Pulmonary edema in cats

Pulmonary edema is a condition in which the amount of fluid in the lung tissue exceeds an acceptable level. It is not a disease, but a symptom caused by an underlying pathology. Pulmonary edema is extremely dangerous and requires immediate medical attention in cats.

Reasons for development

The lung consists of oxygen-containing alveoli and a network of small vessels surrounding them. Gas exchange results in oxygen being transferred from the air-filled alveoli to the blood vessels, while carbon dioxide is removed from the blood and expelled during exhalation.

Fluid accumulation in lung tissue occurs due to a large difference between hydrostatic and colloid osmotic pressure in the capillaries. The former is directed from the interstitial fluid into the capillary, while the latter is directed from within the vessel. If the alveoli fill with fluid, gas exchange is disrupted, resulting in acute oxygen starvation of all body systems. Pulmonary edema, depending on the cause, is divided into two groups.

Cardiogenic edema

This pathology is caused by cardiac dysfunction. It can develop with diseases such as pulmonary embolism, hypertrophic cardiomyopathy, organic heart defects, arterial hypertension, and cardiosclerosis. Weak cardiac function leads to blood stagnation in small vessels and exudate leakage into the alveoli of the lungs.

It is believed that cats of artificially bred breeds are more susceptible to the development of cardiogenic pulmonary edema: Maine Coons, Scottish Folds, British Shorthairs, Tonkinese, Thornwall Rex, Persians, Abyssinians, Peterbalds, and Sphynxes.

Non-cardiogenic edema

This type of edema is characterized by increased permeability of the pulmonary vessel walls; its causes are not related to cardiac pathologies. These may include:

• trauma or acute brain disease;
• inflammatory diseases of internal organs, including pneumonia;
• severe intoxication of the body, developed against the background of renal failure or the disintegration of a malignant tumor;
• poisoning with biological and chemical toxins;
• anaphylactic shock caused by a snake or poisonous insect bite;
• asthma, allergic reaction;
• sepsis leading to blockage of the lymphatic vessels;
• aspiration of the lungs due to the entry of foreign substances into the respiratory tract (for example, vomit);
• dirofilariasis (helminthiasis caused by parasitism of Dirofilaria nematodes).

Symptoms of pulmonary edema

Signs of fluid accumulation in the lung tissue in a cat may include:

• dyspnea,
• hoarse breathing through the mouth with the tongue hanging out,
• wide-legged posture,
• cough,
• foamy discharge from the nose and mouth,
• gagging,
• pallor or bluish discoloration of the mucous membranes (cyanosis),
• a sharp decrease in activity.

If several of these dangerous symptoms appear, the cat must be taken to a veterinary clinic immediately. Pulmonary edema progresses so rapidly that it often takes hours or even minutes.

Diagnostics

If a sick cat's medical history and clinical examination suggest pulmonary edema, a series of diagnostic procedures will be prescribed. If the cat is in critical condition, first aid will be administered without waiting for laboratory and imaging results. This may include injections of medications to reduce swelling and eliminate hypoxia, the use of an oxygen mask, and, if extremely restless, sedatives.

To make a final diagnosis, the following is used:

• X-ray (It will show the presence of exudate in the lungs and the type of edema.) Chest x-rays are taken in both frontal and lateral projections. Cardiogenic edema is characterized by an enlarged cardiac shadow.
• Echocardiography of the heart (to determine the size of the organ and its functional features);
• Blood test (clinical and/or biochemical), which are needed to assess the animal’s condition and identify possible causes of edema.

Treatment

Treatment for pulmonary edema in cats is performed in a hospital setting, usually in the intensive care unit. Symptomatic therapy includes:

• Measures to provide the animal with oxygen are taken. To do this, the cat is placed in an oxygen chamber or an oxygen pillow is used, and ventilation is used if necessary.
• Use of decongestants ― Dexamethasone, Prednisolone, Hydrocortisone, Diprospan.
• Removing excess fluid with injectable or oral diuretics. In veterinary medicine, hypothiazide, indapamide, furosemide, torasemide, amiloride, and spironolactone are used for this purpose.
• To eliminate the stressful condition, the following are prescribed: feline sedatives.

Radical treatment of pulmonary edema necessarily requires addressing the underlying cause of fluid accumulation in the lung tissue. If an infection is present, antibiotics or antiviral agents are prescribed. If heart failure is the cause, appropriate cardiac medications are used.

It takes two to three days for a cat with pulmonary edema to stabilize. If first aid and treatment are administered promptly, the prognosis is usually positive. If the animal is brought to the clinic too late, when oxygen deprivation has caused life-threatening changes in the body, the risk of death is high.

Read also:

• Why does a cat cough?
• Why does a cat sneeze?
• My cat is breathing with its tongue hanging out: why and what to do