Social media as a tool for detecting underdiagnosed parasitic infections: the case of spirocercosis.

Spirocercosis is a parasitic disease caused by the nematode Spirocerca lupi that affects several canids around the world. In Costa Rica, few spirocercosis cases have been reported; however, it is suspected that the infection is currently underdiagnosed. As seen during the COVID-19 pandemic, social media has sped up the spread of scientific knowledge, raising practioner's awareness of the epidemiology and signs and manifestations of infections. The aim of this work was to use social media as a tool for increasing awareness of spirocercosis among veterinarians and investigate the frequency of cases occurring in Costa Rica. Infographic material about the infection was disseminated by Whatsapp, Facebook, and Instagram from January 2021 to July 2022 using a public account of the Laboratory of Helminthology of the University of Costa Rica. In addition, Google Forms questionnaires were completed by veterinarians to report the number of spirocercosis cases in their clinics, associated manifestations, diagnosis, treatment, and outcome of the disease. Remarkably, since 2020, a six-fold increase in the number of cases per year was noted. Clinical manifestations matched those reported elsewhere, and one of every three dogs infected with S. lupi died spontaneously or required euthanasia because of the infection. This work suggests that S. lupi infection in Costa Rica may have been underdiagnosed in the last decade, and the knowledge and awareness of clinical personnel play a major role in the detection of this and other infectious diseases.

Subcutaneous spirocercosis in a dog from Costa Rica and first molecular confirmation of Spirocerca lupi in Central America.

Spirocerca lupi is the etiological agent of spirocercosis in canids from tropics and subtropics in the world. This parasite can lead to life threatening complications, including the formation of fibro and osteosarcomas. A 5-year-old crossbreed Maltese dog from Costa Rica was presented to a veterinary clinic with two nodules in the subcutaneous tissues of the cervical region. One of the nodules resolved with intramuscular antibiotic and anti-inflammatory treatment. However, the other nodule persisted and became purulent. The content of the nodule was excised releasing two coiled 3-cm reddish worms. Identity of the specimens was confirmed by amplifying an 850 bp fragment of the 18S rDNA. The obtained sequence showed 99.96% similarities with S. lupi from Hungary. The present study highlights the need of veterinary clinicians' awareness towards nematode aberrant migrations, and the require of molecular studies to gain insight into the parasite's evolutionary history.

Spirocerca lupi Proteomics and Its Role in Cancer Development: An Overview of Spirocercosis-Induced Sarcomas and Revision of Helminth-Induced Carcinomas.

Spirocerca lupi is a parasitic nematode of canids that induces a myriad of clinical manifestations in its host and, in 25% of infections, leads to the formation of sarcomas. The description of the protein composition of the excretory and secretory products (Sl-ESP) of S. lupi has shed light on its possible interactions with the host environment, including migration within the host and mechanisms of immunomodulation. Despite this, the process by which S. lupi induces cancer in the dog remains poorly understood, and some hypotheses have arisen regarding these possible mechanisms. In this review, we discuss the role of specific ESP from the carcinogenic helminths Clonorchis sinensis, Opisthorchis viverrini and Schistosoma haematobium in inducing chronic inflammation and cancer in their host's tissues. The parasitic worms Taenia solium, Echinococcus granulosus, Heterakis gallinarum, Trichuris muris and Strongyloides stercoralis, which have less-characterized mechanisms of cancer induction, are also analyzed. Based on the pathological findings in spirocercosis and the mechanisms by which other parasitic helminths induce cancer, we propose that the sustained inflammatory response in the dog´s tissues produced in response to the release of Sl-ESP homologous to those of other carcinogenic worms may lead to the malignant process in infected dogs.

Insights on Spirocerca lupi, the Carcinogenic Dog Nematode.

Spirocerca lupi is a nematode transmitted by dung beetles that infects domestic and wild canids in tropical and subtropical regions and is associated with neoplasia. It produces a distinctive pathology with the formation of esophageal nodules classified as inflammatory, preneoplastic, or neoplastic with metastasis to distant organs. Aberrant central nervous system migration of this nematode is also responsible for severe neurological manifestations. Reports of spirocercosis have increased over the last two decades showing spread of this canine helminth in five continents. S. lupi from different geographical locations is genetically distinct with two genotypes, genotype I from Africa, Asia, and Australia, and genotype II from Europe, and recently separated from Spirocerca vulpis, a new species described in red foxes from Europe.

Secretome of the carcinogenic helminth Spirocerca lupi reveals specific parasite proteins associated with its different life stages.

Spirocerca lupi is a parasitic and carcinogenic nematode of canids distributed in tropical and subtropical regions around the world. The excretion-secretion proteins (PES) of S. lupi have been suggested to play a role in the pathogenesis of its infection. We aimed to identify the PES of different stages of S. lupi and search for proteins that would be useful for diagnostic, therapeutic and vaccination purposes as well as understand their functions. A nano-UPLC mass spectrometry de novo analysis was performed on proteins collected from cultures of S. lupi L3 larvae, L4 females, adult females and adult males from naturally infected hosts. A total of 211 proteins were identified in all cultures. Accordingly, 117, 130, 99 and 116 proteins were detected in L3 larva, L4 females, adult females and adult males, respectively, with a strong correlation in the biological replicates (Pearson coefficients > 0.73). Fourty-four proteins were detected in all developmental stages, 64 were stage-specific and 49 were exclusively identified in L4 females. Cell compartment enrichment analysis revealed that proteins common to all stages were cytoplasmatic (p < 9.x10-6), whereas L4 unique proteins were in collagen trimers, and macromolecular complexes (p < 0.00001). Functional enrichment analysis of proteins showed significant enrichment in lipid metabolism in L3-unique proteins (p<0.00005), in mannose metabolism and protein de-glycosylation for L4-unique proteins (p < 0.00004), and in phosphorus metabolism in proteins shared by all stages (p <  2.1 x10-9). Interestingly, annexin 6, associated with cancer in humans, was detected in all life stages, but in a larger abundance in L4 females and adults. These findings indicate that S. lupi establishes complex interactions with its hosts by an arsenal of proteins expressed in different patterns in each life stage which influence the pathogenesis and oncogenesis of S. lupi and may be used as potential targets for diagnostic assays, drug targets or vaccine candidates.

Acute mesenteric ischemia-like syndrome associated with suspected Spirocerca lupi aberrant migration in dogs.

OBJECTIVE: To describe acute mesenteric infarction due to suspected Spirocerca lupi aberrant migration in 5 dogs. CASE SERIES SUMMARY: All dogs were large breed, none of which exhibited typical clinical signs associated with spirocercosis. All dogs were eventually diagnosed with septic peritonitis. On exploratory laparotomy, thickening of the jejunal arteries, surrounding mesojejunum, and segmental necrosis were identified. Similar thickening and hematoma formation were found in other regions of the mesentery. In 4 of the cases, the necrotic segment was located in the distal jejunum. Histology revealed thrombotic mesenteric vessels with intralesional S. lupi nematode larvae. Resection and anastomosis of the necrosed section was performed and all but 1 dog survived and were discharged within 1-6 days. NEW OR UNIQUE INFORMATION PROVIDED: Spirocerca lupi is a potential cause of mesenteric infarction in endemic areas when no other obvious etiology is identified.

Detection of Intraspinal Spirocerca lupi in Canine Cerebrospinal Fluid by Polymerase Chain Reaction.

Aberrant migration of Spirocerca lupi into the spinal cord is an important cause of severe progressive neurological dysfunction in dogs. Although early diagnosis is essential to prevent deterioration, ante-mortem diagnosis of this condition remains challenging. The aim of this study was to evaluate the detection of the 18S ribosomal DNA (rDNA) S. lupi gene in the cerebrospinal fluid (CSF) of presumptively-affected dogs using polymerase chain reaction (PCR). Dogs with a non-compressive spinal cord lesion, pleocytosis with presence of eosinophils in the CSF and a characteristic clinical presentation were included. CSF samples from eight dogs were available for the study, of which seven were definitively diagnosed with intraspinal spirocercosis by PCR of either the CSF samples (6/7) or tissue samples obtained at necropsy examination (3/7), or both (2/7). Of these seven positive cases, only one dog had a negative CSF PCR, indicating a sensitivity of 86% for detecting nematode DNA in the CSF of infected dogs using this PCR protocol. The nematode DNA sequences obtained from the CSF of six dogs and the spinal cord tissue of three dogs were 98-100% identical to the publicly available sequences of S. lupi, confirming the diagnosis. These findings indicate that PCR targeting the 18S rDNA of S. lupi in CSF is useful for the ante-mortem diagnosis of canine intraspinal spirocercosis.

Postmortem detection and histopathological features of canine spirocercosis-induced putative esophageal chondrosarcoma.

AIM: The objective of this study was to describe and characterize the postmortem and histopathological findings of putative esophageal chondrosarcoma associated with Spirocerca lupi. MATERIALS AND METHODS: Spirocerca-associated esophageal nodules were collected from 54 dogs at postmortem examination and were stained with hematoxylin and eosin. Of the cases examined, 15 were selected randomly for further investigation, of which 11 were classified as non-neoplastic nodules while 4 had changes reflecting a neoplastic process. RESULTS: In all four neoplastic cases, the wall of the esophageal nodules contained islands and nests of highly proliferative atypical chondroblasts within a cartilaginous matrix. However, there was no statistically significant association between gender (p=0.228), age (p=0.568), and breeds (p>0.05) with the occurrence of spirocercosis. Moreover, all esophageal nodules identified were located near the caudal segment, and their diameters ranged from 1 to 6 cm (4.7±1.5 cm). A number of worms in each nodule varied from 5 to 25 (11.3±5). CONCLUSION: Histopathology and cytology revealed that the wall of the esophageal nodules contained islands and nests of highly proliferative atypical chondroblasts within a cartilaginous matrix, a rare finding, and clinical challenge in spirocercosis.

Morphological and molecular identification of Spirocerca lupi (Nematoda: Spiruridae) found in the Andean fox (Lycalopex culpaeus).

Lesions compatible with spirocercosis were found in the esophagus and aorta of an Andean fox from Cuzco, Peru. The esophageal and aortic lesions were 5.5 and 1.5 cm in diameter, respectively. A total of 12 adult nematodes (6 males and 6 females) were collected from the esophageal lesion, and all were identified as Spirocerca lupi by morphological and molecular methods. Molecular characterization was performed by analyzing two sources of the cox1 gene, and the sequences were compared with previous S. lupi sequences from other work deposited in GenBank. Analysis of the partial cox1 gene from S. lupi (n = 3) showed 2 haplotypes and had 95-99% nucleotide similarity to previously described sequences. Also, molecular analysis showed that S. lupi is a very diverse group, due to the genetic variability of the partial sequences of the cox1 gene of Spirocerca. This study is the first to report finding of spirocercosis in the Andean fox.

Spirocerca vulpis sp. nov. (Spiruridae: Spirocercidae): description of a new nematode species of the red fox, Vulpes vulpes (Carnivora: Canidae).

Previous studies have reported nematodes of the Spirocercidae family in the stomach nodules of red foxes (Vulpes vulpes) described as Spirocerca sp. or Spirocerca lupi (Rudolphi, 1819). We characterized spirurid worms collected from red foxes and compared them to S. lupi from domestic dogs by morphometric and phylogenetic analyses. Nematodes from red foxes differed from S. lupi by the presence of six triangular teeth-like buccal capsule structures, which are absent in the latter. Additionally, in female worms from red foxes, the distance of the vulva opening to the anterior end and the ratio of the glandular-to-muscular oesophagus lengths were larger than those of S. lupi (P < 0.006). In males, the lengths of the whole oesophagus and glandular part, the ratio of the glandular-to-muscular oesophagus and the comparison of the oesophagus to the total body length were smaller in S. lupi (all P < 0.044). Phylogenetic analyses revealed that S. lupi and the red foxes spirurid represent monophyletic sister groups with pairwise nucleotide distances of 9.2 and 0.2% in the cytochrome oxidase 1 and 18S genes, respectively. Based on these comparisons, the nematodes from red foxes were considered to belong to a separate species, for which the name Spirocerca vulpis sp. nov. is proposed.

Clinical characteristics of Spirocerca lupi migration in the spinal cord.

Spirocerca lupi is a nematode infecting dogs mostly in tropical and subtropical areas. Although its typical target is the esophageal wall, aberrant migration is not uncommon, including migration of unknown incidence into the spinal cord. While successful treatment of intraspinal S. lupi (ISSL) infection depends on early diagnosis, tools for definitive ante-mortem diagnosis are unavailable. We therefore aimed at characterizing clinical signs and clinical pathology findings of ISSL in dogs. For that, we analyzed medical records of dogs hospitalized in 2005-2016 presenting with neurological signs consistent with ISSL, which were diagnosed definitively post-mortem. Retrieved information included signalment, medical history, chief complaint, physical and neurological evaluation, neuroanatomical localization at presentation, clinical pathology, imaging findings, treatment, outcome and post-mortem findings. Ten midsize to large breed dogs were included, 7 of which had received prophylactic treatment. In all 10 dogs, onset was acute and neurological deterioration until presentation (2 h-6 d) was fast. Neurological examination localized the lesions within the spinal cord and paresis or paralysis was asymmetric in all dogs. Spinal pain was documented in 9/10 dogs. Cerebrospinal fluid (CSF) analysis was abnormal in all dogs and was characterized by pleocytosis in 8/10, whereas cytology revealed the presence of eosinophils in all dogs. Advanced imaging excluded spinal cord compression in all dogs tested. Post-mortem examination detected spinal cord migration tract in all cases. Nematodes were found in the spinal cord parenchyma (8/10) or adjacent to it (2/10) in all dogs. A larva was found in the subarachnoid space of one dog and an adult nematode in the thoracic intervertebral artery of another. Esophageal nodules were found in 5/10 dogs. These findings suggest that the combination of sudden onset of acute asymmetric paresis accompanied by pain, presence of eosinophils in the CSF and lack of compressive lesion may serve as sufficient evidence for tentative diagnosis of ISSL in endemic areas.

Nematode eggs observed in cytology of cerebrospinal fluid diagnostic for intramedullary Spirocerca lupi spinal cord migration.

Spinal spirocercosis due to aberrant Spirocerca lupi nematode migration is an emerging etiology for acute myelitis in dogs in Israel, causing severe, mostly nonsymmetrical hind limb paresis or paralysis, and sometimes tetraparesis or tetraparalysis. So far, incidental identification of parasites during spinal surgery or at necropsy provides the only definite diagnosis, while antemortem diagnosis of this condition has been uncertain. Specifically, antemortem diagnosis is based on the typical clinical presentation of acute, progressive, asymmetrical hind limb paresis or paralysis, with moderate to severe eosinophilic to mixed cerebrospinal fluid (CSF) pleocytosis and increased CSF protein concentration. Exclusion of other differential diagnoses also requires using spinal cord imaging. In this novel report, we document a case of an intradural spinal spirocercosis in a dog, diagnosed antemortem, by detecting S lupi eggs in the CSF, and subsequent treatment, resulting in the resolution of the clinical signs.

Detection and quantification of Spirocerca lupi by HRM qPCR in fecal samples from dogs with spirocercosis.

BACKGROUND: Spirocerca lupi, the dog oesophageal nematode, causes a potentially fatal disease in domestic dogs, and is currently clinically diagnosed by coproscopy and oesophagoscopy. To date, a single molecular method, a semi-nested PCR, targeting the cox1 gene, has been developed to aid in the diagnosis of spirocercosis. The present study describes three novel high-resolution melt (HRM) quantitative PCR (qPCR) assays targeting fragments of the ITS1, 18S and cytb loci of S. lupi. The performance of these molecular assays in feces was compared to fecal flotation and to the previously described cox1 gene semi-nested PCR in 18 fecal samples from dogs with clinical oesophageal spirocercosis diagnosed by oesophagoscopy. RESULTS: The HRM qPCR for ITS1 and 18S were both able to detect 0.2 S. lupi eggs per gram (epg), while the HRM qPCR for the cytb and the semi-nested PCR for the cox1 detected 6 epg and 526 epg, respectively. Spirocerca lupi was detected in 61.1%, 44.4%, 27.8%, 11.1% and 5.6% of the fecal samples of dogs diagnosed with spirocercosis by using the ITS1 and 18S HRM qPCR assays, fecal flotation, cytb HRM qPCR and cox1 semi-nested PCR, respectively. All dogs positive by fecal flotation were also positive by ITS1 and 18S HRM qPCRs. Quantification of S. lupi eggs was successfully achieved in the HRM qPCRs and compared to the fecal flotation with no significant difference in the calculated concentrations between the HRM qPCRs that detected the 18S and ITS1 loci and the fecal flotation. The HRM qPCR for the 18S cross-amplified DNA from Toxocara canis and Toxascaris leonina. In contrast, the HRM qPCR for ITS1 did not cross-amplify DNA from other canine gastrointestinal parasites. CONCLUSIONS: This study presents two new molecular assays with significantly increased sensitivity for confirming and quantifying fecal S. lupi eggs. Of these, the HRM qPCR for ITS1 showed the best performance in terms of the limit of detection and absence of cross-amplification with other parasites. These assays will be useful in detecting infection and for follow-up during therapy.

Genotyping and comparative pathology of Spirocerca in black-backed jackals (Canis mesomelas) in South Africa.

BACKGROUND: The pathology of spirocercosis, a disease caused by the infestation of carnivores with the nematode Spirocerca lupi, has been extensively described in domestic dogs and coyotes. However, it has not been described in wild carnivores in South Africa. The aim of this study was to evaluate whether black-backed jackals are a host for Spirocerca species and to provide a detailed description of the associated pathology. Jackals were also stratified according to age and the Spirocerca species recovered were characterized using molecular techniques. METHODS: Standard necropsies were performed on routinely culled jackals from three of the nine provinces of South Africa during the period June 2012 to February 2013. Jackals were screened for the presence of pathognomonic Spirocerca-induced lesions and for evidence of aberrant migration. Relevant samples were submitted for histopathology and collected larvae were genotyped at nine microsatellite loci. RESULTS: Spirocerca lupi-associated aortic lesions were found in 16 of 93 (17%) black-backed jackals. Of these, four (25%) were associated with S. lupi larvae. Genotyping of the larvae revealed amplification of all nine loci that amplified dog-derived S. lupi, with the same level of polymorphism in the allele size ranges. Only 1 of 93 jackals had an esophageal nodule with concurrent S. lupi-induced aortic aneurysms. The single esophageal nodule found did not contain adult nematodes, nor did it communicate with the esophageal lumen. None of the jackals that were examined had macroscopically evident spondylitis, which is frequently reported in the dog. Histopathology of the S. lupi-induced aortic lesions in the jackal revealed replacement of elastic and smooth muscle fibers by fibrous connective tissue. In cases where inflammation was present, the inflammatory infiltrate consisted predominantly of eosinophils. The single esophageal nodule histologically resembled the early inflammatory nodule described in dogs and consisted of fibrous connective tissue, multifocal accumulation of lymphocytes, plasma cells and rare hemosiderin-laden macrophages. CONCLUSIONS: These lesions suggest that the life cycle of S. lupi may not or only rarely be completed in jackals. A possible explanation might be that jackals are relatively resistant to developing significant pathology associated with S. lupi-infection. However, before any conclusions can be drawn, many more jackals, including those that die naturally will have to be investigated for evidence of S. lupi infection.

Influence of physical and chemical factors on the embryonation, hatching and infectivity of Spirocerca lupi.

Spirocerca lupi is a parasitic nematode which causes spirocercosis, a severe disease of dogs. Its life cycle involves dung beetles as intermediate hosts and canids as definitive hosts. The effect of different physical conditions and chemical factors on the embryonation and hatching of S. lupi eggs were investigated in this study in order to understand the triggers for progression in the early development of this parasite. Exposure to potassium dichromate significantly enhanced the embryonation of eggs compared to formaldehyde and controls (p<0.0001), reaching the maximum embryonation level of 83% within 2days of incubation. Hatching of eggs was significantly (p<0.05) enhanced in the presence of 2.5% trypsin, pH 6.0 and 8.0, a temperature of 26°C, 20% CO2 and mechanical force by stirring with 3-mm beads. Dissection of Onthophagus sellatus beetles 8h post-feeding with eggs showed that 13% of the ingested eggs hatched in the buccal cavity and the midgut. Finally, the pH range of the beetle's gut was 6.0-6.2 compared to 7.2±0.4 in dog feces suggesting that this pH change may induce hatching in the beetle. These findings contribute to the understanding of the early steps in the life cycle of S. lupi and may be used in the future to block the development of S. lupi and prevent dog infection and disease.

In vitro lectin binding to the outer surface of Spirocerca lupi at different life-stages.

Spirocerca lupi is the esophageal nematode of dogs. Early, transient eosinophilia occurs in experimentally infected dogs, but is absent in advanced cases, suggesting that the nematode evades the dog's immune system. Lectins are proteins or glycoproteins of plant or animal origin, binding different saccharides, with varying specificities and avidities, used to characterize surface haptens in plant and animal parasitic helminths. This study investigated the in vitro binding of six lectins (Concanavalin A [ConA], wheat germ agglutinin [WGA], peanut agglutinin [PNA], soybean agglutinin [SBA], Dolichus biflorus agglutinin [DBA] and Ulex earopaeus agglutinin I [UEA]) to the surface of S. lupi nematodes at different life stages, the L2 and L3 larvae (dead and alive) and to dead adult worms, with negative controls, with and without addition of the six respective inhibitory sugar haptens. Con A moderately bound to surfaces of both live and frozen L3, to the stoma and excretory pores of adult worms, and to the outer surface nematode's eggs, within a female worm, but not to L2. PNA bound only to stoma and excretory pores surfaces in both frozen and live L3. WGA bound strongly to the outer surfaces of live and dead L2 and L3, which resulted in molting of live larvae. These results suggest that the nematode's surface content change during its development. Such changes may play roles in the nematode's interactions with the intermediate and definitive hosts' tissues, and in its ability to evade the immune response, its long survival within the host, and even induce neoplastic transformation.

Long-term outcome of transendoscopic oesophageal mass ablation in dogs with Spirocerca lupi-associated oesophageal sarcoma.

Oesophageal sarcoma is a potential sequel of Spirocerca lupi infection. Oesophageal mass excision can be performed by open chest surgery. The objectives of this observational study were to evaluate the feasibility, short-term morbidity and long-term outcome of transendoscopic oesophageal mass ablation in dogs with spirocercosis-associated oesophageal neoplasia. A 9 mm video-endoscope and laser or electrocauterisation were used to debulk the oesophageal mass. Long-term follow-up was done by telephonic interviews. Fifteen dogs were included. The median tumour size was 5 cm (range 3.5-9). The median procedure time was 75 minutes (range 35-165) and was deemed successful in 12/15 dogs (80 per cent). Recovery was uneventful in all dogs. Immediate complications included oesophageal damage (two dogs) oesophageal perforation (one dog) and a focal thermal damage (one dog). The median hospitalisation time of all dogs was less than one day, with all but two discharged on the procedure day. The median survival time, available in nine dogs that were followed, was 202 days (range 51-691). Four of these dogs (44 per cent) survived more than six months, of which three survived more than one year. In conclusion, transendoscopic oesophageal mass ablation might be considered an alternative, palliative procedure for open-chest oesophageal surgery. It has comparable long-term survival, lower morbidity, short hospitalisation time and relatively low cost.

Serological cross-reactivity of three commercial in-house immunoassays for detection of Dirofilaria immitis antigens with Spirocerca lupi in dogs with benign esophageal spirocercosis.

The nematode Spirocerca lupi infects dogs and is endemic in Israel. It leads to formation of esophageal nodules and neoplasia. Infection is diagnosed by coproscopy, endoscopy and radiography. Dirofilaria immitis causes heartworm disease in dogs, and has a world-wide distribution, but autochthonous infection has never been detected in Israel. Infection is confirmed based on identifying D. immitis microfilariae, in concentrated blood specimens by microscopy (Knott's test or other tests) and serological tests specifically detecting circulating adult worm antigens. In the first part of this study, sera from dogs definitively diagnosed with esophageal spirocercosis by endoscopy were examined using three in-house immunoassays for detecting D. immitis antigen, and were positive in 2/19 (10.5%), 5/35 (14.3%) and 14/48 (29.2%) dogs, in assays 1 to 3, respectively, with no statistical difference between assays (P=0.08). Next, sera from 32 additional dogs with confirmed esophageal spirocercosis, which were confirmed to be negative for D. immitis and Dirofilaria repens DNA using a sensitive high-resolution melt PCR were tested using assay 3 and 8/32 (25%) were positive. These results demonstrate serological cross-reactivity between D. immitis and S. lupi in blood samples of dogs. In areas where the distributions of both nematodes overlap, this cross-reactivity should be considered when dog are screened for heartworm disease.

The evaluation of retrospective pathological lesions on spirocercosis (Spirocerca lupi) in dogs.

From 1998 to 2012, 42 dogs with spirocercosis referred to pathology Department of Veterinary Faculty, Tehran University. Frequency of spirocercosis was higher in October, November, December, January, February, March months. Averagely, the cases were 4.73 years old of age, so that 59.3 % of them were male. The major pathological findings were located in distal part of esophagus (57 %, n = 24), stomach (24 %, n = 10), and aorta (9.5 %, n = 4), respectively. In addition, 7 % (n = 3) were in esophagus and stomach, 2 % (n = 1) in esophagus and aorta, 42 % (n = 18) indicated pulmonary lesions with hyperemia, atelectasis, edema and pneumonia. In 35 % (n = 15) of cases were with hepatic lesions hyperemia and fatty change. However, 26 % (n = 11) cases demonstrated renal lesions with hyperemia, interstitial nephritis, and 24 % (n = 10) encompassed urinary bladder lesions with hyperemia and adhesive cystitis. Furthermore, sudden death occurred in 7 % (n = 3) as well as cachexia in 7 % (n = 3) cases. Some spirocercosis cases (12 %, n = 5) were accompanied by distemper disease, mixed mammary gland tumor (2 %, n = 1) and parasitic dermatitis due to demodicosis (9.5 %, n = 4). Presumably some of pathological findings were related or emerged by other sort of diseases such as distemper.