What does it mean when your pet has an autoimmune disease like immune-mediated thrombocytopenia?

Immune-mediated thrombocytopenia (IMT) is a condition in which the animal’s immune system attacks and destroys blood platelets. Without platelets, blood cannot clot effectively, leading to internal or external bleeding. This can cause anemia, and is dangerous in times of injury or surgery. IMT can be a primary condition or it can be caused by another illness (including cancer, certain tick-transmitted diseases as well as some viral and bacterial infections). IMT generally responds to treatment, but it can be fatal. Relapses are common.

About Immune-mediated thrombocytopenia (IMT)

IMT is an autoimmune disease. Autoimmune diseases result when the body’s immune system has become unrecognizable/does not recognize itself. In these cases, cells that normally attack invading viruses and bacteria begin attacking the body’s own cells, resulting in damage.

In dogs and cats with IMT, the body’s platelets are attacked and destroyed, resulting in reduced numbers of platelets in the blood vessels. Platelets (also called thrombocytes) are cells that are needed to form blood clots and repair damaged blood vessels. Thrombocytopenia occurs when there are too few platelets in the blood.

Adequate numbers of platelets are essential for survival. Platelets help repair obvious injuries, such as open wounds, as well as microscopic injuries that occur in day-to-day life. If platelet numbers are too low, uncontrolled bleeding can occur. If treatment is unsuccessful, the patient can bleed to death.

IMT can be a primary condition or it can be caused by another illness or event. The underlying cause of primary IMT is rarely determined. Female dogs are more likely to be diagnosed with IMT, but there is no corresponding gender predisposition in cats. Secondary IMT can be associated with certain cancers (including lymphoma); exposure to certain drugs (including some antibiotics); tick-transmitted diseases (such as ehrlichiosis, babesiosis, and anaplasmosis); and some viral and bacterial infections, including canine distemper virus in dogs and feline leukemia (FeLV) and feline immunodeficiency virus (FIV, or feline AIDS) in cats.

Symptoms and Identifying IMT

Platelets are responsible for helping form blood clots and repair damaged blood vessels, which is why the most common sign of IMT is spontaneous bleeding or the inability to stop bleeding. If IMT is caused by another illness, additional clinical signs can result from the underlying condition. Clinical signs of IMT can vary in severity and include:

• Weakness

• Lethargy (tiredness)

• Appetite loss

• Vomiting blood

• Bloody diarrhea or melena (digested blood that appears in feces)

• Bruising on the skin

• Bleeding from the nose

• Bleeding from the gums

• Bloody urine or bleeding from the penis or vulva

• Coughing blood or difficulty breathing

Bleeding can also occur within the brain, causing seizures; within the eyes, causing blindness; or within the abdomen or chest cavity. Severe bleeding can be fatal, especially if it occurs rapidly. If significant blood loss occurs, additional clinical signs (such as pale gums, weakness and even collapse) may be associated with anemia (inadequate numbers of red blood cells).

Owners may also notice other evidence of bleeding, such as minor cuts and scratches that continue to bleed, a heat cycle that seems prolonged or excessive, or skin bruising after playing or grooming.

There is no specific test to diagnose IMT. Your veterinarian will likely recommend blood testing to help confirm a suspected diagnosis of IMT and rule out other conditions that can cause low platelet numbers.

Some veterinarians can perform initial testing at their offices. In other cases, tests are sent to a diagnostic laboratory and results are available in a few days. If your veterinarian suspects an underlying illness (such as FeLV or ehrlichiosis), he or she may recommend more testing.

Who is predisposed for IMT?

Certain dog breeds, such as German Shepherds and Old English Sheepdogs, may be genetically prone to developing primary IMT.

Treatment for IMT

Because IMT is caused by an overactive immune system, initial treatment is aimed at suppressing the immune system and stabilizing the patient. Steroids (given at high doses) are the most common medication prescribed. Additional therapy may include intravenous fluids and supportive care. If the underlying cause of IMT can be treated, such therapy is also generally initiated.

Some pets don’t respond adequately to steroids. In these cases, additional medications can be given to manage the condition.

During treatment, frequent blood testing is required to ensure an adequate response to therapy. Once a pet responds to treatment, medication dosages are gradually adjusted and blood tests are repeated periodically to monitor for relapses.

IMT generally responds to treatment, but it can be fatal. For pets who survive, relapses commonly occur. Your veterinarian may recommend periodic recheck examinations and frequent repeat bloodwork for the life of your pet to help identify and treat relapses early.

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What is Cushing’s Disease?

Clinical signs, tests, and treatment

 

What is Cushing’s Disease?

Cushing’s disease (otherwise known as hyperadrenocorticism), is caused by overproduction of the hormone cortisol or overuse of corticosteroid drugs like prednisone.

Most cortisol in the body is made by the adrenal glands. If an adrenal tumor is present, it can over-secrete the hormone. Adrenal tumors are responsible for about 20% of Cushing’s cases in dogs, usually larger breeds.

A tumor located in the brain (pituitary gland) can also stimulate the adrenal glands to produce more cortisol than normal.

Cushing’s Disease Symptoms in Dogs

Diagnosing Cushing’s disease is not always an easy process. Symptoms are often somewhat nebulous and are seen as other diseases as well. Classic signs of Cushing’s disease, however, are:

• Increased appetite

• Increased thirst and urination

• Skin problems

• Recurrent infections

• Panting

• Muscle weakness

• A pot-bellied appearance

• Neurologic changes in advanced pituitary-dependent hyperadrenocorticism.

It is important to keep in mind that not every dog’s case of Cushing’s disease has every listed symptom.

What to expect at the vet's office

Your vet may proceed with diagnosing a dog with Cushing’s disease when a patient exhibits particular yet suspicious signs, like:

• Run a blood chemistry panel, complete blood cell count, a urinalysis, or any other lab work (heartworm test or fecal exam) that might be called for based on a dog’s physical exam and/or history. The results should either point toward or away Cushing’s, i.e. elevated alkaline phosphatase levels and a stress leukogram.

• With a sample of urine, your veterinarian can run a cortisol: creatinine ratio test. If the results are normal, Cushing’s disease is extremely unlikely. If they are elevated, Cushing’s disease is possible, but not a definitive diagnosis, as other diseases can produce the same result.

• Identify most (but not ALL) cases of Cushing’s disease and determining whether the adrenal or pituitary gland form of the disease is present (which also determines treatment) is done with a combination of an ACTH stimulation test, low dose dexamethasone suppression test (LDDS), high dose dexamethasone suppression test, and/or abdominal ultrasound.

Treatment for Cushing’s Disease

Medications: Dogs with Cushing’s disease caused by a tumor in their pituitary glands are generally treated with either mitotane (Lysodren) or trilostane.

Surgery: Cushing’s disease that is caused by a tumor in the adrenal gland is best treated by surgically removing the tumor.

If a dog’s symptoms are not too serious (i.e. he/she is panting more but is otherwise normal), treatment may not be necessary unless the problems become worse over time. Close monitoring of dogs undergoing treatment for Cushing’s disease is essential. The goal is to suppress cortisol production enough to keep pets healthy, but not so much that a new, opposite problem arises: hypoadrenocorticism, otherwise known as Addison’s disease.

Dogs with Cushing’s disease can be expected to live three years or even longer, after diagnosis with an appropriate treatment and a dash of luck, but while this is a condition that can often be successfully managed, it is only rarely cured.

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Don't forget to subscribe to our email newsletter for more recipes, articles, and clinic updates delivered to your inbox (here). Or, you can keep up to date by liking and following our Facebook page (here). We also have additional helpful articles under our tips category (here).