What is Dr. Zubair Khalid's research focus?

Dr. Zubair Khalid specializes in molecular virology, mRNA vaccine development, and computational biology, with a focus on avian pathogens like IBDV and Avian Reovirus.

Where is Dr. Zubair Khalid currently working?

Dr. Zubair Khalid is a Postdoctoral Research Associate at the University of Maryland (UMD), specifically within the Department of Animal and Avian Sciences.

Dog Coughing Up Blood: Causes and When It Is an Emergency

Name: Dog Coughing Up Blood: Causes and When It Is an Emergency
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-09-19

The Direct Answer

A dog coughing up blood is having a medical emergency until proven otherwise. Blood that comes up with a cough, or that appears as pink, frothy fluid in the mouth after a coughing fit, means bleeding somewhere in the respiratory tract or the lungs. This is called hemoptysis in dogs, and it can be caused by rat poison, heartworm disease, pneumonia, lung tumors, chest trauma, a bleeding disorder, a foreign body, lungworm, or severe heart disease. Some of these conditions kill within hours. Others are chronic but still serious.

Your job in the next ten minutes is simple. Confirm that the blood is coming from the airway and not from the stomach or a cut in the mouth. Keep your dog calm and quiet. Call the closest emergency veterinary hospital and tell them you are bringing in a dog that is coughing blood. Do not wait to see if it stops.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

At a Glance: Is This an Emergency?

What you see	What it likely means	Urgency
Bright red blood or pink froth coughed up after hacking	Bleeding in the airways or lungs (true hemoptysis)	Emergency, go now
Blood-tinged mucus from the nose or mouth with a wet cough	Airway or lung bleeding, possible pneumonia or lungworm	Emergency, go now
Large volume of red or brown liquid, no coughing, belly heaving	Likely vomited blood from the stomach (hematemesis)	Emergency, go now
Blood only on the gums, lips, or tongue with no cough	Mouth injury or a bleeding disorder	Urgent, same day
Blood in the urine or stool, no cough	Not hemoptysis, different problem	Urgent, call your vet
Small streaks of blood once, dog is bright and eating	Still needs evaluation	Urgent, call your vet today
Cough with no blood, normal energy	Many possible causes	Schedule a vet visit

The single most useful question is whether the blood arrived with a cough or with a vomit. That distinction changes the entire diagnostic path.

What Hemoptysis Actually Means

Hemoptysis is the medical term for coughing up blood that originates in the respiratory tract. The blood can come from the nasal passages, the trachea (windpipe), the bronchi, or the lung tissue itself. In dogs, hemoptysis is a symptom, not a diagnosis. It tells you that a blood vessel somewhere in the airway or lung has been damaged, eroded, or ruptured.

The respiratory tract is built to move air, not blood. When blood enters the airways, it triggers coughing because the dog is trying to clear the airway. That is why hemoptysis almost always arrives with a cough, a gag, or a wet respiratory noise. The blood may be bright red and fresh, or it may be darker and mixed with mucus or foam.

Lung tissue is packed with tiny capillaries that sit right against the air sacs where oxygen crosses into the blood. These vessels are delicate. Anything that inflames, erodes, or over-pressures them can cause bleeding. That includes infections, parasites, tumors, clots, toxins that stop blood from clotting, and high pressure in the lung circulation from heart disease.

One important pattern to understand is that bleeding in the chest does not always come out of the mouth. Blood can pool in the pleural space (the gap between the lungs and the chest wall) and cause internal bleeding with no visible blood at all. In a study of 62 dogs with rat poison poisoning, the most common bleeding sites were the pleural space (hemothorax in 37 percent), the lung tissue itself (24 percent), and the abdomen (24 percent) [1]. Only some of those dogs ever coughed blood. Others simply became weak, pale, and short of breath.

Coughed Blood vs. Vomited Blood vs. Mouth Bleeding

Owners often cannot tell these apart, and that is normal. Here is how to sort it out.

Coughed blood (hemoptysis)

Comes with a cough, hack, or gag
The dog lowers its head and extends the neck during the episode
Blood is often bright red, frothy, or mixed with mucus and air bubbles
There may be a wet or rattling sound in the chest
The dog swallows afterward and may lick its lips
Volume is usually smaller than a vomit, but can be large
No food in the material unless the dog just ate

Vomited blood (hematemesis)

Comes with heaving, retching, and abdominal contractions
The dog's belly visibly pumps
Material may contain food, bile, or partially digested matter
Blood may look like coffee grounds (digested blood) or fresh red
Often a larger volume than hemoptysis
The dog may drool heavily or swallow repeatedly before vomiting

Mouth or nose bleeding

Blood appears on the gums, lips, tongue, or around the teeth
No cough involved
The dog may have a visible cut, a broken tooth, or a foreign object stuck in the mouth
Nosebleeds drip from the nostril, not the mouth

One clue that helps: hemoptysis tends to be episodic. The dog coughs, produces blood, then stops for a while. Vomiting tends to be more forceful and repetitive. If you genuinely cannot tell, treat it as an emergency anyway. Both bleeding from the airway and bleeding from the stomach can be life-threatening, and both need a veterinarian.

The Major Causes of Hemoptysis in Dogs

Rodenticide (Rat Poison) Poisoning

Anticoagulant rodenticides are one of the most common and most treatable causes of a dog coughing blood. These poisons block the body's ability to recycle vitamin K, which the liver needs to make clotting factors. Without those factors, the blood cannot clot. The dog bleeds internally, sometimes for days before anyone notices.

In a multi-center study of 62 dogs with anticoagulant rodenticide toxicity, the most common bleeding sites were the pleural space (37 percent), the lung tissue (24 percent), the abdomen (24 percent), the skin (21 percent), and the gastrointestinal tract (18 percent) [1]. Pulmonary hemorrhage, meaning bleeding into the lungs, occurred in roughly a quarter of those dogs and is a direct cause of coughing blood.

A separate imaging study of 14 dogs and 2 cats with rodenticide toxicity found pleural effusion in 63.6 percent of the dogs and pulmonary hemorrhage in 36.4 percent [2]. These dogs often look normal for the first day or two after eating poison, then deteriorate suddenly.

The legal status matters here. In the United States, anticoagulant rodenticides are registered and regulated by the Environmental Protection Agency, and consumer products are restricted to bait stations in many cases. That does not stop dogs from finding them in garages, sheds, barns, or a neighbor's yard. If you know or suspect your dog ate rat bait, tell the emergency veterinarian immediately. Do not wait for symptoms. Treatment started before bleeding begins is far more effective.

Heartworm Disease

Heartworm disease, caused by the mosquito-borne parasite Dirofilaria immitis, is a well-known cause of coughing in dogs. Adult worms live in the pulmonary arteries and the right side of the heart. They damage the vessel walls and trigger inflammation, which can lead to coughing, exercise intolerance, and in some cases coughing up blood.

A case series described five dogs with hemoptysis as an uncommon manifestation of heartworm disease [3]. This is not the most common presentation, but it does occur, and it signals significant damage to the pulmonary arteries. Heartworm is preventable with monthly medication, and prevention is far safer and cheaper than treatment. Monthly heartworm preventive medication is highly effective when given as directed [4]. If your dog is not on a preventive, that is a conversation to have with your veterinarian today.

Pneumonia

Bacterial, viral, or aspiration pneumonia can cause inflammation and bleeding in the lungs. Aspiration pneumonia happens when a dog inhales vomit, food, or liquid into the airways. This is more common in dogs with megaesophagus, laryngeal paralysis, or a history of vomiting while sedated. Severe pneumonia can erode small blood vessels and produce blood-tinged sputum. Pneumonia is treatable, but it needs prompt antibiotics and sometimes oxygen support.

Lung Tumors

Primary lung tumors and metastatic tumors (cancer that has spread to the lungs from elsewhere) can erode into blood vessels and cause hemoptysis. Older dogs are at higher risk. A cough that has been present for weeks and is now producing blood is a classic history for a lung mass. Chest radiographs and sometimes CT are needed to identify these.

Trauma

Blunt trauma from a car accident, a fall, or a crush injury can bruise or tear the lungs and cause bleeding into the airways. Pulmonary contusions are common after high-impact trauma. Any dog that has been hit by a car and is coughing blood needs immediate emergency care, even if it seems alert at first. Internal bleeding can worsen quickly.

Clotting Disorders

Beyond rat poison, other conditions can impair clotting. Liver disease reduces clotting factor production. Some immune-mediated diseases destroy platelets. Disseminated intravascular coagulation (DIC) is a severe clotting disorder that can follow sepsis, severe trauma, or heatstroke. Any of these can cause bleeding into the lungs or airways.

Foreign Bodies

Dogs inhale grass awns, foxtails, sticks, and other plant material more often than owners realize. A foreign body lodged in the trachea or bronchi causes violent coughing, and that coughing can damage the airway lining and produce blood. This is more common in dogs that run through tall grass or fields. The object may need to be removed with bronchoscopy.

Lungworm (Angiostrongylus vasorum)

Lungworm infection is an emerging and important cause of coughing blood in dogs, especially in Europe and parts of North America. The parasite Angiostrongylus vasorum lives in the pulmonary arteries and the right side of the heart [5]. It causes respiratory signs, but it is also a well-documented cause of bleeding disorders.

In that study, the median time from first clinical sign to diagnosis was two weeks, and four dogs died. Two of the dogs that died had been given NSAIDs before diagnosis, and both developed severe hemoptysis. This is a critical warning: NSAIDs can worsen bleeding in these patients.

A larger retrospective study of 180 dogs with A. vasorum infection found that 36.1 percent presented with bleeding diathesis, and the most common types were cutaneous and mucosal bleeding [7]. Twenty dogs had neurological signs from bleeding into the brain or spinal cord. The study found that hematocrit, platelet count, and several clotting measurements were abnormal in bleeding dogs.

The mechanism is becoming clearer. Research has shown that A. vasorum excretory-secretory products can directly cleave coagulation factors II, V, and IX, as well as complement proteins C3, C4-A, and C5 [8]. Another proteomic study found that infection alters the complement and coagulation cascades, including downregulation of mannan-binding lectin serine peptidases, ficolin, and coagulation factor XIII-B [9]. In plain terms, the parasite releases substances that interfere with the dog's ability to clot.

Lungworm is diagnosed with a fecal Baermann test, which detects first-stage larvae, or with an in-clinic antigen test [10]. The antigen test has good sensitivity and specificity and can detect infection before larvae appear in the stool [10]. Treatment typically involves fenbendazole and a topical moxidectin product, and many dogs improve rapidly [11].

Geographic spread is real. A. vasorum has been reported across Europe and is emerging in North America, including a first autochthonous case in mainland Canada [12]. A survey in Austria found positive dogs in multiple regions of the country [13]. If you live in or have traveled to an endemic area and your dog is coughing blood, lungworm should be on the list.

Severe Heart Disease

Left-sided congestive heart failure causes fluid to back up into the lungs, a condition called pulmonary edema. The increased pressure in the pulmonary vessels can cause them to leak or rupture, producing pink, frothy fluid that the dog coughs up. This is a true emergency. Dogs with heart disease may also have a chronic cough from an enlarged heart pressing on the airways, but blood in that cough signals a worsening of the disease.

Why Is My Dog Coughing Up Blood and Mucus?

Blood mixed with mucus is common and does not narrow the diagnosis much on its own. Mucus is produced by the airways as a normal protective layer, and any inflammation increases mucus production. When small blood vessels in the inflamed airway wall leak, the result is blood-streaked mucus.

This pattern is typical of:

Pneumonia
Lungworm infection
Chronic bronchitis with acute bleeding
Lung tumors
Foreign body irritation

The color and amount of blood matter more than the presence of mucus. Bright red blood suggests active fresh bleeding. Dark, brownish blood suggests older blood that has been sitting in the airway. Large amounts of frank blood are more alarming than small streaks, but even small streaks need evaluation.

Risk Factors: Which Dogs Are More Likely?

Age matters. Lung tumors are more common in older dogs. Lungworm and foreign bodies are more common in younger, active dogs that roam and explore [14]. Heartworm is seen in dogs that live in or travel to endemic areas and are not on prevention.

Lifestyle matters. Dogs that spend time in tall grass, fields, or wooded areas are more likely to inhale foxtails and other plant material. Dogs that live on farms or near livestock are more likely to encounter rodenticides. Dogs that are outdoors at dawn and dusk in heartworm-endemic regions are at higher risk of mosquito bites.

Geography matters. Heartworm is endemic in much of the United States, particularly the Southeast and Mississippi River Valley. Lungworm is endemic in parts of Europe and has been reported in eastern Canada and the northeastern United States [12].

Medication history matters. As noted above, NSAID use in dogs with lungworm infection has been associated with severe bleeding [6]. If your dog is coughing blood and has been given an NSAID recently, tell the veterinarian.

What Happens at the Veterinary Hospital

The veterinarian will start with a full physical examination. They will listen to the heart and lungs, check the gums for color and bleeding, feel the abdomen, and look in the mouth for wounds or foreign objects. They will ask you specific questions: When did the coughing start? Was there blood? How much? What color? Has your dog eaten anything unusual? Is your dog on heartworm prevention? Has your dog been in tall grass?

First-line diagnostics

Blood work. A complete blood count checks for anemia and platelet count. A chemistry panel checks liver and kidney function. A coagulation panel (PT and aPTT) checks how well the blood clots. This is essential if rat poison is suspected.
Chest radiographs (X-rays). These show the heart size, lung patterns, fluid in the chest, and masses. They can reveal pneumonia, pulmonary edema, tumors, or bleeding into the lung tissue. In rodenticide cases, radiographs often show pleural effusion and pulmonary hemorrhage [2].
Point-of-care ultrasound. This can quickly detect fluid around the heart or lungs and help guide treatment.
Fecal Baermann test. This detects lungworm larvae. It is the traditional gold standard but can miss infections during the prepatent period or when larvae are shed intermittently [10].
Lungworm antigen test. An in-clinic blood test that detects A. vasorum antigen. It has high sensitivity and specificity and can detect infection earlier than fecal testing [10].

Advanced diagnostics

Bronchoscopy. A camera is passed into the airways to look for foreign bodies, tumors, or bleeding sites. Samples can be collected for culture and cytology.
CT scan. Provides detailed images of the lungs and can identify small masses or bleeding sites that radiographs miss.
Coagulation testing beyond PT and aPTT. Viscoelastic testing such as thromboelastography gives a more complete picture of clot formation and breakdown. This is not available in every practice but is useful in complex bleeding cases [15].
Heartworm antigen test. A simple blood test that detects adult heartworm infection.

What to Do on the Way to the Clinic

Call ahead. Tell the receptionist that your dog is coughing blood. This lets the team prepare oxygen, IV fluids, and emergency drugs before you arrive.
Keep your dog calm. Stress and excitement raise blood pressure and heart rate, which can worsen bleeding. Carry small dogs. Use a leash and harness for larger dogs. Do not let them run.
Do not give any medications. Do not give aspirin, ibuprofen, naproxen, or any other NSAID. These thin the blood and can make bleeding worse. Do not give human cough suppressants.
Do not force food or water. If your dog is having trouble breathing, eating or drinking can make it worse.
Collect a sample if you can. If your dog coughs up blood onto a clean surface, take a photo or scoop a small amount into a clean container. This helps the veterinarian confirm the source.
Bring medication bottles. If you suspect rat poison or any other toxin, bring the packaging or a photo of it.
Note the timeline. Write down when the coughing started, how often it happens, and how much blood you have seen. This history is valuable.
Drive safely. Do not speed or take risks. You are more useful to your dog alive and calm.

Emergency Red Flags

Go to an emergency hospital immediately if you see any of these:

Bright red blood or pink froth coming from the mouth or nose
Coughing that produces blood more than once
Difficulty breathing, especially with the elbows out and neck stretched
Pale, white, or blue gums
Collapse, weakness, or inability to stand
A distended or painful abdomen
Known or suspected exposure to rat poison
Bleeding from more than one site (nose, gums, rectum, urine)
A dog that has been hit by a car or had a major fall
A dog that is already on heartworm treatment and develops a cough with blood

Treatment: What the Veterinarian Will Do

Treatment depends entirely on the cause, but the first priorities are always the same: stabilize breathing, stop bleeding, and support circulation.

Oxygen and airway support

Dogs with hemoptysis often need oxygen. This may be delivered by mask, nasal cannula, or oxygen cage. Severe cases may need sedation to reduce anxiety and oxygen demand. In extreme cases, mechanical ventilation may be required.

Stopping the bleeding

If rat poison is confirmed or suspected, the treatment is vitamin K1. This is given by injection and then orally for several weeks. The duration depends on the specific poison. The veterinarian will recheck clotting times to make sure the treatment is working.

If a clotting disorder is identified, treatment may include plasma transfusions, fresh frozen plasma, or specific clotting factor support. Platelet disorders may require different treatments.

If a foreign body is found, it must be removed. This is usually done with bronchoscopy under anesthesia.

If a lung tumor is found, surgery may be an option depending on the location and how far it has spread.

Treating the underlying disease

Pneumonia: antibiotics, sometimes for several weeks, plus oxygen and supportive care.
Heartworm: treatment follows the American Heartworm Society protocol, which includes a macrocyclic lactone, doxycycline, and melarsomine injections. A study of 35 dogs treated with this protocol found that all dogs survived treatment, though side effects occurred [16]. Another study evaluated kidney values during treatment and found that monitoring is important [17].
Lungworm: fenbendazole and topical moxidectin. Many dogs improve within weeks [11].
Heart failure: diuretics, ACE inhibitors, and other cardiac medications. Oxygen and rest are critical.
Trauma: pain control, oxygen, and sometimes surgery.

Supportive care

IV fluids, anti-nausea medication, pain control, and cage rest are common. Some dogs need a blood transfusion if they have lost a lot of blood.

Unsafe Home Remedies

Do not try to treat this at home. Specifically:

Do not give NSAIDs. Aspirin, ibuprofen, and naproxen can worsen bleeding, especially in lungworm and rodenticide cases [6].
Do not give human cough medicine. These are not formulated for dogs and can be toxic.
Do not give vitamin K on your own. The dose and duration depend on the specific poison and the dog's clotting status. Giving the wrong dose can delay proper treatment.
Do not induce vomiting. If your dog has swallowed a foreign body or poison, inducing vomiting can cause more damage. Let the veterinarian decide.
Do not wait. Hemoptysis can progress from a small streak to fatal hemorrhage in hours.

Prevention

Keep your dog on heartworm prevention year-round. Monthly preventive medication is highly effective [4].
Use flea and tick prevention that also covers lungworm if you live in or travel to an endemic area. Ask your veterinarian which product is right for your region.
Store rodenticides securely. Keep bait stations out of reach. If you must use them, place them where dogs cannot access them.
Supervise your dog outdoors. Prevent them from eating unknown substances and from running through tall grass where foxtails grow.
Schedule regular wellness exams. Early detection of heart disease, lung disease, and other chronic conditions improves outcomes.
Tell your veterinarian about travel. If you move or travel with your dog, let your vet know so they can adjust preventive care.

Prognosis

Prognosis depends on the cause and how quickly treatment starts. Rat poison poisoning has a good prognosis if treated before severe hemorrhage. Lungworm infection often resolves completely with treatment [11]. Pneumonia can be cured with antibiotics. Heartworm disease is treatable but requires months of care and restricted activity. Lung tumors carry a more guarded prognosis, especially if they have spread. Severe heart failure is managed, not cured.

The common thread is time. Dogs that arrive at the hospital early, before they have lost too much blood or gone into respiratory failure, do far better than dogs that arrive late.

Limitations and When to Contact a Veterinarian

This article is educational and cannot replace an examination by a veterinarian who can see your dog, listen to its chest, and run tests. Individual cases vary widely, and the same symptom can have very different causes in different dogs.

Contact a veterinarian immediately if:

Your dog coughs up blood again, even a small amount
Your dog's breathing becomes fast, noisy, or labored
Your dog's gums look pale, white, or blue
Your dog collapses or seems weak
You suspect rat poison exposure, even if your dog seems fine
Your dog has been in tall grass and is now coughing violently
Your dog is on heartworm treatment and develops a new cough
Your dog has a known bleeding disorder and starts bleeding from any site

Do not wait for an appointment. Call the emergency hospital and go.

Frequently Asked Questions

Is a dog coughing up blood always an emergency?

Yes. Any amount of blood coming from the airway is an emergency until a veterinarian confirms otherwise. Even a small streak can be the first sign of a serious bleeding disorder, a lung tumor, or rat poison poisoning. Call an emergency hospital and go.

How can I tell if my dog is coughing up blood or vomiting blood?

Coughed blood comes with a cough, hack, or gag, and often looks frothy or mixed with mucus. Vomited blood comes with abdominal heaving and may contain food or bile. If you cannot tell the difference, treat it as an emergency and go to the vet.

What poisons cause a dog to cough up blood?

Anticoagulant rodenticides (rat poison) are the most common toxin. They stop the blood from clotting and cause bleeding into the lungs, chest, and other organs. In one study, 37 percent of poisoned dogs had bleeding into the pleural space and 24 percent had bleeding into the lung tissue [1]. Other toxins can also cause bleeding, so bring the packaging if you have it.

Can heartworm disease make a dog cough up blood?

Yes, though it is uncommon. Heartworm disease damages the pulmonary arteries, and in some dogs this leads to bleeding into the airways [3]. Heartworm is preventable with monthly medication, so talk to your veterinarian about prevention.

What is lungworm and can it cause hemoptysis in dogs?

Lungworm (Angiostrongylus vasorum) is a parasite that lives in the pulmonary arteries and heart. It causes respiratory signs and bleeding disorders, including hemoptysis [6]. It is diagnosed with a fecal test or an in-clinic antigen test [10] and is treated with fenbendazole and moxidectin [11].

Should I give my dog aspirin if it is coughing blood?

No. Never give aspirin or any other NSAID to a dog that is coughing blood. NSAIDs can worsen bleeding, and in one study, dogs with lungworm that received NSAIDs developed severe hemoptysis [6]. Keep your dog calm and get to the vet.

What tests will the veterinarian run for a dog coughing blood?

The veterinarian will likely start with blood work (complete blood count, chemistry, coagulation panel), chest X-rays, and possibly point-of-care ultrasound. If lungworm is suspected, a fecal Baermann test or an antigen test will be done [10]. More advanced tests include bronchoscopy and CT.

Can a dog survive coughing up blood?

Yes, many dogs survive if they get treatment quickly. The outcome depends on the cause. Rat poison poisoning has a good prognosis if treated early. Lungworm often resolves completely with treatment [11]. Lung tumors and severe heart failure have a more guarded prognosis. Time is the most important factor.