Abdominal radiography

• Many exotic animals present to the veterinary clinician for non-specific clinical signs of ill-health, including lethargy, depressed demeanor and anorexia. Abdominal radiography may form part of the initial diagnostic investigation in these cases.
• Certain presenting conditions such as abdominal pain, abdominal distension and/or masses, vomiting/regurgitation, dysuria, dystocia may suggest abnormalities of the abdominal organs (including but not exclusive of the gastrointestinal, urinary, or reproductive tract), and thus abdominal radiography would be of value in these cases.
• When clinical history and physical exam may indicate that there are high probabilities that the problem is found in the abdominal cavity, for example when the clinical history indicate pregnancy or foreign body ingestion or when a female guinea pig is presented with bilateral alopecia (which is indicative of ovarian cysts).

Uses

• Imaging of the abdominal cavity forms part of the veterinarian’s initial diagnostic investigation when disease process(es) pertaining to abdominal viscera are suspected:
  • Gastrointestinal tract including the liver: abdominal radiography is considered an essential part of the diagnostic process of gastrointestinal stasis in guinea pigs Gastrointestinal stasis.
  • Spleen Splenomegaly.
  • Urinary tract: urolithiasis Urolithiasis in a common condition in both male and female guinea pigs and affected animals may present with non-specific clinical signs.
  • Reproductive tract: cystic ovaries Cystic ovarian disease are commonly identified in older female guinea pigs; concurrent disease of the reproductive tract such as uterine leiomyoma Uterine neoplasia may also be present.
  • Identification of gravidity or dystocia:
    • Use of radiography in early mammalian pregnancy can be contraindicated due to effects of radiation on the developing fetus.
    • Confirmation of a gravid uterus in mammals using abdominal radiography may not be possible until mid- to late gestation.
  • Abdominal masses.
  • Radiography is usually a readily accessible and inexpensive imaging modality for most veterinarians and clients, therefore is often the primary imaging modality.

Advantages

• Non-invasive.
• Relatively straightforward and affordable procedure, using equipment available to the majority of veterinarians.
• Readily performed and interpreted compared to ultrasonography or other advanced imaging techniques.
• Often forms part of the initial database when an animal presents with non-specific signs of disease.

Disadvantages

• Sedation/anesthesia is generally required unless the animal is in poor clinical status and is minimally responsive and/or obtunded.
• The extensive gastrointestinal tract of mammalian hindgut fermenters such as the guinea pig which is typically filled with digesta can create a mass effect that may limit serosal detail of other abdominal organs.
• Relatively insensitive for the confirmation of gravidity early in the mammalian gestation period. Radiography in early mammalian pregnancy can also be contraindicated due to effects of radiation on the developing fetus.
• Adjunctive diagnostic imaging modalities such as ultrasonography, may be required to fully assess the morphology in the organ of interest, eg hepatomegaly Hepatomegaly, splenomegaly Splenomegaly, cystitis Cystitis, prostatomegaly, confirmation of gravidity early in the gestation period.

Technical problems

• Poor patient positioning:
  • Inadequate patient restraint, including inadequate sedation/anesthesia.
  • Conscious snakes typically show some degree of spinal curvature and rotation.
• Poor radiographic contrast:
  • Exposure errors: can be adjusted to some extent if digital radiology system used.
  • Patients that are lean or underweight will have poorer abdominal serosal detail.
  • The extensive gastrointestinal tract of the guinea pig which is typically filled with digesta can create a mass effect that may limit serosal detail of other abdominal organs. Also seen when there is extensive gastrointestinal gas accumulation.

Alternative techniques

• Ultrasonography:
  • The extensive gastrointestinal tract of mammalian hindgut fermenters such as the guinea pig may limit the acoustic window available for sonographic examination of the abdominal viscera.
  • Provides added diagnostic value for the investigation of intraluminal abnormalities, eg gastrointestinal foreign body, and/or the morphology in an organ of interest.
  • Investigation of abdominal endocrine organs (adrenal glands, pancreas).
• Computed tomography.
• Endoscopy:
  • Proximal and distal gastrointestinal tract:
    • Enables partial thickness biopsy Biopsy overview.
    • Limited value in guinea pigs due to their gastrointestinal anatomy and physiology.
• Distal urinary tract.
• Exploratory laparotomy Laparotomy.

Time required

Preparation

• Patient sedation/anesthesia if necessary: 10-20 min.
• Set appropriate radiographic exposure settings for the species and size of patient:
  • Particularly important if using a film-screen radiographic system (compared to digital radiology).
  • Usually <5 min if species-specific techniques and parameters have been established.

Procedure

• 2-10 min.
• Experienced operators with a good knowledge of the behavior of these species may reduce the time of the procedure.

Decision taking

Criteria for choosing test

• Investigation or confirmation of disease process(es) or conditions pertaining to abdominal or coelomic viscera:
  • Gastrointestinal tract including the liver:
    • Abdominal radiography is considered an essential part of the diagnostic process of gastrointestinal stasis in guinea pigs Gastrointestinal stasis.
  • Spleen Splenomegaly.
  • Urinary tract: urolithiasis Urolithiasis in a common condition in both male and female guinea pigs and affected animals may present with non-specific clinical signs.
  • Reproductive tract: cystic ovaries Cystic ovarian disease are commonly identified in older female guinea pigs; concurrent disease of the reproductive tract such as uterine leiomyoma Uterine neoplasia may also be present.
• Identification of gravidity or dystocia Dystocia.

Risk assessment

• It is a procedure that carries minimal risk for most patients. 
• The ventrodorsal view may result in further compromise in mammalian patients with cardiovascular Heart disease and/or respiratory disease Dyspnea Pneumonia:
  • Oxygen supplementation via a facemask before and during the procedure is likely to be of benefit in these cases.
  • Thorough preparation of all required equipment, consumables, and personnel can help expedite the procedure to limit further patient compromise.