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26 Section I: Diagnostics and Planning

systemic side effects but furosemide can contribute to electrolyte
abnormalities, and long‐term prednisone therapy may cause iatro-
genic Cushing’s disease. Routine blood chemistry is evaluated prior
to surgery and should include an electrolyte panel. Electrolyte
abnormalities should be corrected prior to anesthesia and surgical
decompression.
Many candidates for FMD are healthy juveniles or young adults,
most commonly of the Cavalier King Charles Spaniel (CKCS) and
Brussels Griffon breeds [19]. The CKCS breed also has a high inci-
dence of mitral valve disease and prolapse, although Rusbridge and
Knowler [20] found that dogs with earlier onset of clinical signs
associated with caudal occipital malformation and syringohydro-
myelia often have a later onset of cardiac disease and vice versa.
This was theorized to be a result of modifications of breeding
Figure 3.8 Left lateral projection demonstrating left‐sided heart enlarge- protocols when mitral valve disease was being documented in the
ment associated with chronic valvular disease in a geriatric Chihuahua. young CKCS population. For this reason, it may be prudent to eval-
uate cardiac function more extensively prior to surgery in CKCS.
That being said, the operative complication rate associated with
FMD is extremely low and most often related to transient worsen-
ing of existing clinical neurological signs after recovery [21–23].

Ventriculoperitoneal Shunt Placement
Ventriculoperitoneal shunt placement for the treatment of hydro-
cephalus is pursued in patients with progressive signs of obstruc-
tive ventricular disease and resultant cerebrospinal fluid (CSF)
accumulation. Hydrocephalus may be congenital or acquired and
causes clinical signs related to forebrain dysfunction. The most
common congenital cause of obstructive hydrocephalus is atresia
of the mesencephalic aqueduct associated with fusion of the ros-
tral colliculi [24].
Elevated ICP is a concern in these patients and clinical parame-
ters that reflect intracranial hypertension should be evaluated as
previously stated. For patients with malignant causes of obstructive
hydrocephalus (neoplasia, inflammatory disease), minimum data-
base testing is dictated based on clinical examination as described
above. Ruling out metastatic disease, extraneural primary tumors,
and infectious diseases is warranted. Some clients will choose to
pursue shunt placement for relief of clinical signs, irrespective of
findings with malignant characteristics. Skin, abdominal, or sys-
temic infections are contraindications for shunt placement and
should be identified and resolved prior to surgery [24].
Over‐shunting is uncommon but can lead to cortical collapse
and tearing of the meninges. Rupture of meningeal vessels can
result in significant bleeding. Current PCV and blood typing prior
to surgery may be indicated.
Like patients undergoing FMD, patients with hydrocephalus may
have been medically managed prior to surgery. At a minimum, elec-
trolytes should be evaluated preoperatively. It is not uncommon for
patients with hydrocephalus to have seizures and recent serum con-
Figure 3.9 Ventrodorsal view of the patient shown in Figure 3.8.
centrations of antiepileptic drugs should be available.
neuroprotective properties [18] and some individuals advocate Posttraumatic Decompression and Intracranial
their use in the perioperative period for patients undergoing sur- Abscess Drainage
gery for prosencephalic lesions even in absence of clinical seizure In emergent situations rapid hematological assessment (PCV,
activity. TS, blood glucose, BUN) may be necessary but complete blood
work should be performed when possible, even if after surgery.
Foramen Magnum Decompression Blood pressure monitoring should be undertaken in these
Many of the patients presenting for consideration of foramen mag- patients to assess hemodynamic stability. If excessive bleeding
num decompression (FMD) have been medically managed for a occurred at the time of injury, blood transfusion prior to surgery
period of time with corticosteroids, furosemide, and/or proton and further hematological evaluation may be indicated. Colloids
pump inhibitors after initial imaging diagnosis. The latter has few and hypertonic saline are advantageous in acute resuscitation of