There are a few health conditions for which the long-term use of a steroid may be indicated, such as certain autoimmune conditions and Addison’s disease. When used long-term, the dosage should be maintained at the lowest effective level. Steroids are perhaps one of the most ubiquitous medications in the veterinary world. They can be used for a host of problems ranging from inflammation and allergies to autoimmune disease. While they are incredibly useful and diverse medications, steroids are not without significant side effects. It is important to know why they are used and how they can best be used. It is also critical to realize the possible negative effects and interactions that can occur. Steroids are not benign. Corticosteroids, as they are more correctly called, includes a varied group of medications. Some of the most commonly used in veterinary medicine are prednisone, Temaril-P, Neopredef (topical), dexamethasone, dexamethasone sodium phosphate (“Dex-SP”), methylprednisolone (Depo Medrol), and triamcinolone (Vetalog). They come in many preparations including oral, injectable, ophthalmic (for use in the eye), otic (ear), and topical sprays and powders. Steroids exert their activity in the body in many different ways. They affect every system, which is why it is important to make sure your veterinarian is aware of any medications that you give your dog, including over-the-counter supplements or pain relievers.
Uses for Steroids
One of the most general uses of steroids is in fighting “the itch” (pruritus) caused by allergies. Allergies are common in dogs, especially breeds like Boxers, Labradors, Maltese, West Highland White Terriers, Bulldogs, and pit bulls. These allergies can be food- and flea-related, or caused by seasonal allergens – a condition called atopy. The mechanism by which steroids control itching is complicated, but it includes decreasing the number of allergen-fighting cells (mast cells) in circulation and suppressing release of histamine. Histamine is one of the substances that leads to the formation of itchy hives and wheals. For allergies, only short-term doses of steroids are recommended. Itching should be controlled while the inciting cause is identified and secondary infections treated, and then the steroids should be tapered off slowly. Newer drugs such as Apoquel (oral) and Cytopoint (injection) are slowly supplanting the regular use of steroids for itching.
The most commonly used oral steroids for allergies are prednisone and Temaril-P. Some veterinarians use longer-acting injections such as Vetalog, as well. Long-acting steroid injections can cause more pronounced side effects than their oral counterparts. Their use is becoming less common as other methods of itch control and more allergy management options become available. Topical steroids for both the skin and ears have extensive uses and may prove to be a better option than oral medications, as they cause fewer side effects. Topical use can decrease inflammation and itching. This is important within the ear canal, as less inflammation allows ear medications to penetrate deeper. It also damps down itching, so dogs are not continuously self-traumatizing.
In conditions such as inflammatory bowel disease (IBD), steroid-responsive meningitis, and intervertebral disc disease, inflammatory cells dominate, causing redness, swelling, and pain. Steroids decrease inflammation by lowering white blood cell release from the bone marrow, among several other pathways. This effect is helpful for addressing IBD and steroid-responsive meningitis. Doctors find steroids useful for treating intervertebral disc disease in humans, and anecdotally, some veterinarians report success with steroids for the same condition in their canine patients, but the scientific literature isn’t really clear either way. The anti-inflammatory dose of steroids is generally fairly low, but side effects are still noted. Prednisone is used most often for this problem.
Autoimmune (AI) disease, a general term describing a variety of ways that the body attacks itself, is common in dogs. The triggers for AI disease are poorly understood. Some antibiotics like cephalosporins have been implicated, as well as vaccines. Cancer also can induce autoimmune processes. In most cases, an underlying cause is never identified. The list of autoimmune diseases are too numerous for this article, but they can affect all of the organ systems in the body, including the skin, brain, blood cells, joints, and other internal organs. Some of the more commonly seen disorders in veterinary medicine are immune-mediated hemolytic anemia (IMHA), immune-mediated thrombocytopenia (ITP), brain and spinal cord diseases such as meningitis, and skin diseases like pemphigus foliaceous and lupoid onychodystrophy. ITP is an example of a well-known and frequently seen autoimmune disease, in which the body turns its defenses on its own platelets. Platelets are important in the first step of clotting. As the body attacks and destroys them, the platelet numbers drop rapidly. Bruises become visible on the skin and gums.
Steroids treat this and other immune diseases by suppressing the body’s immune system, its natural defense against infection and illness. In these cases, steroids are started at very high levels (as much as 2 to 4 mg/kg body per day). As the symptoms improve, the steroids are slowly tapered to the lowest dose possible. This is to keep the autoimmune disease in check while avoiding the worst side effects of steroids. Most dogs with an autoimmune disease will remain on steroids or other immunosuppressive medication for life.
Another common condition in dogs is Addison’s disease. The body of a dog with Addison’s does not produce enough steroids and/or mineralocorticoids (responsible for water and electrolyte balance within the body). Cortisol and mineralocorticoids are essential for life, and when a dog’s body is not producing them, serious illness results. The general symptoms of Addison’s are waxing and waning GI signs: weight loss, vomiting, diarrhea, and picky appetite. Addison’s is often called the “great pretender” because it can look like many other diseases and can be difficult to diagnose. In these cases, steroids are indicated to replace those that the body is not making, as well as supplementation with a medication called Percorten or Florinef to replace the other corticoids. A few rare dogs with Addison’s can be maintained on Percorten alone; however, in times of stress or illness, they would require prednisone as well. Some dogs are affected by atypical Addison’s disease, in which only the cortisol levels are low. These patients can be even more difficult to diagnose, as the characteristic electrolyte changes on bloodwork are absent. Once diagnosed, these dogs must remain on a steroid for the rest of their lives. In this case, the steroids are usually administered on a twice daily to daily basis. The most commonly used steroid for this is prednisone, an inexpensive tablet.
Several cancers respond to steroids by shrinking. Lymphoma is a frequent cancer of dogs. The earliest symptoms are usually general malaise and enlarged peripheral lymph nodes (found underneath the jaw, in front of the shoulder blade, in the groin area, and behind the knee). Lymphoma is highly sensitive to chemotherapy and carries a good prognosis if treated aggressively. Many owners opt for palliative care however, for a variety of reasons, including cost and concern for quality of life. Prednisone is an excellent palliative agent for lymphoma and can often keep it in remission for weeks to months. However, it is important to know that prednisone will interfere with chemotherapy. If your dog has been diagnosed with lymphoma, and you are considering chemotherapy, prednisone should not be started until speaking with an oncologist. Many other cancers are often treated with oral steroids, as well. These are usually used adjunct to chemotherapy and/or radiation. Doses are higher than with anti-inflammation and anti-pruritus, usually in the range of 2 mg/kg of body weight per day or higher.
When Should Steroids Not Be Used on Dogs?
There are many cases where steroids are not an appropriate treatment. For some of the following examples, steroids remain controversial. Some veterinarians continue to use them based on years of experience (anecdotal), while others have discontinued use based on the same reasoning. Scientific data is somewhat conflicting and lacking on the subject, but these are the most current thoughts on steroid in certain situations:
Steroids were once a common and well-accepted treatment in cases of shock. For example, if a dog was hit by a car, one of the first ministrations would be a large dose of steroids given by injection. Over the years, it has become apparent in human medicine that steroids during shock are not helpful and are likely detrimental. They can downregulate important enzymes throughout the body, leading to worsening of low oxygen conditions (hypoxia, present during shock).This can lead to kidney and gastrointestinal damage as evidenced by bloody diarrhea and vomiting. Steroids should no longer be used to treat shock. Instead, treatment should focus on oxygen therapy, pain relief, control of hemorrhage, and intravenous (IV) fluids.
In Combination with NSAIDs
Non-steroidal anti-inflammatory drugs are very common in veterinary medicine and have a similar action in certain parts of the body. NSAIDs include meloxicam, carprofen, deracoxib, firocoxib, and several others. Using them with steroids can compound negative side effects and lead to gastrointestinal ulcers, hemorrhage, kidney damage, and in extreme cases, death. They should almost never be administered in tandem. The one exception is in the case of immune-mediated hemolytic anemia (IMHA). Patients with IMHA are prone to blood clot formation, so while steroids are used for immuno-suppression, very low dose aspirin also may be used to prevent clot formation. If a switch is required between these drugs, a wash-out period of at least two to three days is recommended to avoid these interactions. It is also critical to tell your veterinarian if you are administering any medications to your dog, especially over-the-counter pain relievers like canine aspirin (or human aspirin).
Even today, steroids are still used to treat snakebite victims. It has become apparent through research that steroids do not provide much (if any) benefit for these patients. The cases in which they might be useful are upper airway swelling as occurs with a bite to the mouth or neck or during an allergic reaction to antivenin. Otherwise, steroids are not indicated.
Side Effects of Steroids on Dogs
There are many well-known side effects of steroids. In the short term, dogs will drink and urinate excessively. A previously house-trained dog may start having accidents in the house. Dogs also will eat more. Often, heavy panting occurs. Restlessness and pacing are also side effects. Occasionally, dogs will behave in an agitated or aggressive way (the well-known “‘roid rage” syndrome noted in humans). If steroids are used long term, symptoms become more pronounced, and your dog may develop iatrogenic (caused by medication) Cushing’s disease.
Cushing’s disease occurs naturally when the adrenal glands overproduce cortisol (it is the opposite of Addison’s disease), the body’s natural steroid. This can occur due to either a brain tumor called a pituitary adenoma or an adrenal tumor. The symptoms of Cushing’s are weight gain, hair loss, panting, restlessness, frequent skin and urinary tract infections, and dramatic increases in urination and drinking. If oral or injectable steroids are administered frequently over extended periods of time, this syndrome can occur. Discontinuation of the steroids will reverse this. Steroids should never be stopped abruptly. When steroids are taken orally or by injection, the body’s natural steroid levels drop. If the exogenous (originating from outside the body) source is stopped, the body needs time to recover and resume making its own (endogenous) cortisol. In this gap, patients can develop a steroid insufficiency and exhibit signs of Addison’s disease: vomiting, diarrhea, weight loss, and anorexia. Because of this, steroids should always be tapered slowly. Most courses will go from twice a day, to once a day, to every other day.
Steroids are very useful and important medications. But, as with any medication, using them correctly is critical to success. They have many side effects. Make sure to work closely with your veterinarian to ensure that steroids are the best option, as many medications are now available to take their place.
STEROIDS FOR DOGS: OVERVIEW
1. If your veterinarian recommends or prescribes a corticosteroid, make sure you have informed her about every drug and supplement you give your dog, to ensure there are no adverse drug reactions caused by incompatible medications. 2. Be sure you understand the dosing amounts and schedule, particularly when it comes to “weaning” your dog off of the medication. 3. Don’t ask or allow your veterinarian to prescribe steroids for the long-term management of allergies; this use in particular can cause the development of other, even more serious health problems. Allergies are better addressed by applying oneself to discovering the offending allergen(s) and managing your dog’s exposure, and using steroids only to control an acute flare-up of a “hot spot,” for example, and just on a short-term basis. Catherine Ashe, DVM, graduated the University of Tennessee College of Veterinary Medicine in 2008. After a small-animal intensive emergency internship, she practiced ER medicine for nine years. She is now working as a relief veterinarian in Asheville, North Carolina, and loves the GP side of medicine. In her spare time, she spends time with her family and reads voraciously.