Criteria for Selection of Cases

A computerized database maintained by the UMC-VMTH was searched for cats evaluated from 1993 to 2004 for nasal discharge of > 1 month's duration. Cases were excluded if complete medical records were unavailable.

Procedures

Retrospective record review was used to gather information relevant to nasal discharge. Historical information included character of the nasal discharge, location (unilateral or bilateral), progression of clinical signs, duration of nasal discharge, and vaccination status. When available, additional information regarding the cat's environment, changes in appetite or activity level, the presence or absence of sneezing or vomiting, and any known concurrent diseases was also recorded. Physical examination findings including oral lesions, facial deformity, patency of airflow, otic abnormalities, ocular abnormalities, and neurologic signs were noted. Results of diagnostic tests including laboratory testing, imaging studies, rhinoscopy, biopsy and histologic examination, cytologic examination, and microbial culture were recorded. Final diagnosis and treatment were recorded, along with notation of treatment efficacy when available. Diseases that were likely the primary cause of nasal discharge were considered the etiologic diagnosis. Findings of retroviral infection, suppurative nasal inflammation, and positive results of bacterial cultures were recorded for cats with and without another etiologic diagnosis. Because these findings may have had either a primary or secondary role in nasal discharge, they were not considered the etiologic diagnosis. C² Tests were used to compare sex of cats with chronic nasal discharge versus all cats evaluated at the UMC-VMTH during the same period; a value of P < 0.05 was considered significant.

Results

Seventy-five cats with nasal discharge of > 1 month's duration were identified. Thirty-nine cats were evaluated by the UMC-VMTH internal medicine service, whereas 36 were evaluated by other services, primarily the community-practice service. Although there were more males (n = 46 [61%]) than females (29 [39%]), males were not overrepresented, compared with all cats evaluated at the UMC-VMTH (P = 0.16). Ages ranged from 3 months to 19 years, with a median age of 6.8 years (mean, 7.0 ± 6.0 years). The median age of cats evaluated by the internal medicine service (9 years) was greater than the median age of cats evaluated by other hospital services (0.75 years). The median age of cats that received an etiologic diagnosis was greater (8.5 years) than the median age of cats that did not receive a diagnosis (2 years). Twenty-two cats were < 1 year of age, and in all but one of these, the cause of nasal discharge remained undetermined. An etiologic diagnosis was identified in 8 of the 19 cats > 11 years of age. Median age of cats with confirmed neoplasia was 9 years (mean, 9.7 ± 4.4 years). Few purebred cats were identified (4 Siamese; 3 Persian; and 1 each of Russian Blue, Maine Coon, and Himalayan). The majority of the cats were housed indoors only (n = 36) or indoors and outdoors (24), with only 9 known to live outdoors only.

Historical findings varied. By definition, duration of nasal discharge was > 1 month for all cats but varied from just > 1 month to as long as 4 years. Advanced diagnostic testing (ie, nasal imaging, rhinoscopy, or cytologic or histologic assessment) was performed in 22 of 32 (69%) cats with nasal discharge present for > 6 months, 10 of 18 cats with nasal discharge for 2.1 to 6 months, and 8 of 25 (32%) cats with nasal discharge for 1 to 2 months. An etiologic diagnosis was made most often in cats with the longest duration of nasal discharge (15/32 [47%] cats) and less often when duration of signs ranged from 2.1 to 6 months (7/18) or 1 to 2 months (5/25 [20%]). Sneezing was reported in 69 (92%) cats, and vomiting was reported in 52 (69%) cats. Normal activity was observed in 49 (65%) cats and was decreased noticeably in 26 (35%) cats. Appetite was diminished in 27 (36%) cats. Of 32 cats with decreased activity, anorexia, or both, an etiologic diagnosis was recorded for 11 (34%). Vaccination status was not recorded or was unknown in 26 (35%) cats. Rabies vaccine had been administered every 1 to 3 years in 45 (60%) cats, feline viral rhinotracheitis virus-calicivirus-parvo-virus vaccine had been administered in 48 (64%) cats, and FeLV vaccine had been administered in 29 (39%) cats; 27 (36%) cats were current on all 3 vaccines.

Nasal discharge was characterized as mucopurulent (n = 30), serous (16), mucoid (14), or sanguinous (7); in 9 additional cats, the nasal discharge was said to be blood tinged on occasion. More than 1 type of nasal discharge was described in 10 cats, and character of nasal discharge was unrecorded for 7 cats. Nasal discharge was described as unilateral in 12 cats and bilateral in 58. Etiologic diagnosis was made in 5 of 12 cats with unilateral nasal discharge (neoplasia or foreign body) and 19 of 58 cats with bilateral nasal discharge. Severity and character of nasal discharge were stable in 44 cats and progressive or changing in 26. For 27 cats with a confirmed etiologic diagnosis for nasal discharge, features of the nasal discharge were tabulated (Table 1).

Physical examination findings were recorded. Dental abnormalities included tartar or gingivitis (n = 13), missing or fractured teeth (4), tooth root abscess (2), oral masses (1), and oral ulcers (1). Oral disease (tooth root abscess) was the cause of nasal discharge in 1 cat. Patency of nasal airflow was recorded for 22 cats. Air-flow was completely obstructed in 11 of 22 cats, and unilateral obstruction existed in 4 of 22 cats. An etiologic diagnosis was recorded for 7 of 22 cats with obstructed airflow. Facial deformity was seen in 11 cats, 10 of which received an etiologic diagnosis. Otic abnormalities in 15 cats included otitis externa and media as well as ear mites, but in none of these was otic disease believed to be related to nasal discharge. Ocular discharge, detected in 27 cats, was described as epiphora (n = 12), was not described (11), or was mucopurulent (2). Other ocular abnormalities included protruded third eyelid (n = 3), anisocoria (2), edema (2), prolapsed iris (1), choroid granulomas (1), sluggish pupilary light response (1), mydriasis (1), optic nerve scarring (1), and Horner syndrome (1); 1 cat was described as having conjunctivitis. A diagnosis was obtained for 13 of 37 (35%) cats with any ocular sign. Neurologic abnormalities found in 1 cat each included seizures, menace deficits, ataxia, nystagmus, Horner syndrome, and head tilt. The cat with seizures was found to have nasal carcinoma; the cause of nasal discharge was not determined for the other 5 cats with neurologic signs.

Several diagnostic modalities were used. Complete blood count was performed for 44 cats; abnormalities were rare but included leukocytosis (n = 4), leukopenia (2), and anemia (2). Serum biochemical analyses were performed on 41 cats; common abnormalities were not identified. Many cats (n = 52) were tested for FIV, FeLV, or both. Forty-one cats had negative results for both viruses, and 4 had positive results for either or both viruses. Latex agglutination titers for Cryptococcus antigen were positive in 3 of 10 cats tested.

Diagnostic testing beyond physical examination or blood tests either was not offered or was declined for 32 cats, most of which were evaluated by the community practice service. An etiologic diagnosis was made in 22 of 39 (56%) cats evaluated by the internal medicine service but in only 5 of 36 (14%) cats evaluated by other services, likely because fewer diagnostic tests were performed.

Many cats underwent imaging studies. Thoracic radiographs were obtained on 32 cats. For 15 (47%) of these, radiographic findings were considered normal. Abnormalities identified included cardiomegaly (n = 7), interstitial or bronchointerstitial lung pattern (6), pulmonary vascular enlargement (2), megaesophagus (1), and pulmonary nodule (1). In the latter 2 cats, the radiographic findings were directly related to an etiologic diagnosis of nasal discharge. Skull radiographs revealed increased nasal opacity (n = 2), osteomyelitis (1), nasopharyngeal polyp (1), tooth abscess (1), or normal findings (1). For 4 of 6 cats imaged via skull radiographs, a cause of nasal discharge was not found. Computed tomography of the skull, performed on 23 cats, always revealed abnormal results. Nasal or sinus exudate or thickening was detected in 7 cats. A nasal mass was identified in 11 cats, and bone or turbinate destruction was detected in 8 cats. For 5 cats, both a mass and bone destruction were identified. An etiologic diagnosis was found in 15 of the 23 (65%) cats that underwent a CT scan, with a diagnosis confirmed in 10 of 11 cats in which a mass effect was identified.

Rhinoscopy, biopsy, nasal cytology, or a combination of these were performed in almost half of the 75 cats. Twenty-nine cats underwent rhinoscopy, including 21 of the 23 cats imaged by means of CT scan. In 20 of 29 (69%) cats, an etiologic diagnosis was achieved. Rhinoscopic findings included mucopurulent discharge (n = 12), nasal mass (9), foreign body (2), normal nasal passages (2), and hemorrhagic discharge (1). Intranasal biopsies were performed in 28 cats. Biopsy findings included neoplasia (n = 15), suppurative rhinitis (6), lymphoplasmacytic rhinitis (4), hemorrhage (1), and fibrosis (1). An etiologic diagnosis was achieved largely on the basis of biopsy results in 19 of 28 (68%) cats that underwent biopsy. Nasal cytology specimens were acquired either via lavage, brush, or swab in 27 cats. A diagnosis was achieved in 14 of these 27 (52%) cats, but cytologic findings directly supported the eventual diagnosis in only 7 cats and were potentially misleading in another 3 cats.

Suppurative inflammation may result from secondary bacterial infection associated with a wide variety of underlying disease processes and thus was not considered an etiologic diagnosis in this study. Nine cats had suppurative nasal inflammation as indicated by results of nasal cytologic examination (n = 5), nasal biopsy (5), or both (3). For 3 of these cats, other etiologic causes of nasal discharge were discovered. Bacteriologic cultures were performed in only 2 of 9 cats with suppurative inflammation. Staphylococcus epidermidis and Actinomyces sp were recovered from 1 cat each. Bacilli and cocci were observed in nasal cytologic specimens from an additional 2 cats with suppurative inflammation.

In total, bacterial cultures were performed from nasal specimens of 17 cats. Seldom was the type of specimen noted in the record (eg, nasal swab specimen, nasal biopsy specimen, or bacteriologic culture of nasal discharge). Bacterial cultures yielded positive results in all but 3 cats. In an additional 2 cats, bacteria were identified via nasal cytologic examination but culture was not performed. Bacteria recovered via culture included coagulase-positive Staphylococci spp (n = 4), Pseudomonas aeruginosa (3), Corynebacterium spp (2), Bordetella bronchiseptica (1), Actinomyces spp (1), Acinetobacter woffi (1), Enterobacter cloacae (1), and Peptostreptococcus anaerobius (1). In some cats, more than 1 species of bacteria was cultured simultaneously. Etiologic diagnoses for nasal discharge in cats with positive results of bacterial culture included nasal neoplasia (n = 3 cats) and nasal cryptococcosis (1).

An etiologic diagnosis was recorded for only 27 of the 75 (36%) cats. Neoplasia was the most common single etiology of nasal discharge (n = 15), but no single type of neoplasm predominated. Carcinoma accounted for 8 of 15 nasal tumors (adenocarcinoma [n = 3], carcinoma [3], and squamous cell carcinoma [2]). Nasal lymphoma was diagnosed in 4 cats, and 1 cat each was recorded as having nasal sarcoma or basal cell tumor. For a single cat, the type of neoplasm was not specified. Fungal rhinitis caused by Cryptococcus neoformans was the etiologic diagnosis in 3 cats. Other etiologies for nasal discharge included lymphocytic-plasmacytic rhinitis (n = 4), nasal foreign bodies (2), pharyngeal polyp (1), and periapical tooth abscess (1). Megaesophagus with recurrent regurgitation was believed to cause nasal discharge in a single cat. Other diagnoses, many unrelated to nasal signs, were recorded in the medical record for the remaining 48 cats. The recorded diagnosis in 13 cats was upper respiratory infection, although in only 3 of these cats was there culture-based evidence of potential nasal pathogens. Eight cats had a diagnosis of suppurative rhinitis. Seven cats had positive results for FIV, and FIV was the sole diagnosis recorded for 4 cats. No diagnoses were recorded for the remaining cats.

Various treatments were prescribed. The 3 cats with cryptococcosis were apparently cured by administration of itraconazole (n = 2) or ketoconazole (1). Cats with neoplastic disease were treated with a variety of modalities, including radiation and chemotherapy; improvements for up to a year were noted in several of these cats. Cats that did not receive a diagnosis were usually treated nonetheless, typically with antimicrobials. Amoxicillin trihydrate-clavulanic acid was the most frequently prescribed antimicrobial (n = 19), but multiple antimicrobials often were prescribed sequentially or simultaneously. Corticosteroids were prescribed to cats when no diagnosis existed in 3 cases, twice combined with antimicrobials. In only 9 cats was treatment withheld in the absence of a diagnosis. Unfortunately, follow-up was inadequate to derive meaningful conclusions about the outcome of treatment for most cats. For cats with follow-up available at least 6 months after evaluation, 5 cats improved after antimicrobial treatment, 3 improved without any treatment, and 1 improved after corticosteroid administration.

Discussion

To our knowledge, only 1 other study³ of retrospectively reviewed chronic nasal discharge of all causes in cats has been published. That study evaluated a referral population exclusively, whereas the present study included cats evaluated for both primary and referral care. In the present study, more males were evaluated than females but this was not significant. Results of prior studies^2,9,15 suggest that intranasal neoplasia is detected more often in male cats, but this has not been detected for other causes of nasal discharge.^3,16 Cats with nasal neoplasia were typically older than other cats with nasal discharge, a finding compatible with prior studies.^2,3,9 In the present study, younger cats (especially those < 1 year of age) were far less likely to have a definitive cause of nasal discharge identified than were older cats. This may be because nasal neoplasia accounted for most cases in which a specific etiologic cause of nasal discharge was found, and neoplasia was not found in the youngest cats. Additionally, fewer young cats underwent advanced diagnostic testing. Although results of a prior study¹⁶ indicate that Siamese cats are more likely to be examined for intranasal disease than other breeds, there were few purebred cats of any type in the population reported here. Most cats lived indoors, either completely or in part. This may reflect a bias in that nasal discharge is readily observed in indoor cats, nasal discharge may be more problematic for the owners of indoor cats, or indoor cats may be more likely to be evaluated by a veterinarian than cats kept entirely outdoors. Sixty-four percent of cats in this study were vaccinated within 3 years for the common viral causes of diseases of the upper portion of the respiratory tract. Although statistical comparisons could not be made, it seems likely that this proportion is at least as high as for cats evaluated for nonrespiratory illness. There was no difference in the proportion of vaccinated cats that received an etiologic diagnosis versus the proportion of unvaccinated cats with a definitive diagnosis.

Not surprisingly, sneezing was the most common concurrent clinical sign and was identified in almost all cats with nasal discharge, similar to findings in other studies.^3,14,16 Vomiting was reported in 70% of the cats in the present study, which differed from other retrospective reports^3,14,16 on cats with rhinitis in which vomiting was not mentioned. Nasal discharge may cause irritation of the pharynx, leading to gagging and retching, which could be reported as vomiting.¹⁷ Despite the frequent reports of vomiting in the cats with nasal discharge reported here, appetite was diminished in only a third. Decreased activity level was also reported in a third of cats. Although fever, anorexia, and diminished activity level are common in cats with acute upper airway infection,¹⁸ systemic signs are less common in cats with chronic rhinitis.^3,14,16 An etiologic diagnosis was not more likely in cats with diminished appetite or activity than in cats lacking these systemic signs.

Regardless of diagnosis, mucopurulent discharge was the most common type of nasal discharge reported and discharge was usually bilateral. Mucopurulent discharge predominated in prior case series of cats with chronic rhinosinusitis and was common in cats with nasal neoplasia.^3,14,16 Bloody or blood-tinged nasal discharge was seen in 33% of cats with nasal neoplasia but was also observed in cats with multiple other known (17%) or unknown (25%) causes of nasal discharge. A prior study³ detected bloody nasal discharge twice as often in cats with neoplasia as in cats with rhinitis from other causes.³ Most cats in the present series had bilateral nasal discharge. Although nasal tumors are described as an important cause of unilateral nasal discharge,^15,19 bilateral nasal discharge was more common than unilateral nasal discharge even in cats with neoplasia. As described in dogs and cats, inflammatory nasal disease resulted in both unilateral and bilateral nasal discharge.^16,20 The proportion of cats with an identified etiologic cause of unilateral nasal discharge (42%) was similar to the proportion with an etiologic diagnosis for bilateral nasal discharge (33%). Although the description of nasal discharge may suggest a diagnosis, diagnosis can be neither confirmed nor excluded on the basis of discharge type, location, or both.

Routine laboratory tests seldom contributed directly to a diagnosis of nasal discharge. Findings on CBC and serum biochemical profiles were usually unremarkable. Nonetheless, these tests may identify concurrent or predisposing disease conditions prior to initiation of more costly or invasive diagnostic examinations and may be particularly indicated prior to performance of general anesthesia.

Serologic testing for infectious diseases was used in several cats. The proportion of cats in this study with positive results for FeLV (7%) and FIV (7%) was similar to retroviral prevalence in owned and unowned cats in the United States.²¹ This was in keeping with findings from another retrospective study,¹⁶ which did not define a role for retroviral infection in chronic rhinosinusitis in cats. Retroviral infections predispose cats to other infectious and neoplastic diseases, but predominant nasal signs are seldom described.^22,23 Nonetheless, retroviral status can affect differential diagnosis, management, and prognosis.²⁴ In at least 1 cat in the present study, further diagnostic testing was declined on the basis of positive retroviral status alone. Serologic antigen titers for C neoformans were used in only a few cats, most of which had facial deformity (a swollen nose) that raised the index of suspicion for cryptococcal infection.⁶ Titers were positive in the 3 cats confirmed to have cryptococcal infection via cytologic examination and negative in the other 7 cats tested. Latex agglutination titers can be used to gauge efficacy of treatment even when cryptococcal organisms are identified cytologically at the time of diagnosis.²⁵ None of these 75 cats were tested for feline herpesvirus or calicivirus, the 2 viral infections most commonly implicated as the cause of acute upper respiratory tract infection in cats.¹⁸ Both viral pathogens are capable of causing chronic infections and carrier states.7,8,16,26 Serologic assays for these viral infections are generally not useful in diagnosis.^18,27 In a recent prospective study,²⁶ detection rates for feline herpesvirus-1 DNA were not different between cats with and without chronic rhinosinusitis. Difficulties in proving a viral etiology for chronic upper respiratory signs in cats do not negate a role for these pathogens in chronic rhinosinusitis. Recrudescence of chronic infection could lead directly to respiratory signs, viral damage to nasal turbinates and mucosa could predispose to secondary bacterial infection, or viral infection might lead to nasal inflammation and resultant clinical signs.7,16,26,28 It remains to be determined what proportion of otherwise undiagnosed cases of chronic rhinosinusitis in cats is related to viral infection.

Cats with chronic nasal discharge often have a transient response to administration of antimicrobials, as did several cats in the present study. It is difficult to determine whether bacteria cultured from the nasal passages are part of the normal nasal flora, opportunistic secondary pathogens, or primary pathogens. Organisms previously implicated as potential nasal pathogens in cats include Pasteurella multocida, Streptococcus viridans, B bronchiseptica, Staphylococcus intermedius, P aeruginosa, Escherichia coli, Corynebacterium spp, Actinomyces spp, Mycoplasma spp, and anaerobic species.^3,16,26 However, many of these bacteria can also be found as normal inhabitants of the upper portion of the feline respiratory tract.^16,29 Multiple retrospective studies^14,16,30 have yielded positive results of nasal cultures in cats with idiopathic chronic rhinitis. In a recent prospective study²⁶ of feline nasal flora, potentially pathogenic bacteria were isolated from cats with and without idiopathic chronic rhinosinusitis, although Mycoplasma sp and anaerobes were isolated only from cats with rhinitis. In the present study, bacteria were cultured from cats for which a nonbacterial cause of rhinitis was discovered (n = 4) and from cats in which no other cause of rhinitis was identified (10). It is entirely possible that primary or secondary bacterial infections contributed to nasal discharge in these and other cats because the role of bacterial infection in chronic feline rhinitis remains to be determined. It is likewise possible that isolated bacteria either did not contribute to clinical signs or merely potentiated signs related to underlying disease.

Imaging studies were completed on many cats. Thoracic radiography revealed a lesion believed to be related to the cause of nasal discharge in only 2 cats; pulmonary metastasis and megaesophagus were identified in 1 cat each. A specific etiologic diagnosis was determined in 19 of 29 cats that underwent imaging studies but usually only after additional diagnostic procedures were completed. Imaging of the nasal cavity may be useful to identify structural abnormalities of the nasal cavity and related tissues and to guide other diagnostic procedures such as biopsy of specific areas of interest. Rhinoscopy was used to visualize the nasal cavity in 29 cats, and a specific etiologic diagnosis was achieved in 20 of these. Visualization cannot be used to accurately predict histologic changes in the nasal mucosa.¹² At least as important as visualizing the nasal passages, rhinoscopy is a means of facilitating nasal biopsy. Biopsy specimens were obtained during rhinoscopy in 28 of the 29 cases. Twenty-one of the 23 cats imaged by CT scan were also evaluated rhinoscopically and via biopsy. Sixteen of 23 cats that underwent all 3 procedures (nasal imaging, rhinoscopy, and nasal biopsy) received an etiologic diagnosis. Because these 3 procedures usually were performed concurrently, it was difficult to determine whether 1 test enhanced likelihood of achieving a diagnosis more than another.

The most common etiologic diagnosis for cats with chronic nasal discharge was neoplasia (24.5%), which may account for as much as 39% of chronic feline nasal disease.³ In that study, the most common single type of neoplasm was lymphoma (21/30 tumors), versus 4 of 15 cases in the present study. In this study and others,^2,9,15 neoplasia of epithelial origin was more common than lymphoma. Tumors of the nasal planum in cats are predominantly squamous cell carcinomas and may also cause nasal discharge.^2,15 However, cats with obvious nasal planum tumors would likely not have been evaluated with the primary complaint of nasal discharge and therefore were likely missed in our medical records search. Benign nasopharyngeal polyps are well described in cats and sometimes cause nasal discharge in addition to stertor, stridor, respiratory distress, and neurologic signs.⁴ Only 1 cat in the present study was found to have such a polyp, but the nasopharyngeal area was not examined for all cats.

A specific etiologic diagnosis was achieved for only a small proportion (36%) of cats, which was similar to that reported from other retrospective studies.^3,14 However, all diagnostic tests beyond physical examination were refused for 43% of the cats in our study and a specific diagnosis was not achieved for any of these cats. For approximately 25% of the cats, diagnostic tests did not include nasal imaging, rhinoscopy, or nasal biopsy. An etiologic diagnosis was achieved for only 2 cats that did not undergo any of these tests. Although this study was not able to identify a single test as having the best diagnostic performance, a combination of imaging, rhinoscopy, and biopsy may offer the best chance of diagnosis. Because bacteria can be isolated from nasal passages of cats with and without nasal disease and can be found as a secondary complication of noninfectious nasal disease, the role of microbiologic sampling in cats with chronic nasal discharge remains to be determined.