The Case: Breathing Difficulty in a "Well" Cat

Presentation

• 3-year-old outdoor, spayed female domestic shorthair was presented for annual physical examination/vaccination along with a senior family dog. Owner voiced no concerns.

Physical Examination

• Body weight: 15 lb, body condition score 8/9

• Pet was panting/stressed/resisting handling. It jumped down from the examination table and was searching for an escape.

• Eyes/ears/mouth: normal. Tongue was pink despite panting.

• Thorax: ++ dyspnea with bilateral moderately increased bronchovesicular sounds (sounded like a train) that made cardiac auscultation difficult. Owner denied history of asthma/had seen no breathing difficulty at home; suggested allowing pet to walk around to calm down. As cat’s tongue was pink, veterinarian agreed to let cat walk around while he/she examined the dog and kept an eye on it. Cat’s breathing became increasingly difficult; it began to look cyanotic. Chest auscultation was similar to previous auscultation. Palpation of abdomen found no obvious problem.

Treatment

• Dexamethasone (4 mg IM) to counter possible asthma attack. In face of continued deterioration, pet was moved to surgery, oxygen therapy via face mask instituted, 0.2 cc 1:10,000 epinephrine administered SC. Severe cyanosis made x-ray procedure too dangerous. Attempts to remove oxygen led to worsening cyanosis. Blood oxygen level was ~ 85% with oxygen but ~ 70% without.

Outcome

Staff was trying to devise a way to continue oxygen/obtain a chest radiograph when owner elected euthanasia. As mask was removed to administer beuthanasia solution, pet experienced respiratory arrest. Postmortem lateral chest x-ray revealed a hernia of the liver into the mediastinum, causing cardiac tamponade. There was no evidence of recent injury.

The Specialist's Opinion

This case is a classic example of the quandary we face as veterinary professionals: “What do you do with the cat in respiratory distress?” I have frequently seen a cat, demonstrating open-mouthed breathing and a frantic appearance, rushed into our triage area and placed in an oxygen cage, only to be told “Oh, that’s Dr. So-and-So’s 3:30 vaccination appointment!” The stress of being caught, forced into a small cage, then being transported to the clinic can all contribute to pretty severe clinical signs of respiratory distress, even in a seemingly healthy cat.

The veterinarian made a great choice in giving this cat a chance to settle down and acclimate to its surroundings while being watched. The unfortunate aspect about the case is that the cat’s condition deteriorated. Given that it spent part of its time outdoors, trauma (pneumothorax, pulmonary contusions, and diaphragmatic hernia) should have been on the list of possibilities.

Drug & Route Choices

With clinical signs of severe and worsening respiratory distress and increased or harsh lung sounds on thoracic auscultation, administration of dexamethasone was not a bad idea and likely would not be detrimental. In my opinion, if an animal is in severe respiratory distress but not truly in cardiac arrest, administration of epinephrine is not likely to be useful. Additionally, any medication administered subcutaneously to an animal in severe distress may not be well absorbed, so I would have administered it intramuscularly if I had chosen it. More likely, I would have chosen a bronchodilator such as terbutaline (0.01 mg/kg IM or IV) rather than epinephrine.

Finally, in an animal whose respiratory status is deteriorating before your eyes, I would recommend intramuscular administration of ketamine and midazolam or, if placement of an intravenous catheter is possible, midazolam with ketamine or propofol, then rapid-sequence intubation with placement of a cuffed endotracheal tube. After the patient is intubated, administration of oxygen via endotracheal tube with an anesthetic circuit (anesthetic gas off) or an Ambu bag would help maintain oxygenation and help to maintain lung expansion.

Whether to Get Images/What to Look for

Another excellent choice that the veterinarian made was to forestall performing radiographs in this stressed patient with respiratory difficulty. From the description in the case report, it is difficult to decipher whether the problem was truly due to a traumatic diaphragmatic hernia or secondary to a congenital anomaly (peritoneal-pericardial diaphragmatic hernia [PPDH]) that was exacerbated for some unknown reason. If the liver passed through the diaphragm and just into the thorax/mediastinum, then I suspect the arrest was due to high vagal tone and possible compression of the caudal vena cava, impairing venous return to the right heart. If the liver was truly entrapped within a PPDH, then yes, the term tamponade is appropriate. In either case, it would be challenging to diagnose this premortem without some form of imaging (radiographs or ultrasound). Even if ultrasound were attempted, I suspect that it would be difficult to determine whether the lung was consolidated or appeared “hepatized” from atelectasis or whether the veterinarian could identify the liver with the ultrasound.

In this case, review of the postmortem radiograph shows what the veterinarian describes––herniation of the liver into the caudal mediastinum. I cannot tell whether there is anything herniated into the pericardial sac. There is poor abdominal detail (hindsight is always 20:20), so I wonder if this is because of lack of cranial abdominal contents in their normal anatomic locations or whether it is caused by abdominal effusion.

This is a very interesting case of yet another reason that cats––and, in particular, cats with respiratory distress––continue to challenge and thwart us time and again, despite our best efforts. I often say, “Cats with respiratory distress will try to die and will take you with them!”

Elisa M. Mazzaferro, MS, DVM, PhD, DACVECC, is director of emergency services for Wheat Ridge Veterinary Specialists in Wheat Ridge, Colorado. She chairs the scientific program committee for the Veterinary Emergency and Critical Care Society (VECCS) and the Denver Area Veterinary Medical Society and is the interactive laboratory coordinator for the American Veterinary Medical Association’s annual convention. Dr. Mazzaferro is an active lecturer at national and international veterinary meetings. She has authored numerous peer-reviewed manuscripts, book chapters, and textbooks on the subjects of veterinary emergency and critical care.

The Generalist’s Opinion

Every practice should have an emergency protocol in place. A “crash” kit is critical but so is a staff trained to respond to emergencies. Most general practices do not encounter emergencies on a regular basis, so training sessions for the entire staff every few months are extremely important. It’s best to review a mock emergency to be sure every team member knows how best to contribute. It is equally important for veterinarians to stay current on emergency protocols, as we ourselves can get stale if we do not engage in these situations regularly.

The Need for “Hands Off”

The choice to let the cat walk around the room was a good one as it is best to handle any distressed cat minimally. If there is any concern about respiratory effort, administering oxygen, again with minimal intervention, is vital. Oxygen via mask is helpful but requires restraining the cat, which, depending on the cat, can increase the stress response. An oxygen cage is more “hands off,” allowing the cat to calm, during which time ideally it can be watched for improvement. If an oxygen cage is not available, one can be rigged by feeding anesthetic tubes into a cage and wrapping the front bars with cellophane. Because this improvised cage can get humid and hot, placing ice packs under some towels within it helps. While not ideal, this makeshift oxygen delivery system will do in a pinch.

Radiographing a cat in respiratory distress can be a delicate process. It’s best to have everything set up in advance. Take a single lateral thoracic view only and then place the cat back on oxygen. Take any additional needed radiographs one at a time.

Prediagnostic Treatment

Prior to reaching a diagnosis in this case, dexamethasone was administered followed by epinephrine. The most common rule-outs for a cat in respiratory distress are heart disease, asthma, traumatic lung injury, neoplasia, and infection (bacterial, fungal). Steroids will exacerbate cardiac disease so without a diagnosis dexamethasone is not ideal. Giving epinephrine to a distressed cat can increase the stress response, as the sympathetic nervous system is already releasing epinephrine and norepinephrine. A good emergency drug to have on hand is terbutaline, a β2 agonist that enhances airway dilation and is beneficial in cases of asthma without producing any strain on the heart. In the absence of a diagnosis, giving terbutaline (0.01 mg/kg IV, IM, SC) and furosemide (2.2 mg/kg IV, IM, SC) together carries little risk for the patient and could help in stabilization. Both drugs are best given IV but patient stress needs to be considered.

The sympathetic or “fight-or-flight” response is known to anyone in the veterinary profession. Once a cat has activated that response, it is in an extremely fragile state. Cats can decompensate more quickly than any other species; thus, minimizing stressful stimuli (restraint, barking dogs, etc) is key to their safety as well as our own. Whether this case could have been handled in a manner that would have contributed to a successful outcome is difficult to say. Sometimes we lose before we walk in the door. Having a solid protocol in place for all emergencies is the best tool that we can devise.

Barak Benaryeh, DVM, DABVP, is the owner of Spicewood Springs Animal Hospital. He graduated from University of California–Davis School of Veterinary Medicine in 1997 and completed an internship in Small Animal Medicine, Surgery, and Emergency at University of Pennsylvania. Dr. Benaryeh has also taught practical coursework to first-year veterinary students and was a primary veterinary surgeon for the Helping Hands Program, which trains assistance monkeys for quadriplegic people. Dr. Benaryeh is certified by the American Board of Veterinary Practitioners in Canine and Feline Practice.