A dog coughing up blood can be one of the most alarming things to see. Whether it’s a small streak of red in the saliva or a more noticeable amount, it’s a clear sign that something isn’t right with your dog’s respiratory or digestive system.
We outline the common reasons why a dog may cough up blood, what you can do and why urgent veterinary care is necessary.
Dog Coughing Up Blood: Why It Happens
A dog coughing up blood is called hemoptysis, and it can happen for many different reasons, ranging from mild irritation to serious internal illness. It may be caused by a throat injury, infection, heart disease, or even bleeding in the lungs.
Sometimes, dogs may appear to cough blood when the bleeding actually originates from the mouth or stomach rather than the lungs.
Because it can indicate anything from a minor irritation to a life-threatening condition, it’s essential to take it seriously and determine the source quickly.
Dog Coughing Up Blood: Common Causes
Respiratory Infections
Respiratory infections are one of the more common causes of coughing up blood in dogs. When bacteria, viruses, or fungi infect the lungs or airways, they can cause inflammation and damage to the delicate lining of the respiratory tract.
This inflammation can make small blood vessels burst, resulting in traces of blood appearing in the saliva or mucus your dog coughs up.
Dogs with respiratory infections often show additional signs like sneezing, nasal discharge, lethargy, and loss of appetite.
Kennel cough, pneumonia, and fungal infections such as blastomycosis or aspergillosis can all lead to coughing fits that produce blood.
While some infections resolve with antibiotics or rest, others may require more intensive veterinary care, especially if the dog is struggling to breathe or seems weak.
Read more: Dog Coughing Up Mucus and Blood (What it could mean)
Foreign Object in the Throat
Sometimes, a dog coughing up blood is the result of a simple but dangerous cause — a foreign object lodged in the throat or airway.
Dogs explore the world with their mouths, and a sharp stick, piece of bone, or small toy can easily scrape or puncture the tissues inside the throat.
This irritation or injury may cause bleeding, especially if the object remains stuck and continues to cause trauma when the dog breathes or swallows. You might also notice excessive drooling, gagging, or attempts to swallow repeatedly.
If you suspect something is stuck, don’t try to remove it yourself — doing so can push it further in. A vet can perform a safe examination and remove the object under controlled conditions.
Lung Disease or Pulmonary Bleeding
Serious lung conditions can cause dogs to cough up blood due to internal bleeding within the airways. Pulmonary bleeding may result from infections, parasites, trauma, or underlying diseases such as pulmonary hypertension or cancer.
In these cases, the blood typically appears frothy and bright red, indicating it’s from the lungs. You might also see labored breathing, weakness, and exercise intolerance.
Some dogs may develop a bluish tint to their gums due to reduced oxygen levels. Because pulmonary bleeding is life-threatening, it requires emergency veterinary care.
Diagnostic tests like chest X-rays, bloodwork, and possibly a bronchoscopy help identify the cause and guide treatment.
Read more: Dog Coughing Up White Foam (Possible causes explained)
Heart Disease
Heart disease, particularly in older dogs or certain breeds prone to cardiac issues, can also lead to coughing up blood. When the heart doesn’t pump efficiently, blood pressure increases in the vessels of the lungs.
This pressure can cause fluid and, in some cases, small amounts of blood to leak into the airways, leading to coughing that produces a pink-tinged or bloody foam.
Dogs with heart disease often show additional symptoms like fatigue, reduced exercise tolerance, and difficulty breathing after mild activity.
A heart murmur may be detectable during a vet exam. Treatment typically involves managing the underlying heart condition with medications that reduce fluid buildup and improve heart function.
Stomach Ulcers
Sometimes what appears to be coughing up blood actually originates from the stomach or esophagus rather than the lungs.
Stomach ulcers, ingestion of toxic substances (like rat poison or NSAIDs), or internal bleeding can cause dogs to vomit or regurgitate blood that owners mistake for coughing.
This blood is often darker, resembling coffee grounds, and may be accompanied by other signs such as vomiting, abdominal pain, loss of appetite, or black tarry stools (melena).
Gastrointestinal bleeding can quickly become serious, leading to anemia or collapse if untreated. Prompt veterinary attention is crucial to stop the bleeding and address its source.
Trauma or Injury to the Chest or Mouth
Physical injury to a dog’s chest, mouth, or throat can also result in coughing up blood. Blunt trauma, such as being hit by a car or rough play, can damage internal blood vessels or lung tissue.
Similarly, oral injuries from chewing sharp objects may cause bleeding that mixes with saliva during coughing or gagging.
Even a minor wound in the mouth can look alarming if it bleeds heavily, so examining where the blood is truly coming from helps the vet pinpoint the issue. X-rays or an oral exam may be necessary, depending on the suspected site of injury.
Poisoning
Certain toxins, especially rodenticides (rat poison), can interfere with the blood’s ability to clot. When this happens, a dog may start bleeding internally — including into the lungs or airways — resulting in coughing up blood.
Rodenticide poisoning is extremely dangerous. Signs may include lethargy, weakness, pale gums, blood in urine or feces, or unexplained bruising.
Because symptoms might not appear until several days after ingestion, it’s essential to seek immediate veterinary help if you suspect your dog may have eaten a toxic substance.
Read more: Dog Coughing Up Yellow Mucus (What it really means)
What to Do If Your Dog Is Coughing Up Blood
If your dog is coughing up blood, stay calm but act quickly. The first step is to determine whether the blood is coming from the mouth, lungs, or stomach. Look for other symptoms like vomiting, gagging, breathing difficulties, or bleeding elsewhere on the body.
Avoid giving any over-the-counter medications, as some can worsen bleeding or irritate the stomach further. Keep your dog calm and limit physical activity — excessive movement can increase circulation and bleeding.
If the bleeding is minor (just a small amount in saliva) and your dog seems otherwise normal, you can monitor them closely for a short time while arranging a vet visit.
However, if there’s a significant amount of blood, persistent coughing, weakness, or labored breathing, go to the vet or an emergency clinic right away.
Your vet will likely perform diagnostic tests such as bloodwork, imaging, or endoscopy to identify the source. Treatment might involve antibiotics, anti-inflammatory drugs, oxygen therapy, or surgery in severe cases. The key is prompt action before the condition worsens.
When to Call or Visit Your Vet
You should contact your veterinarian immediately if your dog:
Coughs up more than a small streak or two of blood.
Has trouble breathing or seems to be gasping for air.
Is weak, pale, or lethargic.
Vomits or passes dark, tarry stool.
Recently ingested toxins, sharp objects, or foreign material.
Has a history of heart disease, lung problems, or bleeding disorders.
Even if the bleeding seems minor, coughing up blood is never something to ignore. Some causes are easily treatable, but others can become life-threatening within hours. A prompt veterinary exam ensures your dog receives the right care as quickly as possible.
Read more: Dog Coughing Up Green Mucus (Is it serious?)
Key Takeaway
Coughing up blood in dogs is always a red flag that something deeper may be wrong. While minor causes like throat irritation are possible, serious conditions involving the lungs, heart, or stomach shouldn’t be ruled out.
Stay calm, note how much blood you see, and contact your vet promptly for evaluation.
Quick diagnosis and treatment can make all the difference, helping your dog recover comfortably and safely from what might otherwise become a serious health crisis.