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Current IssueSpecial IssueEditorial BoardOnline First ArticlesArchive

Short Communication

Extra-genital Canine Transmissible Venereal Tumor (CTVT) with Concurrent Aspergillosis and Staphylococcal Infection in a Dog

U
Utpal Barman1
A
Arup Das1,*
0000-0002-0916-2693
A
Abhijit Deka1
S
Shasanka Sandilya2
B
Bendangla Changkija2
D
Deepa Lahkar2
M
Mousumi Hazorika1
1Veterinary Clinical Complex, College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara, Guwahati-781 022, Assam, India.
2Department of Veterinary Medicine, College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara, Guwahati-781 022, Assam, India.

ABSTRACT

Background: Canine transmissible venereal tumor (CTVT) is one of the oldest tumors of dogs. It is transmitted horizontally among dogs during mating, sniffing, licking, biting of the tumor affected areas. Extra-genital canine transmissible venereal tumor is an uncommon presentation often complicated with secondary infection. The present case describes a rare occurrence of paranasal CTVT complicated with bacterial and fungal infection.

Methods: An adult male non-descript dog was presented to the outpatient department (OPD) of veterinary clinical complex (VCC), College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara with complaint of swelling in the paranasal area with pus discharge. On detailed clinical examination, an ulcerated growth on paranasal area with purulent discharge and difficulty in respiration was observed; however, body vitals were within normal limits. Fine needle aspirates for cytological and swab samples were collected for cultural examination.

Result: Cytology revealed round nucleated cells with basophilic cytoplasm with vacuoles and microbial cultures of swab samples revealed Staphylococcus aureus. and Aspergillus spp.  Based on these findings, it was diagnosed as extra genital transmissible venereal tumor concurrent with bacterial and fungal infections. The dog was treated with vincristine sulphate @ 0.5 mg/m2 BSA parenterally, itraconazole @ 10 mg/kg bwt, PO on alternate days for four weeks, linezolid @ 10 mg/kg bwt, PO once daily for 21 days along with supportives. An uneventful improvement and resolution of paranasal lesions were observed within a few weeks following treatment and complete recovery was noted by the 5th week after initiation of treatment.  

INTRODUCTION

The most common neoplastic syndrome affecting either sex in dogs is the canine transmissible venereal tumor (CTVT). It is one of the oldest known tumors of canines and is also known as venereal granuloma, infectious sarcoma, or Sticker’s sarcoma. It is a histiocytic or more specifically a round cell tumor of the reticuloendothelial system of dogs (Goldschmidt, 2002). CTVT is a highly contagious tumor that is transmitted horizontally from one dog to another during mating when abraded mucosa is exposed to the tumor of an infected dog (Chikweto et al., 2013; Daleck and Denardi, 2016; Kucukbekir et al., 2021, Otter et al., 2015). CTVT can also be transmitted by other social behaviours such as licking, sniffing and biting of the tumor affected areas (Gurel et al., 2002, Strakova and Murchison, 2014; Oliveira, 2019) as evidenced by clinical lesions seen in body parts other than genitalia in both male and female dogs (Bandaranayaka et al., 2023; Sumathi et al., 2025). CTVTs are widespread and prevalent worldwide (Strakova and Murchison, 2014) and the disease is most prevalent in those countries with free-roaming dog populations (Kucukbekir et al., 2021; Gibson et al., 2021). CTVTs are more commonly observed in young and sexually active dogs between 2-5 years of age (Kucukbekir et al., 2021) and lower incidences are seen in dogs older than 10 years (Chikweto et al., 2013; Kucukbekir et al., 2021; Pastor et al., 2018). Males are at greater risk of metastasis (16-17%) than females (2-3%) (Martins et al., 2005; Gupta and Sood, 2012) however, no sex predilection has been reported (Costa et al., 2023; Schectman et al., 2022). Although, CTVT primarily affects external genitalia, extra-genital involvement has also been reported in the oro-nasal cavity, skin and eyes. Extra-genital CTVT are relatively uncommon and is primarily reported as an isolated case reports. Genital form of TVT is mainly dominating in the dogs as compared to extra-genital manifestations. Chikweto et al. (2013) observed extra-genital lesions in 15 of 78 dogs with prevalence of about 19.2% with nasal cavity being one of the affected sites.
       
Common clinical signs of CTVT affecting genitalia includes haemorrhagic discharge, cauliflower- like mass with or without necrosis. In female, vulvar mucosa, vaginal mucosa and in males, glans penis, preputial mucosa are more commonly affected areas. (Brandão et al., 2002; Ganguly et al., 2016). When located extragenitally, either primarily or after metastasis, clinical signs are nonspecific if there is no concurrent genital lesion. Depending on their anatomical localization, signs of extra-genital CTVT may include enlargement of regional lymph nodes along with sneezing, epistaxis, epiphora, exophthalmos, skin bumps, halitosis or dental fistula, facial deformity (Rogers et al., 1998).
       
Diagnosis is mainly achieved by cytological analysis of fine needle aspirates (FNAC) or impression smears (Ganguly et al., 2016; Rogers et al., 1998).  CTVT cells can be differentiated from other neoplasms using a PCR-based detection assay targeting specific long interspersed nuclear elements (LINEs) inserted upstream of the myc gene (Rogers et al., 1998). Although spontaneous regression can occur, CTVT is usually progressive and treated accordingly. Several treatment options like complete surgical excision, radiotherapy and chemotherapy are effective treatments. Chemotherapy with vincristine sulfate is the treatment of choice for CTVT in canines provided all the blood parameters are within the normal range (Cohen, 1985). This communication discusses a rare case of extra-genital CTVT complicated with aspergillosis and staphylococcal infection and its uneventful recovery in a nondescript dog.
 
Case presentation
 
An adult nondescript dog was presented to the Veterinary Clinical Complex, College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara, Guwahati, Assam, India, in the month of August 2025, with complaints of inappetance, a wound in the paranasal region (Fig 1) with pus discharge over the past three months with no history of deworming or vaccination. Detailed clinical examination revealed the animal to be extremely weak with mild dehydration, pale mucous membrane and a non-healing fistulous perforation in paranasal region with discharge of pus causing difficulty in breathing. Body vitals like respiratory (28/min) and heart rate (95 bpm) and rectal temperature (101.3°F) were within normal range. No genital lesions were observed on examination.

Fig 1: Perforation in nasal bone with discharge of pus causing difficulty in breathing.


       
Approximately 4 ml of whole blood was collected from the affected dog on the day of presentation by using a 22-gauge needle attached to a 5ml syringe through saphenous venipuncture. A fraction of whole blood was transferred into K3-EDTA vacutainer and was subjected to haematological analysis. Haematological parameters viz., haemoglobin (g/dl), packed cell volume (%), total erythrocyte count (×106/µl), RBC indices, thrombocyte count (×106/µl) and leukogram profile were estimated using an automated hematology analyzer (MELET SCHLOESING Laboratoires, FLS257). Serum samples were used for determination of hepatic enzymes (ALT, AST) and total protein (TP) and globulin by using a fully automated chemistry analyzer (IDEXX’s the Catalyst OneTM Chemistry Analyzer) based on dry-slide technology. 
       
For cytological examination, fine needle aspirates were collected and aspirated material was smeared onto clean glass slides, air-dried, stained with Giemsa stain and examined microscopically as per standard protocol described by Valenciano and Cowell (2019). Sterile nasal swab samples were collected for microbiological examination which followed by culture and identification of bacterial and fungal agents following standard procedures described by Quinn et al., (2011) and Markey et al., (2013).
       
The leukogram revealed granulocytic leukocytosis while the erythrogram indicated normocytic normochromic anemia (Table 1), serum biochemistry showed mild elevation in hepatic enzymes (ALT, AST), increased total protein (TP) and globulin. Serum albumin was low and albumin to globulin (A/G) ratio was lower than normal (Table 2). Microbiological examination revealed Staphylococcus aureus. after 72 hours of incubation (Fig 2) and Aspergillus spp. after 7 days of incubation (Fig 3). Bacterial isolates were identified by cultural and biochemical test. The isolates were gram positive cocci and on biochemical test it was positive for catalase and coagulase and also capable for mannitol fermentation, thus confirming their identity as Staphylococcus aureus. However, species level identification of Aspergillus spp. was not performed and may be considered in further studies using molecular diagnostic approaches. FNAC revealed neutrophils (Red arrow), large pleomorphic cells with variable shaped (anisocytosis) and hyperchromatic nuclei and basophilic cytoplasm with multiple distinct vacuoles (Red arrow head) (Fig 4). Presence of condensed chromatin in the nuclei, multiple nuclei and moderate mitotic figures (Blue arrow) (Fig 5) were also observed. After that an antibiotic susceptibility testing was done and revealed that Staphylococcus aureus was susceptible to linezolid while the Aspergillus spp. was found susceptible to itraconazole in antifungal susceptibility test. Thus, linezolid and itraconazole were included in the treatment regimen. Although, diagnosis of CTVT was based on characteristic clinical, cytological findings, molecular based confirmation using LINE-c-myc insertion, a molecular marker for CTVT was not performed. Further studies incorporating molecular techniques may further strengthen diagnostic confirmation.

Table 1: Haematology (0th week).



Table 2: Biochemical parameters (0th week).



Fig 2: Swab samples were cultured and revealed Staphylococcus sp. organism after 72 hours of incubation (×1000).



Fig 3: Swab samples were cultured and revealed Aspergillus sp. after 7 days of incubation (×1000).



Fig 4: Cytology of fine needle aspirate (Giemsa stain) reveals neutrophils (Red arrow) large pleomorphic cells with variable shaped hyperchromatic nuclei, bluish cytoplasm with multiple vacuoles (Red arrow head) (×1000).



Fig 5: Cytology of fine needle aspirate (Giemsa stain) reveals variable sized nuclei with condensed chromatin, multiple nuclei and moderate mitotic figures (Blue arrow) (×1000).


 
Diagnosis
 
Based on the clinical examination, haemato-biochemical analysis, cultural examination and FNAC findings from the nasal region the case was diagnosed as extra-genital canine transmissible venereal tumor (CTVT) complicated with bacterial and fungal infection.
 
Treatment
 
The dog was treated with vincristine sulphate (VinlonTM 1) @ 0.5 mg per m2 body surface area IV at weekly intervals for 5 occasions, Linezolid (LNZ 300 mg tablet) @10 mg per kg body weight orally once daily for 21 days, Itraconazole (Itrapet 100 mg tablet) @10 mg per kg body weight orally on alternate days for 4 weeks along with proton pump inhibitor pantoprazole (Pan 40 mg), oral hematinic (Sharkoferrol pet 200 g) and oral multivitamin amino acid (Zip-vit 200 ml) supplementation were provided as supportive therapy. Clinical recovery (absence of discharge from fistula) and gradual resolution of lesion on the paranasal region was seen as early as 3 weeks (Fig 6) following initiation of treatment and complete resolution of the lesion was observed by the 5th week post treatment (Fig 7). Hematological evaluation was done before weekly vincristine sulphate administration to monitor the treatment response (Table 3) and biochemical parameters were assessed after 4th week of treatment (Table 4).

Fig 6: 3rd week post treatment.



Fig 7: 5th week post treatment.



Table 3: Haematology report (weekly follow-up).



Table 4: Biochemistry parameters (after 4th week of treatment).


 
Discussion
 
The present case highlights the uncommon manifestation of canine transmissible venereal tumor (CTVT) involving the oronasal cavity complicated with bacterial and fungal infections. Mating is the commonest route of CTVT transmission and usually manifests clinically as tumors associated with the external genitalia in both male and female dogs (Pimentel et al., 2021). However, extragenital body sites, including the skin, eyes, nasal areas, mouth, rectum and internal organs, can also be affected (Chikweto et al., 2013; Bandaranayaka et al., 2023; Sumathi et al., 2025; Das and Das, 2000; Ndiritu et al., 1977). In cases where both genital and extragenital lesions are present, the most likely route of transmission would appear to be either internal metastatic dissemination or self-transmission (Das and Das, 2000; Weir et al., 1978). The latter could occur, when a dog licks its own genital tumor or makes oronasal contact with its genital tumor while in a curled-up sleeping position. However, in the present case, there was no evidence of genital involvement and lesions were restricted to the nasal bone rendering it to be a rare occurrence of primary extra-genital CTVT.  Extra-genital CTVTs are most likely related to social behaviours among dogs because of the means of species communication-for example, licking, sniffing, fighting during the breeding season and routine socialization. (Strakova and Murchison, 2014; Rogers et al., 1998; Priyadarshini et al., 2021; Cizmeci et al., 2012). As such, the extra-genital CTVT type is found more frequently in males than in females due to natural behaviors (Das and Das, 2000).
       
The most common extra-genital locations of CTVT are nasal cavity, eye and skin or subcutaneous tissues and often the sub mandibular, cervical and inguinal lymph nodes were shown to contain TVT metastases (Chikweto et al., 2013; Bandaranayaka et al., 2023). Tumors on the oronasal site are accompanied by epistaxis, purulent nasal discharge, halitosis and facial deformities. In the present case, the site of tumor was the nasal bone with perforation and purulent nasal discharge with severe bacterial and fungal infection and difficulty in respiration. Similar observations were reported by Bandaranayaka et al. (2023) in a 6-year-old, intact male, crossbred dog presented with a progressive facial swelling for 1 ½ months. Another notable observation in the present case was that there was no cauliflower-like growth that is typical of genital form of CTVT. Similar findings were reported by Bandaranayaka et al. (2023) in a number of dogs with extra-genital CTVT.
       
Mild to moderate, normochromic normocytic anemia was noted in the present case, similar to that reported by Kumar et al. (2017) and Kabuusu et al. (2010). Anemia in dogs with CTVT may be attributed to the continuous loss of blood over a prolonged period (Sharkey et al., 1996). Leukocytosis with marked neutrophilia and lymphopenia recorded in the present case is a consistent finding in CTVT due to infection in tumoral tissue and its periphery as a result of immunosuppression, leading to secondary bacterial invasion (Sharkey et al., 1996). Granulopoiesis (neutrophilic leukocytosis) is a characteristic observation reported in many cases of CTVT (Sharkey et al., 1996; Lucroy and Madewell, 1999) which may be nonspecifically stimulated by a variety of underlying disease processes including local or systemic inflammation, infection, immune mediated disease, neoplasia, tissue damage, or a combination of these (Weltan et al., 2008; Han et al., 2009; Ziccardi et al., 2022; Behera et al., 2012; Thrall et al., 2012).
       
Hypoproteinemia, hypoalbuminemia and hypoglobulinemia with higher levels of blood urea nitrogen and creatinine and increased activities of alanine aminotransferase and alkaline phosphatase are the biochemical changes often reported in CTVT, probably due to metastasis to these organs affecting the organ function (Peeters et al., 2005). However, in the present case, hyperproteinemia with hypoalbuminemia and hyperglobulinemia was observed, the hypoalbuminemia may be due to an inflammatory reaction (negative acute phase proteins), whereas the severe increase in globulin levels (6.2 g/dL; reference range 2.7-4.4) may be the result of a polyclonal antibody production due to chronic antigenic stimulation to inflammation (Peeters et al., 2007) however, other contributing factors cannot be entirely ruled out. Immunologic studies relating to CTVT also state that it has an antigenic effect which increases as the tumor grows (Rogers et al., 1998; DeBoer and Marsella, 2001). Mild elevation in BUN levels was suggestive of possible dehydration (DeBoer and Marsella, 2001).
       
Prompt diagnosis and early aggressive therapy is the key in treating the disease. Cytological analysis remains the mainstay for diagnosis of CTVT (Ganguly et al., 2016; Cingi et al., 2020). In this case, the dog was diagnosed to be affected with atypical form of CTVT by cytological examination of fine needle aspirate and impression smears and also the presence of foul-smelling purulent discharge led to microbiological examination resulting in detection of Aspergillus spp. and Staphylococcus aureus coinfection. Aspergillus spp. is known to cause canine sinonasal aspergillosis (SNA) characterized by a unilateral or bilateral infection of the frontal sinus and nasal cavity (Sharp et al., 1991). Nasal aspergillosis invades the nasal turbinate bone and is a common cause of chronic mucopurulent nasal discharge, sneezing and pain. It is hypothesized that local deficiencies in mucosal defenses predispose to fungal infection (Peeters et al., 2007). Staphylococcus spp. forms part of the skin and nasal resident microbiota of healthy dogs (Paul et al., 2011). Dogs with dermatological conditions caused by infectious agents including mites and dermatophytes and allergens associated with fleas, food and the environment often shows secondary bacterial infection predominately caused by Staphylococcus spp., particularly Staphylococcus pseudintermedius (Paul et al., 2011; Kunakornsawat et al., 2010; Martins et al., 2005). The presence of Aspergillus spp. and Staphylococcus aureus coinfection may be attributed to the lowered local defense mechanism owing to the chronic nature of the tumor. Chronic tumor associated inflammation and disruption of normal mucosal barriers could have facilitated opportunistic bacterial and fungal colonization resulting in secondary infection.
       
Due to the nature of the disease condition and progression of the tumor, the dog was treated rationally with vincristine sulphate (anticancer), Linezolid (antibiotic), Itraconazole (antifungal) along with supportive therapy. Clinical recovery as early as 3 weeks after the initiation of treatment was observed. Most cases of CTVT may regress spontaneously because they are generally benign in nature but it is suggested that all of them should receive treatment because of their aggressive nature (Das and Das, 2000).
       
Several treatment methodologies are available like radiotherapy (Dobson et al., 2008), chemotherapy (Coppoc, 2009), surgery (Boscos and Ververidis, 2004), immunotherapy, autohaemotherapy or their combination for CTVT management (Gupta and Sood, 2012). However, the most preferred treatment choice is chemotherapy with Vincristine sulphate in canines (Amber et al., 1990; Dobson et al., 2008; Kumar et al., 2021; Punchkande et al., 2022). Vincristine, a chemotherapeutic agent is a plant alkaloid, that is widely used to treat various neoplastic disorders, such as lymphomas, leukemias and sarcomas in dogs and cats (Behera et al., 2012; Boogaerts and Maertens, 2001). This alkaloid exerts cytotoxic activity by disrupting cellular microtubule formation. This sequence induces the inhibition of cell replication, including the replication of the cancer cells (Hasbach et al., 2017). The CTVT treatment consists of the weekly administration of vincristine at a dosage of 0.5 to 0.7 mg/m2 of body surface area for a period of 4–8 weeks (Dobson et al., 2008). Hantrakul et al. (2014) studied the pharmacokinetic parameters of vincristine sulfate in dogs with CTVT which showed rapid elimination and no accumulation, resulting in good clinical effects by dosing once a week @ 0.7 mg/m2.
       
In order to prevent relapse of bacterial infection and avoid development of antibiotic resistance, linezolid was chosen in the present case and the response was found to be favourable as there were no relapses following treatment. Linezolid is a synthetic oxazolidinone antimicrobial drug indicated for gram-positive infections and approved for the treatment of bacterial pneumonia, skin and skin structure infections and vancomycin-resistant enterococcal (VRE) infections, including infections complicated by bacteremia (Dryden, 2011).
       
The antifungal itraconazole was used effectively in the present case. Itraconazole is one of the commonly used antifungals for treatment of systemic and cutaneous fungal infections because of its broad spectrum activity and safety profile in both human and animals (Willems et al., 2001; Maertens, 2004; Prentice and Glasmacher, 2005; Domínguez-Gil et al., 2006; White et al., 1998; Abuhelwa et al., 2015). Itraconazole is widely distributed in the body, especially in keratinized tissues, such as the skin and appendages (hair, nails); also in lungs, kidney, liver, stomach, bones, muscles and spleen and is metabolized mainly by the liver through the enzyme CYP3A4 (Prentice and Glasmacher, 2005; Domínguez-Gil et al., 2006; White et al., 1998). Itraconazole acts by inhibition of the cytochrome P450 (CYP) enzymes, which play an essential role in sterol biosynthesis, a vital component of fungal cell membranes (White et al., 1998; Abuhelwa et al., 2015). When CYP51A1 is blocked, the ergosterol biosynthesis is blocked leading to accumulation of 14α-methyl sterols and formation of fungal membranes with altered properties, causing fungal death (White et al., 1998; Abuhelwa et al., 2015).

CONCLUSION

The dog was diagnosed with CTVT showing atypical or extra-genital form i.e., oronasal form of CTVT with two concurrent infections. Treatment was initiated for all the diseases simultaneously and there was complete resolution of the oronasal lesions. This report highlights the importance of a multimodal diagnostic and treatment approach while treating CTVT associated with concurrent etiologies.
 
Consent to publish
 
The authors obtained informed consent from the owner of the animal for publication of the clinical details, images included in this manuscript.
 
Funding statement
 
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
 
Ethical approval
 
Appropriate procedure and institutional animal ethics regulations were followed while carrying out the treatment.

CONFLICT OF INTEREST

The authors declare no conflict of interest.

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    Short Communication

    Extra-genital Canine Transmissible Venereal Tumor (CTVT) with Concurrent Aspergillosis and Staphylococcal Infection in a Dog

    U
    Utpal Barman1
    A
    Arup Das1,*
    0000-0002-0916-2693
    A
    Abhijit Deka1
    S
    Shasanka Sandilya2
    B
    Bendangla Changkija2
    D
    Deepa Lahkar2
    M
    Mousumi Hazorika1
    1Veterinary Clinical Complex, College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara, Guwahati-781 022, Assam, India.
    2Department of Veterinary Medicine, College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara, Guwahati-781 022, Assam, India.

    ABSTRACT

    Background: Canine transmissible venereal tumor (CTVT) is one of the oldest tumors of dogs. It is transmitted horizontally among dogs during mating, sniffing, licking, biting of the tumor affected areas. Extra-genital canine transmissible venereal tumor is an uncommon presentation often complicated with secondary infection. The present case describes a rare occurrence of paranasal CTVT complicated with bacterial and fungal infection.

    Methods: An adult male non-descript dog was presented to the outpatient department (OPD) of veterinary clinical complex (VCC), College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara with complaint of swelling in the paranasal area with pus discharge. On detailed clinical examination, an ulcerated growth on paranasal area with purulent discharge and difficulty in respiration was observed; however, body vitals were within normal limits. Fine needle aspirates for cytological and swab samples were collected for cultural examination.

    Result: Cytology revealed round nucleated cells with basophilic cytoplasm with vacuoles and microbial cultures of swab samples revealed Staphylococcus aureus. and Aspergillus spp.  Based on these findings, it was diagnosed as extra genital transmissible venereal tumor concurrent with bacterial and fungal infections. The dog was treated with vincristine sulphate @ 0.5 mg/m2 BSA parenterally, itraconazole @ 10 mg/kg bwt, PO on alternate days for four weeks, linezolid @ 10 mg/kg bwt, PO once daily for 21 days along with supportives. An uneventful improvement and resolution of paranasal lesions were observed within a few weeks following treatment and complete recovery was noted by the 5th week after initiation of treatment.  

    INTRODUCTION

    The most common neoplastic syndrome affecting either sex in dogs is the canine transmissible venereal tumor (CTVT). It is one of the oldest known tumors of canines and is also known as venereal granuloma, infectious sarcoma, or Sticker’s sarcoma. It is a histiocytic or more specifically a round cell tumor of the reticuloendothelial system of dogs (Goldschmidt, 2002). CTVT is a highly contagious tumor that is transmitted horizontally from one dog to another during mating when abraded mucosa is exposed to the tumor of an infected dog (Chikweto et al., 2013; Daleck and Denardi, 2016; Kucukbekir et al., 2021, Otter et al., 2015). CTVT can also be transmitted by other social behaviours such as licking, sniffing and biting of the tumor affected areas (Gurel et al., 2002, Strakova and Murchison, 2014; Oliveira, 2019) as evidenced by clinical lesions seen in body parts other than genitalia in both male and female dogs (Bandaranayaka et al., 2023; Sumathi et al., 2025). CTVTs are widespread and prevalent worldwide (Strakova and Murchison, 2014) and the disease is most prevalent in those countries with free-roaming dog populations (Kucukbekir et al., 2021; Gibson et al., 2021). CTVTs are more commonly observed in young and sexually active dogs between 2-5 years of age (Kucukbekir et al., 2021) and lower incidences are seen in dogs older than 10 years (Chikweto et al., 2013; Kucukbekir et al., 2021; Pastor et al., 2018). Males are at greater risk of metastasis (16-17%) than females (2-3%) (Martins et al., 2005; Gupta and Sood, 2012) however, no sex predilection has been reported (Costa et al., 2023; Schectman et al., 2022). Although, CTVT primarily affects external genitalia, extra-genital involvement has also been reported in the oro-nasal cavity, skin and eyes. Extra-genital CTVT are relatively uncommon and is primarily reported as an isolated case reports. Genital form of TVT is mainly dominating in the dogs as compared to extra-genital manifestations. Chikweto et al. (2013) observed extra-genital lesions in 15 of 78 dogs with prevalence of about 19.2% with nasal cavity being one of the affected sites.
           
    Common clinical signs of CTVT affecting genitalia includes haemorrhagic discharge, cauliflower- like mass with or without necrosis. In female, vulvar mucosa, vaginal mucosa and in males, glans penis, preputial mucosa are more commonly affected areas. (Brandão et al., 2002; Ganguly et al., 2016). When located extragenitally, either primarily or after metastasis, clinical signs are nonspecific if there is no concurrent genital lesion. Depending on their anatomical localization, signs of extra-genital CTVT may include enlargement of regional lymph nodes along with sneezing, epistaxis, epiphora, exophthalmos, skin bumps, halitosis or dental fistula, facial deformity (Rogers et al., 1998).
           
    Diagnosis is mainly achieved by cytological analysis of fine needle aspirates (FNAC) or impression smears (Ganguly et al., 2016; Rogers et al., 1998).  CTVT cells can be differentiated from other neoplasms using a PCR-based detection assay targeting specific long interspersed nuclear elements (LINEs) inserted upstream of the myc gene (Rogers et al., 1998). Although spontaneous regression can occur, CTVT is usually progressive and treated accordingly. Several treatment options like complete surgical excision, radiotherapy and chemotherapy are effective treatments. Chemotherapy with vincristine sulfate is the treatment of choice for CTVT in canines provided all the blood parameters are within the normal range (Cohen, 1985). This communication discusses a rare case of extra-genital CTVT complicated with aspergillosis and staphylococcal infection and its uneventful recovery in a nondescript dog.
     
    Case presentation
     
    An adult nondescript dog was presented to the Veterinary Clinical Complex, College of Veterinary Science, Assam Veterinary and Fishery University, Khanapara, Guwahati, Assam, India, in the month of August 2025, with complaints of inappetance, a wound in the paranasal region (Fig 1) with pus discharge over the past three months with no history of deworming or vaccination. Detailed clinical examination revealed the animal to be extremely weak with mild dehydration, pale mucous membrane and a non-healing fistulous perforation in paranasal region with discharge of pus causing difficulty in breathing. Body vitals like respiratory (28/min) and heart rate (95 bpm) and rectal temperature (101.3°F) were within normal range. No genital lesions were observed on examination.

    Fig 1: Perforation in nasal bone with discharge of pus causing difficulty in breathing.


           
    Approximately 4 ml of whole blood was collected from the affected dog on the day of presentation by using a 22-gauge needle attached to a 5ml syringe through saphenous venipuncture. A fraction of whole blood was transferred into K3-EDTA vacutainer and was subjected to haematological analysis. Haematological parameters viz., haemoglobin (g/dl), packed cell volume (%), total erythrocyte count (×106/µl), RBC indices, thrombocyte count (×106/µl) and leukogram profile were estimated using an automated hematology analyzer (MELET SCHLOESING Laboratoires, FLS257). Serum samples were used for determination of hepatic enzymes (ALT, AST) and total protein (TP) and globulin by using a fully automated chemistry analyzer (IDEXX’s the Catalyst OneTM Chemistry Analyzer) based on dry-slide technology. 
           
    For cytological examination, fine needle aspirates were collected and aspirated material was smeared onto clean glass slides, air-dried, stained with Giemsa stain and examined microscopically as per standard protocol described by Valenciano and Cowell (2019). Sterile nasal swab samples were collected for microbiological examination which followed by culture and identification of bacterial and fungal agents following standard procedures described by Quinn et al., (2011) and Markey et al., (2013).
           
    The leukogram revealed granulocytic leukocytosis while the erythrogram indicated normocytic normochromic anemia (Table 1), serum biochemistry showed mild elevation in hepatic enzymes (ALT, AST), increased total protein (TP) and globulin. Serum albumin was low and albumin to globulin (A/G) ratio was lower than normal (Table 2). Microbiological examination revealed Staphylococcus aureus. after 72 hours of incubation (Fig 2) and Aspergillus spp. after 7 days of incubation (Fig 3). Bacterial isolates were identified by cultural and biochemical test. The isolates were gram positive cocci and on biochemical test it was positive for catalase and coagulase and also capable for mannitol fermentation, thus confirming their identity as Staphylococcus aureus. However, species level identification of Aspergillus spp. was not performed and may be considered in further studies using molecular diagnostic approaches. FNAC revealed neutrophils (Red arrow), large pleomorphic cells with variable shaped (anisocytosis) and hyperchromatic nuclei and basophilic cytoplasm with multiple distinct vacuoles (Red arrow head) (Fig 4). Presence of condensed chromatin in the nuclei, multiple nuclei and moderate mitotic figures (Blue arrow) (Fig 5) were also observed. After that an antibiotic susceptibility testing was done and revealed that Staphylococcus aureus was susceptible to linezolid while the Aspergillus spp. was found susceptible to itraconazole in antifungal susceptibility test. Thus, linezolid and itraconazole were included in the treatment regimen. Although, diagnosis of CTVT was based on characteristic clinical, cytological findings, molecular based confirmation using LINE-c-myc insertion, a molecular marker for CTVT was not performed. Further studies incorporating molecular techniques may further strengthen diagnostic confirmation.

    Table 1: Haematology (0th week).



    Table 2: Biochemical parameters (0th week).



    Fig 2: Swab samples were cultured and revealed Staphylococcus sp. organism after 72 hours of incubation (×1000).



    Fig 3: Swab samples were cultured and revealed Aspergillus sp. after 7 days of incubation (×1000).



    Fig 4: Cytology of fine needle aspirate (Giemsa stain) reveals neutrophils (Red arrow) large pleomorphic cells with variable shaped hyperchromatic nuclei, bluish cytoplasm with multiple vacuoles (Red arrow head) (×1000).



    Fig 5: Cytology of fine needle aspirate (Giemsa stain) reveals variable sized nuclei with condensed chromatin, multiple nuclei and moderate mitotic figures (Blue arrow) (×1000).


     
    Diagnosis
     
    Based on the clinical examination, haemato-biochemical analysis, cultural examination and FNAC findings from the nasal region the case was diagnosed as extra-genital canine transmissible venereal tumor (CTVT) complicated with bacterial and fungal infection.
     
    Treatment
     
    The dog was treated with vincristine sulphate (VinlonTM 1) @ 0.5 mg per m2 body surface area IV at weekly intervals for 5 occasions, Linezolid (LNZ 300 mg tablet) @10 mg per kg body weight orally once daily for 21 days, Itraconazole (Itrapet 100 mg tablet) @10 mg per kg body weight orally on alternate days for 4 weeks along with proton pump inhibitor pantoprazole (Pan 40 mg), oral hematinic (Sharkoferrol pet 200 g) and oral multivitamin amino acid (Zip-vit 200 ml) supplementation were provided as supportive therapy. Clinical recovery (absence of discharge from fistula) and gradual resolution of lesion on the paranasal region was seen as early as 3 weeks (Fig 6) following initiation of treatment and complete resolution of the lesion was observed by the 5th week post treatment (Fig 7). Hematological evaluation was done before weekly vincristine sulphate administration to monitor the treatment response (Table 3) and biochemical parameters were assessed after 4th week of treatment (Table 4).

    Fig 6: 3rd week post treatment.



    Fig 7: 5th week post treatment.



    Table 3: Haematology report (weekly follow-up).



    Table 4: Biochemistry parameters (after 4th week of treatment).


     
    Discussion
     
    The present case highlights the uncommon manifestation of canine transmissible venereal tumor (CTVT) involving the oronasal cavity complicated with bacterial and fungal infections. Mating is the commonest route of CTVT transmission and usually manifests clinically as tumors associated with the external genitalia in both male and female dogs (Pimentel et al., 2021). However, extragenital body sites, including the skin, eyes, nasal areas, mouth, rectum and internal organs, can also be affected (Chikweto et al., 2013; Bandaranayaka et al., 2023; Sumathi et al., 2025; Das and Das, 2000; Ndiritu et al., 1977). In cases where both genital and extragenital lesions are present, the most likely route of transmission would appear to be either internal metastatic dissemination or self-transmission (Das and Das, 2000; Weir et al., 1978). The latter could occur, when a dog licks its own genital tumor or makes oronasal contact with its genital tumor while in a curled-up sleeping position. However, in the present case, there was no evidence of genital involvement and lesions were restricted to the nasal bone rendering it to be a rare occurrence of primary extra-genital CTVT.  Extra-genital CTVTs are most likely related to social behaviours among dogs because of the means of species communication-for example, licking, sniffing, fighting during the breeding season and routine socialization. (Strakova and Murchison, 2014; Rogers et al., 1998; Priyadarshini et al., 2021; Cizmeci et al., 2012). As such, the extra-genital CTVT type is found more frequently in males than in females due to natural behaviors (Das and Das, 2000).
           
    The most common extra-genital locations of CTVT are nasal cavity, eye and skin or subcutaneous tissues and often the sub mandibular, cervical and inguinal lymph nodes were shown to contain TVT metastases (Chikweto et al., 2013; Bandaranayaka et al., 2023). Tumors on the oronasal site are accompanied by epistaxis, purulent nasal discharge, halitosis and facial deformities. In the present case, the site of tumor was the nasal bone with perforation and purulent nasal discharge with severe bacterial and fungal infection and difficulty in respiration. Similar observations were reported by Bandaranayaka et al. (2023) in a 6-year-old, intact male, crossbred dog presented with a progressive facial swelling for 1 ½ months. Another notable observation in the present case was that there was no cauliflower-like growth that is typical of genital form of CTVT. Similar findings were reported by Bandaranayaka et al. (2023) in a number of dogs with extra-genital CTVT.
           
    Mild to moderate, normochromic normocytic anemia was noted in the present case, similar to that reported by Kumar et al. (2017) and Kabuusu et al. (2010). Anemia in dogs with CTVT may be attributed to the continuous loss of blood over a prolonged period (Sharkey et al., 1996). Leukocytosis with marked neutrophilia and lymphopenia recorded in the present case is a consistent finding in CTVT due to infection in tumoral tissue and its periphery as a result of immunosuppression, leading to secondary bacterial invasion (Sharkey et al., 1996). Granulopoiesis (neutrophilic leukocytosis) is a characteristic observation reported in many cases of CTVT (Sharkey et al., 1996; Lucroy and Madewell, 1999) which may be nonspecifically stimulated by a variety of underlying disease processes including local or systemic inflammation, infection, immune mediated disease, neoplasia, tissue damage, or a combination of these (Weltan et al., 2008; Han et al., 2009; Ziccardi et al., 2022; Behera et al., 2012; Thrall et al., 2012).
           
    Hypoproteinemia, hypoalbuminemia and hypoglobulinemia with higher levels of blood urea nitrogen and creatinine and increased activities of alanine aminotransferase and alkaline phosphatase are the biochemical changes often reported in CTVT, probably due to metastasis to these organs affecting the organ function (Peeters et al., 2005). However, in the present case, hyperproteinemia with hypoalbuminemia and hyperglobulinemia was observed, the hypoalbuminemia may be due to an inflammatory reaction (negative acute phase proteins), whereas the severe increase in globulin levels (6.2 g/dL; reference range 2.7-4.4) may be the result of a polyclonal antibody production due to chronic antigenic stimulation to inflammation (Peeters et al., 2007) however, other contributing factors cannot be entirely ruled out. Immunologic studies relating to CTVT also state that it has an antigenic effect which increases as the tumor grows (Rogers et al., 1998; DeBoer and Marsella, 2001). Mild elevation in BUN levels was suggestive of possible dehydration (DeBoer and Marsella, 2001).
           
    Prompt diagnosis and early aggressive therapy is the key in treating the disease. Cytological analysis remains the mainstay for diagnosis of CTVT (Ganguly et al., 2016; Cingi et al., 2020). In this case, the dog was diagnosed to be affected with atypical form of CTVT by cytological examination of fine needle aspirate and impression smears and also the presence of foul-smelling purulent discharge led to microbiological examination resulting in detection of Aspergillus spp. and Staphylococcus aureus coinfection. Aspergillus spp. is known to cause canine sinonasal aspergillosis (SNA) characterized by a unilateral or bilateral infection of the frontal sinus and nasal cavity (Sharp et al., 1991). Nasal aspergillosis invades the nasal turbinate bone and is a common cause of chronic mucopurulent nasal discharge, sneezing and pain. It is hypothesized that local deficiencies in mucosal defenses predispose to fungal infection (Peeters et al., 2007). Staphylococcus spp. forms part of the skin and nasal resident microbiota of healthy dogs (Paul et al., 2011). Dogs with dermatological conditions caused by infectious agents including mites and dermatophytes and allergens associated with fleas, food and the environment often shows secondary bacterial infection predominately caused by Staphylococcus spp., particularly Staphylococcus pseudintermedius (Paul et al., 2011; Kunakornsawat et al., 2010; Martins et al., 2005). The presence of Aspergillus spp. and Staphylococcus aureus coinfection may be attributed to the lowered local defense mechanism owing to the chronic nature of the tumor. Chronic tumor associated inflammation and disruption of normal mucosal barriers could have facilitated opportunistic bacterial and fungal colonization resulting in secondary infection.
           
    Due to the nature of the disease condition and progression of the tumor, the dog was treated rationally with vincristine sulphate (anticancer), Linezolid (antibiotic), Itraconazole (antifungal) along with supportive therapy. Clinical recovery as early as 3 weeks after the initiation of treatment was observed. Most cases of CTVT may regress spontaneously because they are generally benign in nature but it is suggested that all of them should receive treatment because of their aggressive nature (Das and Das, 2000).
           
    Several treatment methodologies are available like radiotherapy (Dobson et al., 2008), chemotherapy (Coppoc, 2009), surgery (Boscos and Ververidis, 2004), immunotherapy, autohaemotherapy or their combination for CTVT management (Gupta and Sood, 2012). However, the most preferred treatment choice is chemotherapy with Vincristine sulphate in canines (Amber et al., 1990; Dobson et al., 2008; Kumar et al., 2021; Punchkande et al., 2022). Vincristine, a chemotherapeutic agent is a plant alkaloid, that is widely used to treat various neoplastic disorders, such as lymphomas, leukemias and sarcomas in dogs and cats (Behera et al., 2012; Boogaerts and Maertens, 2001). This alkaloid exerts cytotoxic activity by disrupting cellular microtubule formation. This sequence induces the inhibition of cell replication, including the replication of the cancer cells (Hasbach et al., 2017). The CTVT treatment consists of the weekly administration of vincristine at a dosage of 0.5 to 0.7 mg/m2 of body surface area for a period of 4–8 weeks (Dobson et al., 2008). Hantrakul et al. (2014) studied the pharmacokinetic parameters of vincristine sulfate in dogs with CTVT which showed rapid elimination and no accumulation, resulting in good clinical effects by dosing once a week @ 0.7 mg/m2.
           
    In order to prevent relapse of bacterial infection and avoid development of antibiotic resistance, linezolid was chosen in the present case and the response was found to be favourable as there were no relapses following treatment. Linezolid is a synthetic oxazolidinone antimicrobial drug indicated for gram-positive infections and approved for the treatment of bacterial pneumonia, skin and skin structure infections and vancomycin-resistant enterococcal (VRE) infections, including infections complicated by bacteremia (Dryden, 2011).
           
    The antifungal itraconazole was used effectively in the present case. Itraconazole is one of the commonly used antifungals for treatment of systemic and cutaneous fungal infections because of its broad spectrum activity and safety profile in both human and animals (Willems et al., 2001; Maertens, 2004; Prentice and Glasmacher, 2005; Domínguez-Gil et al., 2006; White et al., 1998; Abuhelwa et al., 2015). Itraconazole is widely distributed in the body, especially in keratinized tissues, such as the skin and appendages (hair, nails); also in lungs, kidney, liver, stomach, bones, muscles and spleen and is metabolized mainly by the liver through the enzyme CYP3A4 (Prentice and Glasmacher, 2005; Domínguez-Gil et al., 2006; White et al., 1998). Itraconazole acts by inhibition of the cytochrome P450 (CYP) enzymes, which play an essential role in sterol biosynthesis, a vital component of fungal cell membranes (White et al., 1998; Abuhelwa et al., 2015). When CYP51A1 is blocked, the ergosterol biosynthesis is blocked leading to accumulation of 14α-methyl sterols and formation of fungal membranes with altered properties, causing fungal death (White et al., 1998; Abuhelwa et al., 2015).

    CONCLUSION

    The dog was diagnosed with CTVT showing atypical or extra-genital form i.e., oronasal form of CTVT with two concurrent infections. Treatment was initiated for all the diseases simultaneously and there was complete resolution of the oronasal lesions. This report highlights the importance of a multimodal diagnostic and treatment approach while treating CTVT associated with concurrent etiologies.
     
    Consent to publish
     
    The authors obtained informed consent from the owner of the animal for publication of the clinical details, images included in this manuscript.
     
    Funding statement
     
    This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
     
    Ethical approval
     
    Appropriate procedure and institutional animal ethics regulations were followed while carrying out the treatment.

    CONFLICT OF INTEREST

    The authors declare no conflict of interest.

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