Today's Veterinary Practice

MAR-APR 2013

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| gi inTerVenTion: aPProach To Diagnosis anD TheraPy of The VomiTing PaTienT warrant immediate diagnostic investigation and treatment. This category includes patients with: • Hematemesis (vomiting blood) or melena • Frequent vomiting (8–10 times in 1 day) • Concurrent signs (such as anorexia; lethargy; fever; apparent abdominal pain; or pale, "muddy," congested, or jaundiced mucous membranes). Diagnostic evaluation is mandatory to attempt to determine the underlying cause and guide therapy, and includes: • Survey abdominal radiographs • CBC, serum biochemical profile, urinalysis • SNAP Parvo Test (idexx.com) (puppies or kittens), regardless of vaccination history. Additional diagnostic studies may include further laboratory testing, such as: • Canine or feline pancreatic lipase (Spec cPL or fPL Tests, idexx.com) • Resting cortisol and/or adrenocorticotropic hormone (ACTH) stimulation testing • Abdominal ultrasonography • Upper GI endoscopy and/or barium contrast series • Surgical exploration of abdomen. ACUTE vOMITING: MEDICAL THErAPY The goals of symptomatic or supportive therapy for acute vomiting are: • Treating or removing the underlying cause • Controlling the vomiting episodes • Addressing abdominal pain, if present • Correcting the fluid, electrolyte, and acid– base abnormalities that may occur as a consequence of frequent vomiting. Antiemetic Therapy Antiemetic therapy is warranted when: 1. Vomiting is frequent or severe, making the animal uncomfortable 2. Persistent vomiting puts the animal at risk for aspiration pneumonia or acid–base and electrolyte disturbances 3. The animal is not suffering from GI obstruction or toxicity. Antiemetics control emesis by either central or peripheral blockade of neurotransmission at receptor sites (see Medications for Vomiting: Dogs & Cats, page 26). • In the emetic center, neurokinin (NK)1 receptors and alpha-2 adrenergic receptors are the most clinically important. Selective NK1 receptor antagonists (ie, maropitant) act by blocking the binding of substance P within the emetic center and CRTZ; therefore, they uniquely inhibit vomiting through both the humoral and neural pathways. 20 Today's Veterinary Practice March/April 2013 Maropitant: A Multimodal Antiemetic maropitant citrate (cerenia, zoetis.com), a potent selective nK1 receptor antagonist, plays an important role in managing vomiting, mediated via both the vomiting center and crTZ (ie, humoral and neural pathways).3-5 The drug is effective for: • Prevention of motion sickness in dogs • chemotherapy-induced nausea and vomiting • management of vomiting due to other causes. Nausea nausea cannot be reliably assessed in animals, but signs interpreted as nausea include salivation, increased frequency of or exaggerated swallowing motions, and licking of lips. a recent study evaluating maropitant as an antiemetic for dogs premedicated with hydromorphone found that maropitant effectively prevented vomiting, retching, and nausea associated with hydromorphone administration.6 Analgesia Two recent studies indicate that maropitant also provides visceral analgesia in dogs and cats.7,8 During visceral ovarian and ovarian ligament stimulation, maropitant decreased anesthetic requirements. This analgesic property makes maropitant especially suitable for managing vomiting caused by painful intra-abdominal conditions, such as pancreatitis and cholangitis, and painful gastric or intestinal disorders. Note: At this time, this use of maropitant should only be considered adjunctive to other methods of pain control. Administration common doses for maropitant are given in Medications for vomiting: Dogs & Cats, page 26. maropitant is commonly administered off label in both dogs and cats. hickman and colleagues reported on the pharmacokinetics of Po, sc, and iV use in cats.5 Because maropitant is metabolized by the liver, a lower dosage of 0.5 mg/kg iV is sometimes used for treatment or prevention of vomiting in both species, if there is concern about liver function. The label states that using cerenia for treatment or prevention of acute emesis should not last longer than 5 consecutive days. • maropitant has nonlinear pharmacokinetics in dogs. Pharmacokinetic studies conducted since the approval of cerenia have shown that a steady state is reached in dogs in 4 days (at 2 mg/kg daily). a steady state is reached in cats in 7 days. • another reason for this concern is that, if vomiting persists longer than 5 days, the underlying cause needs to be thoroughly reinvestigated. in dogs, the injectable solution and tablets may be used interchangeably for once daily dosing to prevent acute vomiting. Safety cerenia has been tested for safety in both dogs and cats at 1×, 3×, and 5× the label dose for 15 days (3× the duration of treatment recommended on the label) as required by the fDa.

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