Canine atypical Addison's disease, also known as atypical hypoadrenocorticism, is a less recognized but important condition that can affect your dog. Unlike classic Addison's, this version does not affect or impact your dog's electrolytes and can go unnoticed due to its subtler and vague symptoms. Atypical Addison's disease in dogs can manifest through signs of lethargy, vomiting, or poor appetite, easily mistaken for other illnesses. If your dog has mysterious clinical signs and testing has come up unrewarding, you may want to consider atypical Addison's.
What is Canine Atypical Addison's Disease?
Addison's disease in dogs comes in two forms, the typical or classical form and the atypical form. While it shares similarities with the more typical form of Addison's disease, there are distinct differences that you should be aware of.
Canine atypical Addison's disease involves the underproduction of certain hormones by a dog's adrenal glands. Unlike the typical form, which affects both mineralocorticoid and glucocorticoid hormones, the atypical variety impacts only the latter.
Essentially, the atypical form is when there are low levels of cortisol but normal levels of sodium and potassium.
The cause of atypical Addison's disease remains unclear although we feel it occurs due to the immune-mediated destruction of the adrenal cortex, which is the outer region of the adrenal gland.
Dogs of any breed can be affected, but it seems some are more predisposed than others. The majority of cases are female and the breeds at risk include Labrador retrievers, West Highland White terriers, Great Danes, Cocker Spaniels, Portuguese Water Dogs, and Standard Poodles.
Symptoms of Canine Atypical Addison's Disease
The symptoms of Atypical Addison's Disease can often be nonspecific and easily mistaken for other issues, which makes them tricky to pin down. General signs might include:
- Lethargy and fatigue
- Failure to thrive
- Gastrointestinal upset, such as vomiting or diarrhea
- Decreased appetite
- Weakness
- Progressive weight loss
- Excessive thirst and urination
It is important to note that not all dogs need to show all symptoms. If you notice any of these signs in your dog, it's important to see your veterinarian for proper diagnosis and treatment.
How are the symptoms of atypical Addison's disease different from the classical type of Addison's in dogs?
The primary symptomatic difference between the two types is that with the classic form, many dogs will present in a physiological crisis. As such, symptoms may be more severe and include collapse, shock, weak pulses, low body temperature, and extreme weakness. This is not typically seen in atypical Addisonian dogs.
In contrast, the symptoms of atypical Addison's disease are often milder and more insidious in their onset. Additionally, dogs with atypical Addison's disease may also experience recurrent episodes of gastrointestinal signs or other vague symptoms before being diagnosed.
In both cases of hypoadrenocorticism (Addison's), dogs are often intolerant to stressful events and you may find vague symptoms of vomiting, diarrhea, lack of appetite, or lethargy after a stressful event. This is because the body's stress response relies on cortisol, which is not being produced in dogs with Addison's disease.
How is Atypical Addison's Disease Diagnosed in Dogs?
Diagnosis of atypical Addison's disease can be challenging, as symptoms may be subtle, non-specific, and wax and wane.
The recommended diagnostic test to diagnose canine atypical Addison's disease is the ACTH stimulation test. This test measures the body's ability to produce cortisol in response to an injection of synthetic adrenocorticotropic hormone (ACTH). Dogs with atypical Addison's disease will have a lower-than-normal cortisol response.
Other diagnostic tests may include bloodwork, imaging tests such as abdominal ultrasound, and additional hormonal testing.
What is the Treatment for Canine Atypical Addison's Disease?
Treatment for canine atypical Addison's disease primarily involves hormone replacement to compensate for what the dog's body cannot produce. Prednisone, a type of corticosteroid, is the key remedy here.
This medication effectively replaces the cortisol that your dog is lacking, helping to regulate the body's metabolism and immune response. It is important to follow your veterinarian's instructions carefully when giving your dog prednisone, as the dosage may need to be adjusted over time depending on your dog's response to treatment.
While prednisone does not cure atypical Addison's disease, it enables dogs to lead normal, happy lives by managing the condition effectively.
Can the Atypical Form Develop or Progress to the Classic Form of Addison's Disease?
In some cases, however, the disease may never develop into the typical form of Addison's.
But, unfortunately, yes, the atypical form can progress to the classic form. There will then be subsequent electrolyte changes and symptoms will intensify, often despite being on prednisone therapy.
Living with a dog diagnosed with Atypical Addison's Disease
Living with a dog diagnosed with atypical Addison's disease can be challenging but is certainly manageable with the right care and attention.
Dogs with both types of Addison's disease can have a difficult time dealing with stress. Stress for dogs is different from stress in people, as it is often not readily apparent. Stressors for dogs can include anything from changes in their environment, such as a new home or the loss of a family member, to illness or injury.
During stressful events, we often recommend temporarily increasing the dose of prednisone. This can help prevent symptoms from appearing. It is important to ask your veterinarian what dose they would increase your dog to, based on their current dose and body weight.
In closing, although living with a dog diagnosed with atypical Addison's disease may require some extra attention and care, it is still entirely possible for these dogs to live full and happy lives. Symptoms of atypical Addison's can be different from the classic form and can often go unnoticed due to the waxing and waning. Diagnosis can be challenging and the ACTH test is currently our recommended test of choice. Treating a dog with atypical Addison's is straightforward as they only require prednisone because their electrolytes will be normal.
If you have any further questions or concerns, please reach out to your veterinarian.