How I approach... The sneezing cat

Introduction

Sneezing represents the body’s efforts to clear irritants from the nose, and is generally an involuntary process. Some causes of sneezing are self-limiting, such as exposure to a dusty basement, while others may be more progressive and even life-limiting.

Practically, I feel that it often appears to make sense to divide sneezing cats into categories of “easy” or “complex” when determining the types of investigations that should be pursued when presented with these cats; “easy” cases are typically represented by kittens with mild upper respiratory infections, whilst “complex” cases represent cats with chronic disease that stubbornly refuses to resolve, or cases where the etiology remains elusive despite extensive testing. This paper offers a brief overview for the clinician presented with a sneezing cat.

Key historical questions and physical exam

As with almost all diseases, signalment is very useful in the evaluation of a cat that is sneezing. Other key historical questions I ask include verification of exposure to the outdoors or to other cats, the duration of clinical signs, the animal’s general appetite and activity levels, and the success of any prior therapies. It is important to identify if there has been any nasal discharge, including its characteristics, and whether it is uni or bilateral.

From a physical examination perspective, fever can support the diagnosis of infection; viral infections in particular are commonly accompanied by a high fever. Facial asymmetry or lack of airflow through one or both nostrils may be identified and more directly support the identification of nasal obstruction.

Severe dental disease or the presence of an oronasal fistula may direct therapeutics towards treatment of dental pathology. Enlarged mandibular lymph nodes may support a diagnosis of infection (e.g., with Cryptococcus) or neoplasia. Cats that have recent significant weight loss, or appear otherwise unthrifty, are more likely to have serious underlying disease.

Potential etiologies

A multitude of potential causes of sneeze exist, and these can be largely divided into the following subcategories:

• Foreign body/irritant. This category includes inhaled objects such as cuterebra or blades of grass (Figure 1). Inhaled nasal foreign bodies as a cause of sneezing are more commonly seen in cats with outdoor access, and cases are most commonly encountered during the warmer months. Clinical signs tend to be peracute, and concurrent gagging is also common. Many cases are self-limiting and subsequently resolve, but for cases that do not resolve, further evaluation includes (at a minimum) an oral examination under sedation, and a nasal flush is often advisable 1.

• Traumatic. This category includes cats with facial fractures which are most commonly due to road traffic accidents (RTA). These cats will have sneezing due to trauma to the nasal turbinates and bleeding into the nasal cavity, often associated with facial fractures. This category rarely represents a diagnostic dilemma, although cats may refuse to eat if their nose is clogged with dried blood, and sneezing fits may result in significant hemorrhage. Advanced diagnostics are not warranted for sneezing associated with trauma, but may be useful for further evaluating the extent of the cat’s injuries.
  
  
• Infection. This is the one of the most common causes of sneezing in cats, with the most frequent agents being viral (herpesvirus, calicivirus) in origin. Bacterial infections, including Bordetella bronchiseptica, Streptococcus canis, Mycoplasma spp., and Chlamydophila felis have also been implicated as primary causes of upper respiratory tract infections in cats, although these are relatively rare. However, any case of rhinitis may become secondarily colonized by bacteria. Note that culture from a nasal swab is rarely helpful, as results typically reflect secondary colonization. For viral infections, isolation of the causal agent is challenging, and has more recently been largely replaced by PCR (polymerase chain reaction) testing. Cryptococcus infection may also result in sneezing; this is often easily documented via cytology, and serology is useful for demonstration of both infection and resolution.
  
  
• Inflammatory. Chronic rhinitis will result in the destruction of the turbinates and accumulation of mucus and debris, which may result in sneezing. Chronic rhinitis may be initially triggered by a variety of underlying diseases, but all will result in nasal discharge and sneezing 2. Histopathological evaluation may support the diagnosis of an underlying allergic cause if certain cellular infiltrates (e.g., lymphocytic-plasmacytic) are identified. Dental disease may also be considered inflammatory, or in some cases infectious.
  
  
• Neoplastic. Nasal neoplasia may cause sneezing, with the final diagnosis requiring histopathological sampling in order to determine tissue type (Figure 2).

Age and lifestyle – specific considerations

Kittens and young cats are very prone to upper respiratory infections, particularly when housed in a shelter setting or other small groups. Viral infections are easily spread from cat to cat, and even via fomites on caregivers. Other, far less common, causes of sneezing in young animals include nasopharyngeal polyps (Figure 3), nasopharyngeal stenosis, foreign body, and – rarely – persistent right aortic arch, (resulting in pooling of fluid in the esophagus and subsequent nasal reflux).

Outdoor or primarily outdoor cats are more prone to trauma and foreign bodies. Note that outdoor cats that are not members of a free-roaming colony often do not develop respiratory infection as they are quite solitary and are rarely exposed to other cats.

Middle-aged and older cats are more likely to be affected with neoplastic diseases, and this diagnosis may be suspected in an appropriately aged cat which has no prior history of nasal and airway disease. Many cats with chronic rhinitis have a past history of an apparently favorable response to antibiotics.

Diagnostics

I am typically much more enthusiastic to advise a complete work-up in an older cat with new onset of signs. Various diagnostic options are available for investigation of the sneezing cat, and the choice of tests should be based upon the assessment of the patient and the owner’s wishes 3.

• Routine laboratory testing with complete blood count/ chemistry profile and urinalysis are commonly performed when evaluating sick cats. While useful for general screening purposes, it is uncommon for routine laboratory testing to be very helpful in identifying a cause for sneezing. If general anesthesia is planned, pre-anesthetic laboratory screening is useful to establish normal organ function. Testing for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) is helpful in cats that have not otherwise been previously shown to be retroviral negative. FeLV in particular may predispose a patient to lymphoma, and any type of immunosuppression may increase the likelihood of Cryptococcus infection.
  
  

• Advanced laboratory diagnostics, and in particular PCR testing, can be beneficial. PCR has evolved into an exceedingly useful method to identify underlying infectious organisms, particularly viral infections 4. PCR typically acts by identifying a specific DNA sequence, and can be used to demonstrate the presence of a given pathogen. A positive PCR result confirms that the organism was found in the sample submitted, but a negative test result does not necessarily exclude infection, whilst a positive PCR for an organism not associated with clinical disease is of uncertain significance. If investigating an outbreak of sneezing in a multi-cat population, consider the possibility of asymptomatic carriers; such cats may test positive on PCR, and the approach in this situation depends upon the agent isolated. For cats that are actively sneezing, positive PCR results for upper respiratory pathogens should be considered relevant. As noted above, aerobic cultures of nasal discharge should be avoided as a diagnostic tool; whilst such cultures almost invariably result in a positive bacterial growth, this simply reflects secondary colonization of the nasal passages, rather than the actual pathogen.
  
  

• Skull radiographs are commonly performed for evaluation of nasal disease; however, due to the small size of a cat’s skull, and superimposition of various body structures, it may be hard to interpret such radiographs, especially if any soft tissue lesions are discrete. Dental radiography, where available, may also be useful to evaluate the nasal cavity.
  
  

• Advanced imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) are increasingly available to the general practitioner via referral to academic centers and larger specialist hospitals. The nasal cavity is amenable to both CT and MRI, and images obtained through these techniques far exceed the detail that may be seen using plain radiography (Figure 4).

• Rhinoscopy can be helpful when investigating a sneezing cat, although size restrictions mean that it is perhaps less helpful than in larger dogs. The nasal cavity may be evaluated from a retroflexed view (from the caudal oropharynx) as well as from the rostral aspect of the nose 5; some hemorrhage is to be expected from the technique. If a rhinoscope is unavailable, some clinicians employ an otoscope cone to inspect the rostral region of the nose, and a spay hook and dental mirror may be successfully used to evaluate the caudal aspect of the nasal cavity.
  
  

• Histopathological evaluation of biopsy material is very useful for detection of an underlying pathology and can be advantageous when determining a treatment plan. Biopsy should always be performed under general anesthesia, and the oral pharynx should be packed with gauze to collect any fluids or tissue samples. Several options are available for biopsy sampling, including via rhinoscopy if a mass lesion is visualized, or blindly using biopsy forceps (either one designed for endoscopic work, or a larger instrument). If forceps are not available, a large gauge (14-16 G) IV catheter (minus the stylet) may be inserted into the nasal chamber; 10-20 mL of saline can then be flushed rostral-to-caudal through the catheter, collecting any biopsy samples from gauze preplaced in the pharynx. If a blind biopsy is performed, care should be taken not to enter the cribriform plate and inadvertently biopsy the brain.
  
  

• Rhinotomy may be performed in cats with chronic nasal disease to debulk a nasal mass, to obtain deep biopsies, or to explore for a nasal foreign body. Fortunately, this procedure is rarely needed, as it is an aggressive undertaking, and I rarely perform it for evaluation of sneezing. As a therapeutic tool, it is unlikely to be curative; chronic rhinitis tends to be persistent, and rhinotomy in my experience is rarely successful.
  
  

Therapy

• Antimicrobials are commonly prescribed for upper respiratory signs, but judicious use is advisable; in cats with primarily viral disease, antibiotics are not indicated. However, secondary bacterial infection is common following viral infection, and in cats that are systemically affected there may be benefit from antibiosis. Most widely available antibiotics are associated with an improvement in clinical signs, although it is likely that that improvement will occur without therapy. Azithromycin, doxycycline, amoxicillin-clavulanate, and fluoroquinolones are all reasonable choices, along with standard supportive care 6 7. Antibiotics often result in an apparent short-term improvement in the clinical signs in cats with chronic rhinitis; owners should be advised that this is due to treatment of the secondary infection, and that because the turbinates have been permanently damaged or destroyed, a “stronger” antibiotic will not result in a cure.
  
  

• Anti-viral agents such as famciclovir (62.5-125 mg per cat once or twice a day) may be used to shorten the duration of clinical signs in affected cats, but are rarely chosen clinically since improvement typically occurs quickly. A recent study using a single oral dose of famciclovir administered to cats at intake to a shelter did not show any benefit in preventing disease outbreak 8.
  
  

• Local therapy may be pursued in amenable cats using intra-nasal saline drops or hypertonic saline to help loosen mucus. Additionally, topical therapy with antibiotics (e.g., ciprofloxacin drops) or anti-inflammatory agents (e.g., dexamethasone drops) may be helpful. In cases where a cat will be under anesthesia for a diagnostic evaluation, a nasal flush using saline can be useful to help remove mucus and debris, and may result in short-term improvement.
  
  

• Systemic anti-inflammatory agents may be helpful. Treatment with glucocorticoids may be useful to decrease inflammation in some cats; other cats apparently have more significant improvement when treated with non-steroidal anti-inflammatory drugs (NSAIDs). However, it is advisable to confirm the manufacturer’s recommendations whenever considering long-term use of NSAIDs in cats.
  
  

• Alternative therapies are also available and may be worth considering. These include humidification (e.g., placing the cat in a bathroom with a hot shower running, or using a humidifier) to encourage drainage of secretions, or administering N-acetylcysteine (70-100 mg/kg PO Q12-24h) may help thin the nasal mucus. Fish oil supplements added to the diet may decrease inflammation of the nasal tissues. One small pilot study showed that immunotherapy may be useful in decreasing sneezing in older cats with chronic rhinitis 9.
  
  

• Oncological therapy may be required for cats with nasal neoplasia, and animals may respond well to therapy, at least in the short term. Radiotherapy treatment may be helpful for both carcinomas and lymphoma, and chemotherapy has also been used successfully in some cats with nasal lymphoma and can be worth consideration in such cases 10.
  
  

Further comments

Anesthesia

General anesthesia is required for almost all diagnostic procedures involving the nose, and any commonly used anesthetic protocol is usually acceptable for a cat that is sneezing. However, the caudal oropharynx is very sensitive in this species, and any examination can result in coughing and gagging. As mentioned above, cats should be intubated if biopsy or flushing is to be performed, and remember that any gauze placed in the oral pharynx should be removed prior to recovery. Cats should always be monitored very closely during recovery.

Prevention

Strategies to prevent sneezing in cats are dependent on the etiology. Obviously, vaccinations are widely available for protection against herpes and calicivirus; interestingly, a recent study 11 showed that intranasal vaccination against viral agents was also effective in decreasing signs caused by bacterial challenge. Introduction of a new cat or kitten to a household already populated with cats should be undertaken with care 12, and a suitable period of quarantine for any new arrival is certainly advisable.

Dietary recommendations

In most cases of sneezing, no dietary changes are required, although cats that are reluctant to eat due to an upper respiratory infection may benefit from a palatable recovery diet. In cats with nasal tumors, or other conditions that can result in more long-term anorexia, an esophageal feeding tube may be placed (see paper on page 46) and a suitable recovery diet administered. In cats with suspected allergy, it may be prudent to consider a hypoallergenic diet.

Other thoughts

• Middle-aged and older cats almost never have nasopharyngeal polyps. Polyps are almost exclusively a disease of young cats.
• Chronic rhinitis is very frustrating, and while improvement is likely to occur, the disease is almost always chronic. Owners should be prepared for the fact that a permanent cure is unlikely.
• Some cats with upper airway disease have concurrent lower airway disease or “asthma”. Cats with chronic sneezing that also cough should be evaluated for lower airway disease, and any cough should not simply be assumed to represent post-nasal drip.
  
  

Summary

Sneezing is a common presenting complaint in cats. In young, otherwise healthy cats with an acute onset, an infectious etiology is most likely and will be expected to resolve regardless of the therapy (or lack of!) that is pursued. Foreign bodies, while less common, are certainly possible, especially in cats with outdoor access where there is a sudden onset of signs, and in particular if no fever is present. For kittens that are systemically ill, careful nursing care and antibiotics are advised.

In older cats, or in cats with an acute onset of sneezing, further diagnostics are warranted, and these should be chosen based upon the assessment of the patient and the owner’s wishes. If possible, a CT scan, biopsy, and rhinoscopy will be the most likely investigations to result in a diagnosis.

PCR can be pursued for confirmation of a chronic infection or if treating a large group of cats. Chronic rhinitis is a long-term medical condition and is unlikely to be curable, but may be palliated with a number of therapies.