Page 661 - Small Animal Internal Medicine, 6th Edition

CHAPTER 37 The Exocrine Pancreas 633

available as Cerenia (Zoetis, Madison, NJ) in an injectable Treatment of biliary tract obstruction
solution (10 mg/mL) or as tablets (16, 24, 60, and 160 mg). associated with pancreatitis
VetBooks.ir The dose of injection is 1 mg/kg (1 mL/10 kg body weight Most cases of extrahepatic biliary obstruction secondary to
acute-on-chronic pancreatitis resolve with conservative
q24h for up to 5 days). The dose of the tablets is 2 mg/kg
q24h for up to 5 days. Maropitant also has potential analgesic
bladder and stenting of the bile duct are usually unnecessary
properties because substance P, which acts on the NK1 management; surgical or needle decompression of the gall-
receptor, is involved in pancreatic pain, but no clinical in dogs and cats. In humans it has now been demonstrated
studies have demonstrated its efficacy. It would be indicated that there is no advantage to surgical intervention in most
as part of multimodal analgesia in animals with acute pan- patients and no difference in the severity and chronicity of
creatitis and would not be sufficient alone. secondary liver disease between those treated medically and
Metoclopramide has been used successfully in dogs with those treated surgically, provided that there is no neoplasia
pancreatitis (0.5–1 mg/kg, administered intramuscularly, and the jaundice resolves within a month (Abdallah et al.,
subcutaneously, or orally [PO] q8h, or 1–2 mg/kg, adminis- 2007). No such study has been undertaken in small animals,
tered intravenously over 24 hours as a slow infusion), but its so treatment advice is empiric; if the feces remain colored
effect on stimulating gastric motility may increase pain and (not white or acholic, which implies complete biliary obstruc-
pancreatic enzyme release in some animals. It is also of tion) and the jaundice gradually resolves over a week to 10
limited efficacy in cats. Butorphanol, used as an analgesic in days, then surgical intervention is not indicated and conser-
animals with pancreatitis causing mild to moderate pain, vative management with antioxidants and ursodeoxycholic
also has antiemetic properties. A phenothiazine antiemetic acid is advised (see Chapters 35 and 36).
such as chlorpromazine may be more effective for some
patients, but phenothiazines have sedative and hypotensive
effects, which may be particularly marked if they are used CHRONIC PANCREATITIS
together with opioid analgesia, so care should be taken in Etiology and Pathogenesis
these cases. 5-HT 3 receptor antagonists such as ondansetron
are useful for other types of vomiting in dogs (e.g., Chronic pancreatitis is defined as “a continuing inflam-
chemotherapy-induced emesis) but are best avoided in pan- matory disease characterized by the destruction of pan-
creatitis because they have occasionally been reported to creatic parenchyma leading to progressive or permanent
trigger pancreatitis in humans. impairment of exocrine or endocrine function, or both”
(Etemad et al., 2001). The gold standard for diagnosis is
Gastroprotectants histology (see Fig. 37.2), but this is rarely indicated or per-
Patients with acute pancreatitis have an increased risk of gas- formed in dogs or cats. Noninvasive diagnosis is difficult
troduodenal ulceration, probably caused by local peritonitis. with the currently available diagnostic imaging, and clini-
They should be monitored carefully for evidence of melena copathologic testing has a lower sensitivity than for acute
or hematemesis and treated as necessary with sucralfate and disease.
acid secretory inhibitors (e.g., H 2 blockers such as cimeti- Chronic pancreatitis has been considered a rare and not
dine, famotidine, ranitidine, or nizatidine, or the proton particularly important disease in dogs, whereas it is recog-
pump inhibitor omeprazole). Cimetidine should be avoided nized as the most common form of pancreatitis in cats.
in animals with concurrent liver disease because of its effect However, the early literature published on canine pancreatic
on the cytochrome P-450 system. Ranitidine can be used disease in the 1960s and 1970s recognized it as a common
instead in these animals, but its additional gastric prokinetic disease of clinical significance. It was noted that a high pro-
effect can cause vomiting in some individuals; it should be portion of cases of EPI in dogs were caused by chronic pan-
discontinued if this occurs. Famotidine is preferable because creatitis, and it might be responsible for 30% of cases of DM
it does not have these prokinetic effects. or more. More recent pathologic and clinical studies in both
dogs (Bostrom et al., 2013; Newman et al., 2004; Watson
Antibiotics et al., 2007, 2011) and cats (De Cock et al., 2007) have recon-
Infectious complications are reportedly rare in dogs and cats firmed it as a common and clinically relevant disease in dogs
with pancreatitis, but when they occur, they can be serious; and cats. It is likely to cause intermittent and/or ongoing
the efficacy of antibiotic therapy in preventing such compli- recurrent gastrointestinal signs and epigastric pain in many
cations remains contentious in humans. Nonetheless, most dogs and cats, but it is frequently underrecognized because
veterinary experts advise the use of broad-spectrum antibi- of the difficulty of obtaining a noninvasive diagnosis. In dogs
otics prophylactically in dogs and cats with severe acute pan- the postmortem prevalence of chronic pancreatitis is up to
creatitis. IV potentiated amoxicillin is most often used. 34%, particularly in susceptible breeds, and even in studies
Fluoroquinolones penetrate the pancreas well, but respon- of fatal acute pancreatitis, acute-on-chronic disease accounts
sible antibiotic use indicates that these should not be used as for 40% of cases. In cats an even higher postmortem preva-
first-line antibiotic treatment unless there is a specific indica- lence of chronic pancreatitis of 60% has been reported. It
tion. Animals at the milder end of the disease spectrum do must be noted that postmortem studies tend to overestimate
not require antibiotic therapy. the prevalence of chronic diseases, which leave permanent