SYMPTOM
Blood from the nose
Owners notice blood coming from one or both nostrils, which may appear as occasional spots, a persistent trickle, or blood mixed into sneezed discharge.
Local Trauma or Minor Vessel Injury
A bump to the nose, vigorous scratching or paw trauma, or a hard sneeze can rupture a small superficial blood vessel in the nasal lining. This is common in young, active dogs and typically produces a brief, usually one-sided bleed without other illness signs.
Foreign Material Lodged in the Nasal Passage
Grass seeds and other plant material are drawn up into the nostril, especially in outdoor and field-active dogs during warmer months. They can become lodged and cause localised irritation, sneezing fits and intermittent one-sided bleeding until dislodged.
Nasal or Sinus Infection and Inflammation
Fungal rhinitis, notably from Aspergillus fumigatus and more common in dolichocephalic breeds, along with bacterial secondary infection or chronic inflammatory rhinitis, can erode the delicate nasal lining over time. This tends to produce recurring, often one-sided bleeding with nasal discharge and sneezing.
Dental Root Disease Extending into the Nasal Cavity
The roots of the upper canine and premolar teeth sit close to the nasal cavity floor. Longstanding periodontal infection can erode through this thin bone, particularly in small-breed dogs and older animals with dental disease, presenting as nasal bleeding.
Growth Within the Nasal Passage
Nasal tumours become more common with age in both species, though the typical type differs: in dogs these are most often carcinomas, including adenocarcinoma, while lymphoma is the more usual nasal tumour type in cats. Whatever the type, they tend to cause progressive, usually one-sided, recurrent bleeding, often together with reduced airflow through the affected nostril and facial changes as they enlarge over time.
Bleeding Tendency Affecting the Whole Body
Conditions that impair normal clotting — anticoagulant rodenticide exposure, immune-mediated platelet destruction, or tick-borne infection — reduce the blood's ability to clot and can present with nasal bleeding alongside bruising elsewhere. Elevated blood pressure in older cats can also rupture small nasal vessels directly.
Why timing matters
Early observation
A first, brief, self-limiting bleed — especially after obvious activity like digging, sniffing intently at undergrowth, or a minor bump — is most consistent with a local, mechanical cause. At this stage there's typically no accompanying illness, and the bleeding usually stops within minutes.
Later presentation
Bleeding that recurs over days to weeks, especially if it becomes more frequent or is joined by nasal discharge, snoring-type noises, or visible facial swelling, points toward an underlying process within the nasal passage rather than a one-off injury. Bleeding that becomes bilateral, or is accompanied by bruising elsewhere on the body, shifts the pattern toward a whole-body explanation.
Because local causes such as a scratch or a lodged grass seed tend to resolve or stay confined to brief episodes, while erosive or growth-related causes tend to become more frequent and one-sided over time, the pattern across repeated episodes carries more information than any single bleed. Keeping track of the interval between episodes, rather than just the presence of blood, is what builds a useful picture over time.
Conditions commonly associated
Aspergillosis (Nasal)
Fungal infection of the nasal passages can erode the delicate mucosal lining over time, producing recurring, often one-sided nasal bleeding together with sneezing and nasal discharge.
Anticoagulant Rodenticide Toxicity
Ingestion of anticoagulant rodenticide impairs the body's normal clotting mechanisms, and nosebleeds can be an early visible sign of a wider bleeding tendency.
Periodontal Disease
Longstanding infection around the tooth roots, particularly the upper canines and premolars, can erode through the thin bone separating the mouth from the nasal cavity and present as nasal bleeding.
Systemic Hypertension in Cats
Elevated blood pressure, often linked to underlying kidney disease or an overactive thyroid in older cats, can cause small vessels within the nose to rupture spontaneously.
Chronic Upper Respiratory Disease in Cats
Ongoing viral or bacterial inflammation of the nasal passages in cats can damage the mucosal lining over time, contributing to intermittent bleeding alongside sneezing and discharge.
Lymphoma in Dogs
Nasal lymphoma is one of the growths that can arise within the nasal cavity of older dogs, typically producing progressive, one-sided bleeding together with reduced airflow through the affected nostril.
Immune-Mediated Haemolytic Anaemia (IMHA)
This condition can occur alongside immune-mediated destruction of platelets, and the resulting drop in platelet numbers can contribute to spontaneous bleeding from mucosal surfaces including the nose.
When to explore further
Whether the bleeding is from one nostril only or both, and whether it's a single episode versus something recurring over days, is useful descriptive detail.
Sneezing that continues to bring up fresh blood, or bleeding paired with facial swelling or a change in the shape of the nose, adds further characterisation.
In an older individual, bleeding alongside lethargy, appetite change or bruising elsewhere on the body points toward a whole-body process rather than a purely local one.
Any known access to rodenticide products, or a recent tick bite, is relevant background to note alongside the bleeding itself.
Noting the date, which nostril, and roughly how much blood was seen — a spot on the floor versus a more substantial trickle — for each episode builds a timeline. A photo of any facial swelling or nasal discharge alongside the bleeding, and a note of any known outdoor exposure to long grass or rodenticide bait boxes nearby, or a recent tick attachment, adds useful context for later characterisation.
Last reviewed: 13 September 2026 · Dr Alastair Greenway MRCVS