Cushing's syndrome: How does it affect a dog's back leg?

Cushing's disease is an endocrine problem that arises due to overproduction of either adrenocorticotropic hormone or cortisol. Because of these hormones, this condition is also known as hyperadrenocorticism or hypercortisolism.

Dogs, usually adults and seniors, are affected by Cushing's disease. In this comprehensive article, we are going to explain Cushing's syndrome, its causes, symptoms, and complications associated with this.

Adrenocorticotropic hormone:

This is a pituitary hormone produced by the anterior lobe of the pituitary gland and acts on the adrenal gland to produce corticosteroid hormone. 

Cortisol or corticosteroid hormone:

It is an endocrine hormone produced by the adrenal gland. It deals with stress and emergency situations as well as other roles. 

Pituitary gland:

A small pea-sized gland located behind the thalamus at the base of the brain is the pituitary gland; it is also called the master gland because it secretes many hormones that regulate the secretions of other endocrine glands. 

Adrenal glands:

These are minute glands present at the top of each kidney, consisting of two major parts: the outer adrenal cortex and the inner adrenal medulla. The adrenal cortex secretes corticosteroids or cortisol, which regulate bodily functions and help cope with stressful situations. 

What is actually Cushing's syndrome in dogs?

There is a balanced natural phenomenon where adrenocorticotropic hormone from the pituitary gland is secreted into the bloodstream, which causes the adrenal cortex to produce cortisol. When enough cortisol is secreted, it feedbacks negatively and shuts down the production of adrenocorticotropic hormone from the pituitary gland. When this balance is disturbed, there is excessive production of adrenocorticotropic hormone and cortisol, leading to various health problems and symptoms.

Types of Cushing's syndrome:

Depending on the abnormality in the pituitary or adrenal gland, Cushing's disease can be of two types.

Pituitary-dependent Cushing's disease:

It is most commonly occurring in dogs, which is caused by tumors in the pituitary gland leading to hypersecretion of adrenocorticotropic hormone. 

Adrenal-dependent Cushing's disease:

 This occurs due to an abnormality of the tumor in the adrenal gland. During this condition, there is too much production of cortisol, causing other health complications.

Signs and symptoms of adrenocorticotropism in dogs:

Cushing's disease causes many behavioral and physiological symptoms such as  

• Loss of hair and coat condition.
• Excessive thirst and hunger.
• Panting.Unexpected weight loss.
• Potbelly appearance is a specific symptom of Cushing's disease.
• Skin and ear infections.
• Asthenia.
• Thin skin, etc.

Causes of Cushing's syndrome:

There are many cases of Cushing's disease in dogs.

Pituitary gland adenoma:

Pituitary gland adenoma is a tumor of the pituitary gland that leads to overproduction of adrenocorticotropic hormone, which in turn leads to cortisol overproduction. 

Tumor of adrenal gland:

Adrenal gland adenoma (benign) or carcinoma (malignant) causes excessive secretion of cortisol. 

Latrogenic adrenocorticotropism:

When more cortisol or corticosteroid is administered for treatment of other health issues, it leads to Cushing's syndrome even though both pituitary and adrenal glands are functioning well. 

Diagnosis of Cushing's syndrome:

It is crucial to examine the entire body physically to see any visible signs of diseases. Veterinarians may take present and past history by directly talking to the pet parent. You are advised to inform if your dog is on medications.

 If a veterinarian suspects Cushing's syndrome, there are two easy tests that may confirm this.

Dexamethasone suppression test:

First of all, a small amount of blood is taken to measure blood cortisol level. After that, inject a small amount of dexamethasone into the vein and muscle, and take a blood sample after four and eight hours to measure corticosteroid levels again.In normal dogs, cortisol levels suppress after eight hours, but in dogs with Cushing's disease, cortisol levels remain elevated. This is an easy and less expensive confirmatory test for Cushing syndrome.

Adrenocorticotropic hormone stimulation test:

Collect a blood sample before and after the administration of ACTH to measure cortisol levels. One hour after injection of ACTH, measure cortisol level; if it remains high, it confirms Cushing syndrome in dogs.

Imaging technique:

 Apart from chemical and blood tests, ultrasound, CT scans, and MRIs are also available imaging techniques for Cushing's disease.

How to treat Cushing's syndrome:

Adrenal dependent Cushing syndrome can be treated by surgery to remove the tumor while pituitary-dependent Cushing can be treated by radiation and surgery; extreme care has to be taken to avoid unintended damage and loss.The majority of the causes cannot be cured but can be managed to some extent only.

Medications frequently used for treatment include;

Trilostane: This drug blocks enzymes necessary for cortisol production.

Mitotane: It is an agent that destroys part of the adrenal gland responsible for cortisol production.

Low-fat diet: There is high production of cholesterol in dogs with Cushing's syndrome; therefore, a low-fat diet is recommended; otherwise, arterial and heart problems may arise.

How does Cushing's syndrome affect the back leg?

Cushing syndrome causes back leg issues in dogs because it leads to muscle wasting and weakness. Cushing syndrome causes some of the back leg problems in dogs such as ;

Muscle wasting: It causes muscle weakness, which has a direct impact on back leg growth and performance, affecting mobility. 

Gait issues: It interferes with gait, subsequently causing difficulty in walking and jumping. It causes stiff gait and improper walking patterns.

Jumping difficulty: Due to muscle atrophy and joint issues, jumping, playing, and running become difficult for dogs. 

Conclusion:

Cushing's syndrome is a debilitating health problem which affects back leg and causes other health complications. Here information regarding Cushing's disease in dogs has been provided with professional tips and strategies to deal with such case.