Determining the Cause of Epistaxis in the Dog

kirsten johnsonby Kirstin Johnson, DVM, DACVIM (Internal Medicine)

The underlying cause of epistaxis in the dog can be divided into a local process or disease within the nasal cavity versus a systemic process.  Systemic etiologies that can lead to epistaxis include coagulopathies, hyperviscosity, hypertension, thrombocytopenia, thrombocytopathia and vascultitis.  Local etiologies include direct trauma, foreign bodies, inflammation, infection, neoplasia and dental disease (see Table 1). Local processes are the most common causes of epistaxis in the dog representing about 75% of cases.  In humans, epistaxis is more common in young children, the elderly and males and occurs more frequently during the winter months. A specific primary cause may not be identified in up to 80-90% of human cases. In dogs that present with epistaxis, there is no seasonal association and a definitive diagnosis is reached in just over 60% of cases.

Table 1:  Causes of Epistaxis; local vs. systemic processes
Local Processes:

  • Infection: viral, bacterial, parasitic or fungal
  • Inflammation: lymphoplasmasitic vs eosinophilic vs other
  • Dental disease :tooth root abscess or oronasal fisula
  • Neoplasia: benign polyp or malignant neoplasm including carcinomas, sarcomas and round cell tumors
  • Foreign body
  • Direct trauma

Systemic Process:

  • Thrombocytopenia
  • Thrombocytopathy
  • Coagulation factor deficiency
  • Hypertension
  • Hyperviscosity syndrome


The patient’s signalment, a complete history taking and a careful physical exam can help you determine the more likely definitive rule outs for epistaxis in your patient.  Regarding signalment, sinonasal aspergillosis affects primarily mesaticephalic and dolichocephalic breeds; brachycephalic dogs are rarely affected. Older, large breed dogs are more likely to have nasal neoplasia and doliocephalic breeds are 2.5 times more likely to develop nasal neoplasia. In one retrospective study of 176 canine cases of epistaxis in the United States, young, small to medium sized dogs were more likely to have trauma related epistaxis and large dogs were more likely to have idiopathic rhinitis.

Historical information should include a complete travel history and life style of the pet. Many of our rescue animals and purebred dogs in the northeast come to us from the Southern US or the Midwest. It is not unusual for clients in the Boston area to travel internationally with their pets. Diseases that can lead to epistaxis that are not common in this area include pithium, transmissible venereal tumor, American canine hepatozoonosis and canine leishmaniasis. Dogs that spend more time outside hiking and roaming are more likely to be exposed to tick borne illnesses, leptospirosis, trauma, fungal organism and rodenticide.

Spontaneous epistaxis can be caused by a coagulopathy including consumption of clotting factors or reduced production in clotting factors such as with rodenticide toxicity. Severe thrombocytopenia and thrombocytopathia are also potential causes of epistaxis. Patients exposed to estrogens, phenulbutazone or chemotherapy may develop thrombocytopenia from bone marrow suppression. Recent vaccination, medication administration, or tick exposure with subsequent infection with a tick borne illness could trigger an immune mediated thrombocytopenia.

Hereditary illnesses such as Von Willibrand’s disease can cause thrombocytopathia. Thrombocytopathia can also be induced by acquired illnesses including neoplasia and severe renal, liver or pancreatic disease. NSAIDS inhibit platelet function and can cause spontaneous epistaxis especially when paired with another disease process that causes a decrease in platelet count or function.

Chronicity and other nasal signs are important to note.  Intense sneezing and facial rubbing can be seen more often with nasal mites, nasal foreign bodies and oronasal fistulas. Determine if the epistaxis is acute, chronic or intermittent. Is there also a history of serous, mucoid, purulent or mixed nasal discharge? Has the discharge been unilateral, bilateral or did it begin unilaterally and progressed to bilateral? Intranasal foreign bodies, neoplasia, dental disease and fungal rhinitis often begin with unilateral nasal discharge or epistaxis and progress to bilateral. In the retrospective study mentioned above, thrombocytopenic dogs were more likely to have bilateral epistaxis than dogs with other disorders. Also, the severity of the epistaxis was not significantly associated with a local vs systemic cause, although dogs with idiopathic rhinitis were more likely to have severe epistaxis than dogs without.

Epistaxis---webResponse to previous therapy including anti-histamines or antibiotics can be misleading. Anti-histamines focus on treating a symptom rather than the underlying cause. Antibiotics may be treating a secondary infection or have their own anti-inflammatory or immune modulating effects such as doxycycline or azithromycin.

Physical examination should pay careful attention to dental health and evaluation of the hard palate, facial symmetry, and airflow through both nostrils. I prefer to use a glass slide in front of each nostril to look for condensation. A Q-tip can also be unraveled and held in front of each nostril to test for airflow. Retropulsion of both eyes and evaluation of possible boney defects along the bridge of the nose, facial bones or ocular orbits is also important.  Check for pain when opening the mouth or during palpation of the muzzle. Note any ulceration over the bridge of the nose or nasal planum as well as depigmentation of the nasal planum or polypoid tissue near the nasal apertures.  These findings may support a diagnosis of fungal infection or neoplasia.

A fundic exam may show evidence of systemic hypertension, hyperviscoity or disease elsewhere in the body. Careful evaluation of the regional lymph nodes is also important.  Keep in mind that many times metastatic disease from the nose can be present in normal sized mandibular lymph nodes. Although only about 8% of nasal cancers spread to the mandibular lymph nodes, this is a simple, non-invasive way of obtaining a definitive diagnosis.

Look elsewhere on the body for evidence of petechia such as along the mucus membranes or ventral abdomen. A rectal exam is important especially to demonstrate possible melena. Signs of a coagulopathy may include hints of free fluid in body cavities or swollen joints from hemarthrosis.

Most dogs with disease limited to the nose feel well unless their disease extends into the brain and neurologic signs develop or they are painful. If your patient has a history of weight loss, inappetance or lethargy, focus on searching for a systemic process.


A minimum database for these animals should include a CBC, general chemistry, urinalysis and blood pressure (see Table 2).  Coagulation times may also be added if indicated. Spontaneous bleeding from thrombocytopenia does not generally occur unless the platelet count is under 60,000/ microliter. If the platelet count is moderately low but not low enough to cause spontaneous bleeding, a consumptive process should be considered such as vasculitis or DIC. Thrombocytopathy is demonstrated by performing a buccal mucosal bleeding time  (BMBT) on a patient with a normal platelet count.

Table 2:  Diagnostic approach
Minimum database for our practicing area should include:

  • Complete blood count
  • A complete blood chemistry panel
  • Urinalysis
  • Coagulation panel
  • Tick panel
  • Buccal mucosal bleeding time if the platelet count is normal
  • Blood pressure
  • If neoplasia is suspected elsewhere in the body thoracic radiographs and abdominal ultrasound may be indicated


Further investigation of local disease

  • Sedated oral exam
  • Nasal/ oral imaging
    • Skull radiographs
    • Dental radiographs
    • Head CT
    • Head MRI
  • Nasal cavity flush
    • Mite identification, cytology or histopathology if a piece of tissue is retrieved.
    • Do not culture this specimen.
  • Rhinoscopy
  • Nasal biopsy
    • Histopathology
    • Aerobic culture
    • Fungal culture or identification

Mycoplasma PCR

If these results combined with your physical exam and history lead you to believe your patient has a local process, there are a few diagnostics that can be done to help you gain a definitive diagnosis before the need for advanced imaging and rhinoscopy.

As stated before, aspiration of the mandibular lymph nodes, although low yield, is a non-invasive method of obtaining a potential diagnosis. This might be reserved for older, large breed dogs with a history of nasal discharge and therefore a greater suspicion of neoplasia.

If aspergillosis is suspected due to breed, life style, chronic nasal discharge and possible nasal pain or ulceration over the bridge of the nose or depigmentation/ ulceration of the nasal planum, agar-gel immunodiffusion or IgG enzyme–linked immunosorbent assays can be performed. These blood tests provide excellent specificity but moderate sensitivity for sinonasal aspergillosis.  Therefore, false negative results are possible. If your patient tests positive for this disease, a CT scan is recommended before instituting topical antifungal therapy to screen for destruction of the cribriform plate and involvement of the frontal sinuses.

Nasal lavage requires general anesthesia to protect the airway. This technique can be used to dislodge foreign material, nasal mites or tumor tissue to submit for histopathology. Bacteria and fungal cultures using a sample collected via nasal flush is not recommended since surface mucosal bacteria and fungi are part of the normal flora of the nasal passages. Pathology is present only when these organisms invade into the deeper layers of the nasal passages. Therefore, culture of a biopsy sample is required to demonstrate a significant bacterial or fungal infection contributing to clinical signs of nasal disease.

Blind nasal biopsies may result in a definitive diagnosis. However, they can also be misleading. Your biopsy could come back as inflammatory if the tissue you collected was nearby a neoplasm or foreign body. Also, biopsies disrupt the nasal tissue and prevent accurate CT planning for near future radiation therapy if indicated. Before nasal biopsies PT/PTT clotting times and a BMBT should be performed.

Advanced imaging and rhinoscopy is the gold standard for investigating nasal disease. Advanced imaging most typically involves CT scan but in some cases MRI is indicated. These modalities can help locate the disease and provide information regarding the extent of disease, presence of bony destruction and invasion of structures outside of the nasal cavity. CT with contrast can distinguish between a soft tissue structure or mass with a blood supply vs fluid or mucus. CT can also be used for radiation planning when a nasal tumor is found. As stated above, rhinoscopy and nasal biopsies should always be performed after imaging to prevent confusion of lesion location.

At Angell, we routinely investigate epistaxis. If a local process is suspected, our patients are placed under general anesthesia and a head CT scan is performed. This test takes about 10-15 minutes. Our on-site radiologists then go over the images with the internist on the case and a plan is formulated. If indicated, retroflex nasopharyngoscopy is then performed to evaluate the back of the nasal passages and choanae. Biopsies may be taken at this point if appropriate. Next, the back of the nasopharynx is packed off with gauze sponges and a nasal flush may be performed. Tissue is collected on the gauze sponges and the nasophaynx is again packed off.  Lastly, rigid rhinoscopy is performed moving from the rostral nasal apertures caudally to the level of the medial canthus. Rhinoscopy can provide a definitive diagnosis or help to guide tissue biopsy for a higher likelihood of gaining a definitive diagnosis. Visualization of nasal mites, foreign material and fungal plaques can help establish a diagnosis before histopathology returns. Biopsies are submitted for histopathology and may also be submitted for bacterial culture, fungal ID or culture and mycoplasma PCR. After this procedure, the patient goes home the same day or the following day if epistaxis persists.

If you have a case of epistaxis that you would like to refer or need help with please feel free to contact Angell’s internal medicine department at 617-541-5186 or

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