Persistent Vomiting in Cats? Gastric Dysmotility May Be the Missing Piece

In feline practice, vomiting and reduced appetite are among the most commonly reported complaints. While many cats respond well to symptomatic therapy, some patients continue to show nausea, regurgitation, abdominal discomfort, or poor feeding despite treatment. In such cases, gastric dysmotility (GD) may be an overlooked contributor¹. 

GD can complicate both gastrointestinal and systemic illnesses in cats, yet recognizing it in practice is challenging because the clinical signs are nonspecific. Stress, concurrent disease, hospitalization, and medication effects can all mimic or mask delayed gastric emptying. Adding to the challenge, traditional methods used to assess gastric motility are often invasive, time-consuming, and impractical in routine veterinary settings¹. 

Why Gastric Emptying Matters Clinically 

Delayed gastric emptying can prolong hospitalization, delay nutritional recovery, and reduce response to supportive care¹. Yet treatment options for feline GI motility disorders remain limited. Much of the available clinical guidance still relies on anecdotal experience or studies from other species because feline-specific in vivo data on prokinetics remains sparse². 

This has led clinicians to explore drugs that target motilin receptors. Although cats display unique gastrointestinal motility patterns compared to dogs and humans, motilin receptors are still strongly expressed in the feline gastric antrum and duodenum. Multiple studies have demonstrated that motilin agonists can enhance GI motility in cats, making these receptors an important therapeutic target¹. 

Azithromycin: An Emerging Alternative to Erythromycin 

Erythromycin has long been recognized as a prokinetic agent because of its motilin agonist activity. However, its use in cats has been questioned historically due to poor oral bioavailability. More recently, azithromycin has gained attention because it also acts on motilin receptors while offering several pharmacological advantages¹. 

A prospective, randomized, double-blinded crossover study evaluated azithromycin, erythromycin, and placebo in healthy cats using ultrasonographic assessment of gastric emptying (GE). The findings showed that azithromycin significantly accelerated GE in the later stages compared to placebo, producing effects comparable to erythromycin. 

Interestingly, both drugs improved gastric emptying despite producing only mild changes in measurable antral motility variables. This is clinically important because gastric emptying does not always correlate directly with visible contractility. Efficient gastric transit depends on coordinated interaction between the gastric antrum, pylorus, and proximal duodenum rather than isolated muscular contractions alone¹. 

Why This Matters in Everyday Practice 

For practicing veterinarians, azithromycin offers several practical advantages over erythromycin¹: 

• Better oral bioavailability in cats 

• Longer half-life allowing less frequent dosing 

• Availability in both oral and injectable formulations  

• Easier administration for owners struggling to medicate cats  

• Lower overall treatment cost in many settings  

These points become especially relevant in feline medicine, where repeated oral dosing often reduces compliance and increases stress for both cats and owners. 

The study also highlighted another clinically relevant observation: hospitalized animals may show altered gastric emptying patterns because stress itself can influence GI function.21 This means that delayed recovery in hospitalized feline GI patients may sometimes involve a motility component rather than simply progression of the primary disease¹. 

Important Considerations Before Use 

Despite promising findings, clinicians should avoid viewing azithromycin as a routine first-line solution for all vomiting cats. The study was performed in healthy purpose-bred cats rather than client-owned patients with naturally occurring GD. In addition, standardized veterinary dosing recommendations are still unavailable. 

Antibiotic stewardship is another important consideration. Using macrolides for noninfectious conditions may contribute to antimicrobial resistance and could potentially disrupt the gut microbiome. Human pediatric studies have shown temporary reductions in microbial diversity after azithromycin use, although similar feline studies are lacking^1,3,4,5. 

The Bigger Clinical Takeaway 

Persistent vomiting and poor appetite should not always be managed as isolated symptoms alone. In some feline patients, impaired gastric emptying may be an important underlying factor delaying recovery. 

As more feline-specific research becomes available, azithromycin may emerge as a practical adjunctive option for carefully selected cases of gastric dysmotility. Until then, patient selection, clinical judgment, and responsible antimicrobial use remain essential when incorporating prokinetics into feline GI management. 

Reference 

1. Rutherford S, Gaschen F, Husnik R, Fletcher J, Gaschen L. Ultrasonographic evaluation of the effects of azithromycin on antral motility and gastric emptying in healthy cats. Journal of veterinary internal medicine. 2022 Mar;36(2):508-14. https://academic.oup.com/jvim/article-pdf/36/2/508/66666515/jvim16385.pdf 

2. Husnik R, Gaschen FP, Fletcher JM, Gaschen L. Ultrasonographic assessment of the effect of metoclopramide, erythromycin, and exenatide on solid-phase gastric emptying in healthy cats. Journal of veterinary internal medicine. 2020 Jul;34(4):1440-6. https://academic.oup.com/jvim/article-pdf/34/4/1440/66660463/jvim15787.pdf 

3. Holmes AH, Moore LS, Sundsfjord A, Steinbakk M, Regmi S, Karkey A, Guerin PJ, Piddock LJ. Understanding the mechanisms and drivers of antimicrobial resistance. The Lancet. 2016 Jan 9;387(10014):176-87. https://courses.edx.org/assets/courseware/v1/3ef0ee294452911304073dcedcf14d8a/c4x/KIx/KIGlobalHx/asset/Lancet_2.pdf 

4. Whittemore JC, Stokes JE, Price JM, Suchodolski JS. Effects of a synbiotic on the fecal microbiome and metabolomic profiles of healthy research cats administered clindamycin: a randomized, controlled trial. Gut Microbes. 2019 Jul 4;10(4):521-39. https://www.tandfonline.com/doi/pdf/10.1080/19490976.2018.1560754 

5. Wei S, Mortensen MS, Stokholm J, Brejnrod AD, Thorsen J, Rasmussen MA, Trivedi U, Bisgaard H, Sørensen SJ. Short-and long-term impacts of azithromycin treatment on the gut microbiota in children: a double-blind, randomized, placebo-controlled trial. EBioMedicine. 2018 Dec 1;38:265-72. https://www.thelancet.com/article/S2352-3964(18)30539-5/pdf