Tag Archives: cortisone

Diseases of dogs, Dogs, Internal diseases of Dogs

Cushing’s disease

In dogs with Cushing’s disease the adrenal glands overproduce some of the body’s regulators, particularly cortisol.

What are the signs of Cushing’s disease?

The most common signs of Cushing’s disease are marked increases in appetite, water consumption and urination. Lethargy, panting and a poor hair coat are also common. We often see a pot-bellied or bloated abdomen due to increased fat within the abdominal organs and thinning of the muscular abdominal wall.

What causes Cushing’s disease?

The three major causes of Cushing’s Disease:

  1. A tumour of the pituitary gland, that stimulates the adrenal glands to produce excessive  amounts of cortisol.
  2. Excessive administration of synthetic cortisones cortisones such as prednisolone, triamcinolone or dexamethasone may cause Iatrogenic Cushing’s disease.
  3. An adrenal gland tumour is an uncommon cause of Cushing’s Disease.

If we suspect Cushing’s Disease we run a blood test to check your dog’s general health. An enzyme called Alkaline Phosphatase (ALKP) is often high in dogs with Cushing’s disease. A Low Dose Dexamethasone test (LDDT) confirms or denies Cushing’s disease.

To determine which type of Cushing’s disease your pet has, we ultrasound the adrenal glands and/or do an endogenous ACTH blood test.

What are the treatment options?

Pituitary Tumour: This is the most common cause of Cushing’s disease. There are two treatment options for it. Trilostane is our drug of choice. A daily capsule of Trilostane reduces the production of cortisone and another important hormone, aldosterone.  We monitor your dog’s response to Trilostane with a test called the ACTH stimulation test. Too little Trilostane won’t reduce appetite or water consumption but too much will cause illness.

If your dog has liver or kidney disease we may suggest treatment with Mitotane (also known as Lysodren). This drug destroys part of the adrenal gland. Careful monitoring and good communication with your vet is necessary during the initial intensive treatment to achieve good results and avoid life-threatening adrenal damage.

Although the pituitary tumour remains present and continues to stimulate the adrenal gland if the tumour is small successful control for many years in most dogs is possible.  If the tumour is large, it may invade surrounding brain tissue and cause other signs, but this is rare.

Iatrogenic Cushing’s Disease: To treat this type of Cushing’s disease we must stop the synthetic cortisone in a very controlled way. If we stop intensive cortisone treatment abruptly your dog may lose his appetite, vomit, develop diarrhea and collapse. The suppressed adrenal gland takes a while to regain normal production of cortisol.

Treatment of an Adrenal Tumour:

Adrenal tumours tend to invade surrounding tissue but if we can surgically remove it all and it is not malignant your dog will regain normal health. Otherwise we treat adrenal tumours with Trilostane also.

Medicines & Treatments

Cortisone

Cortisone

We often prescribe cortisone for allergies and immune related diseases. Prednisolone, Macrolone or Antihistalone tablets contain a form of cortisone called prednisolone.  Short or long acting cortisone injections contain dexamethasone.

After 5 days of prednisolone tabs every day the adrenal glands start to slow their production of natural cortisol. It is safe to stop after 5 days of daily tablets but if we prescribe a longer course follow our instructions carefully.  Usually we recommend every other day tablets so that the adrenal glands keep functioning.

On a long course of prednisolone do not stop giving the tablets suddenly. Your pet may not be able to step up the production of cortisol fast enough to cope with an emergency, like a dog attack, a new pet or illness, and may collapse.

Side effects of cortisone include:

  • Increased fluid intake
  • Increased urine production
  • Increased appetite

Longer term and more serious side effects of cortisone include:

  • Cushings disease signs like a pot belly, flakey skin, enlarged liver and weak legs
  • Diabetes mellitus

Cortisone and anti-inflammatories given at the same time cause stomach ulcers.  We give anti-inflammatories such as Previcox, Deramax, Rimadyl, Metacam and Meloxicam for postoperative pain relief or arthritis. Please make sure your vet knows that your pet is on anti-inflammatories already.

A short acting dexamethasone injection rarely causes more than a mild increase in fluid and food intake.

We only inject long-acting dexamethasone if your pet is difficult to medicate or if your cat has a chronic condition that is not responsive to other cortisones.  Cats are generally more resistant than dogs to the side-effects of cortisone but very occasionally long-acting dexamethasone tips a weak heart into failure.

Diseases of dogs

Itchy Dogs

Many itchy dogs have the doggy equivalent of hayfever, which is called atopy.  A lot of dogs are allergic to flea saliva but only a few are allergic to food.

Common causes, or allergens, include pollen, grasses and dust mites.

Atopic dogs also have a poor skin barrier that allows the allergens to penetrate the skin and provoke the allergic reaction.

How does atopy affect my dog?

Dogs with atopy constantly scratch, bite, rub or chew themselves.  Itchy dogs don’t always scratch. They may rub their faces, flap their ears, or lick and chew their feet.

Some dogs scratch continuously but don’t damage their skin, whilst others quickly rub themselves raw. Recurrent ear infections are common.

Some dogs show signs of atopy as young as 3 months old, but usually it first occurs between 1 and 3 years of age. Initially most dogs will only be itchy during certain seasons, usually spring and early summer. As your dog ages, these itchy periods become longer.

As atopic dogs age, they become allergic to more things. Each dog has an allergenic load he can tolerate before he starts to itch. Exposure to one extra pollen or flea bite pushes him over the threshold into scratching or rubbing.

Diagnosis depends on the information you supply and examination of the skin. Tests such as skin scrapings and cytology rule out mites and secondary infections.

We may also rule out flea and food allergy by eliminating fleas and starting a dietary trial.

Skin testing by a specialist dermatologist will identify the allergens.

How to we treat atopy?

It is rare to cure atopy. We control it with a combination of strategies:

Improving the skin barrier:

  • Use shampoos without sulphates
  • Add essential fatty acids like Nutricoat, Megaderm, and fish oil to the diet
  • Apply sphingosines found in Nutriderm shampoo and conditioner,
  • Minimise bathing as much as possible

Avoiding allergens:

  • Vacuum carpeted areas frequently and minimise bedding to reduce dust mites
  • Keep your pet inside on windy days or when mowing

Treatments:

  • Cortisone offers immediate relief but can have serious side-effects if used long term
  • Atopica has fewer side-effects than cortisone and is often very effective but can be expensive in large dogs in the initial stages
  • Hyposensitization with repeated small injections of low doses of a combination of allergens chosen by a dermatologist on the basis of skin tests. These suppress the allergic reaction successfully in approximately 70% of atopic pets. Relief is not immediate and they usually require injections at least monthly for the rest of their lives. However in responsive pets hyposensitisation minimises the use of other medication.
  • Antihistamines such as Claratyne, Fexotabs, Claramax or Zyrtec are helpful in some cases but are rarely as effective as in humans.
  • Shampoos containing aloe vera and oatmeal may ease itchy skin

Skin allergies can be challenging to control and require a systematic approach to diagnose and treatment.  With commitment and care, most pets can enjoy a comfortable life despite ongoing exposure to environmental allergens.