Discharge in the Dog
Chronic nasal discharge
and sneezing are common clinical complaints in many species. The most
common causes of chronic nasal discharge include neoplasia, aspergillosis,
nasal foreign body, rhinitis secondary to dental disease, and idiopathic
or inflammatory rhinitis. An accurate history, physical examination, and
a complete diagnostic work-up are helpful in determining the etiology
of disease; however, these disorder are challenging to control and are
often refractory to therapy.
Nasal tumors represent a small percentage of neoplasms in animals;
however, the majority of cases exhibit malignant behavior through local
invasion of facial bones or the central nervous system and via extension
to regional lymph nodes. Tumor types include lymphosarcoma, adenocarcinoma,
squamous cell carcinoma, undifferentiated carcinoma, and fibrosarcoma.
Nasal aspergillosis is most commonly seen in young to middle aged
dolicocephalic dogs. German Shepherd dogs and Rottweilers seem to be
predisposed. In some cases, aspergillus invasion occurs because of previous
trauma to the nose or in association with a nasal foreign body.
Idiopathic lymphoplasmacytic rhinitis (LPR) has been referred to
as immune-mediated or allergic rhinitis because initial reports of this
disorder suggested that steroid therapy was curative; however, more recent
evidence suggests these dogs often fail to respond to steroid therapy. Dogs
with idiopathic LPR generally are young to middle-aged, large-breed dogs.
Males and females are equally affected. German Shepherd Dogs and shepherd
mixes, Labrador Retriever mixes, and Collies are affected commonly.
Dogs with nasal neoplasia develop typical clinical signs of nasal
discharge (unilateral or bilateral), epistaxis, sneezing, and pawing
at the face. Neurologic signs such as seizures, behavioral changes, or
cerebral dysfunction may be seen alone or in conjunction with upper respiratory
signs. The presence of these signs is highly suggestive of tumor invasion
into the central nervous system and warrants a guarded prognosis. Dogs
with nasal aspergillosis usually present with copious nasal discharge that
can be unilateral or bilateral, and depigmentation of the nasal planum
may be noted by the owner. Chronic unilateral or bilateral nasal discharge
is the most common clinical complaint in dogs with LPR. Discharge is typically
mucoid or mucopurulent in most dogs but can be serous, and hemorrhagic
or blood-tinged discharge is not uncommon. Some dogs may present with true
epistaxis rather than nasal discharge.
Physical examination should include an assessment of nasal air flow
(decreased or normal, unilateral or bilateral change) and palpation of
the palate and facial bones for pain, swelling, or evidence of bony lysis.
Loss of nasal airflow is a prominent finding in neoplastic processes.
Dental examination and palpation of the gingival margins will help rule
out periodontal disease as cause for epistaxis or nasal discharge; however,
occult dental disease or oronasal fistulae can be easily missed on physical
exam. Neurologic exam should focus on detecting signs of cerebral dysfunction
such as weakness and visual deficits. These may signify either neoplastic
invasion of the cranium or extension of a fungal infection through the
cribriform plate. In aspergillosis, nasal airflow is usually present, depigmentation
may be noted, and some dogs exhibit facial pain. In dogs with LPR, physical
examination is generally unremarkable in dogs. Any cause of nasal discharge
may result in regional lymphadenopathy.
A minimum database is required for animals with nasal discharge
since further diagnostics will require general anesthesia. A platelet
count and coagulation profile should be obtained when hemorrhagic nasal
discharge is present, and blood pressure evaluation should be performed
when epistaxis is the primary complaint. Whenever possible, regional
lymph nodes should be aspirated. When suspicious of aspergillosis, fungal
serology (agar gel immunodiffusion) should be considered since a positive
result is likely to indicate disease.
The second wave of diagnostics includes skull radiographs or CT
under general anesthesia and rhinoscopy with biopsy. A full skull series
would include lateral views, an open mouth or intra-oral view, and the
frog-eye view that highlights the frontal sinuses. Visualization of nasal
structures is limited on the lateral view because of superimposition of
densities in the region of the nasal cavity, but it may show loss of the
air column within the nasopharynx, suggesting the presence of a mass lesion.
The most useful view is the open mouth view since it allows characterization
of bony destruction and turbinate lysis within each side of the nasal
cavity. Radiographic changes seen in nasal neoplasia include increased soft
tissue density in the nasal cavity, lysis of the nasal turbinates, and lysis
or deviation of the vomer bone; however, many of the radiographic changes
of neoplasia overlap with those of chronic rhinitis.
Computed tomography provides more complete information on the extent
of disease within the nasal cavity. Tumors lead to turbinate destruction
that can involve one or both nasal cavities, soft tissue masses that are
either unilateral or bilateral, and sinus disease due to mass effect or
obstruction of fluid drainage. Importantly, CT allows evaluation of the
cribriform plate. Tumor-related destruction of this bony barrier to the central
nervous system warrants a guarded prognosis. Finally, CT scans are recommended
in the staging of nasal tumors in order to define tumor boundaries and to
plan radiation therapy.
Biopsies of masses should be obtained with direct visualization
with rhinoscopy whenever possible; however, a blind approach may be required
when blood or mucus obscures the view. The biopsy instrument should not
be extended beyond the medial canthus of the eye in order to avoid penetrating
the central nervous system. Collection of multiple biopsy samples is recommended
to increase the likelihood of obtaining a diagnosis; however, bleeding can
be significant. Cytologic impression smears of mass lesions or nasal cytology
can be used to document lymphoma; however, other tumors usually require
Diagnosis of aspergillosis is made by a combination of characteristic
findings on CT and rhinoscopy as well as detection of fungal hyphae in
biopsy samples of plaques from the nasal cavity. Radiographs and CT are
usually remarkable for dramatic turbinate loss in the nasal cavity, with
variable sinus involvement. In some cases, only the sinuses are involved
and fungal granulomas can be visualized in this region with various imaging
modalities. CT is preferred for evaluation of dogs with Aspergillus because
it provides the opportunity to evaluate the integrity of the cribriform
plate prior to local anti-fungal therapy. Rhinoscopy is an important part
of both diagnosis and therapy for aspergillosis. Visualization of fungal
plaques with biopsy of these lesions provides the diagnosis. It is important
to biopsy the plaque itself, since surrounding nasal tissue may be characterized
by lymphoplasmacytic or neutrophilic rhinitis. The fungi are observed
as long, septate hyphae.
The diagnostic work-up for LPR serves to rule out aggressive causes
of nasal discharge such as neoplasia or aspergillosis that require specific
treatment. Nasal radiography has low sensitivity in differentiating inflammatory
rhinitis from neoplasia or mycotic rhinitis, since soft tissue opacification,
turbinate destruction, and frontal sinus disease can be seen with all
three conditions. Computed tomography provides improved definition of the
extent and severity of abnormalities of the nasal cavity, although LPR
can cause aggressive CT lesions that mimic those found with these other
conditions. Turbinate destruction is found commonly, although it is generally
mild or moderate in most cases. Fluid accumulation, soft tissue opacification,
gas pocketing, and frontal sinus involvement are also common CT findings,
and abnormalities can be unilateral or bilateral. Rhinoscopy typically
reveals hyperemic, friable, inflamed epithelium, and mucus accumulation.
Mild turbinate destruction is sometimes seen. Biopsies reveal variable
severity of lymphoplasmacytic infiltrates, mucosal edema, and bony remodeling
of turbinates. Culture of nasal swabs usually results in minimal growth
of bacterial flora. Molecular studies suggest an increase in fungal DNA
in the nasal cavity of dogs with LPR; however, it is unclear what role this
might play in disease or therapy.
Nasal lymphoma typically responds to radiation therapy or chemotherapy.
Other tumors respond variably to radiation therapy, with predicted disease-free
intervals ranging from 6 to 16 months depending on the size of the tumor
and local spread. Predictable early side effects of radiation therapy include
mucositis and skin irritation. When radiation therapy is not an option,
chemotherapy might be considered. Some success has been reported using
combination therapies. Finally, piroxicam
(0.3 mg/kg PO once daily) is recommended for palliative therapy
of epithelial or mesenchymal nasal neoplasia until epistaxis or neurologic
signs worsen quality of life.
Nasal infection with Aspergillus is best treated with topical infusion
of an anti-fungal agent (clotrimazole or enilconazole) since oral agents
have relatively poor efficacy against infection. Clotrimazole has been
reported to be effective as a single, one-hour instillation, with 39 of
60 dogs cured in one study. A second treatment cured an additional 11 of
60 dogs. Clotrimazole is available over the counter as a 1% solution in
10 mL bottles. One hour infusion of enilconazole given for two to three
treatments through endoscopically placed tubes has also been effective
in the cases reported. Enilconazole is supplied as a concentrated, commercial-grade
solution that must be diluted to a 1%, 2%, or 5% solution prior to instillation
in the nasal cavity.
If local therapy for Aspergillus is not possible because the cribriform
plate is breached or neurologic signs are evident, the best option for
therapy would likely be voriconazole, a new-generation azole used in human
medicine. However, this medication is very expensive and has not been
evaluated in veterinary medicine. Itraconazole therapy is preferred over
ketoconazole because of greater efficacy and fewer side effects. Itraconazole,
administered at 5 mg/kg BID for 2 to 6 months may cure up to 60% of dogs
with aspergillosis, although some studies have shown no effect of itraconazole
on nasal aspergillosis.
Treatment of dogs with idiopathic LPR is frustrating. Systemic and
topical corticosteroids do not appear to be effective in controlling signs
in most dogs, and attempts at allergen avoidance may or may not be helpful.
Modulatory antimicrobial therapy with long-term doxycycline or azithromycin
and antiinflammatory treatment with piroxicam can be helpful in some
dogs, although a guarded prognosis for cure must be given. Further investigations
into the potential etiology of lymphoplasmacytic infiltration of the nasal
cavity are required for improved treatment recommendations.
reprinted with kind permission from John Gardiner
Webmaster, School of Veterinary Medicine, Office
of the Dean
School of Veterinary Medicine, University of California,
Davis, CA, USA.
This is a severe fungal infection that generally affects
the nasal passages of German Shepherds, but can affect the lungs and bones.
The majority of cases that have been reported have occurred within this
breed. All affected individuals who have been tested have widely disparate
serum Ig A levels. The disease is generally rapidly progressive and treatment
is often of little avail ie. It is fatal. German Shepherds have a
higher incidence of fungal infections of the body systems than most other
breeds, including Nocardia infections of the lungs and similar infections
of the bones.
The above information is simply informational. It's intent
is not to replace the advice of a veterinarian nor to assist you in making
a diagnosis of your pet. Please consult with your own veterinarian for
confirmation of any diagnosis. Your pets life may depend on it.