Radiology in the Ferret

Restraint

Ferrets (Mustela putorius furo) are lively, active creatures, and most individuals tend to be quite wiggly. For appropriate radiographic positioning, sedation or general anesthesia is extremely helpful unless the patient is moribund.

Equipment and technique

Equipment needed for radiography of the ferret should include:

• Equipment capable of producing 300 mA in 1/120 (0.008) second (to reduce risk of motion artifact)
• Fine or detail-intensifying screens

Use tabletop technique is used for these small mammals. Rectangular film is ideal for whole body radiographs of the long, lean ferret.

Radiographic anatomy

In many ways, radiographic anatomy of the ferret is similar to that seen in dogs and cats. Unique features include the:

1. Heart:  The heart is located approximately between the sixth and eighth intercostal spaces. The shape of the ferret heart is relatively globoid. The right ventricle normally makes slight contact with the sternum (Fig 1).
   

   Figure 1. Normal lateral chest radiograph in a ferret (Mustela putorius furo). Photo provided by Dr. Heidi Hoefer. Click image to enlarge.

   The typical landmarks used to evaluate heart size in dogs and cats are inaccurate in the ferret due to the long, tubular shape of the chest cavity. Scoring systems have been described using vertebral length (Onuma 2009, Stepien 1999). With cardiomegaly the cardiac silhouette may be enlarged and rounded with tracheal elevation and increased sternal contact (Fig 2). On the ventrodorsal view, the heart size may appear longer and wider, filling up more of the thorax.

   

   Figure 2. Lateral radiograph in a ferret (Mustela putorius furo) with cardiomegaly. Photo provided by Dr. H. Hoefer. Click image to enlarge.

2. Spleen:  Splenomegaly is extremely common finding in the ferret. The spleen can measure approximately 5 cm in length and 2 cm in width (FIg 3). The margins of the spleen should be smooth and regular. n the ventrodorsal view, the spleen will often appear as a radiopaque structure beginning on the left and extending across midline (Fig 4).
   

   Figure 3. Survey radiograph in a ferret (Mustela putorius furo). The large spleen appears as a radiopaque structure along the ventral abdomen. Photo by C. Pollock. Click image to enlarge.

   

   Figure 4. Ventrodorsal view of a ferret (Mustela putorius furo) with splenomegaly (arrow). Photo by C. Pollock. Click image to enlarge.

3. Gastrointestinal tract:  There is normally very little gas within the stomach or intestinal loops.
4. Urogenital tract:  In rare instances, the prostate may appear as a mass lesion dorsal to the urinary bladder in male ferrets suffering from adrenocortical disease. More commonly the bladder will appear enlarged, however the enlarged prostate is not typically visible on survey radiographs. The ferret also possesses an os penis that is easily visible radiographically.

Coronavirus

Common radiographic findings reported with ferret systemic coronavirus infection (FSCV) include (Dominguez 2011):

• Loss of lumbar musculature
• Decreased peritoneal detail
• Presence of mid-abdominal soft-tissue masses
• Splenomegaly

Ultrasound

In some medical conditions, abdominal detail is poor and ultrasound is superior as an imaging modality in the ferret. Renal cysts are a common incidental ultrasonographic finding in the normal ferret.

References