Addison's disease in dogs

Health and Wellbeing

Addison’s disease is the common name for “hypoadrenocorticism”, a condition that affects your dog’s adrenal glands and the production of vital hormones in their body.

Addison’s disease in dogs can be life-threatening if left untreated, but luckily, the condition is easy to treat and most dogs will live a normal life provided they take regular medication to manage their condition.

Addison's disease in dogs

It’s not a common illness, but it’s not rare either, so it’s important for pet parents to understand what Addison’s disease is, which dogs can be affected, and how the condition can be managed.

WHAT IS ADDISON’S DISEASE IN DOGS?

Addison’s disease is when a dog’s adrenal gland doesn’t produce enough steroid hormones.

If a dog is suffering from Addison’s disease their adrenal gland will stop producing the hormones cortisol or aldosterone, or both. These hormones are vital for your dog to live a healthy, normal life because they help to regulate the electrolytes in their body and play a part in the function of various internal organs.

Aldosterone influences the receptor cells of the kidneys. In a healthy dog, aldosterone tells the kidneys to reabsorb sodium and fluid into the blood, increasing blood volume and keeping your pooch hydrated. It also triggers the excretion of excess potassium in urine so it doesn’t build up in your pup’s body and make them sick. When there’s no aldosterone, the kidneys don’t recycle sodium or remove potassium, leading to an imbalance of electrolytes in addition to altering the pH of your dog’s blood.

Cortisol meanwhile is known as the stress hormone and manages your dog’s flight or fight response. It’s also important in a number of functions such as metabolism, regulating blood pressure, increasing blood sugar, and combatting inflammation.

When your dog’s adrenal glands aren’t producing enough of these hormones, they can’t complete any of the functions they’re used for and your pooch become increasingly unwell.

THE TYPES OF ADDISON’S DISEASE

The most common type of Addison’s in dogs is called “typical Addison’s disease”. “Typical” Addison’s is when the dog’s body lacks both glucocorticoids and mineralocorticoids. It’s diagnosed through blood tests which show an imbalance of electrolytes in the body, and it will require ongoing treatment to replace the missing hormones.

The other form of Addison’s disease in dogs is called “atypical Addison’s disease” because it’s much less common. In this type, the dog is only missing glucocorticoids, so only needs medication to replace their missing cortisol. This is more difficult to diagnose because the affected pooch often won’t have abnormal electrolyte levels. Plus, their symptoms will be vague and similar to many other common illnesses. A dog with atypical Addison’s might only show symptoms like a lack of appetite, and periods of vomiting and diarrhoea. However, atypical Addison’s disease can progress into typical Addison’s disease.

As well as these two types, a dog can have either primary or secondary Addison’s disease.

Primary Addison’s means that the disease has been caused by a problem with the adrenal gland itself. Whereas secondary Addison’s disease is caused by a problem in the pituitary gland, which is what stimulates the adrenal gland to create hormones. Even if a dog’s adrenal gland is healthy, if their pituitary gland has a problem and isn’t sending the signals to trigger the gland to work, their body still won’t produce the hormones they need.

WHAT CAUSES ADDISON’S DISEASE?

Addison’s disease is caused by the dog’s immune system attacking and destroying the cells of their adrenal gland. For whatever reason, your dog will undergo an auto-immune response that causes the destruction of the cells in the adrenal cortex, which is a specific layer in the gland responsible for the production of cortisol. Once these cells are destroyed the dog can no longer make this important hormone.

The adrenal gland might also be damaged or destroyed by trauma, such as an injury, infection, or cancer.

It’s much less common, but Addison’s can also be caused by damage to the pituitary gland. The pituitary gland is responsible for producing hormones that stimulate the adrenal gland into creating steroid hormones. If the pituitary gland has been damaged or destroyed by a defect, tumour, or cancer, then it will not produce the chemical signals needed to stimulate the adrenal gland, which means the body won’t produce any adrenal hormones.

Sometimes a dog can develop Addison’s disease after they have been treated for Cushing’s disease, also called hyperadrenocorticism. Cushing’s is like the opposite of Addison’s and instead of the body not making enough steroid hormones, it makes too much. When a dog is being medicated to treat Cushing’s and lower the amount of cortisol in their body, if the dose of medication is too high, it can make their cortisol levels too low. This is preventable and reversible though.

Dogs who have been receiving long-term steroid treatment can develop what’s called iatrogenic secondary hypoadrenocorticism, another form of Addison’s. Long-term use of steroids can cause the adrenal glands to shrink and impair the gland’s function, however, this is usually a short-term problem and will eventually correct itself. This is why your pooch will need to be slowly weaned off their medication to give the body time to adapt to the change.

WHAT IS AN ADDISONIAN CRISIS?

In severe cases, a dog can suffer from an Addisonian crisis, also known as an adrenal crisis. This is a very severe episode of illness caused by Addison’s disease that can be life-threatening. Dogs suffering an Addisonian crisis often suffer from severe vomiting and diarrhoea, shaking, weakness, and collapse.

An Addisonian crisis is when the dog’s sodium levels have dropped significantly and their potassium levels are dangerously high (hyperkalemia). This imbalance of electrolytes causes low blood pressure and cardiac changes, and the high potassium levels mean your dog is at risk of suffering a heart attack.

THE EFFECTS OF ADDISON’S DISEASE IN DOGS

The steroid hormones cortisol and aldosterone are important for a number of bodily functions, and several internal organs will be affected by Addison’s disease.

One of the hormones your dog will be lacking is cortisol, the stress hormone. Cortisol is vital in triggering the fight or flight response in dangerous situations, so a dog with Addison’s disease will lose their stress response. The hormone is also important for several bodily functions including regulating your dog’s metabolism. Dogs with Addison’s will often lose weight without any obvious cause and can struggle to maintain a normal weight.

Cortisol stimulates the production of glucose in the liver, increasing a dog’s blood sugar. A lack of cortisol will lead to impaired liver function. The hormone also counteracts insulin, but having too little cortisol means your dog’s blood sugar will nosedive, leading to lethargy and weakness.

Cortisol also has anti-inflammatory effects which can help alleviate conditions such as arthritis. It also regulates the tone of the muscles in the blood vessels, so without this hormone, the integrity and function of your dog’s blood vessels will decline and weaken.

Addison’s can also cause a lowered production of aldosterone, which is important for balancing electrolytes in your dog’s body. This hormone is what makes the kidneys reabsorb sodium back into the blood while filtering potassium out to be excreted in urine. No aldosterone means that sodium will leave the body, and low sodium leads to the kidneys not absorbing as much fluid, so liquids are lost in your dog’s urine leading to dehydration, even if they’re drinking more than usual. Meanwhile, the inability to filter out potassium can lead to dangerously high levels in their blood which can cause a heart attack.

ARE SOME DOGS MORE AT RISK OF ADDISON’S DISEASE?

Any dog regardless of its gender, breed, or age can be affected by Addison’s disease. However, the disease is usually diagnosed while a dog is still young or reaching middle age. Additionally, female dogs are far more likely to develop Addison’s disease compared to male dogs.

Some dog breeds seem to be at greater risk of developing the disease. Some of the dog breeds prone to Addison’s disease are:

Generally, crossbreeds are at less risk of inheriting genetic diseases, but they are not immune to conditions that affect all dogs or their parent breeds. If your pooch is a crossbreed with one of these at-risk breeds in their parentage, like a standard Cockapoo which has both standard Poodle and Cocker Spaniel in its bloodline, they can still be at higher risk of Addison’s disease compared to other breeds.

HOW TO PREVENT ADDISON’S IN DOGS

Sadly, there is no way to prevent Addison’s disease in dogs and there’s no way to cure it either. Because prevention is not possible, and the disease seems to be inherited in most cases, it’s important that dogs diagnosed with Addison’s disease are not used for breeding because their puppies are much more likely to develop the condition.

If your dog seems to be lethargic or tired a lot of the time and suffers from a periodic illness, you should take them to the vet to be examined. If your vet suspects Addison’s or a shortage of the adrenal hormones, treatment is important to manage the condition and to prevent a life-threatening Addisonian crisis.

The only kind of Addison’s disease that is preventable is those caused by the use of other drugs. If your dog has been on steroids or is being treated for Cushing’s disease, they can develop Addison’s disease if they suddenly stop taking their medication, or if they receive too high a dose. If your pooch is on medication, you should always follow instructions from your vet regarding their dosage to prevent any secondary problems like Addison’s from developing. And if you ever notice your pooch showing any sign of illness, you should take them to the vets for an examination and catch problems before they worsen.

SIGNS AND SYMPTOMS OF ADDISON’S IN DOGS

Most dogs diagnosed with Addison’s are typically young dogs that have had repeated bouts of illness and listlessness, but their symptoms have come and gone several times. They might also show signs of their body going into shock without any obvious cause.

SYMPTOMS OF ADDISON’S IN DOGS ARE:

As mentioned, these symptoms usually come and go, so if your dog has sudden episodes of illness, and becomes thirstier than usual and urinates more often, then Addison’s disease may be the cause for their intermittent illness.

DIAGNOSING ADDISON’S IN DOGS

You and your vet will discuss your dog’s medical history and symptoms, and if the vet suspects Addison’s may be the underlying cause they’ll conduct a baseline cortisol measurement. This is when the vet tests a sample of your dog’s blood to see what your dog’s cortisol level is.

A normal dog should have a cortisol level of 2, but it can fluctuate. If your dog’s result is less than 2 they might not have Addison’s disease, but their cortisol level is low, so your vet will conduct a more reliable test called an ACTH stimulation test.

In this test, they will inject some synthetic ACTH hormone into your dog and wait to see how they respond. ACTH is the chemical signal the body uses to stimulate the adrenal gland into producing cortisol. After waiting about an hour, the vet will test your dog’s blood again to check their cortisol levels. If your dog’s adrenal gland functions correctly, their cortisol levels would have risen in response to the ACTH. However, if the cortisol levels are still low, it indicates that your dog’s adrenal gland isn’t functioning as well as it should be and isn’t producing enough cortisol.

Your vet might also conduct other tests including further blood tests or x-rays to rule out any other conditions that might be making your dog unwell and to ensure they begin the correct course of treatment.

TREATMENT FOR ADDISON’S DISEASE IN DOGS

If your dog is suffering from shock or an Addisonian crisis then they will need prompt treatment to alleviate their symptoms and to try and stabilise their condition.

Dogs that are in shock or suffering an Addisonian crisis will need intravenous fluids. IV fluids will not only help to rehydrate the pooch, but it will restore their blood volume. The fluids will contain sodium chloride to increase the sodium levels in your pooch’s blood and help to retain fluid and reduce the levels of potassium, which will lower their risk of cardiac problems or heart attack.

Once a dog is stable and at no risk of hyperkalemia, you and your vet can begin treatment for Addison’s disease. There is no cure for Addison’s disease, so long-term treatment will be required to manage the condition for the rest of your dog’s life.

Ongoing treatment for Addison’s disease in dogs will involve daily medication to balance their electrolyte levels and to replace the hormones that are missing from your dog’s body. Managing the condition with replacement hormones is important to not only improve your dog’s health and wellbeing by maintaining normal bodily functions, but it will also prevent a life-threatening Addisonian crisis by balancing their electrolytes.

HOW IS ADDISON’S DISEASE IN DOGS TREATED?

Dogs with typical Addison’s disease will need to be put on steroids because their adrenal gland cannot make them. They may need one or two kinds of steroids, depending on whether they aren’t producing enough cortisol, aldosterone, or both.

Your pooch might be given an oral medication called fludrocortisone acetate every day to replace the missing cortisol from their body. If your dog is missing aldosterone they will need to have an injection of desoxycorticosterone pivalate, which is a long-lasting mineralocorticoid. This injection lasts for about a month before your dog will need another one. If your dog is only missing one hormone, they might only need one of these treatments. But if their body is failing to produce both hormones they will need to have both pills and injections.

When your pooch is first diagnosed with Addison’s they will need blood tests every month to monitor their electrolyte and hormone levels until the vet finds a dose of medication that works at balancing them. Once an appropriate dose has been found and your pooch seems stable, they will only need blood tests every six months to keep tabs on their electrolyte and hormone levels to make sure the medication is still effective. Regular monitoring also means your vet can see early on any fluctuations in your dog’s hormones and can adjust their medication accordingly to stabilise them and prevent illness.

As well as medication to manage the condition, you will need to try and prevent any stressful situations in your dog’s life. Stress can make a dog with Addison’s disease very sick because they lack the steroid hormones that regulate their stress response and keeps them healthy in stressful periods.

When a stressful period is coming up, for example, bonfire night or New Year’s eve when fireworks are likely, your vet might increase your dog’s medication as a precaution to make sure they have adequate cortisol to cope with stress. Remember you should never change your dog’s medication dosage without talking to your vet.

WHAT HAPPENS IF ADDISON’S IN DOGS IS UNTREATED?

If left untreated, a dog will become sicker and their symptoms will become increasingly severe. Untreated Addison’s disease leaves a dog at risk of suffering from an Addisonian crisis or heart attack and is often fatal if left untreated.

On the other hand, a dog who receives regular treatment to manage their condition will usually live a perfectly normal, healthy life. They can be as active and happy as other dogs and will live to their normal life expectancy.

It is very rare, but some dogs might not respond to treatment for Addison’s disease. Additionally, some pooches might have another condition like diabetes that makes managing their Addison’s more complicated. In these cases, the outlook is not as positive, but they will still live much longer and healthier lives on medication than if they were left untreated.

HOME REMEDIES FOR ADDISON’S DISEASE IN DOGS

There is no home remedy that can replace the hormones your dog’s body is missing, and none that are as effective as the treatment provided by your vet. You should never attempt to treat your dog yourself or provide home remedies without first discussing them with your vet, as you may unwittingly make your dog’s condition worse.

However, many vets are open to discussion and will gladly help you find holistic therapies that might make your dog more comfortable and improve their wellbeing.

One of these possible treatments is pet massage. Pet massage and acupressure might help to relax your dog and relieve stress, which can help to prevent further illness.

Further study is needed, but liquorice root might have a positive impact on people and pets suffering from Addison’s. Liquorice stimulates the body to retain sodium which could help to prevent an Addisonian crisis. In herbal medicine, liquorice root is also used as an anti-inflammatory and to relieve stress, which are both important for dogs with Addison’s.

In humans, it has also been found that liquorice root can block the enzyme 11-beta-hydroxysteroid dehydrogenase which metabolises cortisol. With less cortisol metabolised, the levels of cortisol in the body should increase, provided your pup can produce some of the hormone in the first place. However, if no hormone is being made, it won’t have a huge effect.

Just remember, liquorice root is a herb and it’s not the same as the black liquorice sweets you find in shops!

Although liquorice root sounds promising, there is still very little research into its effect on people or pooches suffering from Addison’s disease. However, you can talk to your vet about the potential benefits of liquorice root and they might help you to work out how you can safely supplement your dog’s diet to see if it will benefit them, alongside proper medication to treat their condition.

Because cortisol is important for the body’s anti-inflammatory response, you will need to try and remove anything from your dog’s environment that could be causing inflammation. One of the main culprits for causing chronic inflammation is allergens in your dog’s food. Swapping your pooch onto an all-natural and allergen-free diet can reduce inflammation and improve your pup’s overall wellbeing.

WHAT’S THE BEST DOG FOOD FOR ADDISON’S DISEASE IN DOGS?

Best dog food for Addison's disease

The best diet for a dog suffering from Addison’s disease will be made using high-quality ingredients and it will avoid using common allergens or artificial ingredients that are known to cause inflammation in dogs.

The sorts of ingredients you need to avoid will often be grains and low-quality carbs like corn or wheat, as well as common canine allergens like dairy and soy.

Certain proteins can also cause inflammation and an allergic response. Beef and chicken are other common causes for a dog’s allergies. If your dog has a known allergy, or doesn’t seem to tolerate a certain kind of meat very well, you can swap them onto a new protein source like lamb, turkey, or duck to see if it relieves their discomfort.

Because a dog with Addison’s disease cannot produce enough cortisol, their body can’t produce as many anti-inflammatories as a healthy pooch. That means that any inflammation they suffer from will seem more severe, and their body is not able to combat it effectively. This means it’s important to avoid allergens and irritants like these because it means your dog’s less likely to suffer from inflammation in the first place.

Artificial ingredients like preservatives and flavourings can also cause inflammation as well as irritation to your dog’s gut, so swapping to an all-natural dog food could provide some relief.

Having enough essential fatty acids such as omega-3 and omega-6 will also help to combat inflammation in your pooch’s body and make them much more comfortable. Omega-3 is useful in reducing inflammation and it can help to manage auto-immune conditions. You can find these fatty acids in foods like oily fish and flax oil.

One of the best natural anti-inflammatories comes from antioxidants in the diet. Free radicals in the body can damage your dog’s cells and cause chronic inflammation. Antioxidants are molecules designed to fight and neutralise these free radicals. Ergo, making sure your dog is eating a diet rich in antioxidants will help to combat free radicals and inflammation.

Antioxidants can be found in plenty of fresh fruit and veggies like blueberriesraspberries, and broccoli, which are all perfectly safe for your dog to eat. You can use these healthy foods as a nutritious snack, a tasty meal topping, pureed for a Kong filler, or as ingredients in fresh dog food.

Pure Pet Food is packed full of natural and high-quality ingredients, including plenty of fresh vegetables to provide those all important antioxidants. We also never ever use any artificial nasties or allergens which could cause inflammation.

Dr Andrew Miller BVSc MRCVS

Written by: Dr Andrew Miller MRCVS

Andy graduated from Bristol University in 2010 and sees nutrition as a foundation for our pet's wellbeing and takes a common-sense approach. We are what we eat, and it shouldn't be any different for our pets.

Sources
  1. Omega-3 fatty acids in inflammation and autoimmune diseases Journal of the American College of Nutrition, 21, (6), Dec 2002, 495-505, doi:10.1080/07315724.2002

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