Nosebleeds in dogs: first aid, causes and tests

Overview

A nosebleed may be a single sudden event or part of longstanding symptoms. The nasopharynx lies behind the nasal cavity, above the soft palate. Some blood can drain into the throat and be swallowed. Swallowed blood may later appear as dark clots in vomit or black stools.

When 176 dogs were investigated for nosebleeds, an underlying cause was identified in 109 (62%). There were 115 diseases or injuries in total because some dogs had more than one finding. Of these findings, 90 were local. The remaining 25 affected the whole body. Of the dogs, 132 were examined through the emergency service (75%).

Causes

Conditions in and around the nose

An injury can rupture a nasal blood vessel. A grass awn in the nose can cause sudden sneezing and nasal discharge. Persistent bloody nasal discharge may be caused by a nasal tumour or fungal infection. Nasal aspergillosis can extend from the nasal cavity into the maxillary or frontal sinuses. An upper tooth root abscess may drain into the nasal cavity.

Among local causes in the study of 176 dogs, 35 tumours and 33 injuries were found. Nasal inflammation without an identified underlying cause was diagnosed in 20 cases. A tooth root abscess caused the nosebleed in 2 cases. Nasal mites can cause sneezing, nasal discharge and nosebleeds.

Platelets and clotting factors

Thrombocytopenia means an abnormally low platelet count, which can predispose a dog to bleeding. In immune-mediated thrombocytopenia, the body may destroy its own platelets. In von Willebrand disease, platelets do not adhere properly to damaged blood vessel walls. Anticoagulant rodent poisons interfere with vitamin K recycling, preventing normal production of certain clotting factors. Bleeding signs typically appear 3–7 days after a dangerous amount of such a poison is swallowed. Nosebleeds can also occur with haemophilia, in which an inherited clotting factor deficiency impairs clotting. Liver failure is another possible cause of nosebleeds.

In the study investigating nosebleed causes, low platelet counts were found in 12 dogs. Platelet dysfunction was identified in 7 dogs with nosebleeds. Clotting factor dysfunction was identified in 3 cases.

Risk factors

Dogs aged at least 6 years were more common among the 176 dogs investigated for nosebleeds than among comparison dogs. Males were also proportionally more common in that nosebleed group than among comparison dogs. Dogs weighing at least 26 kg were overrepresented too. In another study of 35 dogs, those with nasal tumours had a mean age of 10.0 years. Dogs with other intranasal disease had a mean age of 5.6 years. Long-muzzled dogs are predisposed to nasal and sinus aspergillosis. Inherited type III von Willebrand disease is recognised in Kooikerhondjes.

Typical symptoms

Blood may appear at only one nostril even when your dog has a disease affecting the whole body. In one study, 11 of 21 dogs with systemic disease had one-sided bleeding (52%).

• Your dog may sneeze or rub their muzzle.
• Blood may be mixed with mucus in nasal discharge.
• Breathing may become noisy around the nose or throat.
• The muzzle may change shape or the bridge of the nose may swell.
• The nose may show loss of pigment or an ulcer.
• There may be bleeding gums or unusually easy bruising of the skin.

Airflow through the nose may be reduced, particularly when a lesion occupies space in the nasal cavity.

In the 35-dog study, symptoms lasting over 1 month were more often associated with intranasal than systemic disease. In a British aspergillosis study, nosebleeds were recorded in 292 of 461 dogs for which this symptom was documented (63%).

Complications and consequences

Blood loss and bleeding elsewhere in the body

Heavy bleeding can impair circulation; mucous membrane colour and pulse help assess how serious this is. Significant blood loss can cause anaemia. If clotting is impaired, bleeding may also occur into the chest cavity or other tissues. A Canadian rodent poison study recorded bleeding sites in 81 cases. Nosebleeds occurred in 13 of them. The most common site was the pleural cavity, where blood was found in 35 cases.

Severely reduced platelet counts can cause life-threatening bleeding, although another dog with the same count may have no symptoms. Aspergillosis can damage bony structures in the nasal cavity, including the nasal turbinates and septum. A malignant nasal tumour can invade and destroy surrounding bone.

Diagnosis at the vet

Blood tests and clotting assessment

In a dog bleeding heavily, your vet assesses circulation using findings such as heart rate, pulse and mucous membrane colour. A blood count establishes whether your dog is anaemic. It also provides a platelet count. An unusually low platelet count can be checked on a blood smear because platelets may clump in the sample. Tests such as prothrombin time (PT) and activated partial thromboplastin time (APTT) measure different stages of clotting. A urine sample can show whether blood in the urine accompanies the nosebleed. Blood biochemistry tests can assess liver and kidney status. Blood pressure is measured if hypertension is suspected to contribute to bleeding.

Routine clotting times may be normal despite platelet dysfunction. The level of von Willebrand factor can be measured in blood if an inherited bleeding disorder is suspected. Clotting test changes may not appear until 2–5 days after a dog eats anticoagulant poison. With anticoagulant poisoning, PT can become prolonged before APTT.

Nasal imaging, endoscopy and sampling

If a local cause is suspected, your vet examines the muzzle, eyes and mouth and assesses airflow through the nostrils. CT shows nasal soft tissues and bone structures more clearly than conventional skull X-rays. Imaging is usually performed before biopsies because bleeding from sampling can make findings harder to assess. During nasal endoscopy, your vet may see a lodged foreign body, fungal plaque or tissue mass. Thorough endoscopy of the nasal cavity and nasopharynx is performed under general anaesthesia. If a tumour is suspected, a biopsy may be taken for tissue examination. Culture of a nasal fungal plaque sample helps identify aspergillosis. If Aspergillus grows only from a flushing sample, microscopic evidence of fungal hyphae also helps assess its significance.

In a study in which all animals had a nasal foreign body, the object was visible in only 14 of 40 CT scans (35%). One-sided fluid accumulation may indicate a foreign body on CT even when the object itself is invisible. In the British aspergillosis study, fungal culture was positive in 67 of 93 plaque samples (72%). Of 80 mucosal biopsy samples, 37 were positive (46%).

Treatment

Managing heavy bleeding at the practice

When bleeding is heavy, your vet first assesses circulation and your dog's general condition. They may control severe bleeding locally, for example by applying pressure with nasal packing. If bleeding has caused severe anaemia, your dog may need a red blood cell transfusion. A plasma transfusion can replace missing clotting factors. In the Canadian rodent poison study, blood products were given to 68 of the 81 dogs with bleeding (84%). Of the dogs showing bleeding signs, 70 survived to discharge (86%).

Treating the underlying cause

A nasal foreign body is removed during endoscopy where possible. If it is lodged deeply, surgery may be needed to remove it. Treatment of aspergillosis starts with removal of fungal plaques so that topical antifungal medicine can contact the treatment area. Radiotherapy may be used to treat a nasal tumour. Among 17 dogs receiving radiotherapy, 11 had nosebleeds before treatment (65%). Median survival in this nasal carcinoma radiotherapy group was 298 days. In 24 dogs treated with a different radiotherapy protocol, median survival was 375 days.

In immune-mediated thrombocytopenia, first-line medication suppresses the body's immune reaction against platelets. Vitamin K is used as an antidote to anticoagulant rodent poison. Improvement in clotting time may be seen within 12–24 hours of starting treatment. Clotting is usually rechecked 2–3 days after treatment ends.

Rodent poison containing cholecalciferol can raise blood calcium and damage the kidneys.

Prevention

Keep rodent poisons and baits where your dog cannot reach them. Storing poisons in a locked cupboard helps prevent accidental exposure. Do not store pesticides beside dog food. Collecting dead rodents reduces your dog's opportunities to eat them. In areas where grass awns grow, keeping your dog on a lead and on the path reduces contact with sharp seed heads.

Following bait label instructions helps prevent accidental exposure, including when products are used outdoors. Using an appropriate breed-specific genetic test in breeding decisions can help prevent inherited von Willebrand disease becoming more common within a family line.

Important for dog owners

Keep your dog calm, as the rise in blood pressure associated with excitement can increase bleeding. You can gently hold a cold pack over the bridge of the nose if your dog tolerates it and can breathe freely. Do not push cotton wool, tissue or a cotton bud into a nostril: it can trigger sneezing and worsen bleeding. Do not give medicines for bleeding or pain on your own initiative.

If nosebleeds recur, contact your vet even if the bleeding stops between episodes. Tell your vet which nostril bled or whether both did. Also mention any impact, possible rodent poison exposure or sneezing that began before the bleeding. Explain whether bleeding has recurred or your dog has also had bruises elsewhere on the skin. List all medicines and supplements your dog has received in the past 30 days, including medicines swallowed accidentally.

Frequently asked questions

Can bleeding from one nostril be caused by a clotting disorder?

One-sided bleeding is common with local nasal disease. However, it also occurred in 11 of 21 dogs diagnosed with systemic disease in one study (52%). Your vet may check platelet counts and clotting factor function even when blood comes from only one nostril.

Should I plug my dog's nostril to stop the bleeding?

Cotton wool or tissue pushed into a nostril can cause sneezing that worsens bleeding. A cold pack can be placed over the bridge of the nose if your dog can breathe freely with it there. If bleeding continues or breathing becomes difficult, your dog needs immediate veterinary assessment.

Can swallowed nasal blood appear in stools or vomit?

Blood draining from the nose can pass through the throat into the stomach. Swallowed blood may turn stools black or appear as clots in vomit. Tell your vet about both symptoms, as they may help assess the cause and extent of bleeding.

Can a dog seem healthy immediately after eating rodent poison?

Anticoagulant rodent poison affects clotting after a delay because existing clotting factors in the blood typically become depleted over 24–64 hours. Bleeding is usually noticed 3–7 days after a dangerous amount of anticoagulant poison is swallowed. Contact an emergency vet immediately if you suspect exposure, even if your dog has no signs yet.

Why does the vet examine both the blood and the nose?

Blood tests can reveal anaemia, a low platelet count or changes in clotting times. CT shows the nasal cavity and helps identify a possible tissue mass or bone changes. Endoscopy allows your vet to see findings such as a foreign body or fungal plaque in the nasal cavity.