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I dedicate this article to my little Harley, the love of my life, who is battling this awful disease.
Just like the human body, a canine’s endocrine system makes up the collective glands in the body which produce and secrete hormones. Cortisol is one of those hormones. When Cortisol is at its normal range, it performs various functions to help a canine’s body.
One of these functions is helping your little one to cope with stress and to regulate his or her immune system. Just like humans, the endocrine system can be compromised by the growth of various types of tumors that result in the development of Cushing’s disease.
- What is Cushing’s Disease?
- Pituitary Gland Cancer
- Clinical Signs of Pituitary Gland Cancer
- Adrenal Gland Cancer
- Clinical Signs of Adrenal Gland Cancer
- Latrogenic Cushing’s Disease
- How Is Cushing’s Diagnosed & Treated?
- Breeds with Higher Risk
- Deciding Your Dog’s Fate
What is Cushing’s Disease?
Cushing’s Disease, also known as hyperadrenocorticism, is a disease that develops in dogs when the endocrine system produces an excess amount of cortisol in the body. It is also the most common disease to attack canines.
According to PetMD, “Cushing’s disease can develop when a dog’s own body overproduces cortisol or when a dog is given corticosteroid medications (prednisone, dexamethasone, triamcinolone, etc.) at high doses over a long period of time.” Unfortunately, Cushing’s raises the Cortisol distributed to your dog’s body and as a result, causes severe damage to your little one’s internal organs.
There are three types of Cushing’s disease: pituitary gland tumor, adrenal gland tumor, and latrogenic. In order to figure out which Cushing’s your pooch is suffering from, immediate testing is necessary. Each type of Cushing affects your canine’s body differently, and each has its own prognosis which could mean prolonged life or fast death to your little one.
According to the American Kennel Club (AKC), “more than 90 percent of dogs with CD have a pituitary-gland tumor.” The tumor may be either benign or malignant.
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When a canine is diagnosed with Pituitary Dependent Hyperadrenocorticsm (PDH), this means the Cushing’s disease developed from the over production of the PDH hormone affecting the pituitary gland.
According to VCA, “the pituitary gland is an endocrine gland located at the base of the brain. Endocrine glands produce specialized chemicals called hormones, which regulate and integrate many activities to maintain internal stability of the body. The hormones pass directly into the blood to affect target cells elsewhere.”
The pituitary gland links the adrenal, thyroid, sexual organs, and diurnal rhythm (daily activity cycles) through its hormones. It also regulates their hormone production.
The most common hormone produced by the pituitary gland is the Adrenocorticotrophic hormone (ACTH). When ACTH is overproduced by the pituitary tumors, the over abundant ACTH hormones increase the size of the adrenal cortex and causes the over-production of adrenal hormones. These excessive adrenal hormones produce tumors that may be microscopic or very large. Clinical signs vary and depend on the size of the tumor. Sometimes, the tumor causes other symptoms associated with other diseases. So your pooch will end up with both Cushing’s and another ailment.
In many cases, the adrenal gland activity is controlled via medication and some doggies are able to live normal lives. They must be under constant supervision and not miss their dose of medicine. However, if the pituitary tumor continues to grow, your dog will begin to suffer from neurological issues, including but not limited to seizures. Since the pituitary gland affects the brain, the prognosis for your little one is not a good one.
Tumors measuring more than 1 centimeter long are considered large tumors. When these tumors are benign, they are called macroadenomas. Macroadenomas are usually benign and do not cause neurological issues with your dog. On the same token, benign microadenomas are small tumors measuring less than 1 centimeter long. Microadenomas are not known to cause neurological symptoms.
Clinical Signs of Pituitary Gland Cancer
Pituitary tumors are difficult to diagnose. Usually, once they have metastasized canines begin to experience clinical problems. If a tumor does not produce hormones and cannot be clinically treated, it is not curable. This type of tumor is malignant and will contribute to persistent clinical signs. A tumor’s growth rate depends on the individual tumor.
According to VCA, “in cases of pituitary tumors causing hyperadrenocorticism that are medically managed, the treatment needs monitoring and life expectancy is variable from days to ten years but averaging less than three years. Relapses are common. Deaths are usually due to problems associated with the original disease (e.g. heart failure, infection, pancreatic disease such as diabetes) rather than drug toxicity.”
According to AKC, dogs affected by Cushing’s Disease “develop symptoms that are identical to those of the tumor-based disease.”
Clinical signs for Cushing’s are the same regardless of which type of Cushing’s your dog may have. These clinical signs are:
- Increased appetite due to the elevated cortisol levels which stimulate hunger
- Increased thirst
- Hair loss
- Dry skin
- Blackheads on the belly
- Calcium masses in the skin on the neck and back due to skin mineralization
- Sagging belly from fat distribution to the body
- Weakened muscles
- Damaged immune system that causes persistent infections
Unfortunately, tumors in the pituitary gland eventually manifest into a large mass that presses against a canine’s brain. The more the pressure compacts against a dog’s cerebellum, the worse your dog’s functions will be affected. Your dog’s vision will become impaired and their inability to concentrate urine will become apparent. Moreover, your pooch will develop excessive drinking and urination associated to diabetes insipidus.
As the pituitary gland continues to be compromised, your dog’s bodily functions begin to slow down. Your dog will eventually develop low blood sugar and lose his/her sexual libido and performance. One of the most painful and horrid characteristics of pituitary tumors is their ability to exert severe pressure on tissues it surrounds. As a result, the tumors affect the gland’s function and it can be very painful.
Imagine having gall stones piercing your stomach every day and feeling them press against your organs and stomach. This is the visual I have of tumors that may start to grow inside my little Harley.
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Per VCA, the adrenals are groups of endocrine glands located near the kidneys. The cortex is the outer part of the gland controlled by the adrenocorticotrophic hormone (ACTH) produced by the pituitary gland. The cortex makes diverse steroid hormones.
The the first group of adrenal glands work with the kidneys to control the body’s salt concentration. The second group controls the sex hormones, and the third group reduces inflammation, heals and controls the activities of the immune system. Moreover, the adrenal gland also “controls carbohydrate and fat metabolism in conjunction with other hormones from the pancreas”.
Some tumors affect the medulla, the inner part of the gland. When this happens, your pooch will have neurological disorders such as seizures that attack the sympathetic nervous system. Cortex tumors may be benign or malignant (adenoma or carcinoma). Benign tumors may be removed surgically and will most likely cure Cushing’s.
However, if the tumor is malignant, surgery will not take care of the problem because the tumors metastasize rapidly. One of the most painful and horrid characteristics of adrenal tumors is their ability to exert severe pressure on tissues it surrounds. As a result, the tumors affect the gland’s function.
Clinical Signs of Adrenal Gland Cancer
Clinical signs of adrenal gland cancer are the same as those of pituitary glands tumors, as listed above.
Adrenal gland tumors also bring about persistent bladder infections, panting, thin skin, chronic skin infections (pyoderma) and dark-colored spots (hyperpigmentation).
Just like dogs with pituitary gland cancer, dogs with adrenal cancer suffer from a compromised immune system. The immune system becomes damaged so infections are frequent. Malignant adrenal tumors invade the blood vessels adjacent to the glands and as a result spread through the body. These cancerous growths metastasize inside the body’s cavities and organs.
Perhaps, the harshest and horrid realization for me was to know that regardless of the type of Cushing’s, if the tumors are malignant they will grow at a rapid rate. Their growth will result in tumors pressing against the brain or pressing against the kidneys or any other organ.
Latrogenic Cushing’s Disease
According to AKC, dogs affected by Cushing’s Disease “develop symptoms that are identical to those of the tumor-based disease. This form resolves once the steroids are stopped.”
Just like humans, canines can develop adverse effects when treated with steroids. In dogs, Cushing’s developed from the treatment of steroids must be controlled with the discontinuation of the steroids. This is done gradually, but it also means that the illness that was controlled by the steroids will come back. So, it’s a catch 22.
In some cases, the adrenal glands are also effected by the steroids, so that means the hormones produced by the adrenal gland will need to be replaced.
How Is Cushing’s Diagnosed & Treated?
Cushing’s is a disease associated with most middle-aged or senior dogs. When dogs reach old age, most of them develop benign, non-spreading pituitary tumors. Harley had little ones when she turned 8 or so. I called them old lady bumpies. These growths are not painful but look nasty and make you cringe when you feel them on your dog’s back, feet, or head.
Unfortunately, when Cushing’s attacks your little one, those bumps are no longer just skin lesions. These bumps may be tumors that must be diagnosed to make sure they are not malignant.
Another heartbreak is knowing that diagnosing and treating for Cushing’s is one of the most expensive diseases to diagnose and treat. For the most part, recognizing the clinical signs is a good start. However, it is financially and emotionally draining from there on.
ACTH Stimulation Test
In order to have the most concrete diagnosis, canines go through extensive blood tests. One of these tests is the adrenocorticotropic hormone (ACTH) stimulation test. This test verifies the levels of ACTH in your dog’s body.
The test begins with a blood sample from your dog. This is followed by an injection of ACTH. A few hours later, a second blood sample is taken. If the blood level starts normal and the cortisol level rises, then this indicates his/her adrenal response is normal. However, if the blood sample is high from the beginning, and rises even higher after the ACTH injection, that means Cushing’s is present.
Dexamethasone Suppression Test
In order to test the response to cortisol levels caused by the adverse effect of a steroid medication, an injection of the dexamethasone steroid is given to your dog. Dogs who are healthy will begin to drop the cortisol levels within hours because the dexamethasone steroid suppresses the production of adrenaline. However, if the cortisol level does not drop, this is conclusive that a tumor is present and not responding to the steroid.
Ultrasounds are also given to determine whether the tumor is in the pituitary or adrenal gland. If an ultrasound of the abdomen does not show the tumor in the adrenal gland, chances are the tumor is in the pituitary gland and your canine’s brain.
According to AKC, “more than 90 percent of dogs with CD have a pituitary-gland tumor”.
Pituitary gland tumors are usually very small and often benign. Unfortunately, this surgery has only been performed on humans. Pituitary gland tumors are treated with the oral medications Mitotane (Lysodren) and trilostane (Vetory). These medicines “selectively destroy part of the adrenal cortex so that although the pituitary gland tumor continues to release ACTH, cortisol levels remain normal.”
It is imperative to stick to the treatment once it has been started. The medication must be given for life and usually works within a few weeks after treatment begins. Your pooch will drink water less frequently and his/her panting will calm down. Unfortunately, skin lesions take slower to heal.
Adrenal-based tumors must be surgically removed because half of the growths are malignant. They are aggressive and metastasize quickly. Although this is the rarest of the two types of Cushing’s, those canines diagnosed with cancerous adrenal-based tumors will suffer in excruciating pain as the tumors around the internal organs continue to grow and press against them.
There are ointments and over the counter medications you can find that will help your doggie not be frustrated or restless. These medications also suppress the clinical symptoms but don’t stop the tumor growth. However, before you give your furry one over the counter medication, make sure you consult with your baby’s vet.
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Although Cushing’s affects all canines, there are some breeds more susceptible to Cushing’s than others.
Poodles, Dachshunds, Boston Terriers, Boxers and Beagles older than eight have a higher risk to develop Cushing’s. Bichon Frises are also prone to this horrid disease.
Deciding Your Dog’s Fate
Although the prognosis given is about four years, most canines with Cushing’s last only two years. Because mostly senior dogs are affected, complications related to a dog’s senior status usually kills them first. Others die early from complications of the disease. Yes, the disease can be controlled with medication, but this does not mean cancer won’t develop. As a doggy parent, you know every inch of your baby’s habits, behavior, and health. You are the only one that can understand when your pooch is not well.
Therefore, if your dog is on medication, you must determine if the medication is working. Most importantly, if your dog is in pain or suffering in any way, you may have to decide not to prolong it. Sadly, this is something I’ve come to know too well during the last four months. My little Harley was diagnosed with Cushing’s Disease a few weeks after her 14th birthday and it has been a tough battle for both of us.
With the help of six charities, I’ve been able to pay for the extensive testing and medication. Harley’s vet wants to rule out the tumor in the adrenal glands so I’ve been saving up to get the ultrasound done by the end of May. One month after the medication started working, my little one’s obsession with drinking water and heavy panting ceased. However, she started developing symptoms of an adrenal gland tumor which is why the ultrasound is my priority.
The last thing you want is to see your dog suffer. Canines are very good at hiding their pain. It is when they finally can’t tolerate the pain that they will wine, cry and howl. This is when it is time to say goodbye. As I get closer to getting the ultrasound, I am stressed and dread the day I find out what will become of my baby’s future.
In the meantime, while my Harley hops around, tosses her ducky in the air, plays tag, and maintains a good appetite, I am thankful each day she is in good spirits, not suffering, and still in my life. She, on the other hand, is adamant about continuing to watch over me to make sure I am ok. She is my little shadow and little love.
It was important for me to write this article to bring awareness to dog owners about this nasty disease. My hope is that you won’t be surprised should your little senior develop it in the future.