Rapid Breathing (Tachypnea) in Cats

About

Rapid breathing (tachypnea) is a respiratory disorder characterised by abnormal breathing that is rapid and shallow. It is caused by a reduced level of oxygen, mechanical disorders (where the lungs aren’t able to expand as they should, usually due to a build-up of fluid in or around the lungs), and physiological disorders in which the cat’s respiratory centre in the brain is overstimulated.

When is rapid breathing normal?

Rapid breathing after exercise or exertion or at times of stress, such as a trip to the veterinarian and will settle down on its own.

The average respiration rate for cats is 20-30 breaths per minute, which is approximately twice that of humans. There are several types of breathing disorders that can affect cats; this article will focus on tachypnea only. Differences in the other types of breathing can be subtle, and many definitions can cross over.

Causes

There are three leading causes of rapid breathing in cats, reduced oxygen, mechanical difficulty and physiological.

Reduced oxygen levels in the blood:

Anemia: Reduced number of red blood (also known as erythrocytes) cells in the blood. Is not a disease in itself but a symptom of an underlying condition. It can be due to the premature destruction of the red blood cells, decreased production (due to cancers, kidney disease, certain infections or drugs), blood loss, tumours, blood clotting disorders and parasites such as fleas and hookworm.

Treatment:

The goal is to treat the underlying cause where possible and provide supportive care which may include:

• Volume replacement – Hypovolemic shock is a life-threatening condition that occurs when a large portion of the blood is lost. Immediate treatment for this is volume replacement to ensure blood volume to prevent ischemia (restricted blood supply to the tissues, which results in lack of oxygen and glucose), shock and multi-organ failure.
• Blood transfusion for acutely anemic cats or cats who have suffered significant blood loss or kittens who have neonatal isoerythrolysis. Blood typing must be carried out before a blood transfusion. Cats have three blood types, Type A, Type B and Type AB. Type A cats can only receive type A blood, Type B cats can only receive type B blood, and Type AB cats can receive blood from type AB blood or type A blood.
• Erythropoietin: The kidneys produce a hormone, erythropoietin, which instructs the bone marrow to produce red blood cells. Cats with kidney failure often have a low red blood cell count. Only the human form is available, and some cats may eventually recognise this substance as foreign and antibodies will be created against it.
• Oral iron supplementation for cats with iron deficiency.
• Oxygen therapy for severely anemic cats.

Pneumonia: An infectious/inflammatory disorder of the lung parenchyma. Tiny bronchi fill the lungs; each one ends in smaller sacs known as alveoli which contain tiny blood vessels. Oxygen is added to the blood and carbon dioxide is removed via the alveoli. Pneumonia causes these alveoli to fill with pus and fluids which affect the lung’s ability to exchange gases. There are several causes including infection (viral, fungal, bacterial, parasitic), aspiration of gastric contents or medications.

Treatment:

• Antibiotics to treat a bacterial infection or toxoplasmosis. Selection is based on bacterial culture and sensitivity. Mycotic (fungal) pneumonia typically requires long-term (2+ months) with systemic anti-fungal medication.
• Supportive care such as a nebuliser or oxygen therapy if the cat is experiencing breathing difficulty.
• Fluid therapy to correct dehydration.
• Nutritional support if the cat is not eating which may include strong-smelling food, appetite stimulants or a feeding tube.

Hypoglycemia: A life-threatening condition in which the blood sugar levels drop dangerously low. The pancreatic beta cells produce the hormone insulin which helps to move glucose from food into the cells (for energy). Hypoglycemia is a symptom of an underlying disorder. Causes include excessive insulin administration in the diabetic cat, decreased glucose production (missed meal, vomiting, certain medications, glycogen storage disease), and excessive glucose consumption due to sepsis (bacterial infection of the blood).

Treatment:

• If your cat is still conscious and can swallow, administer a sugar solution such as corn syrup, maple syrup or honey on his tongue. If the cat is unable to swallow, rub this solution onto the gums or under the tongue. Never force fluids or food into the mouth as this could cause choking or asphyxiation.
• If your cat is having seizures or is unconscious, take him to the veterinarian immediately, along the way administer sugar as outlined above.
• It is important to follow up with your veterinarian, even if your cat appears to be okay. It may be necessary to re-adjust insulin levels in the diabetic cat.
• Non-diabetic cats will require additional tests to determine and treat the cause. Once at the veterinary surgery, your cat’s blood glucose level will be immediately checked, and if necessary he will be given intravenous dextrose.
• Glucocorticoids such as prednisone to help stabilise blood sugar levels.
• Do not administer insulin to a cat after hypoglycemia until a veterinarian gives you the okay.

Congestive heart failure: A life-threatening disorder that occurs when the heart doesn’t pump blood as efficiently as it should which causes fluid to back up in the lungs and abdomen, while other organs don’t receive enough blood to function properly. It can be caused by heart diseases such as cardiomyopathy, heartworm, myocarditis, endocarditis, congenital disorders, high blood pressure, tumours, hyperthyroidism and acromegaly.

Treatment:

Treatment for congestive heart failure is aimed at managing the medical cause of the condition as well as relieving symptoms associated with fluid build-up in the lungs, pleural space, and abdomen. In a few situations, once the cause has been treated (such as hyperthyroidism), the heart may recover, however, most cases of CHF are irreversible, but it may be managed to slow down the progress. Stabilising your cat if he has fluid build up in the lungs or pleural cavity, relieving symptoms and this may include:

• Oxygen therapy either with a mask or in an oxygen tent to avoid stressing him.
• Thoracentesis (as listed above).
• Diuretics such as Furosemide to remove fluid by increasing urine output.
• Vasodilators to open up the vessels, which helps prevent fluid buildup.
• Angiotensin-converting enzyme inhibitor (ACE inhibitor). These drugs help to relax blood vessels and lower blood pressure.

Heartworm disease: Also known as dirofilariasis, heartworm disease (HW) is a serious parasitic infection caused by the nematode Dirofilaria immitis which lives in the pulmonary arteries, lungs, and hearts of cats. Heartworms are a type of roundworm, with adult heartworms reaching a length of 12 to 30 cm. Microfilaria (baby heartworms) are present in the blood of an infected animal (in most cases, a dog) when a female mosquito feeds on the blood, microfilaria are also ingested, once, inside the gut of the mosquito, they undergo further development before migrating to the labium (a part of the mouth) of the mosquito. When the infected mosquito feeds on another host (in this case, your cat), the larvae move from the mouthpart and onto the skin of the cat (or dog), from there, they enter the bloodstream via the bite wound left behind by the mosquito.

Treatment:

There is no approved adulticide (medications to kill adult heartworms) treatments for cats. Adulticides are themselves dangerous. A single dead worm can be fatal in cats as it can break away and cause a blockage of the pulmonary artery (pulmonary embolism). Heartworms in cats have a shorter lifespan than those in dogs; therefore it is preferable to manage symptoms and use a wait and see approach.

Mechanical difficulty:

Pleural effusion: An abnormal buildup of fluid up in the pleural cavity, the thin fluid-filled space that lies between the lungs and the chest wall. Pleural effusion is a symptom with an underlying disorder causing this fluid to build up. The buildup of excess fluid leads to difficulty breathing, due to the inability of the lungs to fully expand. Causes include congestive heart failure, liver failure, fluid overload, blood clotting disorders (usually due to ingestion of rat poison), lung lobe torsion, pulmonary edema, and diaphragmatic hernia.

Treatment:

• Thoracentesis: Fluid is removed by thoracentesis which allows the lungs to expand. A needle or drainage tube will be inserted through the skin and into the pleural cavity to remove the fluid. A chest drain may remain in place for several days to help drain away excess fluid.

Treatment for the underlying condition varies depending on the cause. But may include:

• Antibiotics to treat bacterial infections.
• Furosemide to promote diuresis in cats with chronic heart failure.
• Surgery for neoplasia, trauma, foreign body inhalation, obstruction, hernia, lung lobe torsion.
• Supportive care and anti-virals for FIP.
• Nutritional support, pain medications, supportive care, antibiotics, and antiemetics for pancreatitis.
• Medications to treat heartworm or fungal infections.
• Induce vomiting, activated charcoal, stomach pump, vitamin K and possibly blood transfusion for rat poisoning.

Pulmonary edema: A buildup of fluid within these air sacs leading to shortness of breath. Located in the lungs are thousands of air sacs (alveoli) which are small balloon-like structures where the exchange of carbon dioxide and oxygen occurs. Tiny capillaries surround the alveoli on the outside. When the cat breathes in, air enters the lungs, causing the alveoli to expand. Oxygen passes from the alveoli and into the capillaries, carbon dioxide from the capillaries pass into the alveoli and is exhaled out. The most common causes of pulmonary edema relate to problems with the heart, such as hypertrophic cardiomyopathy. Heart diseases can lead to reduced movement of blood through the capillaries in the lungs. As the blood flow slows, fluid leaks out of the vessels into the airways. [1]

Other causes of pulmonary edema include electric shock, certain medications, anemia, kidney disease, airway obstruction, cancer, pneumonia, lungworm, allergic reactions, seizures, smoke inhalation, hypervolemia (fluid overload due to the administration of fluids), and head trauma.

Treatment:

The goal of treatment is to address the underlying cause as well as manage symptoms; this can include:

• Diuretics which help in the removal of excess fluids by increasing urine output.
• Oxygen therapy to help your cat to breathe.
• Vasodilators to open up the vessels, preventing the fluid from building up.
• Sedatives and analgesics to relieve pain and anxiety.
• Cage rest while your cat recuperates.

Pyothorax: Also known as pleural empyema, pyothorax is the presence of pus in the pleural space in the chest cavity, the thin, fluid-filled space that lies between the lungs and the chest wall. Any pathogenic organism can cause pyothorax including fungal, viral, bacterial or protozoal; however, a bacterial infection is by far the most common pathogen. The collection of pus is due to dead white blood cells and dead bacteria. Common bacteria involved in pyothorax include Pasteurella spp (the most common), Nocardia spp, Streptococcus spp, Clostridium spp, Proteus spp, Bacteroides spp and Mycoplasma spp.

There are several possible ways cats can develop pyothorax. In many cases, the initial cause may remain undetermined. Some causes include bite wounds, trauma, inhalation of an object such as a grass awn, bacteria ascending from the mouth, diffusion of bacterial infection, parasitic migration, perioperative aspiration, tumours, ruptured abscess and lung lobe torsion.

Treatment:

The goal of treatment is to relieve symptoms and treat the underlying cause. Antibiotic therapy will be necessary for up to six weeks. While he is in care, he will receive the following treatments:

• Respiratory support such as oxygen therapy, bronchodilators or nebulisers may be necessary. Cats are often very sick and need to be treated with great care.
• Thoracic drainage tubes to remove fluids from the pleural cavity. Local anesthesia and IV sedation are administered to keep your cat comfortable during this procedure. Tubes will be flushed several times a day with 0.9% saline or lactated Ringers solution warmed to body temperature to wash the chest cavity (pleural lavage). Tubes will need to remain in place for between 4-6 days.
• While the tubes are in place, the cat will wear an Elizabethan collar to prevent him from pulling them out.
• Cytologic examination of the fluids removed which will be checked daily to look for signs of resolution.
• Administration of broad-spectrum IV antibiotics until cytology results return, after which, your veterinarian will tailor antibiotics to the type of bacteria present.
• Pain medication.
• Supportive care including intravenous fluids to correct dehydration, increase blood volume and electrolyte imbalance.

Airway obstruction: Airway obstruction is a partial or blockage in any part of the airway which prevents air from getting into the lungs. A blockage can be due to an ingested foreign object, asthma or a tumour or growth.

Treatment:

The goal of treatment is to find and address the underlying cause; this can include:

• Surgery to remove a tumour
• Bronchodilators to open the airways
• Surgery to remove a foreign object

Lung hemorrhage: Bleeding of the lung is caused by a tear or crush due to trauma. Blood clotting disorders can also lead to bleeding in the lungs.

Treatment:

The goal of treatment is to manage symptoms and address the underlying cause; this may include:

• Surgery
• Oxygen therapy
• Fluid and nutritional support
• Cage rest

Pulmonary thromboembolism: Pulmonary thromboembolism (PTE) is a blockage in the pulmonary artery or one of its branches in the lungs that is caused by an embolism, a substance that has travelled through the circulatory system from another part of the body. The most common cause of pulmonary thromboembolism is a blood clot other causes include heartworm and a globule of fat. Blood can clot as a result of increased clotting disorders, heart disease, tumours, heartworm, polycythemia (increased red blood cells), and damage to the blood vessel walls.

Treatment:

Supportive care, thromboembolic drugs and treating the underlying cause.

Immediate treatment to stabilise your cat.

• Supportive care may include strict cage rest, oxygen therapy, and fluid therapy.
• Thrombolytics or tissue plasminogen activator (t-PA) drugs – Streptokinase or Alteplase administered via IV to dissolve the clot. Bleeding may occur in cats given these medications.
• Anticoagulants (blood thinners) and antiaggregants (antiplatelet) – These drugs reduce the occurrence of blood clots forming. Anticoagulants work by delaying the clotting of blood; common medications include Warfarin and Heparin. Antiaggregants stop platelets from clumping together to form a plug. Aspirin and clopidogrel are two drugs in this category.

Other:

Other causes of rapid breathing not related to breathing difficulty can include the following:

• Pain
• Fever
• Stress
• Metabolic acidosis due to aspirin toxicity, kidney disease and shock
• Heatstroke

Symptoms

• Rapid, shallow breathing
• Cyanosis (blue-tinged mucous membranes)
• Coughing and gagging
• Exercise intolerance/reluctance to move
• Lethargy

Additional symptoms will vary depending on the underlying cause.

Any breathing difficulty is a medical emergency and requires urgent veterinary attention.

Diagnosis

Your veterinarian will perform a complete physical examination of your cat including listening to the heart and lungs for signs of heart abnormalities or fluid build-up in or around the lungs.

Medical history:

• Onset of symptoms
• Is the cat on any medication (prescribed or non-prescribed)?
• Underlying medical conditions

Diagnostic workup:

• Baseline tests: Complete blood count, biochemical profile, and urinalysis to look for signs of anemia, infection or organ dysfunction.
• Imaging: Xrays or ultrasound to evaluate the heart, liver, and lungs for signs of enlargement, fluid, tumours, hernia or obstruction.
• Echocardiogram: An ultrasound of the heart to evaluate the size and function as well as look for heartworms.
• Arterial blood gas test: A measure of the amounts of arterial gases, such as oxygen and carbon dioxide in the blood.
• Thoracentesis: A procedure in which a needle is inserted into the pleural space between the lungs and the chest wall to remove fluid from the pleural space. The thoracentesis serves two purposes, to reduce compression which improves breathing and it provides the veterinarian with fluid samples for analysis.
• Antibody or antigen tests: To evaluate for heartworm infection.
• T3 and T4 blood tests: A measurement of the hormones T3 and T4 for cats with suspected hyperthyroidism.

Home care

• Restrict activity during the recovery period.
• Administer all medications as prescribed by your veterinarian.
• Carefully monitor your cat and seek medical help if you notice any changes.
• Your veterinarian will likely need follow-up appointments with your cat to monitor his condition.