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Breathing Easy: Common Disorders of the Respiratory and Cardiovascular Systems in Pets

Originating in the Respiratory System

The respiratory system is the organ system responsible for providing oxygen to the body and eliminating carbon dioxide. When something goes wrong with the respiratory system, it can cause various symptoms, including coughing, difficulty breathing, and chest pain.

In this article, we will discuss different respiratory system disorders that can originate from different anatomical parts of the respiratory system and their symptoms, causes, diagnosis, and treatments.


The larynx is a cartilage tube connecting the pharynx to the trachea. It is responsible for breathing, protecting the airway during swallowing, and producing sound through vocal cords.

When something goes wrong with the larynx, it can cause voice changes, breathing difficulties, and stridor (a high-pitched wheezing sound).

Paralysis of the larynx can be caused by nerve damage or compression, resulting in difficult or absent breathing, and lack of voice.

Laryngeal collapse, on the other hand, is a condition in which the laryngeal cartilage weakens and narrows the airway, leading to progressive breathing obstruction. Laryngeal spasm is a sudden contraction of the larynx that causes a difficulty in breathing.

Laryngeal cancer is rare in animals, but it can cause symptoms like coughing, difficulty breathing, and dysphagia (difficulty swallowing).

Diagnosis of laryngeal disorders usually involves physical examination and imaging such as X-rays, ultrasound, or CT scans.

Treatment for laryngeal disorders can range from medications to surgery depending on the diagnosis.


The trachea is a tube made of cartilage and smooth muscle located between the larynx and bronchi. It transports air to the lungs while filtering out any foreign material.

When something goes wrong with the trachea, it can cause coughing, wheezing, and difficulty breathing.

Tracheal collapse is a disorder in which the cartilage rings that support the trachea weaken and allow the trachea to collapse, narrowing the airway.

Tracheal neoplasia is a rare type of cancer that can cause difficulty breathing, coughing, and wheezing.

Foreign bodies that accidentally enter the trachea, especially in young animals that like to chew on things and explore new environments, can cause choking, coughing, and wheezing.

Diagnosis of tracheal disorders usually involves imaging techniques such as X-rays, CT scans, and endoscopy.

Treatment for tracheal disorders usually involves medications, surgery, or a combination of both, depending on the severity and the cause of the disorder.

Lower airway

The lower airway includes the bronchioles, alveoli, and surrounding tissues. When something goes wrong with the lower airway, it can cause coughing, shortness of breath, and chest pain.

Pneumonia is an infection of the lower respiratory tract that can cause shortness of breath, wheezing, and fever. Bronchiole swelling can be caused by viral infections, allergies, or stimulants, leading to coughing, wheezing, and shortness of breath.

Asthma is a chronic respiratory disease that causes airway inflammation and bronchospasm, leading to coughing, wheezing, and shortness of breath. Lung cancer can occur in both dogs and cats, and can cause symptoms like coughing, weight loss, and shortness of breath.

Foreign bodies and parasites can cause an obstruction of airflow and can result in coughing, wheezing or difficulty breathing.

Diagnosis of lower airway disorders usually involves a physical examination, blood tests, and imaging. In some cases, bronchoscopy and thoracocentesis may also be required.

Treatment for lower airway disorders usually involves oxygen therapy, medications, and occasionally surgery.

Pleural Space

The pleural space is the space between the lungs and the chest wall. It contains lubricating fluid that allows the lungs to move within the chest.

When something goes wrong with the pleural space, it can cause chest pain, difficulty breathing, and coughing. Pleural infections can cause fluid accumulation within the pleural space, leading to coughing, shortness of breath, and fever.

Pleural cancer can also develop in cats and dogs; leading to symptoms such as coughing, weight loss and difficulty breathing.

Diagnosis of pleural disorders usually involves chest x-rays, ultrasound, and, in some cases, CT scans.

Treatment may include medications, chemotherapy, and surgery for cancer or even draining of the accumulated fluid, if present.

Chest wall or diaphragm

The chest wall and diaphragm muscles are crucial in breathing, aiding in the expansion and contraction of lungs during respiration. When something goes wrong, it can cause shortness of breath, chest pain, and fatigue.

Congenital defects such as cleft palate and lip or chondrodystrophy (a genetic mutation leading to abnormal growth of cartilage) can affect breathing and cause frequent respiratory infections. Traumatic injuries can cause chest wall fractures or diaphragmatic hernia, which prevents the lungs from expanding and releasing carbon dioxide.

Diagnosis of chest wall or diaphragm disorders usually involves a physical exam, ultrasound or radiographs.

Treatment involves surgical repair of the injured tissue or additional medical or supportive care as needed.


Respiratory disorders can be life-threatening if not treated appropriately. Some of the common respiratory system disorders discussed in this article include those originating in the larynx, trachea, lower airway, pleural space, and chest wall or diaphragm.

Early diagnosis and treatment can help prevent severe injury to the lungs and respiratory system. Therefore, pet owners are encouraged to monitor their pets for any signs of respiratory distress and seek veterinary attention as early as possible.

Originating in the Cardiovascular System

The cardiovascular system is responsible for the body’s oxygen and nutrient delivery, pumping blood and regulating blood pressure. When something goes wrong with the cardiovascular system, it can cause serious complications such as heart attacks, strokes, and pulmonary insults.

In this article, we will discuss different cardiovascular system disorders that can originate from different parts of the cardiovascular system and their symptoms, causes, diagnosis, and treatments.

Congenital Defects

Congenital defects are defects in the cardiovascular system that arise during fetal development and are present at birth. Congenital heart defects (CHDs) affect approximately 1 in every 100 newborns globally.

Some of the most common defects include mitral valve disease and hypertrophic cardiomyopathy. Mitral valve disease is a heart defect characterized by a leaky or narrowed heart valve, causing improper blood flow.

The valve can stiffen with age, and if left untreated, it can lead to heart failure. Signs and symptoms of this malfunction include abnormal breathing patterns, coughing, lethargy, and collapse.

Hypertrophic cardiomyopathy (HCM) is a genetic heart disease in which the heart muscles thicken and stiffen, making it harder for the heart to pump blood.

Symptoms of HCM include dyspnea, chest pain, heart palpitations, and sudden death.

Veterinarians typically diagnose CHDs through a thorough physical exam and imaging techniques such as ultrasound.

Acquired Diseases

Acquired cardiovascular diseases are those that develop later in life due to various factors like age, lifestyle, environment, and underlying health conditions. Some of the most common acquired cardiovascular diseases in cats and dogs include fluid collection around the heart, clotting in lung blood vessels, and pulmonary hypertension.

Fluid around the heart – also known as pericardial effusion – is a condition where the protective sac around the heart fills with extra fluid, exerting pressure on the heart and affecting its function. This condition can occur due to trauma, cancer, or bacterial infection.

Other signs of fluid accumulation include coughing, rapid breathing, and lethargy. Clotting in lung blood vessels – also known as pulmonary thromboembolism – is a condition where a blood clot gets lodged in the blood vessels of the lungs, preventing blood flow and oxygen delivery.

This condition typically occurs due to other underlying health conditions such as Heartworm infection, hypercoagulable conditions or even blunt trauma. Some common signs of this condition include coughing, rapid breathing, and lethargy.

Pulmonary hypertension is a condition in which the blood pressure in the pulmonary artery, which carries blood from the heart to the lungs, becomes too high. This disorder usually occurs due to underling Heart worm infection, COPD, or even chest injury.

Common symptoms include coughing, rapid breathing, and lethargy.

Peripheral Blood Vessel Disease

Peripheral blood vessel disease is a condition in which blood doesn’t flow properly through the vessels. This condition is typically characterized by a reduced flow of oxygen and nutrients to various parts of the body.

The exact cause of this condition in pets is unknown, but it may be related to age, genetics, diet, or underlying health conditions. Some of the common signs of peripheral vascular disease include a cool-to-the-touch leg or paw, changes in skin color, hair loss, and slow healing wounds.

Veterinarians usually diagnose this disease through a physical exam or diagnostic tests, such as Doppler ultrasounds or angiography.

Treatment may include medications, diet changes, or surgery depending on the cause and severity of the condition.

Originating in the Neuromusculoskeletal System

The neuromusculoskeletal system comprises the nervous system, the muscles, and the bones. When something goes wrong with this system, it can cause various symptoms such as pain, lethargy, and paralysis.

In this section of the article, we’ll cover some common neuromusculoskeletal disorders in pets and their causes, symptoms, diagnosis, and treatments.

Brain-Stem Dysfunction

The brainstem, located at the base of the brain, controls various functions such as breathing, swallowing, and heart rate. When something goes wrong with the brainstem, it can cause various symptoms such as swelling, trauma, bleeding, cancer, or drug-induced depression.

Some common brainstem disorders in pets include brainstem stroke, brain tumors, and brainstem encephalitis.

Symptoms of these disorders include weakness or paralysis in various body parts, seizures, and loss of balance.

Veterinarians typically diagnose brainstem disorders through a physical exam, blood tests, and imaging such as CT or MRI scans.

Treatment may include medications, radiation therapy, or surgery depending on the cause and severity of the disorder.

Spinal Cord Dysfunction

The spinal cord is a long bundle of nerves running from the brain to the lower back, controlling various functions such as movement and sensation. When something goes wrong with the spinal cord, it can cause various symptoms such as swelling, trauma, fractures, or slippage.

Some common spinal cord disorders in pets include herniated discs, intervertebral disc disease, and spinal tumors.

Symptoms of these disorders include paralysis, loss of coordination, and loss of bladder or bowel control.

Veterinarians typically diagnose spinal cord dysfunction through a physical exam and imaging such as MRI or CT scans.

Treatment may include pain relievers, anti-inflammatory medication, and physical therapy depending on the cause and severity of the disorder.

In some cases, surgery may be required to repair or stabilize the spinal cord.

Neuromuscular Dysfunction

Neuromuscular dysfunction is a broad term that refers to various disorders affecting the nerves and muscles. Common causes of neuromuscular dysfunction in pets include drug overdose, tick paralysis, and botulism.

Some common neuromuscular disorders in pets include Myasthenia gravis, polyneuropathy, and muscular dystrophy.

Symptoms of these disorders include muscle weakness, difficulty breathing, and muscle atrophy.

Diagnosis of neuromuscular disorders may involve blood tests, imaging, or muscle biopsy.

Treatment may involve medications, physical therapy or supportive care depending on the cause and severity of the disorder.


The cardiovascular and neuromusculoskeletal systems play a crucial role in pets’ overall health and well-being. Various disorders can affect these systems, leading to various symptoms and complications.

Early diagnosis and treatment can help prevent further injury and improve the chances of recovery. Therefore, pet owners should keep an eye on their pets for any signs of discomfort and seek veterinary care as early as possible.

Methemoglobinemia is a rare blood disorder that affects both dogs and cats, leading to reduced oxygen-carrying capacity of blood, and in severe cases, can lead to death. In this article, we will discuss methemoglobinemia, its causes, symptoms, diagnosis, and treatment.

What is Methemoglobinemia? Methemoglobinemia is a type of blood disorder that causes the oxygen-carrying capacity of blood to decrease.

It occurs when red blood cells contain an abnormal form of hemoglobin, known as methemoglobin, that cannot transport oxygen to the cells effectively. This lack of oxygen often leads to cyanosis, a bluish or gray coloration to the skin and mucous membranes.

Methemoglobinemia can be classified as congenital or acquired, depending on the underlying cause.

Congenitally acquired NADH-methaemoglobin reductase deficiency

NADH-methemoglobin reductase is an enzyme that plays a crucial role in converting methemoglobin back to functional hemoglobin. Methemoglobinemia can occur when there is a genetic defect, leading to a deficiency of NADH-methemoglobin reductase in red blood cells.

This deficiency can often be congenital, and pets can be born with methemoglobinemia. Inherited Methemoglobinemia is rare in cats and most commonly expressed in certain breeds like the Dalmatians or the common European cat breed, and usually presents in the juvenile or neonatal period.

They often show symptoms such as lethargy, shortness of breath, cyanosis, or death.

Linked to ingestion of oxidant chemicals

Methemoglobinemia can be acquired when the pet ingests certain medications or toxic chemicals that can cause the oxidation of hemoglobin, leading to the formation of methemoglobin. Some of the common chemicals that cause methemoglobinemia include acetaminophen, nitrates, and aniline dyes.

Acetaminophen, found in products like Tylenol and other painkillers, is safe for humans but extremely toxic to pets, causing methemoglobinemia in dogs and cats. Acetaminophen overdoses can cause severe anemia, swelling of the face, and respiratory distress.

Nitrates and nitrites, commonly found in fertilizers, herbicides, and pesticides, can lead to methemoglobinemia when ingested by pets, especially in cattle. Aniline dyes are used in textile and leather industries and have been known to cause methemoglobinemia in dogs.


Symptoms of methemoglobinemia usually present as those associated with lack of oxygen, including shortness of breath, lethargy, cyanosis, and weakness. In severe cases, pets may experience seizures, coma, or death.


Diagnosis of methemoglobinemia requires a thorough physical exam and a detailed history of any recent medication ingestion or toxic chemical exposure. Blood tests, including a blood gas analysis, can be done to determine the level of methemoglobin in the blood and to differentiate it from other medical conditions causing cyanosis.

Veterinarians may also perform an arterial blood gas test to determine the exact concentration of methemoglobin.


Treatment of methemoglobinemia depends on the underlying cause and severity of the condition.

Treatment may include oxygen therapy, medications that reduce methemoglobin levels, and identifying and avoiding potential toxins.

In severe cases, blood transfusion may be required to quickly increase oxygen-carrying capacity and survival. For instance, administering Methylene Blue (1-8mg/kg IV, administered over 5-10 minutes) can reduce methemoglobin concentrations in pets and animals.

Vitamin C administration can help reduce methemoglobin formation, and in some cases, blood transfusions may be necessary. Veterinarians will also treat other symptoms and underlying medical conditions that may have contributed to methemoglobinemia.

Close monitoring of the patient’s condition for any complications is vital to ensure a good prognosis.


Methemoglobinemia is a rare blood disorder that can lead to serious complications and

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