An Unusual Growth of Migrating Foxtail Foreign Body in A Dalmatian Dog: A Case Report

Case History
Seed heads of various types of grass are called foxtail due to their brush-like appearance (Philp et al., 2022). Green foxtail (Setaria viridis) is widely distributed in various parts of the world and adapts rapidly to local conditions (Dekker, 2003; Fukunaga & Kawase, 2024; Griffeuille et al., 2023). Plant-derived objects (e.g. grass awn), are the usual cause of foreign body-related diseases in animals. They migrate easily due to their shape, facilitating their forward movement (Dennis et al., 2005). In most cases, this disease occurs in young to middle-aged dogs and during the summer months (Caivano et al., 2022). Some breeds are more susceptible to foxtail disease than others, including Springer Spaniels, Golden Retrievers, Brittany Spaniels, and Airedale Terriers; it is less prevalent in German Shepherds, Miniature Poodles and Dachshunds (Schultz & Zwingenberger, 2008). 
The pathogenicity of the grass awns is usually related to secondary bacterial infections at the site (Corbett & Rissi, 2023; Schultz & Zwingenberger, 2008). These grass-awn foreign bodies are mostly reported to occur in the external ear canal, interdigital region, third eyelid, and nasal cavity. They have also been observed in the eye and orbit, cranium, spinal canal and peritoneal and thoracic cavities (Doyle et al., 2011). This paper discussed the clinical course of an unusual case of an intramuscular foxtail foreign body in the femoral region of a Dalmatian dog. 
Clinical Presentation 
A 6-years-old spayed female Dalmatian was referred to the Small Animal Hospital, Faculty of Veterinary Medicine, University of Tehran (FVM-UT), following a two-day history of hyporexia, fever, lameness, and an open wound with purulent discharge on the medial aspect of the left femur. The wound was irrigated and no foreign object was detected. Treatment consisted initially of injectable first-line antibiotics (Cefazolin 22.00 mg/kg, IM, q8h, Loghmanpharma, Tehran, Iran). Antibiotic treatment was continued for ten days with a partial response. The purulent discharge decreased with antibiotic therapy; however, it was resumed after the cessation of treatment. Subsequently, the regimen was changed to clindamycin (11.00 mg/kg, IM, q12h, Aburaihan Pharmaceutical Co, Tehran, Iran) and ampicillin (15.00 mg/kg, IM, q8h, Daanapharma, Tabriz, Iran). Despite the change in the treatment regimen, the therapeutic response was temporary, and there was no complete resolution of signs by day 30 of treatment. 
Diagnostic Testing
For further evaluation of the condition of the disease and the extent of the open wound, a pre-contrast and post-contrast computed tomography (CT) scan of the left hindlimb was taken from the dog. There was a rim-enhanced intramuscular draining tract in the medial muscular region of the left femur, which extended at the level of the proximal third diaphysis of the femur to the distal diaphysis (Figure 1 white arrow).

The possibility of the presence of a soft tissue foreign body was speculated. In comparison, similar imaging features have been reported in cases of rare foreign body migration or localized inflammatory responses, where soft tissue masses were identified using advanced imaging techniques, such as magnetic resonance imaging (MRI). For instance, in the case of olfactory neuroendocrine carcinoma in a dog, MRI findings highlighted the value of post-contrast enhancement in delineating abnormal tissues and detecting irregular structures that might otherwise go unnoticed (Molazem et al., 2024; Molazem et al., 2022; Ramezani et al., 2023; Zehtabvar et al., 2023). Given the extension of the fistula to the pelvis and the long distance to the end part of the fistula, surgery did not seem feasible. As expected, inguinal lymph nodes were enlarged and antibiotic treatment was continued. 
By day 40, during the process of wound irrigation, a bump appeared in the wound area and a foreign body resembling grass was discovered. After the foreign body was slowly removed from the location by forceps, it was found to be a 30 cm foxtail, which had caused a fistula in its path (Figure 2). 

Within five days following the removal of the foxtail, marked improvement was noticed. The purulent discharge decreased, and the dog’s attitude and appetite improved considerably. 
Assessments 
Vegetal foreign bodies can penetrate through intact skin or natural orifices and migrate through the body. Foxtail is one of the most common causes of foreign body-related disease in dogs (Philp et al., 2022). Foreign body-related diseases are less common in cats because of their living conditions and greater exposure to the outdoor environment. This can also be due to their grooming behavior and lifestyle. In cats, these grass awns are mostly reported in domestic shorthairs, in the ocular conjunctiva (62.2%), and third eyelid (18.9%) (Griffeuille et al., 2023; Philp et al., 2022). Although foxtails are less commonly reported in cats than dogs, one case of foxtails migrating and growing to an unusual location of the cat’s body has been reported (Doyle et al., 2011). 
Philip et al. (2022) conducted a study on 745 dogs. They reported that these grass awns are mostly found in the aural canal (28.6%), subcutaneous tissues (24.1%), nasal canal (18%) and ocular conjunctival membranes (6.8%) (Philp et al., 2022). In such lesions, the symptoms of foxtail foreign body become noticeable in a shorter period; hence, these cases were immediately referred to the veterinary centers and the detection of foxtail is faster. In these cases, due to the quick detection of the foreign body and quick removal from the wound site, the treatment is started sooner, which prevents the plant from having a chance to grow within the body. Usually, these lesions can be treated on an outpatient basis (Philp et al., 2022).
However, in a smaller number of cases, according to the unusual locations of penetration, often not associated with severe symptoms, a quick diagnosis is difficult to achieve. Detection and treatment require diagnostic imaging or exploratory surgery, which is usually performed after a longer period, when foxtail penetration has been associated with fistula and secondary infection (Philp et al., 2022). Also, it is not always possible to remove the foxtail even with surgery (Schultz & Zwingenberger, 2008). Late diagnosis can lead to a complicated medical situation, allowing foxtail to migrate and grow within the body, potentially reaching vital internal organs where the presence of a foreign body is unusual (Dennis et al., 2005). For instance, it has been reported to cause ventricular meningoencephalitis and encephalitis in dogs by migrating to the intracranial region (Dennis et al., 2005), and acute pancreatitis by being inhaled and migrating to the right pancreatic lobe through the lung (Citi et al., 2017; Zaidi et al., 2024). It can also cause infectious inflammation of the lung by penetrating the pleural cavity (Elizondo-Quiroga et al., 2024; Schultz & Zwingenberger, 2008). It should be noted that foreign bodies, like grass awns in the mediastinal cavity, can appear with signs similar to many other diseases and should be distinguished from pleural effusion or pleural thickening by radiographs or CT scans (Schultz & Zwingenberger, 2008). In several cases, this condition is not diagnosed until death. 
The penetration of a foreign body contaminated by bacteria may cause a purulent fistula (Schultz & Zwingenberger, 2008). In the case reviewed in this article, hyporexia, fever, lameness, and an open wound with purulent discharge in the medial aspect of the left femur were observed. The penetration of grass awns into the skin or natural orifices and their migration to different parts of the body can result in various clinical signs and lesions (Griffeuille et al., 2023; Marchesi et al., 2020). In the report by Marchesi et al. (2020), after a 13-year-old male dog was examined for hematuria and pyrexia, ultrasonography of the genitourinary tract revealed a migrating grass awn in the right prostatic lobe. During laparotomy, the grass awn was completely removed from the prostatic parenchyma. Four months after the surgery, the dog’s symptoms improved (Karami et al., 2023; Marchesi et al., 2020). 
Based on this and other similar cases, it is apparent that the existence of incurable lesions with persistent purulent discharge indicates that the foreign object is still present in those lesions. If a simple examination does not reveal the foreign body, a more thorough examination of the inside of the wound should be conducted. Also, if the treatment of the lesions is not successful within 10 to 20 days, the migration, growth, and size of the foreign body should be assessed using diagnostic imaging and exploratory laparoscopy. In the case studied in this article, the path of the fistula was determined by a CT scan. However, the growth length and location of the foreign body made the decision to surgically remove it prohibitive. 
Numerous reports have documented plant-like foreign objects migrating within a dog’s body. To the best of our knowledge, there have been no reports of a 30 cm growth of foxtail in different parts of the dog’s body. In this case, the abnormal excessive growth of foxtail within the dog’s body was noteworthy.

Ethical Considerations
Compliance with ethical guidelines
There were no ethical considerations to be considered.
Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 
Authors' contributions
All authors equally contributed to preparing this article.
Conflict of interest
The authors declared no conflict of interest.
Acknowledgments
The authors thank the Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran, for assisting them in carrying out this study.

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