By Tamara Grubb, DVM
In human medicine, postoperative nausea and vomiting are among the most prevalent and concerning of all postanesthetic complications. The conditions are so common and have such an impact on human health care that they have earned their own acronym from the National Health Library, PONV.
A recent PubMed search of PONV garnered almost 10,000 hits. For the human patient, PONV is unpleasant and results in dissatisfaction with perioperative care (Gan et al. 2014). Humans would pay extra to prevent PONV (Gan et al. 2014). Unfortunately, PONV is more than just an annoying occurrence. Vomiting itself can cause other postoperative complications, and PONV has been called “distressing” by humans who experience it (Gan et al. 2014).
As all veterinarians and veterinary technicians can attest, PONV also occurs in veterinary patients, and we should ask ourselves this question: is PONV distressing to our patients? Could PONV lead to or add to fear, anxiety, and stress (FAS)?
The author of a recent review of nausea and vomiting in veterinary patients makes a strong argument that these conditions could cause or compound FAS and could be considered an animal welfare issue (Hay Kraus 2017). The point is made in the review that Brambell’s Five Freedoms of animal welfare include freedom from discomfort, pain, and distress. PONV likely causes discomfort, could contribute to pain, especially in patients with preexisting abdominal pain, and could potentially be distressing.
Maybe we can’t definitively know whether an animal experiencing PONV is “distressed” or not, but we can argue that reduction of PONV is medically beneficial to our patients. Potential adverse effects of PONV include dehydration, electrolyte imbalances, esophagitis, aspiration pneumonia, exacerbation of pain, and elevated intracranial and intraocular pressure. In addition, PONV is likely to cause anorexia and may even contribute to agitation in the recovery phase of anesthesia.
Fortunately, we have drugs, such as maropitant, that decrease the incidence of PONV and the associated adverse effects. Numerous studies describe the anti-nausea and anti-emetic effects of maropitant in both dogs and cats (Hay Kraus 2017). One study also showed that dogs receiving maropitant returned to normal food intake postoperatively more rapidly than dogs not receiving maropitant (Ramsey et al. 2014). At 20 hours post-anesthesia, 93 percent of the dogs receiving maropitant versus 46 percent of the control dogs had returned to normal feeding. This could aid in alleviating dehydration, electrolyte imbalances and any nutritional deficits that might affect healing.
In the same study, dogs receiving maropitant had a better quality of recovery than control dogs. This could be due to decreased PONV and could add support to the theory that PONV is distressing to veterinary patients. In human medicine, administering sedatives that also decrease the incidence of PONV is recommended for treating emergence delirium in children (Dahmani et al. 2014).
Finally, reduction of PONV is not only medically appropriate for the patient, it is also important for maintaining the human-animal bond and pet-owner satisfaction with perioperative care. Nausea, vomiting, and anorexia are major concerns for pet owners, and presence of any of these conditions generally leads to owners assuming that their pets are experiencing diminished quality of life. As in human medicine, pet owners are concerned enough about PONV to pay extra money for its prevention (Hay Kraus 2017).
The bottom line is that PONV can be a medical concern both on its own and through complications caused by the act of vomiting or the vomitus itself (i.e., aspiration). PONV can exacerbate pain. PONV may contribute to FAS. Owners are concerned about PONV. We have drugs with high safety margins that effectively alleviate or eliminate PONV, and one of those (maropitant) may even play a role in analgesia. So why wouldn’t we treat or prevent PONV, regardless of the motive?
This article was reviewed/edited by board-certified veterinary behaviorist Dr. Kenneth Martin and/or veterinary technician specialist in behavior Debbie Martin, LVT.