Honey’s illness started with occasional digestive disorders. It’s common for some dogs to suffer from an occasional upset stomach. Honey vomited every few weeks, and she had an occasional episode of diarrhoea, but that was all. She was in great form generally, full of energy, and looking well, so Gillian wasn’t too worried. Even when Honey was checked by the vet for her annual health review at the end of the summer, she had no sign of anything serious going on.
Then, just before Christmas, she had a particularly severe episode, with diarrhoea, progressing to vomiting. She rapidly became seriously dehydrated, causing her to be dull and depressed. She was obviously very unwell, and she had to be admitted to our hospital for rehydration with intravenous fluids. A blood test showed that she had low blood sugars, so her treatment included a special infusion of glucose to help her recover. We also measured her electrolyte levels: these include sodium and potassium, and they were out of kilter, needing special fluids to correct them.
Honey responded promptly to treatment, and was able to go home for Christmas, but alarm bells had been ringing for us. It’s unusual to have such a serious episode of gastroenteritis with changed electrolyte levels without some underlying reason. The specialist veterinary laboratories had shut for the Christmas break, so there was nothing that could be done to look into her problem in more detail, but we set up an appointment for this to be done straight after the break.
We had hoped that Honey would stay well during the holiday period, but unfortunately, she fell ill again on St Stephen’s Day. This time she didn’t vomit, but she had a nasty dose of diarrhoea, and she became dull, trembling continuously. She had to go to the Pet Emergency Hospital, where blood tests again showed up the unusual changes that we had picked up the previous week. She was given general treatment, and as soon as our clinic opened (on 27th December) she came in to have a special blood test to be sent off to an external laboratory to measure her cortisone levels. The results of the special test confirmed that she had a rare condition called Addison’s Disease. This was why she kept having the gastrointestinal upsets, and it explained why she became so dull and miserable at these times. She urgently needed special long term treatment to keep her healthy.
Addison’s disease is also known as hypoadrenocorticism. It happens when the adrenal glands reduce the production of important hormones that help regulate normal body functions. The two types of hormones are known as glucocorticoids (cortisone) and mineralocorticoids. When the levels of these hormones are too low, there’s a wide range of effects. The glucocorticoids have an effect on sugar, fat, and protein metabolism, while the mineralocorticoids control the levels of electrolytes in the bloodstream, including sodium and potassium. Both types of hormones help the body cope with stressful situations, and when levels of the hormones are reduced (which is what happens in Addison’s Diease), even minor episodes of stress can cause signs of illness, with a potentially life threatening outcome.
Addison’s Disease is mostly seen in young to middle-aged female dogs, but it can happen to any dog. Typical signs include lethargy, lack of appetite, vomiting, and muscle weakness. The symptoms typically wax and wane (i.e. dogs get better then worse again), and it can be a difficult disease to diagnose. Usually a vet will suspect the illness from the pattern of disease signs, such as those shown by Honey.
An in-house blood test to measure electrolyte levels can rule the disease in or out, but ultimately, a specialised blood test called an ACTH Stimulation Test is needed to confirm it. This is the test that has to be sent off to a veterinary laboratory.
There are several different reasons why the adrenal glands stop working, with the most common cause being destruction of the glands by the body’s own immune system (a so-called auto-immune disease). There are a range of other, rarer causes as well, but the bottom line is always the same: affected animals need to be given hormone-replacement therapy for life.
Once the disease has been definitively diagnosed, treatment is straightforward. The traditional treatment involves replacing the mineralocorticoids and glucocorticoids in the body by giving tablets twice daily. Regular blood tests are needed to measure electrolytes and cortisone levels until the right dose is established, then after that, repeated blood tests every six months or so are needed on an ongoing basis, adjusting the dose of tablets if needed.
A newer way of treating Addison’s disease involves a drug called DOCP, a long acting injection which replaces the missing hormones. It only needs to be given around once a month, and some tablets may also be needed. Again, blood tests are needed for the rest of the animal’s life to ensure that the correct level of hormones is maintained.
Honey has started this treatment, and she’s in great form. Gillian and her family are hoping that Honey’s occasional digestive upsets and other signs of illness will now be firmly in the past.