What Is Aspiration Pneumonia in Dogs?
Aspiration pneumonia occurs due to lung inflammation triggered by the inhalation of substances like food, regurgitated matter, or vomit.
It typically arises when there are underlying issues with the usual swallowing reflexes and the process of pushing material down the esophagus. In cases of aspiration pneumonia, food particles find their way into the air passages and are inadvertently breathed into the lungs.
Normal Anatomy vs. Abnormal Anatomy
In a typical anatomical setup, after chewing and mixing with saliva, food forms a bolus ready for swallowing. The tongue then propels the food bolus to the pharynx, where it meets the nasal cavity’s end (nasopharynx), separated by the soft palate.
The larynx serves as the gateway to the trachea, with the pharynx and larynx divided by the epiglottis, a cartilaginous structure within the voice box. Extending down the throat, the tongue, a sizable muscle, connects to surrounding muscles and cartilage near the epiglottis.
The coordinated action of the tongue, soft palate, and epiglottis seals the passage to the trachea (larynx), enabling the food bolus to proceed down the esophagus and eventually into the stomach and intestines. During swallowing, a brief cessation of breathing ensures food follows the correct path down the esophagus. In cases of aspiration pneumonia, the laryngeal reflex becomes overwhelmed or malfunctions, leading to the passage of food and liquid into the larynx, down the trachea, and ultimately into the lungs.
Stages of Aspiration Pneumonia
Aspiration pneumonia progresses through several stages, each presenting distinct challenges:
In cases where large particles obstruct the major airways, acute respiratory distress can ensue, constituting a medical emergency. If you suspect your dog is experiencing such symptoms, seek immediate assistance from an emergency veterinary hospital.
Smaller particles, commonly inhaled, may obstruct smaller airways, triggering an inflammatory response. This response generates mucus and inflammatory cells, inducing a constriction of the airway muscles, known as bronchospasm. Symptoms include coughing, wheezing, and discomfort in breathing fully.
Another phase involves damage caused by inhaling acidic gastric enzymes. The altered pH levels easily harm the respiratory epithelium and compromise lung surfactant function, leading to bronchospasms and potentially acute respiratory distress syndrome (ARDS), which requires urgent medical attention.
Lastly, bacterial pneumonia may develop, either immediately overwhelming the dog’s immune system or emerging later in the disease progression.
Symptoms
Symptoms of aspiration pneumonia in dogs may include:
- Vomiting, regurgitation, or difficulty swallowing
- Coughing
- Exercise intolerance
- Fever
- Nasal discharge
- Difficulty breathing or respiratory distress
- Breathing at a fast rate, but may not be panting
- Cyanotic or blue gums and tongue
Causes
Causes of aspiration pneumonia in dogs vary and include:
- Instances such as bottle-feeding puppies where milk flows too rapidly, leading to choking.
- Force-feeding animals that may have difficulty swallowing properly due to mental dullness.
- Puppies born with a cleft palate, allowing milk to enter the nasal cavity and trickle down into the lungs.
- The primary cause of aspiration pneumonia in adult dogs is regurgitation due to a dilated esophagus (megaesophagus). Regurgitation, distinct from vomiting, expels esophageal contents passively, often occurring before food reaches the stomach. It can happen shortly after eating or be delayed for several hours. Regurgitated material may appear undigested and in a tubular form.
- Regurgitation can be triggered by stress or anesthesia, particularly in brachycephalic breeds such as Boston Terriers, Pugs, French Bulldogs, Bullmastiffs, Cane Corsos, Boxers, English and American Bulldogs, and Dogue de Bordeaux.
- Vomiting, on the other hand, is an active response involving abdominal muscle contractions to expel food, liquid, and sometimes bile from the stomach and small intestines.
- Other causes encompass pharyngeal abnormalities (like local paralysis, focal myasthenia gravis, and traumatic nerve damage), esophageal abnormalities, anatomical malformations, generalized neuromuscular disease, forebrain disease, postictal phase (following a seizure), motor dysfunction, post-operative laryngoplasty, altered consciousness, sedation, anesthesia (during or post-recovery), severe metabolic disorders, force-feeding, improper feeding tube placement, and trauma.
Diagnosis
Diagnosing aspiration pneumonia in dogs involves several diagnostic steps:
- Dogs presenting with aspiration pneumonia may be in shock, necessitating immediate and aggressive stabilization.
- In cases where respiratory distress is absent, veterinarians may order bloodwork to identify potential infections. X-rays are also commonly requested to detect a bronchoalveolar pattern in the gravity-dependent lung lobes.
- If respiratory distress is evident, veterinarians conduct an oral examination to check for visible obstructions in the mouth and throat. In instances where a significant obstruction is suspected, a bronchoscopy may be performed. Arterial blood gas tests are often conducted to monitor oxygen levels in emergency settings.
- To confirm the diagnosis of aspiration pneumonia, veterinarians may perform a tracheal or bronchoalveolar wash to collect cellular samples from the trachea or lungs.
- Additionally, various medical conditions can predispose dogs to aspiration pneumonia, each requiring specific diagnostic tests:
- Thyroid tests aid in diagnosing hypothyroidism.
- Adrenal function tests help diagnose hypoadrenocorticism (Addison’s Disease) and polyneuropathy.
- Antiacetylcholine antibodies tests assist in diagnosing myasthenia gravis.
- Antinuclear antibodies tests aid in diagnosing systemic lupus erythematosus.
- Fluoroscopy imaging with contrast is utilized to diagnose swallowing disorders, such as dysphagia.
Treatment
For severe instances of aspiration pneumonia, your dog might require hospitalization at a 24-hour facility equipped with an oxygen cage, bronchodilators for airway clearance, intravenous fluid therapy, antibiotics, and medications to manage nausea and gastrointestinal motility.
In milder cases, outpatient treatment could suffice. The prognosis hinges on the root cause of the regurgitation leading to aspiration pneumonia.
Living and Management
The typical recovery period for aspiration pneumonia spans at least 10 days following symptom resolution. It’s crucial not to halt therapy prematurely to ensure effective treatment, which may extend from 2 to 8 weeks, varying with the severity and root cause of the pneumonia.
Prevention and prognosis of aspiration pneumonia are heavily influenced by the underlying cause. In cases where the cause is severe and there’s a heightened risk of recurrent infections, the prognosis tends to be unfavorable.
Aspiration Pneumonia in Dogs FAQs
Is it possible for dogs to overcome aspiration pneumonia?
Dogs have the potential to recover from aspiration pneumonia through aggressive and suitable treatment.
What is the timeframe for the onset of aspiration pneumonia in my dog?
Symptoms of aspiration pneumonia can manifest immediately or may take days to weeks to become apparent.