Dog question about Cushing’s disease : 7 Pituitary Macroadenoma

Most pituitary tumors responsible for Cushing’s disease are microscopic but approximately 10% to 20% of dogs with pituitary dependent Cushing’s disease have a tumor large enough to take up a significant amount of space. These tumors are called macrotumors and, since there is not much extra space within the skull for extra structures, a macrotumor can compress normal brain tissue and lead to neurologic disease.

How Big is too Big?
Ten millimeters (about half an inch) in diameter is the size a pituitary tumor must reach to be categorized as a macrotumor in a human being. Dogs obviously have more variance in the size and shape of their skulls than do people, thus it may be inaccurate to use the human definition for dogs but so far the veterinary profession is using this size definition. It appears that up to 50% of dogs with pituitary tumors of this size do not have concurrent neurologic disease. We do not have information regarding how many of these asymptomatic dogs will go on to develop neurologic disease. Still, when a dog has a tumor of this size and neurologic signs, the tumor should be considered the cause of the signs.

Is this Cancer?

Not in the way most people think of cancer. Pituitary macrotumors are almost always benign in that they do not spread in any way. They can, however, produce harm simply because of their location.

When Would an Owner Suspect a Pituitary Macrotumor?
When a pituitary mass begins to expand, the owner is likely to notice subtle changes in behavior although nothing may be obvious with a formal physical examination. The dog may seem just “off,” listless or off food. Occasionally signs are more blatantly abnormal (walking in circles or seizures) but a more subtle start is more common. It should be noted in particular that it is extremely abnormal for a dog with Cushing's disease not to have a good appetite even while on therapy. If a dog with Cushing's disease develops a poor appetite, see the veterinarian promptly.

Dogs: Treatment - Pituitary Cushing's Syndrome

Lysodren: The Traditional Therapy
Lysodren (generically known as mitotane and chemically known as o,p’-DDD) has been the only treatment for pituitary dependent Cushing’s disease until relatively recently. It is convenient to use and relatively inexpensive, though it does have the potential for very serious side effects. Because this medication has been in use for canine Cushing’s disease for decades, most veterinarians have extensive experience with its use and with the monitoring tests needed to prevent side effect difficulties. One of the disadvantages of lysodren therapy is the need for regular monitoring blood tests.

How This Medication Works

Lysodren should be considered to be a drug of chemotherapy. It actually erodes the layers of the adrenal gland that produce corticosteroid hormones. The pituitary tumor continues to secrete excess stimulation but the adrenal gland is no longer capable of excess hormone production in response. Problems result when too much of the adrenal cortex is eroded. Short-term lysodren reactions are common (something like 30% of dogs will have one at some point), necessitating the use of a prednisone antidote pill that the veterinarian supplies. In event of such short term reactions, lysodren is discontinued until the adrenal gland can re-grow and therapy is resumed, possibly at a lower dose. Sometimes excess adrenal erosion is permanent and the dog must be treated for cortisone deficiency. This is more serious and the potential for this kind of reaction has been the driving force behind the search for better medications for the treatment of pituitary dependent Cushing’s disease.

How This Medication is Used

Dogs : Cushing's Disease (Hyperadrenocorticism)

This condition represents a classical excess in cortisone-type hormone circulation in the body. Both cats and dogs can be affected (though it is primarily a dog's disease) and the onset is insidious. We have assembled an information center to answer all your questions on this relatively common hormone imbalance.

1 Symptoms of Cushing's Syndrome
Cushing's syndrome (hyperadrenocorticism) is a chronically debilitating hormone imbalance that can affect many species, humans included. We will limit our discussion to dogs and cats, however. Cushing's syndrome, also called Cushing's disease, results from excessive cortisol in the bloodstream and the symptoms all stem from long-term over-exposure to this hormone.

Dogs
There are many clinical signs associated with Cushing’s syndrome (also called hyperadrenocorticism) in dogs. These signs usually come on gradually and, because of this slow onset, these changes are often written off as part of the normal aging process. The following list of common symptoms that an owner might observe in their pet at home is:

• Drinking excessively
• Urinating excessively
• Incontinence 

Owners often notice that lately the water bowl must be filled more frequently than in the past. Some dogs are unable to hold their bladder all night and begin crying to go outside during the night when previously this was unnecessary.

Also, urinary tract infections may also be detected and true urine leaking may be observed.

Dogs : Eight Adrenal Tumor Treatment

We begin here assuming an adrenal tumor has been confirmed with either blood testing, imaging, or both. Two questions must be answered next:

Is the tumor benign or malignant?

Should you choose surgical treatment or medical management?

Benign vs. Malignant

While only approximately 15% of canine Cushing’s syndrome patients have adrenal tumors, half of that 15% will have benign tumors and half will have malignant tumors. The choice of therapy may depend on which type.

If imaging has not yet been done, this is the time to do so. Chest radiographs will be important as malignant adrenal tumors tend to spread to the chest. If such spread is seen, the tumor can be assumed to be malignant. Absence of tumor spread does not mean the tumor is benign. Ultrasound of the stomach, if this has not already been done (or even CT scanning, MRI imaging, or nuclear medicine scanning), will be needed to determine the size of the tumor, and to check for invasion of local abdominal tissues, especially in the liver.

Dog eat Rat Poison? what to do?

The ingestion of rat poison is an unfortunately common occurrence in dogs. Many people do not realize that the taste of rodenticide is not only appealing to dogs, but that it also has the potential to kill dogs. The ASPCA lists rodenticides as one of the top ten pet toxins. All dog owners should educate themselves about all potential toxins and take steps to prevent exposure to the hazards. Take the time now to learn about rat poison and how it can affect your dog.

Types of Rat Poison:

• There are several different types of rat poisons on the market. The effects of rodenticides vary depending upon the active ingredient. Be aware that different types of rat poisons have different toxic doses and poisoning can manifest itself in a variety of ways. There is no type of rat poison considered "dog safe." Most rodenticides have a grain and/or sugar base, making them palatable to rodents as well as dogs. They often come in pellets, blocks, granules or liquids. They may be any color but are commonly teal, blue, green or pink. The color and shape of the rat poison cannot help you determine the active ingredient (poison type) used. The only way to be certain which chemical a rat poison contains is to read it off the packaging. The following is a list of the types of rodenticides:

DOG POISONED!

Here's the deal! Regardless of what others, including your vet, may have told you, in many poisoning situations, there is no time to lose. Your dog staggers towards you, collapses at your feet’what now? Is there time to call the vet? In many cases, no. This is the topic and focus of this article. In short, if you are not ready to concede to a dead dog, you must become "Johnny on the Spot." As author Cargill relates from his Vietnam days, "How are you going to act?" The dog owner facing a poisoning situation has but few precious moments in which to collect himself/herself and to determine what to do. This is the time for immediate action, time to get something done. Question: What if you lack the tools and supplies with which to begin treatment?

Answer: Dead dog.

This is a hard way to start an article to be read by dog lovers, but the reality is this: If you are not prepared to treat poisoning resulting from ingesting a toxic substance, you lose. Not only do you lose, but your dog dies. Acute poisoning requires accurate assessment. The threat is not only related to the potency of the poison, but also to the quantity consumed, the duration of exposure, and to the presence of other active ingredients, such as adjuvant and solvents. The difference between immediate appropriate action and delayed response is the difference between life and death. To this end, the authors advocate that a significant effort be made to be prepared for what might happen, given the environment in which you keep your animals. Being prepared means not only having antidotes and treatment materials on hand, but it means being familiar with the signs and symptoms of poisoning, and knowing what risks are in your dog's environment.

The first step in treating poisoning is prior knowledge. You have to be able to recognize that there has been a poisoning. Symptoms vary significantly from animal to animal, from substance to substance and with the amount ingested. You must be accurate in your differential diagnosis. To treat based on the wrong diagnosis is to increase the probability of death. The second step intreating poisoning is prior knowledge. You have to know the poisons that are in your dog's environment. So many potential poisons are readily available, it is truly amazing more dogs are not poisoned. The third step in treating poisoning is prior knowledge. You must know the immediate actions required, which can include artificial respiration/resuscitation. If you are picking up on a trend here, it is intentional. Because there may be little time in which to reflect on or to research the subject, or to find a veterinarian because of time of day, or distance from a veterinary facility, etc., the owner who is not equipped with the knowledge of the symptoms, the effects of various poisons, and what treatment regimen goes with what poison, stands a very good chance of losing the dog. Remember, also, that not all poisonings are accidental.

Dog : Osteosarcoma

Introduction

Osteosarcoma (OSA) is a rapidly growing, destructive neoplasm of bone that accounts for 80% of all malignant bone tumors in dogs.9,10 Neoplasms of the skeleton are more common in dogs than in any other species. Primary bone tumors such as OSA are five times more common than metastatic skeletal neoplasms, and malignant tumors are more common than benign neoplasms.12

Breed, Age, and Sex Predisposition
Osteosarcoma is most common in giant and large breed dogs (90%) and is uncommon in small and medium breeds.13 Breeds especially predisposed to development of OSA include Saint Bernards, Rottweilers, Great Danes, Golden Retrievers, Irish setters, Doberman Pinschers, and Labrador retrievers. The mean age of occurrence is 7-1/2 years and incidence of OSA is slightly more common in males than females (1.2:1).10,13

Factors Influencing Tumor Development
Ionizing radiation, chemical carcinogens, foreign bodies (including metal implants, such as internal fixators, bullets, and bone transplants), and pre-existing skeletal abnormalities such as sites of healed fractures contribute to the development of OSA. In addition, there have been correlations with genetic predisposition to tumor development in certain family lines. Dogs with OSA have been found to have aberrations of the p53 tumor suppressor gene.11 In laboratory animals, both DNA viruses (polyomavirus and SV-40 virus) and RNA viruses (type C retroviruses) have been found to induce OSA.13

Sites of Origin and Metastasis
OSA can be found in both the appendicular and axial skeleton with the former being 3-4 times more common.10 This neoplasm originates most commonly in the metaphyses of the long bones of forelimbs, especially the distal radius and proximal humerus. 

Dogs - Anemia: Inadequate Red Blood Cells

Red blood cells are basically little microscopic bags of hemoglobin. They have no nucleus and thus no DNA. They have no internal structures and thus no ability to perform complicated metabolism. Despite their simplicity, their function is crucial: they carry hemoglobin, the iron-containing complex protein that allows for oxygen transport to the tissues, as well as carbon dioxide transport to the lung for removal. Inadequate red blood cell quantity means inadequate hemoglobin, which means inadequate oxygen delivery. In the whole patient, this translates to lack of energy, poor appetite, and pallor - basically an important reduction in life quality.

There are three important ways in which the kidney patient loses red blood cells. The first way is bone marrow suppression. The second way is bleeding. The third way is called hemodilution. We will review all these and what can be done about them. Maintaining a stable red blood cell quantity keeps the patient energetic and spirited, and it is crucial to staying alive.

Bone Marrow Suppression
One of the functions of the kidney is the production of the hormone called erythropoietin (pronounced “urithro-po-eetin”). This hormone, often simply referred to as Epo, represents the command to the bone marrow to make more red blood cells. When the kidney is damaged, its ability to produce erythropoietin is compromised. Red cells are still produced but over time the red cell count drops.

Dogs : Heart Disease

No matter your dog's size, he has a big heart - metaphorically speaking, of course. He has a personality all his own, he is a loyal companion and seems to know when you need a good laugh. But this same heart can be at risk for heart disease, an abnormal enlargement of his heart.

Heart disease is an unfortunate but tolerable condition for your dog. Although treatments cannot reverse heart disease, your dog can live a relatively normal life. Aging is the most common reason dogs develop heart conditions, but other factors like heartworm can also lead to heart disease.

If your dog exhibits the following symptoms, take him to your veterinarian for an accurate diagnosis:

• A low-pitched cough that sometimes leads to gagging
• Breathing difficulties that include shortness of breath
• Reduced ability to exercise
• Noticeable weight gain or loss
• Swelling in the abdomen

These symptoms are common in other diseases, so it is important for your veterinarian to check for heart disease using some of the following methods:

• A stethoscope exam can reveal murmurs and fluid in the lungs
• Palpation can reveal unusual pulses
• X-rays reveal heart enlargement
• An EKG can identify heart enlargement and irregular rhythms
• Blood and urine tests can reveal heartworms and the condition of other internal organs

Heart disease typically causes the heart to enlarge, and this enlargement causes a loss of efficiency. The heart then begins to hold more fluid than it should and this is where the real problems begin. For this reason, veterinarians recommend feeding dogs a low-sodium food that will help reduce fluid build-up and make it easier for their hearts to work effectively.

For an accurate diagnosis and treatment options, always consult your veterinarian.

Canine Diseases Causing Weight Loss

Overview

Any canine disease that causes vomiting, appetite loss or diarrhea can also cause weight loss. The relationship between these three things and weight loss is obvious: the fewer calories being retained within the dog’s system, the more likely the dog will lose weight. However, it is also possible for other, more serious, diseases to also cause weight loss in dogs. Due to the seriousness of these diseases, it is important to consult a veterinarian as soon as possible any time a dog experiences unexplained weight loss.

Addison’s Disease

Hypoadrenocorticism, more commonly referred to as canine Addison’s disease, is an uncommon disease that occurs when the adrenal glands produce insufficient quantities of corticosteroids and mineralcorticoids. One potential cause of this disease is an autoimmune response in the dog’s body, causing its immune system to attack its own adrenal glands. It may also be caused by other illnesses or the effects of toxins. Addison’s disease most often affects young to middle-aged female dogs. Dogs of some breeds, including standard poodles, Rottweilers and Portuguese water dogs, may have a genetic predisposition to Addison’s disease. In addition to weight loss, Addison’s symptoms include muscle weakness, unexplained collapse and lethargy.