Page 742 - Clinical Small Animal Internal Medicine

710 Section 7 Diseases of the Liver, Gallbladder, and Bile Ducts

and therefore decrease the volume of ascites. If this q8–12h, with adjustments in dose as needed to achieve a
VetBooks.ir is ineffective, treatment with diuretics is indicated. goal of 2–3 soft, but formed stools daily.
Antibiotics have also been used for HE in an effort to
Spironolactone is the drug of choice in these cases due
to its sodium‐wasting but potassium‐sparing effects,
responsible for production of ammonia. The two most
with a starting dose of 1–2 mg/kg/day. Aldactazide, a decrease the volume of colonic urease‐producing bacteria
combination of spironolactone and hydrochlorothi­ commonly utilized antibiotics are neomycin (22 mg/kg
azide, may also be administered. Low‐dose furosemide q8h) and metronidazole (7.5 mg/kg q12h). Neomycin is an
(1­2 mg/kg PO q12h) can also be utilized, but carries a oral aminoglycoside. Aminoglycosides are very poorly
risk of worsening HE due to its acidifying effects. absorbed by the GI tract, so it is thought that the effects
Therefore, it should only be added to therapy when will usually remain within the GI tract. However, neomycin
other diuretics fail to fully control the ascites. Dietary carries a risk of nephrotoxicity and ototoxicity, even when
sodium restriction may also be beneficial to help given orally, so acute kidney injury can occur. Metronidazole
decrease volume of ascites. Diets with <0.05 g/100 kcal may result in vomiting, diarrhea, or neurotoxicity, espe­
of sodium have been recommended. It is important to cially when administered at high doses or chronically.
monitor electrolytes and renal values while on these Alternatively, amoxicillin/clavulanic acid can be used at
medications, and taper to lowest effective dose to con­ standard doses to decrease in the patient with HE.
trol clinical signs of ascites. Emerging evidence also suggests that inflammatory
Abdominocentesis may be performed when necessary cytokines are synergistic with ammonia in precipitating
for severe abdominal distension resulting in patient HE. Treating concurrent inflammatory and infectious
discomfort or respiratory difficulties. Removing large disease in other organs is therefore an important part of
volumes of ascites may result in cardiovascular collapse managing the patient with HE.
and poor perfusion, in addition to lowering body protein Emergency treatment of HE is warranted if a patient
levels, so it is recommended to only remove 20–50% of presents with seizures or coma, or otherwise is severely
the total volume of effusion in one procedure. neurologic and unable to safely receive oral medica­
tions. A warm water cleansing enema (10–15 mL/kg
water) should be given to remove fecal material and
Hepatic Encephalopathy
allow for a retention enema with lactulose. Lactulose
In treating HE, efforts are classically focused on lowering (5–10 mL/kg) should then be infused at a 30% dilution
the amount of encephalopathic toxins in the colon. This and allowed to remain in the colon for 10–15 minutes.
can be performed by both dietary changes and adminis­ Flumazenil is an antagonist for benzodiazepine recep­
tration of lactulose and/or antibiotic therapy. Because tors and is used as a reversal agent for benzodiazepines.
ammonia is derived from protein sources, historically a Because HE may cause stimulation of GABA/benzodi­
protein­restricted diet with reduction in aromatic amino azepine receptors, flumazenil (0.01–0.02 mg/kg IV)
acids has been recommended in dogs with HE secondary may also provide acute improvement in neurologic
to cirrhosis. However, protein restriction is controversial, depression in cases of HE.
and evidence from human medicine actually suggests If seizures are present, diazepam or other benzodiaze­
that patients with cirrhosis require additional, not pine medications should not be administered as these
reduced, amounts of protein. What is probably more may increase the stimulation of GABA/benzodiazepine
important is to ensure that the protein content of the diet receptors and risk worsening neurologic depression.
is highly digestible and is fed little and often. Dairy and Instead, levetiracetam (20 mg/kg) may be given IV for
soy proteins have been found to promote less HE com­ acute seizure control. Phenobarbital may also be utilized.
pared to meat protein. Commercial hepatic diets are If prolonged seizure activity has been present or there
available for dogs, although in some dogs the protein level are clinical signs of cerebral edema, mannitol infusion
may be too low, and muscle catabolism may occur. In may also be necessary.
these dogs, supplementation with highly digestible, high‐
quality protein in limited amounts may be necessary.
Lactulose is a nonabsorbable disaccharide that acidi­
fies the colonic lumen, converting ammonia (NH 3 ) into Gastrointestinal Ulceration
ammonium (NH 4+ ). The positively charged ammonium Gastrointestinal ulceration and bleeding can increase
is membrane impermeable, compared to the neutral the risk of HE due to digestion of blood proteins and
charge of ammonia. Lactulose is also a cathartic, decreas­ absorption of ammonia. Therefore, aggressive treatment
ing GI transit time for production and absorption of is warranted in cases of GI ulceration. Proton pump
ammonia. Lactulose dosing starts at 0.25 mL/kg PO inhibitors such as omeprazole (1 mg/kg q12–24h) have