Ultrasound of the Canine and Feline Gastrointestinal Tract: Normal and Abnormal Findings

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-11

Key Takeaways

• Normal gastrointestinal wall layering is visualized as five distinct echogenic and hypoechoic bands, corresponding to the mucosal surface, mucosa, submucosa, muscularis, and serosa. Loss of this distinct layering, particularly the hyperechoic submucosa, is a strong indicator of infiltrative disease, most commonly neoplasia such as lymphoma or adenocarcinoma.
• Wall thickness measurements are critical but require careful technique and species-specific reference ranges, with normal values varying by segment (e.g., gastric pylorus is normally thicker than the jejunum). Measurements should exclude intraluminal contents and be taken perpendicular to the beam.
• Distinguishing inflammatory bowel disease (IBD) from low-grade alimentary lymphoma in cats is a significant diagnostic challenge on ultrasound alone, as both can present with symmetric wall thickening and preserved layering. Biopsy is generally required for definitive diagnosis in these cases.
• Mechanical obstruction is identified by dilated, fluid-filled intestinal loops proximal to a transition point, where the calibre abruptly changes. Linear foreign bodies can cause a characteristic "pleated" or "accordion" pattern. Pneumoperitoneum, indicated by reverberation artifact, suggests perforation and mandates surgical exploration.
• Mesenteric lymphadenopathy (enlarged lymph nodes) is a non-specific finding, common in both inflammatory and neoplastic conditions, requiring further investigation to determine the underlying cause.
• Ultrasound is a first-line modality for evaluating vomiting, diarrhea, and weight loss, but its diagnostic accuracy for specific diseases is limited, and histopathology remains the reference standard for definitive diagnosis, especially for differentiating neoplastic from inflammatory processes.

Ultrasonography is a first-line imaging modality for the investigation of vomiting, diarrhea, weight loss, and suspected gastrointestinal neoplasia in dogs and cats. This article provides a structured approach to the sonographic evaluation of the stomach, small intestine, and large intestine, with emphasis on wall layer identification, measurement standards, and the diagnostic reasoning that distinguishes inflammatory from neoplastic disease. It is written for the practicing veterinarian who performs or interprets abdominal ultrasound and who needs a practical framework for recognizing normal variation, artefact, and clinically significant abnormality.

The examination of the gastrointestinal tract requires a systematic technique, a working knowledge of regional anatomy, and an appreciation of how patient positioning, intraluminal content, and transducer frequency affect image quality. This first part establishes the conceptual foundation: the sonographic appearance of the normal bowel wall, the physiological basis of peristalsis and wall thickness, and the interpretive principles that govern the remainder of the article. Later parts address specific disease categories, including foreign bodies, inflammatory disease, neoplasia, and the role of ultrasound in guiding biopsy.

At a Glance

Physical Principles of Gastrointestinal Sonography

The gastrointestinal wall is visualized as alternating hyperechoic and hypoechoic bands that correspond to histological layers. From the lumen outward, these are the mucosal surface, the mucosa, the submucosa, the muscularis, and the serosa. The mucosal surface and submucosa appear hyperechoic, while the mucosa and muscularis appear hypoechoic. The serosa is a thin hyperechoic line that may be difficult to distinguish from surrounding fat.

Transducer frequency determines the resolution of these layers. A 7.5 to 12 MHz linear transducer is required to reliably identify all five layers in cats and small dogs. Lower frequency curvilinear transducers may fail to resolve individual layers in deep-chested or obese patients, and the examiner should record which layers were visible and at what frequency. The American College of Veterinary Radiology resources on diagnostic imaging practice emphasize that image optimization, including appropriate gain settings and focal zone placement, is a prerequisite for accurate interpretation.

Wall thickness is measured from the outer margin of the serosa to the luminal surface of the mucosa, excluding the contents of the lumen. Measurements should be taken at a point where the wall is perpendicular to the ultrasound beam to avoid oblique sectioning, which artificially increases apparent thickness. The stomach should be assessed both when collapsed and when distended with a small volume of fluid or food, because wall thickness varies with distension.

Normal Sonographic Anatomy

The stomach lies in the cranial abdomen, caudal to the liver, and its position varies with gastric filling. The fundus and body are located on the left, while the pyloric antrum and pylorus are on the right. The gastric wall is thickest at the pylorus, and the examiner should not mistake this normal regional variation for pathology. The rugal folds are visible as echogenic projections into the lumen when the stomach is collapsed.

The duodenum is identified in the right cranial abdomen, running caudally from the pylorus. It is the only intestinal segment that consistently lies adjacent to the right lobe of the pancreas, and its identification is aided by the presence of the pancreatic duct entering its wall. The jejunum occupies the mid-abdomen and is the most mobile segment. The ileum is identified by its thicker muscularis and its relationship to the ileocolic junction, which lies in the left cranial abdomen in dogs and is more variable in cats.

Normal peristalsis is visible as rhythmic contractions that propagate aborally. The frequency is higher in the duodenum than in the jejunum or ileum. The examiner should observe at least three to five contraction cycles before concluding that motility is abnormal. The MSD Veterinary Manual provides species-specific reference values for intestinal motility and wall thickness that are useful when interpreting borderline measurements.

Interpretive Principles for Wall Thickening

Wall thickening is the most common abnormality identified in gastrointestinal ultrasound, but it is not specific for any single disease. The distribution of thickening, the preservation or loss of layering, and the echogenicity of the affected wall provide the diagnostic clues. Symmetric thickening with preserved layering is typical of inflammatory disease, while asymmetric thickening with loss of layering is more suggestive of neoplasia.

In cats, the distinction between inflammatory bowel disease and low-grade alimentary lymphoma is particularly challenging. A retrospective study of feline intestinal disorders found that a gastrointestinal mural mass was visualized in 41% of intermediate and high grade alimentary lymphoma cases but in 0% of low-grade cases, and that wall thickening was the most commonly reported abnormality overall. The authors concluded that low-grade lymphoma cannot be reliably distinguished from inflammatory bowel disease on ultrasound alone, and that biopsy is required for diagnosis. This finding is supported by a machine learning study that combined ultrasound radiomics with blood and serum biomarkers, which achieved moderate accuracy for distinguishing lymphoma from inflammatory bowel disease but could not replace histopathology.

Loss of wall layering is a more reliable indicator of neoplasia than wall thickness alone. When layering is lost, the examiner should describe whether the loss is focal or diffuse, and whether it involves the full thickness of the wall or a single layer. Focal loss of layering with a mass effect is typical of adenocarcinoma, while diffuse loss of layering with mild thickening is more typical of lymphoma. The feline infectious peritonitis update reported that intestinal changes in affected cats were characterized by asymmetric wall thickening and loss of layering, with the ileocecocolic junction and colon most commonly involved, which illustrates that these findings are not exclusive to neoplasia.

The Role of Ultrasound in Feline Inflammatory and Neoplastic Disease

Feline chronic enteropathies present a diagnostic dilemma because clinical signs, laboratory findings, and ultrasonographic changes overlap considerably. The concept of feline triaditis, the concurrent inflammation of the pancreas, liver, and intestine, is well recognized, and ultrasound is often the first imaging modality to raise suspicion of multi-organ involvement. The feline triaditis review notes that the short small intestine, high bacterial load, and the anatomic arrangement of the pancreatic and common bile ducts in cats increase the risk of bacterial reflux and parenchymal inflammation, which explains why pancreatic and intestinal changes frequently coexist.

Serum feline pancreatic lipase immunoreactivity (fPLI) is often measured in cats with suspected inflammatory bowel disease, and its relationship to ultrasonographic findings has been examined. A study comparing cats with normal and increased fPLI concentrations found that cats with markedly increased fPLI had significantly lower serum albumin and cobalamin concentrations, suggesting more severe disease, but no significant differences in pancreatic ultrasound findings between groups. This indicates that a normal pancreatic ultrasound does not exclude pancreatitis, and that the absence of ultrasonographic pancreatic changes should not deter the clinician from pursuing a diagnosis of triaditis.

Feline large granular lymphocyte lymphoma is an aggressive subtype that is frequently localized within the gastrointestinal tract. The SIONCOV retrospective study reported that 91.7% of affected cats had gastrointestinal involvement, and that median survival was only 21 days. Ultrasonographic findings in these cats were not described in detail, but the high frequency of gastrointestinal localization underscores the importance of a thorough intestinal examination in any cat presenting with weight loss, vomiting, or diarrhea, particularly when anemia or hypoalbuminaemia is present.

Systematic Examination Protocol

A complete gastrointestinal ultrasound examination follows a fixed sequence so that no segment is overlooked and so that abnormal findings are interpreted in context. Begin with the stomach, then the duodenum, jejunum, ileum, and ileocecocolic junction, and finish with the colon. Use a microconvex or curvilinear transducer for the stomach and deep abdominal segments, then switch to a linear array at 10 to 18 MHz for detailed wall layer assessment. In cats and small dogs, the higher frequency linear probe often suffices for the entire examination.

Position the patient in dorsal recumbency for the duodenum and jejunum, then roll to lateral recumbency to evaluate the gastric fundus and pylorus. The stomach is identified by its rugal folds and location caudal to the liver. The duodenum runs along the right body wall and is distinguished from jejunum by its larger diameter and the presence of the pancreatic limb adjacent to it. The ileum is the segment immediately oral to the ileocecocolic junction and is consistently thicker than the jejunum in normal animals. The colon is recognized by its sacculations and luminal gas pattern.

Apply steady, graded compression to displace gas and improve contact. Excessive pressure collapses the lumen and artificially thickens the wall, so release pressure periodically and re-measure. Evaluate each segment in both longitudinal and transverse planes. Measure wall thickness from the outer serosal surface to the luminal surface of the mucosa, excluding the contents. Take measurements at the thickest point of each segment, and record the thickness of each individual layer when they can be resolved.

Wall Layer Identification and Measurement

The normal gastrointestinal wall shows five layers on high-frequency ultrasound. From lumen outward, these are the hyperechoic mucosal surface, the hypoechoic mucosa, the hyperechoic submucosa, the hypoechoic muscularis, and the hyperechoic serosa. The mucosal surface echo merges with the submucosa when the lumen is collapsed, which can make the wall appear three-layered. Distend the lumen with a small volume of water or oral contrast to separate these layers when differentiation matters.

Normal wall thickness varies by segment and species. The following reference ranges are widely accepted for dogs and cats:

These values apply to measurements taken with the lumen mildly distended. A collapsed loop can measure up to 1 mm thicker. The ileum is normally the thickest small intestinal segment in cats, and the muscularis layer of the feline ileum is often visibly thicker than that of the jejunum. Do not interpret this as pathology without corroborating findings.

Wall layer preservation is as informative as absolute thickness. Loss of the normal five-layer pattern, particularly obliteration of the submucosal hyperechoic line, indicates infiltrative or neoplastic disease. Focal disruption with preservation of adjacent layers suggests a mural mass or foreign body. Symmetric thickening with preserved layering is more consistent with inflammatory disease, though low-grade lymphoma can mimic this pattern closely.

Differential Diagnosis of Wall Thickening

The differential list for gastrointestinal wall thickening is organized by layer pattern, distribution, and signalment. The following table prioritizes diagnoses by sonographic presentation:

Feline infectious peritonitis produces intestinal changes in a substantial proportion of affected cats, with asymmetric wall thickening and loss of layering reported in 68% of cases in one series, most commonly at the ileocecocolic junction and colon. The presence of effusion and lymphadenopathy in the same patient strongly supports FIP over primary intestinal disease. Feline infectious peritonitis abdominal ultrasound findings

Feline low-grade alimentary lymphoma is a particular diagnostic challenge because it often produces only mild, symmetric thickening with preserved layering, indistinguishable from inflammatory bowel disease on ultrasound. In one Australian series, low-grade lymphoma accounted for 28% of all alimentary lymphoma cases when cytologic diagnoses were included, and none of the low-grade cases showed a discrete mural mass. Feline low-grade alimentary lymphoma prevalence A mural mass in a cat is therefore more suggestive of intermediate or high-grade lymphoma, which can often be diagnosed by cytology of the lesion or regional lymph node.

Foreign Bodies and Mechanical Obstruction

Ultrasound detects radiolucent foreign bodies that plain radiography misses. A foreign body appears as an intraluminal structure with a strong luminal surface echo and distal shadowing. The shadow may be clean (bone, metal, dense rubber) or dirty (cloth, sponge, plant material). Cloth foreign bodies can be subtle, appearing as a focal luminal content with mild shadowing and proximal bowel dilation. Look for the "edge shadowing" sign at the margins of the foreign body and for a visible interface between the foreign body and the bowel wall.

The sonographic diagnosis of mechanical obstruction rests on identifying a transition point. Measure the diameter of multiple loops. A small intestinal diameter greater than 1.2 times the height of the L5 vertebral body in dogs, or greater than 6 mm in cats, supports obstruction when combined with a visible transition. The transition point is the segment where dilated, fluid-filled loops abruptly become normal or collapsed. Sweep the transducer slowly along the dilated loops to find this point. Linear foreign bodies produce a characterizticplicated or accordion pattern, with the bowel gathered along the foreign body and multiple luminal interfaces visible.

Pneumoperitoneum, indicated by reverberation artifact between the liver and body wall or between bowel loops, suggests perforation and mandates surgical exploration. Free abdominal fluid with a foreign body increases the suspicion of perforation. When the foreign body is not identified but obstruction is suspected, repeat ultrasound after 6 to 12 hours or proceed to contrast radiography or CT.

Documentation and Reporting

Record the wall thickness of each segment, the layer pattern, the presence or absence of peristalsis, and the location of any abnormality relative to fixed landmarks. Store cine loops of peristalsis and still images of each segment in longitudinal and transverse planes. Measure and record the diameter of dilated loops and the location of any transition point. Note the presence and character of peritoneal fluid, and describe lymph nodes by size, shape, echogenicity, and corticomedullary distinction.

The written report should state whether the gastrointestinal tract is normal or abnormal, list the abnormal segments, and provide a prioritized differential list. State explicitly when a sonographic finding is nonspecific and when tissue sampling is required. For cats with suspected inflammatory or neoplastic disease, ultrasound-guided fine needle aspiration of thickened bowel or enlarged lymph nodes can provide a cytologic diagnosis in intermediate and high-grade lymphoma, but low-grade lymphoma requires full-thickness biopsy for histopathology. Feline large granular lymphocyte lymphoma clinical features The choice between endoscopic and surgical biopsy depends on lesion location, layer involvement, and the need for full-thickness samples. Ultrasound findings guide this decision by identifying which segments are affected and whether the muscularis is involved.

Document the limitations of the examination. Gas-filled loops, deep thoracic conformation, and patient movement all reduce image quality. State in the report when a segment could not be evaluated and recommend re-examination or alternative imaging. Serial ultrasound is valuable for monitoring response to therapy in inflammatory disease, but the changes are often slow and may lag behind clinical improvement.

Recognized Complications and Early Detection

Mechanical obstruction from intraluminal foreign material carries the highest immediate risk in gastrointestinal sonography. The hallmark findings are a distended, fluid-filled stomach or small intestine oral to the obstruction, with a hypermotile segment immediately proximal to the luminal mass and reduced motility distal to it. Early detection depends on identifying the transition zone, the point where bowel calibre changes abruptly. When peristalsis is absent in the distended segment, ischemia or perforation may already be present. Serial examinations performed 6 to 12 hours apart can distinguish progressive distension from transient ileus, and this interval approach is often more informative than a single static study.

Perforation is the most dangerous complication to miss. Free peritoneal gas appears as reverberation artefact with dirty shadowing, most reliably identified with the patient in dorsal recumbency using a high-frequency linear probe over the most non-dependent portion of the abdomen. Focal peritonitis may present as hyperechoic mesenteric fat adjacent to the affected bowel segment, with or without a small volume of anechoic peritoneal fluid. In cats, the presence of effusion with asymmetric intestinal wall thickening and loss of layering should raise suspicion for feline infectious peritonitis, particularly when lymphadenopathy and hepatic changes are also present, as described in an update on abdominal ultrasonographic findings in cats with FIP (Müller et al., institutional publication).

Intussusception is recognized by the target-like or multilayered appearance on transverse imaging. Early detection matters because the intussusceptum may remain viable for hours, and manual reduction or surgical correction is more likely to succeed before vascular compromise develops. Color Doppler interrogation of the intussusceptum can identify residual arterial flow, and absence of flow is a poor prognostic indicator.

Common Errors and Corrective Actions

The most frequent error in gastrointestinal ultrasound is over-interpreting a single thickened loop as pathological. Wall thickness varies with transducer frequency, patient size, and the degree of luminal distension. A collapsed loop can appear falsely thickened, and a tangential section through a normal loop creates an artifactual increase in measured thickness. The corrective action is to measure the wall only when the lumen contains a small amount of fluid or gas and the loop is imaged in true cross-section, with the muscularis layer visible as a distinct hypoechoic band.

A second common error is mistaking the normal hypoechoic muscularis for a mass. This occurs most often in the stomach, where the muscularis is thickest at the pylorus. The discriminating feature is symmetry: normal muscularis thickening is uniform and follows the curvature of the organ, whereas a neoplastic infiltrate produces asymmetric, irregular thickening with disruption of adjacent layers.

A third error is failing to distinguish artefact from pathology. Distal acoustic shadowing from intraluminal gas is frequently misread as a foreign body. The corrective action is to reposition the patient or apply graded compression to displace gas, then reassess whether the shadow persists. True foreign bodies typically produce a clean shadow with a hyperechoic leading edge, whereas gas produces dirty shadowing with reverberation.

The table below summarizes common failure modes and their discriminating checks.

Limitations of Current Evidence

The evidence base for gastrointestinal ultrasound in dogs and cats is strongest for pattern recognition and weakest for diagnostic accuracy in specific diseases. Studies comparing ultrasonographic findings with histopathology are limited by selection bias, because biopsy is more likely to be performed in animals with severe or progressive disease. In feline low-grade alimentary lymphoma, for example, a gastrointestinal mural mass is rarely visualized, and wall thickening is the most commonly reported abnormality, but thickening alone does not distinguish lymphoma from inflammatory bowel disease (Russell et al., institutional publication).

Machine-learning approaches to classify feline intestinal disease from ultrasound images, complete blood count, and serum biochemistry have shown moderate accuracy for distinguishing normal from abnormal, but substantially lower accuracy for discriminating lymphoma from inflammatory bowel disease (Basran et al., institutional publication). These tools are not yet ready for clinical decision-making, and histopathology remains the reference standard.

Expert opinion still differs on the clinical significance of mild wall thickening in cats with chronic gastrointestinal signs. Some authors advocate early biopsy, while others recommend a therapeutic trial before invasive sampling. The presence of concurrent pancreatitis, cholangitis, and inflammatory bowel disease, the feline triaditis complex, further complicates interpretation, because ultrasonographic changes in one organ may reflect disease in another (Černá et al., institutional publication).

Referral, Consultation, and Reporting

Referral to a veterinary radiologist is warranted when the examination is technically difficult, when findings are equivocal but clinical signs are progressive, or when advanced imaging such as contrast-enhanced ultrasound is likely to change management. A specialist should also be consulted when a suspected foreign body cannot be confidently confirmed or excluded, because the consequences of a false negative are severe.

Laboratory involvement is indicated when ultrasonographic findings suggest diffuse infiltrative disease. Serum cobalamin and folate concentrations, pancreatic lipase immunoreactivity, and bile acid testing should be interpreted alongside the ultrasound findings, because no single modality is diagnostic. Cats with inflammatory bowel disease and increased pancreatic lipase immunoreactivity have lower serum albumin and cobalamin concentrations, and this combination carries prognostic significance (Bailey et al., institutional publication).

Regulatory reporting is rarely required for gastrointestinal ultrasound findings. The exceptions are cases where zoonotic disease is suspected, such as intestinal tuberculosis or larval migrans, and cases involving suspected animal cruelty or foreign body ingestion with legal implications. In these circumstances, the AVMA practice resources provide guidance on professional obligations, and the WOAH terrestrial animal health standards apply where international movement of animals is involved.

Frequently Asked Questions

How Should I Adjust My Examination When Only a Low-Frequency Curvilinear Probe Is Available?

A low-frequency curvilinear probe cannot resolve the five-layer mural pattern reliably. Wall thickness measurement remains possible, but layer identification and subtle changes such as focal loss of layering will be missed. Use the urinary bladder as an acoustic window for the duodenum and measure the wall at the gastric body and pylorus where the lumen is compressible. If a linear or microconvex probe is unavailable, document that layer assessment was limited and recommend re-examination with higher-frequency equipment when feasible. The American College of Veterinary Radiology resources provide guidance on transducer selection and image optimization for abdominal studies.

What Is the Minimum Set of Images I Should Store for a Gastrointestinal Ultrasound Study?

Store at least one long-axis and one short-axis clip or cine loop of each segment: gastric fundus, body, pylorus, duodenum, jejunum, ileum, and colon. Include a transverse image with the wall measured at the thickest point and a longitudinal image showing peristalsis. Record the location of any abnormality relative to palpable or visible landmarks, and capture the mesenteric lymph nodes and pancreas in every feline study. This minimum set supports retrospective review, serial comparison, and defensible reporting. The MSD Veterinary Manual recommends consistent image labeling with patient identification, date, and transducer frequency for medicolegal clarity.

How Do I Distinguish a Benign Transient Wall Thickening from a Clinically Significant Lesion?

Transient thickening from spasm or recent eating usually preserves layering, is non-circumferential, and resolves on re-evaluation after 10 to 15 minutes or with gentle compression. Significant lesions show persistent, often asymmetric thickening, loss of layering, or regional lymphadenopathy. In cats, asymmetric thickening with loss of layering was reported in 68% of confirmed or presumed feline infectious peritonitis cases, often at the ileocecocolic junction, so this pattern is not specific to neoplasia (abdominal ultrasonographic findings of cats with feline infectious peritonitis). Repeat the scan after a short interval and correlate with clinical progression before committing to a biopsy recommendation.

What Should I Tell an Owner When Ultrasound Findings Are Equivocal but Clinical Signs Persist?

Explain that ultrasound identifies structural changes but cannot always distinguish inflammation from early neoplasia. In cats, low-grade alimentary lymphoma may show only mild wall thickening without a mural mass, whereas high-grade forms more often present with a visible mass (feline low-grade alimentary lymphoma prevalence study). State that biopsy, endoscopic or full-thickness, is the definitive step when clinical signs warrant it. Offer a staged plan: medical management with re-imaging in two to four weeks, or immediate biopsy if weight loss, hypoalbuminemia, or hypocobalaminemia are present. Frame the discussion around probability, not certainty.

How Should I Document Serial Ultrasound Examinations for Chronic Gastrointestinal Disease?

Use a standardized worksheet that records wall thickness per segment, layer visibility, peristalsis grade, lymph node size and echogenicity, and presence of effusion. Record the same segments at each visit so comparisons are valid. Note the fasting status and whether sedation was used, as both affect motility and wall measurements. Include the ultrasound findings in the medical record alongside body weight, serum cobalamin, and feline pancreatic lipase immunoreactivity when available, since cats with inflammatory bowel disease and increased pancreatic lipase have lower albumin and cobalamin concentrations (comparison of cats with normal and increased fPLI in inflammatory bowel disease). This integrated record supports treatment decisions better than isolated imaging reports.

When Should I Recommend Referral for Advanced Imaging or Endoscopic Ultrasound?

Refer when the lesion is beyond the reach of a standard linear probe, when full-thickness biopsy is needed but surgical risk is high, or when the ultrasound findings do not explain the clinical severity. Endoscopic ultrasound is not widely available in veterinary practice, so referral centers with this capability should be identified in advance. Refer also when a gastrointestinal mural mass is detected in a cat, because high-grade lymphomas are often cytologically diagnosable from fine-needle aspirates and prognosis is poor without prompt treatment (feline large granular lymphocyte lymphoma retrospective study). Early referral avoids repeated inconclusive scans and shortens time to definitive therapy.

Related Clinical & Scientific Guides

• MRI Monitoring of Brain Tumor Response to Therapy in Dogs
• Ultrasound-Guided Drainage of Abscesses in Small Animals
• Radiographic Monitoring of Total Hip Replacement in Dogs

References and Further Reading

• Abdominal ultrasonographic findings of cats with feline infectious peritonitis: an update.. 2023.
• Feline large granular lymphocyte lymphoma: An Italian Society of Veterinary Oncology (SIONCOV) retrospective study.. 2018.
• Feline comorbidities: What do we really know about feline triaditis?. 2020.
• Feline low-grade alimentary lymphoma: how common is it?. 2012.
• Combining ultrasound radiomics, complete blood count, and serum biochemical biomarkers for diagnosing intestinal disorders in cats using machine learning.. 2023.
• Comparisons between cats with normal and increased fPLI concentrations in cats diagnosed with inflammatory bowel disease.. 2010.
• American College of Veterinary Radiology Resources. American College of Veterinary Radiology.
• MSD Veterinary Manual, Professional Edition. MSD Veterinary Manual.
• American Veterinary Medical Association Practice Resources. American Veterinary Medical Association.

Related Articles

• Ultrasound of the Canine and Feline Liver and Biliary System: Normal and Abnormal Findings
• Ultrasound of the Canine and Feline Urinary Tract: Kidneys, Ureters, and Bladder
• Abdominal Ultrasound in Cats: Normal Findings and Common Abnormalities
• Ultrasonography of the Equine Abdomen: Indications and Findings
• Imaging the Canine and Feline Spine: Radiography and Advanced Modalities

This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.