Feline urinary capillariosis - report of two cases

[Capilariose urinária felina - relato de dois casos]

ABSTRACT

Capillaria plica and Capillaria feliscati are nematodes that cause feline urinary capillariosis. These parasites usually cause mild illnesses, they do not affect the lower urinary tract. This report describes two symptomatic cases of feline urinary capillariosis. Case 1: cat, 8 years old, with lack of appetite and cystitis confirmed by urinalysis and ultrasound examination. Eggs of Capillaria spp. were identified in the examination of the urinary sediment. Antiparasitic treatment with Fenbendazole was prescribed. Case 2: cat, 5 years old, with urinary and fecal incontinence. The presence of eggs of Capillaria spp. in the examination of the urinary sediment and then treatment with Fenbendazole was performed, resulting in the elimination of the parasites. Although rare, feline urinary capillariosis can be a differential diagnosis for urinary tract abnormalities in this species.

Keywords:
Capillaria spp; cisitis; nematodes; cat

RESUMO

Capillaria plica e Capillaria feliscati são nematódeos causadores da capilariose urinária felina. Esses parasitas geralmente causam doença branda, não afetando o trato urinário inferior. O presente relato descreve dois casos sintomáticos de capilariose urinária felina. Caso 1: gato, oito anos de idade, apresentando falta de apetite e cistite confirmada por exames de urinálise e ultrassom. Ovos de Capillaria spp. foram identificados no exame do sedimento urinário. Tratamento antiparasitário com Fembendazol foi prescrito. Caso 2: gato, cinco anos de idade, apresentando incontinência urinária e fecal. Foi identificada a presença de ovos de Capillaria spp. no exame do sedimento urinário e, em seguida, realizado tratamento com Fembendazol, resultando na eliminação dos parasitas. Apesar de rara, capilariose urinária felina pode ser um diagnóstico diferencial para anormalidades do trato urinário dessa espécie.

Palavras-chave:
Capillaria spp; cistite; nematoides; gato

INTRODUCTION

Capillaria plica and Capillaria feliscati are nematode species present in several parts of the world. They are known worldwide as “urinary bladder worms” (Del-Angel-Caraza et al., 2018). These parasites cause mild disease in dogs and cats, without pathological findings associated with the lower urinary tract in most cases, possibly due to the low parasite load at hosts (Bédard et al., 2002; Knaus et al., 2014). Clinical signs include fever, hematuria, cystitis (Rossi et al., 2011; Mariacher et al., 2016), abdominal pain (Rossi et al., 2011), urinary incontinence (Pagnoncelli et al., 2011) and dysuria (Pagnoncelli et al., 2011; Miszczak et al., 2022).

The life cycle of both parasites involves earthworms as intermediate hosts, and the transmission of C. plica occurs by ingestion of infective larvae present in the intermediate host (Taylor et al., 2017). Although C. feliscati does not have a fully understood cycle, it is considered like that of C. plica (Pelligra et al., 2020).

The definitive diagnosis is the visualization of eggs through the examination of the urinary sediment; however, this method has low sensitivity, since the daily number of eggs excreted by the adult parasites may be low. Another form of diagnosis consists of identifying adult forms of the parasites through endoscopic examination of the urinary bladder (Basso et al., 2014; Del-Angel-Caraza et al., 2018).

This report describes two cases of urinary capillariosis in cats treated at the Veterinary Hospital of the State University of Maranhão, São Luís, Brazil.

CASUISTRY

Case 1 - An 8-year-old, male, Brazilian mixed breed cat was referred to the Veterinary Hospital of the State University of Maranhão, presenting reduced appetite. According to the owner, the animal had no previous history of illness. On physical examination, the patient presented hyperthermia (39.8°C). Hematological exams, urinalysis and abdominal ultrasound were requested.

All hematological parameters were within the normal range for the species. In the physical-chemical analysis of the urine, it was yellow in color, clear, specific density of 1052, presence of leukocytes (+++), protein (+) and pH of 6.0. An increase in the erythrocyte count (6-9 per field, 40x) was observed in the microscopic analysis of the urinary sediment, as well as the presence of oval structures of thick bark with granular content and bipolar plugs, which were identified as eggs of Capillaria sp. (Taylor et al., 2017) (Fig. 1).

Through abdominal ultrasonography, the internal structures were assessed and found to be within normal limits, except for the urinary bladder, which exhibited increased wall thickness, suggestive of cystitis (Fig. 2). Antiparasitic treatment with fenbendazole (50mg/kg), orally, once a day (QD), was prescribed for five days. The animal did not return for reassessment.

Figure 1
Photomicrograph of urinary sediment (40×) showing the presence ofCapillariaspp. eggs.

Figure 2
Bladder ultrasound. Note wall thickening in 1 and 2.

Case 2 - A 5-year-old, Brazilian mixed breed, male cat, was treated with urinary and fecal incontinence. During physical examination, ataxia was observed. Hematological exams, urinalysis, feces parasitology and abdominal ultrasound were requested.

Lymphopenia (860/μL) and increase in total plasmatic protein levels (10.8g/dL) were hematological alterations observed. The urine was yellow in color, clear, specific density 1029, pH 5 and presence of leukocytes (+++). Eggs of Capillaria spp. were observed in the microscopic analysis of urinary sediment. No helminth eggs were identified in the parasitological examination of feces and no abnormalities were observed in the ultrasonographic examination. Antiparasitic treatment with fenbendazole (50mg/kg), orally, once a day (QD), was prescribed for five days. A neurological evaluation was scheduled, but there was no return from the owner and patient.

After 48 days after the consultation, the patient returned with anorexia, cachexia and prostration. It was hypothermic (34.1ºC) and with pale mucous membranes. Hematological examinations and urinalysis were requested; however, the animal died a few hours after hospitalization. The blood count result indicated thrombocytopenia (46,000/mm³), increase in total plasma protein levels (11 g/dL), reduction in red blood cell count (1.5 million/mm³), hemoglobin concentration (3.4g/dL) and hematocrit (10.3%). Urinary parameters were within normal limits, the presence of Capillaria spp. eggs was not detected in the urinary sediment.

DISCUSSION

Reports of urinary capillariosis in domestic carnivores are uncommon, as cases are usually asymptomatic. Despite this, infections have been reported in Brazil (Guimarães et al., 2020; Pagnoncelli et al., 2011), Mexico (Del-Angel-Caraza et al., 2018), Canada (Bédard et al., 2002), Italy (Mariacher et al., 2016; Pelligra et al., 2020) and Greece (Sioutas et al., 2021).

Proteinuria, hematuria and the presence of leukocytes in urine have been described in cases of feline urinary capillariosis associated with cystitis (Guimarães et al., 2020; Miszczak et al., 2022; Pelligra et al., 2020; Rossi et al., 2011). Such alterations were observed in the urinalysis of patient 1. Cystitis is caused by the contact of helminths with the bladder mucosa, triggering an inflammatory reaction in the epithelium, since adult stages of C. plica can be both free and inserted in the mucosa, while C. feliscati is found free on the mucosal surface (Taylor et al., 2017; Del-Angel-Caraza et al., 2018).

Patient 2 had urinary and fecal incontinence, in addition to ataxia. Although urinary incontinence has been reported in a cat with urinary capillariosis (Pagnoncelli et al., 2011), digestive and neurological manifestations are incompatible. In addition to clinical signs, hematological abnormalities were observed, such as anemia, lymphopenia and thrombocytopenia. The association of these alterations is more consistent with viral infections.

Both patients were treated with fenbendazole, but the effectiveness of the treatment could not be analyzed in patient 1, as it did not return for reassessment, while in patient 2 the treatment proved to be effective, eliminating the parasites. Fenbendazole has shown good results in the treatment of feline urinary capillariosis, with disappearance of clinical signs in symptomatic cases (Rossi et al., 2011; Guimarães et al., 2020; Pelligra et al., 2020), as well as ivermectin, to which it has also been proved to be effective (Bédard et al., 2002; Pagnoncelli et al., 2011). Knaus et al. (2014) using a combination of fipronil, methoprene, eprinomectin and praziquantel (BROADLINE®, Merial) topically to treat naturally infected cats, achieved 100% efficacy in the treated group, while the untreated group remained infected, Miszczak et al. (2022) using this same combination were successful in the treatment of an infected cat, which had dysuria, periuria and stranguria.

Regarding transmission, although the ingestion of earthworms by the definitive host is rare, there is the possibility of infection through the ingestion of paratenic hosts. According to Petersen et al. (2018), rodents and birds may play a role in the cycle of the parasite, as they can consume infected earthworms. Due to their predation habits, felines are prone to becoming infected through the consumption of rodents and birds, since these species are part of their food chain. Despite this factor, epidemiological studies indicate a low occurrence of infections in domestic cats. Ramos et al. (2013) investigated the helminth fauna in 146 necropsied cats belonging to the Metropolitan region of Cuiabá, Midwest Brazil and detected C. feliscati in 3.42% of the animals, while Pelligra et al. (2020) when investigating the occurrence of Capillaria spp. in domestic carnivores in central-north Italy, detected infection in 7.7% of cats sampled. In Germany, Krone et al. (2008) when investigating the helminth fauna in carcasses of domestic and wild cats, detected C. plica at 6% of domestic cats.

The low number of positive animals justifies the lack of epidemiological studies in domestic carnivores, with most records being restricted to sporadic reports in symptomatic or asymptomatic animals, and in the latter the diagnosis ends up being an accidental finding in the urinalysis exam, specifically in the analysis of the urinary sediment.

CONCLUSION

Although it has a low casuistry, feline urinary capillariosis can be included as a differential diagnosis for urinary tract abnormalities in cats, since cases are not always self-limiting and therapeutic intervention may be necessary.

ACKNOWLEDGEMENTS

To Veterinary University Hospital Francisco Edilberto Uchoa Lopes, State University of Maranhão, São Luís, Brazil. To Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES (Finance Code 001) and Fundação de Amparo à Pesquisa e Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA). LMM (88887.625928/2021-00) is a graduate scholarship. HSR (CNPq 150336/2023-3) is postdoctoral research fellow. ALA-S (313348/2021-9) is research productivity fellows by Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq.

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Publication Dates

• Publication in this collection
  14 July 2025
• Date of issue
  Jul-Aug 2025

History

• Received
  10 Oct 2024
• Accepted
  21 Feb 2025