Hepatic abscess caused by an inhaled migrating grass awn in a cat: first description and minimally invasive surgical approach

Abstract

Case summary

A 6-year-old castrated male domestic shorthair cat was presented with a 1-month history of cough, weight loss and partial anorexia, unresponsive to corticosteroid therapy. Initial imaging revealed bronchiectasis and pneumonia in the accessory lung lobe due to an inhaled grass awn, which was successfully removed via bronchoscopy. Subsequent clinical deterioration prompted further investigation, which identified a hepatic abscess containing a vegetal foreign body. The foreign body was suspected to have migrated through the diaphragm from the respiratory system. Surgical exploration confirmed the hepatic lesion. The grass awn was localised and extracted using intraoperative ultrasonographic guidance, avoiding the need for hepatic lobectomy. The cat recovered uneventfully with long-term antibiotic therapy.

Relevance and novel information

To our knowledge, this is the first reported case of a hepatic abscess caused by the migration of a grass awn foreign body in a cat. It is also the first report of intraoperative ultrasonography to localise and extract a non-visible plant-based foreign body within the deep hepatic parenchyma in this species. This case highlights the value of integrating advanced imaging modalities such as CT for preoperative planning and intraoperative ultrasonography to enable targeted and minimally invasive surgical interventions. This approach minimises the need for extensive procedures, reduces associated risks and promotes successful clinical outcomes.

Plain language summary

A liver abscess caused by a swallowed plant fragment in a cat: a world-first and a new surgical approach

The problem: Cats can accidentally inhale small plant seeds (like grass awns). These seeds are dangerous because they have microscopic barbs that allow them to ‘crawl’ through the body’s tissues. They carry bacteria with them, often causing severe infections far from where they originally entered. The case: A 6-year-old cat was treated for a cough and weight loss. Doctors first found and removed a plant fragment from his lung using a small camera (bronchoscopy). However, the cat’s health worsened, and further scans revealed a second problem: a deep infection (abscess) in the liver. A second plant fragment had travelled from the lungs, pierced through the diaphragm (the muscle used for breathing) and lodged itself deep inside the liver tissue. The treatment: This is the first time such a migration from the respiratory system to the liver has been described in a cat. To treat it, the surgical team used a minimally invasive approach. Instead of removing a large piece of the liver (a risky and heavy surgery called a lobectomy), they used an ultrasound probe directly on the liver during the operation. This allowed them to see the hidden seed deep inside the organ and pull it out with small forceps. Why it matters: The cat made a full recovery with long-term antibiotics. This case is important because it shows that plant seeds can travel between different organs like the lungs and the liver. It also demonstrates that using advanced imaging, like ultrasound, during surgery allows veterinarians to perform much safer and more precise operations. This approach reduces risks and helps pets recover faster by avoiding more aggressive and invasive procedures.

Case description

A 6-year-old castrated male domestic shorthair cat with free outdoor access was presented for a 1-month history of cough, partial anorexia and weight loss. The referring veterinarian initially prescribed prednisolone (1 mg/kg q24h), which did not alleviate the clinical signs. Nine days later, cervical and thoracic radiographs were performed and showed a right caudo-dorsal interstitial lung pattern (Figure 1). The blood work revealed a mild normochromic normocytic anaemia (haemoglobin 7.5 g/dl, reference interval [RI] 10.0–15.0) and elevated serum amyloid A (SAA; 54 µg/ml, RI <5) with otherwise normal serum biochemistry.

Figure 1.

(a) Radiographic ventrodorsal and (b) left lateral projections of the thorax showing a right caudo-dorsal interstitial lung pattern (white arrows)

On physical examination, the cat was alert and responsive, afebrile and normothermic. Thoracic auscultation and abdominal palpation revealed no abnormality, and mucous membranes were pale. To better characterise the pulmonary lesions previously identified on thoracic radiographs, CT imaging of the thorax was performed after the patient was placed under general anaesthesia (butorphanol 0.1 mg/kg IV, midazolam 0.2 mg/kg IV, propofol 4 mg/kg IV and isoflurane). Dilation of the lobar bronchus and a dorsolateral peripheral bronchus of the accessory lung lobe were identified, with a linear hyperattenuating element measuring 1.8 cm in length, located in their lumen (Figure 2). The adjacent pulmonary parenchyma was consolidated. In addition, a pleural and/or pulmonary gas-filled cavity lesion was noted caudally on the right side, compatible with a subpleural bulla or bleb. Finally, sternal lymphadenopathy and moderate diffuse bronchial wall thickening were observed. In the included part of the abdomen, a right multicystic hepatic mass was observed, suggestive of a cystadenoma or cystadenocarcinoma.

Figure 2.

(a) Sagittal and (b) dorsal multiplanar reconstruction CT images in lung window of the thorax showing dilation of the lobar bronchus and a dorsolateral peripheral bronchus of the accessory lung lobe with a hyperattenuating, linear element located in their lumen (green arrowheads)

Given the clinical suspicion of a bronchial foreign body, a bronchoscopy was then performed under the same anaesthetic. The lobar bronchus of the accessory lobe showed local hyperaemia, and mucopurulent material and a vegetal foreign body were observed in its lumen. The foreign body was extracted. Post-extraction bronchoscopy revealed mild, self-limiting haemorrhage and no residual foreign body fragments. A bronchoalveolar lavage of the accessory lobe was performed and the fluid submitted for bacterial culture, which yielded growth of Serratia nematodiphila, resistant to amoxicillin-clavulanate and cephalexin, but susceptible to enrofloxacin. Antibiotic therapy was initiated with amoxicillin-clavulanate (17 mg/kg PO q12h) later combined with enrofloxacin (5 mg/kg PO q24h) once the results of sensitivity testing were available and prolonged for 3 weeks. Amoxicillin-clavulanate was continued to cover potential undetected co-pathogens (including anaerobes).

At 1.5 months after completion of the antibiotic therapy, the cat was re-evaluated for lethargy, weight loss and partial anorexia. Blood tests conducted by the treating veterinarian revealed mild normochromic normocytic anaemia (haemoglobin 9.7 g/dl) and elevated SAA (73.9 µg/ml). Thoracic radiographs showed a mild pulmonary interstitial patch at the location of the previously described lesion. Fluid therapy with Ringer’s lactate (1.5 ml/kg/h for 2 days) and antibiotics (amoxicillin-clavulanate; 17 mg/kg PO q12h) provided only slight, unsatisfactory improvement. A follow-up CT scan was then performed, which revealed a stricture and thickening of the bronchus that previously contained the foreign body. Further caudally, this bronchus was dilated by fluid, and a linear parenchymal lesion was observed, communicating between this bronchus and the adjacent thickened bronchus. The previously identified hepatic lesion was ill-defined, occupying most of the right hepatic lobes around a new fusiform element with mineral attenuation (Figure 3). Right cranial peritoneal fat stranding was present. These lesions were suggestive of a hepatic abscess and focal peritonitis, adjacent to the right caudal bronchial persistent lesion, potentially secondary to transdiaphragmatic migration of an inhaled migrating grass awn. Differential diagnoses also included a hepatic tumour with dystrophic mineralisation or a localised area of cholangitis with biliary mineralisation. Abdominal ultrasound confirmed a plant-based foreign body in a well-delineated, hypoechoic mass in the right hepatic parenchyma (Figure 3). A follow-up bronchoscopy showed mucopurulent secretions at the entrance of the accessory lobar bronchus, with no visible foreign body.

Figure 3.

(a) Dorsal multiplanar reconstruction CT image in lung window of the thorax and the cranial abdomen and (b) ultrasonographic image of the right hepatic parenchyma showing fluid dilation of the bronchus that previously contained the foreign body (pink arrow) and a fusiform element with mineral attenuation in the adjacent right hepatic parenchyma (pink arrowhead). The ultrasonographic image confirms the fusiform element is most likely consistent with a plant-based foreign body (white arrow)

Surgical management was undertaken. After placement under general anaesthesia with methadone (0.2 mg/kg IV), diazepam (0.2 mg/kg IV), propofol (dose titrated to effect) and isoflurane, and aseptic preparation of the abdomen, a subxiphoid coeliotomy was performed. The right (medial and lateral) and quadrate hepatic lobes were firm, nodular and extensively adhered to each other and the diaphragm. Their fusion and shared vascularisation would have required a combined lobectomy and cholecystectomy. However, the proximity of the abscess to the caudal vena cava at the hepatic hilum posed a high risk of major vascular injury, rendering en-bloc resection unfeasible. A perioperative ultrasound was then performed. Under sterile conditions, a 7.5 MHz microconvex probe (covered with a sterile polyethylene sheath) was used to visualise the foreign body. Extraction was subsequently performed under ultrasound guidance using sterile Hartmann ear forceps advanced through the liver parenchyma. No bleeding or pus leakage occurred during the extraction. Lavage of the abdominal cavity with warmed saline was performed and conventional closure of the coeliotomy was performed.

The cat recovered uneventfully from surgery. Its good clinical condition allowed for discharge 24 hours postoperatively with meloxicam (0.05 mg/kg PO q24h) for 5 days and amoxicillin-clavulanate (12.5 mg/kg PO q12h). Culture and sensitivity testing conducted on pus and a fragment of the foreign body yielded growth of Peptostreptococcus canis and Porphyromonas macacae susceptible to amoxicillin-clavulanate. The antibiotic treatment was therefore continued for 3 weeks. Subsequent follow-up was provided by the primary care veterinarian. One month postoperatively, clinical examination and SAA levels were within normal limits. One month later, the animal was presented with a coughing episode, prompting a new radiographic examination of the thorax, which revealed a persistent caudo-dorsal consolidation patch, smaller and better defined than on previous radiographs, suggesting a focus of fibrosis or discrete focal pneumonia. No treatment was initiated and a complete resolution of clinical signs was observed within a few days. Four months after surgery, the cat was reported to be free of clinical signs.

Discussion

Hepatic abscesses are rarely reported in cats. They can develop secondary to local disease (eg, bacterial cholecystitis, neutrophilic cholangitis, hepatic neoplasia) but are believed to occur more commonly via haematogenous spread from an extrahepatic infection. ¹ In dogs, they have been described associated with immunosuppressive disorders, such as diabetes mellitus or hyperadrenocorticism, or secondary to foreign bodies. ² Our case is the first feline case to be associated with intrahepatic migration of an inhaled plant-based foreign body.^{3 –6} In humans, hepatic abscesses secondary to foreign bodies are rare and most often reported associated with fish bones, chicken bones or surgical materials. Such cases are often associated with specific dietary habits, such as those observed in some Asian populations.^7,8

Grass awns, with their sharp point and backward pointing barbs, are highly efficient at penetrating skin and migrating into body tissues and cavities. The most frequently affected sites are the external ear canal in dogs and the eyelids in cats, but other common locations in both species include the ears, feet, eyes, nose, lumbar area, costal region and thoracic cavity. ⁹ Hunting dogs are most frequently affected, while German Shepherds, Miniature Poodles, Dachshunds and cats exhibit a decreased prevalence. ⁹ The lower prevalence in cats is likely explained by their more cautious behaviour. In our case, the grass awn was suspected to have migrated from the respiratory tract to the liver, despite no detectable fistulous tract identified on imaging. This hypothesis is supported by the prior extraction of a bronchial foreign body, the anatomical proximity between the hepatic and pulmonary regions, and the adhesions between the diaphragm and the right hepatic lobes observed during surgery.^{9 –16}

Several studies have documented inhaled foreign bodies in dogs and cats. They are most commonly found in the bronchi or parenchyma of the caudal or accessory lung lobes, as well as the pleura and mediastinum. In dogs, they are most commonly found in the right bronchial tree.^{17 –23} In cats, they are often found in the trachea or at the carina, probably due to the significantly narrower luminal diameter of feline bronchi. ¹⁹ When they are in a bronchial position, they also have a predilection for the right side. ²⁰ This is believed to be the result of the more direct anatomical alignment of the right mainstem bronchus with the trachea compared with the left mainstem bronchus. Inhaled grass awns can further migrate through the lung parenchyma, along the diaphragm towards the sublumbar musculature or to the peritoneal cavity;^11,21,22 however, to our knowledge, there is no reported case of inhaled grass awn migrating into hepatic parenchyma in cats or dogs. An alternative hypothesis for the origin of a hepatic grass awn is retrograde migration through the biliary system, a mechanism that has been sparsely reported in cats.^15,23,24 Previous identification of a bronchial foreign body made this hypothesis unlikely in our case.

The imaging findings in the case presented here emphasise the challenges in diagnosing grass awn foreign bodies. Ultrasonography is a valuable tool for detecting such foreign materials.^{25 –28} In the literature, grass awns are described as spindle-shaped structures with two or three linear echogenic interfaces, often surrounded by an anechoic halo created by the associated inflammatory fluid.^26,27 However, these findings can be subtle, especially in chronic cases where tissue degradation alters the physical characteristics of the foreign body. ²⁶ On CT imaging, grass awns can present as elongated gas-filled lesions, slightly hyperattenuating foci or soft tissue structures. However, the sensitivity of CT for detecting foreign bodies is limited, with direct visualisation reported in only 19% of cases. Sensitivity improves significantly when secondary lesions, such as inflammation, abscess, fibrotic alterations or linear inclusion, are considered.^18,29 In this case, the foreign body was not visible on the initial CT scan but was identified on a follow-up CT scan, likely due to secondary mineralisation caused by chronic inflammation, consistent with previously reported findings in the literature.^18,29

The decision to use intraoperative ultrasonography in this case proved to be pivotal. This approach enabled precise localisation of the foreign body within the hepatic parenchyma, facilitating its extraction without the need for a complex en-bloc hepatic lobectomy. Hepatic lobectomy entails significant risks of complications, mainly haemorrhage, with a complication rate of 28.6% observed in a population of dogs with hepatocellular carcinoma. ³⁰ Thus, avoiding a lobectomy reduced surgical time, minimised peri- and postoperative complications, and allowed for a shorter hospitalisation period. Intraoperative ultrasonography is increasingly recognised as a valuable tool for guiding surgical procedures, particularly in cases involving foreign bodies.^{10,15,27,28,31}

Conclusions

This case report shows successful management of a hepatic abscess caused by a grass awn foreign body in a cat, emphasising the importance of considering foreign body migration as a differential diagnosis in cases of unexplained hepatic lesions. It also highlights the importance of a multimodal diagnostic and therapeutic approach. The combined use of CT and ultrasonography allowed for accurate localisation of the foreign body and minimally invasive extraction, which reduced the need for extensive surgical procedures and associated risks. Future studies should further explore the utility of advanced imaging techniques and intraoperative guidance in managing similar cases.