. Finally, the splanchnicus major nerve was stained in all cadavers (100%). These results suggest that this technique could provide analgesia to the abdominal viscera and the abdominal wall, probably with the exception of the cranial aspects of the abdominal wall.

An Ultrasound-Guided Latero-Ventral Approach to Perform the Quadratus Lumborum Block in Dog Cadavers.

The QL block is a high-level locoregional anesthesia technique, which aims to provide analgesia to the abdomen. Several approaches of the QL block have been studied to find out which one allows a greater distribution of the injectate. The aim of this study is to compare the traditional interfascial QL block (IQL) with a new latero-ventral approach (LVQL). We hypothesize that this new approach could be safer and easier to perform, since the injectate is administered more superficially and further away from vital structures. Our second objective is to assess whether a higher volume of injectate (0.6 mL/kg) could reach the ventral branches of the last thoracic nerves, leading to a blockade of the cranial abdomen. Six thawed canine cadavers (12 hemiabdomens) were used for this purpose. Both approaches were performed in all cadavers. A combination of methylene blue/iopromide was administered to each hemiabdomen, randomly assigned to the LVQL or IQL. No differences were found regarding the ease of perform the LVQL with respect to IQL. The results show that both techniques reached the ventral branches from L1 to L3, although only the IQL consistently stained the sympathetic trunk (5/6 IQL vs. 1/6 LVQL). The use of a higher volume did not enhance a more cranial distribution of the injectate.

Ultrasound-guided 'two-in-one' femoral and obturator nerve block in the dog: an anatomical study.

OBJECTIVE: To evaluate the dye extent and distribution at the lumbar plexus (LP) of three volumes of local anaesthetic-methylene-blue solution administered close to the femoral nerve (FN) by the use of a ventral ultrasound (US)-guided suprainguinal approach (SIA). STUDY DESIGN: Prospective experimental trial. ANIMALS: Twenty mongrel canine cadavers weighing 17.7 ± 3.8 kg (mean ± SD). METHODS: The left and right LP of two cadavers were dissected to identify the FN, obturator nerve (ON) and lateral femoral cutaneous nerve (LFCN). The extent and distribution of dye at the LP of each of three volumes of injectate of 0.2, 0.4 and 0.6 mL kg(-1) administered close to the FN by a ventral US-guided SIA then were studied in a further 18 dog cadavers (n = 6 per group). Staining of ≥2 cm along the target nerves was indicative of sufficient spread to produce a nerve block. RESULTS: The ventral US-guided SIA allowed the observation of the FN within the iliopsoas muscle (IPM) in a total of 17 cadavers. The assessment of the dye extent and distribution revealed a similar pattern regardless of the injected volume. From the injection site, the spreading of injectate occurred in cranial, lateral and caudal directions. The FN and ON were effectively stained in all the cases. The LFCN was not effectively stained in any case. CONCLUSIONS AND CLINICAL RELEVANCE: A volume of 0.2 mL kg(-1) administered close to the FN by a ventral US-guided SIA produced a sufficient distribution of the injectate within the IPM to produce effective staining of the FN and ON. This US-guided technique may be an appropriate alternative to previously reported techniques based on electrolocation to block the FN and ON in the dog.

Ultrasonographic assessment of the renal size using a kidney length to vertebral body length ratio in cats.

Ultrasonographic assessment of the renal size can provide useful clinical information, in combination with other ultrasonographic parameters. The aims of this study were to establish the agreement between the ultrasonographic and radiographic measurements of the kidneys (K) and vertebral bodies (L5 and L6), to establish an ultrasonographic measurement of kidney-to-vertebral body (L5 and L6) ratio to estimate the renal size in cats, and to assess the impact of age, body weight, sex, and gonadal status on the ultrasonographic measurements of the kidneys, vertebral bodies, and ratios. The vertebral bodies of L5 and L6 were chosen as they were easy to identify with ultrasonography (US) using the lumbosacral junction as a landmark, and they are not usually affected by vertebral anomalies. A total of 60 cats (19 intact males, 12 neutered males, 17 intact females, and 12 neutered females) were included in the study. The cats were divided into three age groups (<7 months, 7 months-7 years, and >7 years), two body weight categories (≤ 3.5 kg and >3.5 kg), and two sex and gonadal status groups (male and female, and intact and neutered, respectively). Measurements of the renal and vertebral body length were performed on the radiographic and ultrasonographic images. Two different ratios were obtained, namely, K/L5 and K/L6. There was no significant difference between the length of both kidneys and the length of the vertebral bodies of L5 and L6 on ultrasonographic or radiographic images. There was a good agreement between ultrasonographic and radiographic measurements of both kidneys and vertebral bodies. In conclusion, the kidney length to L6 length ratio obtained was 1.81 ± 0.20 (1.76-1.86), which was useful for evaluating the size of the feline kidney and was not influenced by the age, body weight, sex, or gonadal status.

Evaluation of High-Volume Injections Using a Modified Dorsal Quadratus Lumborum Block Approach in Canine Cadavers.

The quadratus lumborum (QL) block targets the fascial plane surrounding the QL muscle providing abdominal somatic and visceral analgesia. The extension of its analgesic effects is a subject of research, as it could not cover areas of the cranial abdomen in dogs. This study assesses in eight thawed canine cadavers, the distribution of high-volume injections (0.6 mL kg-1 of a mixture of methylene blue and iopromide) injected between the psoas minor muscle and the vertebral body of L1. Anatomical features of the area of interest were studied in two cadavers. In another six dogs, QL blocks were performed bilaterally under ultrasound-guidance. The distribution of contrast was evaluated by computed tomography (CT). Hypaxial abdominal muscles were dissected to visualize the dye spread (spinal nerves and sympathetic trunk) in 5 cadavers. The remaining cadaver was refrozen and cross-sectioned. CT studies showed a maximum distribution of contrast from T10 to L7. The methylene blue stained T13 (10%), L1 (100%), L2 (100%), L3 (100%), L4 (60%) and the sympathetic trunk T10 (10%), T11 (20%), T12 (30%), T13 (70%), L1 (80%), L2 (80%), L3 (60%) and L4 (30%). These findings may suggest that despite the high volume of injectate administered, this modified QL block could not produce somatic analgesia of the cranial abdomen, although it could provide visceral analgesia in dogs.

Ultrasonographic measurement of adrenal gland-to-aorta ratio as a method of estimating adrenal size in dogs.

BACKGROUND: Adrenal size has been used as the principal criterion for differentiating a normal gland from adrenal hyperplasia. The objectives of this study were to establish an ultrasonographic measurement of adrenal gland-to-aorta (adrenal/Ao) ratio to estimate the adrenal size and to assess the effects of bodyweight, age and sex on the adrenal/Ao ratio in non-adrenal gland disease dogs. METHODS: Two hundred and thirty-four dogs (120 entire females and 114 entire males) considered non-adrenal gland disease were included in this study. Dogs were allocated into three bodyweight categories (<10 kg, 10-20 kg and >20 kg), and four age groups (<1 year, 1-5 years, 5-10 years and >10 years old). Measurements of the maximal thickness of caudal pole of both adrenal glands and the aortic luminal diameter in sagittal plane were performed on the ultrasonographic images. Three different ratios were calculated for each dog. RESULTS: Sex and age did not influence on the adrenal/Ao ratio. There were differences (P<0.05) between the three dog sizes for adrenal/Ao ratio, being the highest value for small size and the lowest value for large size. CONCLUSIONS: In this study, only bodyweight influences the ultrasound measurement of the adrenal/Ao ratio in non-adrenal gland disease dogs.

Changes in Renal Resistive Index Values in Healthy Puppies during the First Months of Life.

The purpose of this study is to establish renal resistive index (RRI) of normal kidneys in puppies aged from newborn to 20 weeks of age and to determine the age at which RRI reaches adult dog values. Six healthy adult intact beagles and six puppies from 1 day after birth to 20 weeks of age were used. In the adult dogs, the ultrasonographic scans were performed once, and in the puppies, the ultrasonographic studies were performed on the first day after birth and at 1, 2, 3, 4, 6, 8, 12, 16, and 20 weeks of age. RRI was obtained at the interlobular and arcuate arteries in each kidney. There were no statistical differences between the RRI values obtained between the right and left kidney nor between intrarenal arteries (interlobar and arcuate). The RRI was the highest during the first weeks of life, after which it declined gradually with increasing age reaching adult dog values at 12 weeks of age. In conclusion, the normal mean RRI is age dependent in dogs. Twelve weeks can be regarded as the age at which adult mean RRI criteria can be applied to puppies.

Short-Term Effects of Deliberate Subparaneural or Subepineural Injections With Saline Solution or Bupivacaine 0.75% in the Sciatic Nerve of Rabbits.

Background: Ultrasound (US)-guided techniques for peripheral nerve blockade have revealed that intraneural injections are relatively frequent and not necessarily associated with neurological deficits. Objectives: To evaluate the short-term effects of deliberate injections performed under direct vision in two different sites of the sciatic nerve (ScN). Material and Methods: Seventy-two New Zealand white rabbits randomly assigned to one of four experimental groups (n = 18) were employed. All procedures were conducted at a proximal femoral level where the ScN incorporates the common peroneal nerve and the tibial nerve (TN). Fixed volumes of 0.5 ml of saline solution (ES group) or bupivacaine 0.75% (EB group) were administered extrafascicularly inside the paraneurium of the ScN or intrafascicularly (IS and IB groups) under the epineurium of the TN. Cross-sectional area (CSA) and relative echogenicity (RE) of the entire ScN were determined by US before injections, after injections, and at 3 and 7 days. ScN samples were obtained for structural and ultrastructural histopathological studies. Proprioceptive, sensorial, and motor function were clinically evaluated on a daily basis. Results: The CSA of the ScN increased significantly immediately after injections when compared with pre-injection values in all groups (p < 0.05). The RE of the ScN decreased in relation to pre-injection values in all groups (p < 0.05). The CSA and RE of the ScN returned to normal values 7 days after injections in almost all groups. Injected nerves showed histological signs of mild perineural inflammation. Histopathological scores were not significantly different between groups (p > 0.05). The architecture of the ScN was preserved in all rabbits at 3 days and in 31/32 rabbits at 7 days. A focal area of damaged nerve fibers with degeneration of the axons and myelin sheath affecting the TN was observed in one rabbit of the IB group. Nerve function was not clinically impaired in any case. Conclusion: Despite the lack of severe nerve disruption observed in most rabbits, the evidence of a focal area of damaged nerve fibers in one rabbit injected intrafascicularly with bupivacaine confirms that intrafascicular injections should be avoided as they may increase the risk of nerve damage.

Ultrasonographic characteristics (cross-sectional area and relative echogenicity) of the digital flexor tendons and ligaments of the metacarpal region in Purebred Spanish horses.

The objectives of this study were to establish normal values for relative echogenicity (RE) and cross-sectional area (CSA) of the flexor tendons and ligaments of the metacarpal region of Purebred Spanish horses (PBSH), and to determine the effect of body mass index (BMI), age, sex and forelimb on these variables. Transverse ultrasonographic images were obtained using 20 normal PBSH (10 females, 10 males; 2-25 years of age; BMI 132.04-152.25; not in training). The images were digitised and values for CSA and RE were determined for each structure. The suspensory ligament was the most echogenic and the largest structure, and the superficial digital flexor tendon was the least echogenic and smallest of the tissues examined. The tendons and ligaments of the metacarpal region in PBSH showed similar RE but smaller CSAs when compared to other breeds.

Thoracic omentalization for long-term management of neoplastic pleural effusion in a cat.

CASE DESCRIPTION: An 11-year-old neutered female domestic longhair cat was evaluated because of a 1-week history of progressive dyspnea, signs of depression, and loss of appetite. A histiocytic sarcoma had been excised from the mammary gland 6 weeks earlier. CLINICAL FINDINGS: Physical examination findings were consistent with pleural effusion, and thoracic and abdominal radiography and ultrasonography revealed pleural effusion, a thoracic mass involving the aorta and pulmonary artery, and a caudal abdominal mass that most likely represented enlarged iliac lymph nodes. Cytologic examination of the pleural fluid and fine-needle aspirates from the iliac and right popliteal lymph nodes revealed abundant cells with neoplastic characteristics of indeterminate origin. The clinical diagnosis was generalized malignant neoplasia. TREATMENT AND OUTCOME: Pleural drainage was necessary every 5 to 6 days. Exploratory thoracotomy and biopsy of the mass were recommended for better characterization of the thoracic disease. Simultaneously, palliative treatment by advancement of the omentum into the thorax was performed. A final diagnosis of disseminated histiocytic sarcoma was made, and treatment with doxorubicin was begun after surgery. During the 13 months after surgery, the cat was free from signs of respiratory tract disease and had normal activity levels with good exercise tolerance. Fifteen months after surgery, the cat's clinical condition worsened and the cat died. CLINICAL RELEVANCE: Findings suggested that thoracic omentalization may be considered for palliative treatment of cats with refractory neoplastic pleural effusion when frequent thoracocentesis is necessary and other treatments are not suitable.