Acute respiratory distress syndrome (ARDS) is a sudden-onset difficulty with breathing. This is not a diagnosis in itself, but a condition that results from something else happening, such as inhaling smoke or a serious chest infection.
Fluid within the lung tissue prevents oxygen exchange. It develops as a response to some form of lung insult, such as severe irritation, trauma, infection or a shock response elsewhere in the body.
This is a serious condition and many animals are so distressed that, with little hope of recovery, it is kindest to ease their suffering and let them go.
These dogs and cats have extremely labored breathing that comes on suddenly. They can be so desperate that they hold their head and neck extended, as if gulping for air, and breathe through an open mouth.
Some have a soft, moist cough, while others are too sick to cough. If you look at the color of the gums, instead of being a healthy pink, they have a blue tinge.
Some animals lie down, seemingly to concentrate on breathing, and use exaggerated movements of their belly muscles to try and suck air into the lungs.
ARDS is a consequence of damage or injury to the lungs. The causes of this initial problem are wide and varied. Perhaps the most obvious potential causes are a road traffic accident with a blow to the chest or a serious lung infection such as pneumonia.
Other reasons include near drowning, smoke inhalation and chemical irritation of the lungs.
However, sometimes the trigger lies outside the chest cavity such as a head trauma, a severe infection elsewhere in the body or shock.
While it appears odd that disease not directly related to the lungs can cause ARDS, what happens is that mediators of inflammation circulate in the bloodstream to the lungs, where they trigger a cascade of chemical messengers that flood cells into the delicate alveoli.
A vicious circle is established where the lung tissue becomes distressed, triggering more chemicals, which further feeds fluid buildup in the airways.
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The first clue that ARDS may be an issue is a recent history of trauma or an infection. Blood tests can confirm if inflammation or infection are present and look for issues such as low blood protein levels, which can cause fluid to seep into the lung tissue.
Other tests include measuring the oxygen saturation of the blood with a pulse oximeter and chest radiographs. A pattern of density within the alveolar is highly suggestive of either pneumonia or ARDS, and is enough to start treatment.
The animal’s distress is caused by panic over lack of oxygen, thus putting him in an oxygen tent or supplying oxygen by a nasal catheter can help.
In severe cases, a tube may be passed into the dog’s windpipe so he can be artificially ventilated with oxygen. Some cases go into shock and therefore need intravenous fluids to support circulation to their organs.
ARDS is a serious condition. Many pets need to be euthanized to stop their suffering if there is little hope of recovery.
Keeping your pet under control and away from dangerous roads reduces the risk of serious trauma. Likewise, seek prompt veterinary attention when your pet isn’t well, because timely treatment may stop a condition from deteriorating into something potentially life-threatening.
- “Acute lung injury and acute respiratory distress syndrome.” Carpenter, Macintyre & Tyler. Comp Contin Edu Pract Vet, 23: 712–725.
- “Acute respiratory distress syndrome.” King & Waddell. The Veterinary ICU Book. Publisher: Teton New Media.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 1, 2015.