End stage lung cancer in dogs (stage IV) is unfortunately the most debilitating stage that affects quality of life and impairs important physiological functions. It's important that owners of dogs with end stage lung cancer monitor the dog's symptoms and report to their vet so that they can be managed through symptomatic analgesic therapy in hopes of improving as much as possible quality of life. Today, there are many hospice vets who specialize in providing palliative care to dogs with end stage cancer. Awareness of symptoms of end stage lung cancer in dogs and knowledge on what to expect can help dog owners obtain the necessary framework for appropriate pain management.
Metastases to the Lungs
A dog's lungs are often a common site of metastases (cancer spreading to distant body parts), second only to the regional lymph nodes which drain the organ affected by a primary tumor.
Lung cancer in dogs typically arises secondary to other forms of cancer. Virtually any type of malignant tumor has the possibility to spread to the dog's lungs, but some cancers are more likely.
Primary tumors with a high incidence of spreading to a dog's lungs include mammary carcinomas, thyroid carcinomas, osteosarcoma, hemangiosarcoma, squamous cell carcinoma, transitional cell carcinoma and oral and digital melanomas.
When dogs present with primary tumors, it is common practice to perform chest x-rays to confirm or rule out proof of spread to the dog's lungs. Proof of spread to a dog's lungs is ultimately what in many cases limits successful treatment of the primary tumor.
The presence of cancer in the lungs is unfortunately a late finding in the course of the disease. X-rays show that the primary cancer has spread and the lungs are full of nodules.
Did you know? The incidence of primary lung cancer, that is, lung cancer that is not occurring secondary to another cancer account only for about 1% of newly diagnosed tumors in dogs and cats. There are chances though that the percentage may be higher, studies say.
Signs of Lung Cancer in Dogs
Dogs with cancer that has spread to the lung are usually middle-aged or older dogs. Generally, the average age of onset is between 9 and 12 years of age. There are typically no particular sex or breed predispositions.
On top of dogs presenting symptoms derived from the primary tumor, in advanced cases, dogs will also show signs of lung cancer. Dog owners complain of cough, which is typically non-productive, exercise intolerance and respiratory distress.
Affected dog may also exhibit other more systemic signs of cancer such as weight loss, loss of appetite and lethargy.
As the cancer advances these signs are destined to inevitably progress and worsen during the end stage of lung cancer in dogs.
" Even if there is a good chemotherapy regimen for the cancer, if it has already spread to the lungs, the prognosis for long term survival is not good with or without chemotherapy. Most veterinary oncologists will probably give you grave prognosis either way."~Dr. John
Symptoms of End Stage Lung Cancer in Dogs
The end stage of lung cancer in dogs is a very difficult time for dog owners as it's very hard to watch a beloved companion start giving up on life. Following are some symptoms of end stage lung cancer in dogs and some tips for those who chose to provide their dog with some hospice care.
End stage lung cancer in dogs will cause the coughing to progress. At times, the coughing worsens because the tumor may enlarge to such an extent as to compress the dog's trachea evoking a dry, nonproductive cough.
In some cases, the cough can be so hard that the dog ends up vomiting, explains veterinarian Dr. Altman. Although, not very common, at times dogs with lung cancer may cough up mucus with blood in it (hemoptysis). Ask your vet about cough medications to help reduce the coughing.
Loss of Appetite
As the cancer advances, dogs with end stage lung cancer will start losing their appetite. This often occurs because breathlessness makes swallowing difficult which makes eating a challenge.
In some cases, swallowing becomes difficult when large tumors end up pressing on the dog's esophagus. Cancer cachexia causing weight loss and muscle wasting is also common in late stages of cancer.
While appetite stimulants such as steroids, cyproheptadine and mirtazapine may have helped in the past, a point may be reached where these drugs no longer work.
It's OK at this stage to try to tempt the dog to eat with some tasty foods, points out Dr. Damian Dressler, the cancer vet. Hand feeding may help entice the dog to eat. Softer, moister foods may be easier to swallow and small snacks throughout the day may be more readily accepted. If eating is really difficult for your dog, ask your vet about nutritional supplements.
On top of tempting the dog with tasty foods it's important to keep the dog hydrated. If your dog is reluctant to drink, you can try adding some warm, low sodium meat broth to meals. Make sure it has no onion or garlic added. If your dog is reluctant to drink, consider having your vet instruct you on how to give subcutaneous fluids at home.
The end stage of lung cancer in dogs may cause the affected dog to be panting more and more as an attempt to increasing oxygen levels in the bloodstream. Panting is often seen when there is no obvious reason (it's not hot, the dog has not been walking/running/playing).
If there is pleural effusion (fluid around the lungs) secondary to lung cancer, when the fluid is a whole lot, affected dogs may be unable to lie down because when lying down the fluid ends up pooling, making it difficult for the dog to breathe, explains veterinarian Dr St John. Sometimes vets may suggest temporary drainage of such fluids.
Breathing may become raspy and more labored. Breathing difficulties may impair the dog's ability to sleep.
Owners may notice rapid and shallow breaths. Dogs may get anxious when they have trouble breathing. As the disease progresses, poor oxygenation to the tissues may cause the dog's gums to become pale. Pale gums or bluish lips warrant an emergency visit to the vet.
As lung cancer advances, affected dogs may become less interested in their surrounding and reluctant to move and this can lead to several complications. Laying down for a good part of the day may lead to annoying bed sores. Bed sores, just like in people, arise when the body is exposed for too long to surfaces without changing position. To help prevent this, it helps to keep the dog on a well-padded surface and roll the dog over, every 8-12 hours.
A dog who has limited mobility will likely have accidents around the house. If your dog fails to make it outdoors to urinate or defecate, it's important to prevent urine scald and soiling by giving the affected dog a sponge bath at least twice a day.
- Dog Cancer Blog: End of Life Care in Dog Cancer
- DVM360: Treating cancer pain in dogs and cats
Stage IV lung cancer Cancer Research UK -CC BY-SA 4.0