Archive for June, 2016
by admin on June 1st, 2016
Category: Special Offers, Tags:
by admin on June 1st, 2016
Category: Pet of the Month, Tags:
What is Cushing’s disease and how is steroid produced by the body?
Hyperadrenocorticism or ‘Cushing’s disease’ is caused by excessive production or administration of steroid. It can be classified as pituitary dependent, adrenal dependent, or iatrogenic.
A brief overview of how steroid is produced in the body will help with the understanding of this disease. The pituitary gland is a small gland at the base of the brain that secretes a hormone called ACTH. ACTH causes the adrenal glands to secrete steroid hormone. There are two adrenal glands in animals which are located in the abdomen close to the left and right kidneys. The main steroids produced in response to ACTH secreted by the pituitary gland are glucocorticoids and these have widespread effects on the management of proteins and sugars by the body.
What is the cause of Cushing’s disease?
Approximately 85% of dogs with Cushing’s disease have a very small, typically non-cancerous, growth of the pituitary gland that drives the excessive steroid production (via excessive ACTH production). These dogs have what is called ‘pituitary dependent hyperadrenocorticism’ (abbreviated to ‘PDH’). Approximately 75% of dogs with PDH weigh less than 20kg.
Approximately 15% of dogs have a tumour on one of their adrenal glands that drives the excess steroid production. This is known as ‘adrenal dependent hyperadrenocorticism’ (abbreviated to ‘ADH’). Cancerous and non-cancerous growths occur with equal frequency. Approximately 50% of dogs with ADH weigh greater than 20kg.
What are the signs of Cushing’s disease?
The most common presenting signs in dogs with Cushing’s disease are:
- increased drinking
- increased urination
- increased appetite
- enlargement of the abdomen
- hair loss
Dogs with Cushing’s disease are usually 6 years of age or older and many different breeds have been reported to be affected including Poodles, various Terrier breeds, Daschunds, Beagles and Labrador Retrievers.
How is a diagnosis of Cushing’s disease made?
The diagnosis of Cushing’s disease can sometimes be difficult, even with blood tests. Blood test results will be interpreted by your vet in light of the history and findings on examination. A blood test taken after the administration of a hormone or drug is necessary to help make the diagnosis. These tests are called the ‘ACTH stimulation test’ and the ‘low dose dexamethasone suppression test’. Normally only one test is necessary; however, occasionally both tests need to be performed. Urine tests are often performed as well.
Once a diagnosis of Cushing’s disease is made, it is useful to know whether the patient has pituitary dependent Cushing’s disease or adrenal dependent Cushing’s disease. The differentiation can be made with further blood testing or with an ultrasound scan of the abdomen. An ultrasound scan of the abdomen is sometimes required to help in achieving a diagnosis of Cushing’s disease.
How are dogs with Cushing’s disease treated?
Dogs with confirmed pituitary dependent Cushing’s disease are managed with an oral drug called trilostane. Trilostane stops the production of steroid and leads to an improvement in clinical signs in most dogs. Trilostane is absorbed better if given with food. Blood testing is necessary after starting treatment to monitor the effect of the drug. Any blood test result will always be interpreted in combination with the clinical signs. The majority of dogs will show a good response to treatment but will require lifelong therapy. Occasionally the small growth on the pituitary gland can grow and cause neurological signs (fits, behaviour change). Scans of the brain are therefore sometimes performed.
Surgical removal of the adrenal gland mass is the treatment of choice for patients with adrenal dependent Cushing’s disease. The outlook depends upon the degree of invasion of the growth into local blood vessels and analysis of the tumour under a microscope. Trilostane can be trialled in those patients for whom surgery is not an option.
‘Iatrogenic’ Cushing’s disease can be caused by the administration of steroid by mouth or topically. It tends to occur in patients on high dose, long term oral steroid (prednisolone) therapy. Treatment involves gradually stopping steroid therapy.
by admin on June 1st, 2016
Last month we explained what atopic dermatitis is and how it is diagnosed. In this article we consider how atopic dermatitis can be managed in affected dogs and cats.
Can I cure atopic dermatitis?
In one word “No”, but you can manage the condition successfully. Atopic dermatitis in dogs and cats can be compared to asthma in people. Asthma can’t be cured but it can be managed; and just like asthma the management of atopic dermatitis is life-long. It is therefore important to put in place measures that are going to have the least side-effects for your pet in the long term that will provide him/her a good quality of life and that are the most cost effective and affordable for you.
How can I manage the condition?
You need to take a multi-step approach to managing atopic dermatitis. These steps include:
- Treatment and prevention of infections
- Medications to stop the itch
- Treatment that modulates the immune system
- Nutritional supplements
- Topical treatments
- Unfortunately some treatments work some of the time but not all the time and so you may need to switch treatments periodically. Some treatments may result in undesirable side effects and so may need modification.
1) Treatment and prevention of infections:
Any bacterial (mostly staphylococcal) and/or yeast (Malassezia) infections should be treated at the outset. Antibiotics for bacterial infections need to be administered for 7 – 14 days beyond clinical cure and the duration of treatment is generally determined by the depth of the pyoderma.
For yeast infections a shampoo containing either 2% chlorhexidine/2% miconazole or one containing 3% chlorhexidine have shown good efficacy and will suffice; however, if the infection is severe your vet may opt to prescribe antifungal tablets. Because there is a tendency for infections to recur it is best to bath your pet once or twice a week on a regular basis, which will keep the microbial load on the skin low and thus help reduce the frequency of infections.
2) Stopping the itch:
Glucocorticoids (steroids) will stop the itch in most cases, but need to be used with caution, especially if used for a long time. In the short term they can increase water intake, increase urination and appetite. Some owners and pets find these side effects distressing. In the long term they can affect almost any organ in the body, therefore, even when well tolerated, they should be used with caution and your pet should be monitored regularly. Topical steroid containing sprays and ointments may be useful for targeted areas but with long term use thinning of the skin, infections and systemic side effects can occur.
Cyclosporin is used to damp-down (modulate) an over-reacting immune system in an atopic pet. One starts with a high dose and then tapers it down to alternate day, or better still twice a week, treatment. The most common side effects with ciclosporin are vomiting and diarrhoea. In some dogs, gingival hyperplasia and papillomas may also occur.
Oclacitinib is another immunomodulating drug which specifically targets the pathway that results in an itch. It is effective and can stop itching rapidly. This is the newest drug on the market and the reported side effects are vomiting and diarrhoea in a small number of cases. It can be used both short term and long term; however, given that this drug has now been on the open market for only a few months (at the time of writing this) it should be used with caution as side effects with prolonged use are not known.
Antihistamines; the response to this group is variable and they are often used in combination with steroids in order to reduce the steroid dose.
3) Immune Modulation:
Allergen specific immunotherapy is the most specific treatment for Atopic Dermatitis. It involves either an injection, or an oral dose of the allergens your pet is allergic to, to modulate the immune system. It has responses ranging from roughly 33% where there is complete cessation of itch, to 33% improving but requiring additional treatments, to 33% where there is no response. If your pet responds well to immunotherapy, it is likely to have the least adverse side-effects and to be the most cost effective treatment in the long term.
4) Nutritional support:
Omega -3 and Omega -6 essential fatty acids help the skin function by altering the lipid barrier and by reducing inflammation. On their own they are unlikely to benefit your pet but can be helpful when combined with other treatments. Diets that are high in essential fatty acids (EFAs) also help.
5) Topical treatments:
Moisturisers containing ceramides help maintain the skin barrier, which in turn reduces the penetration of allergens and therefore your pet’s reaction to them. Bathing with an oatmeal based shampoo can also help relieve itching and re-hydrate the skin.
Atopic dermatitis is a lifelong condition that requires life-long management; and often more than one type of treatment will be required. So, when your vet chooses a treatment, it should be efficacious, suitable for your pet with the least side effects, easy for you to administer and affordable. Most of all it/they should improve your pet’s (and your) quality of life.