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Side Effects of Steroids in Pets

Updated on January 13, 2017
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eirevet is a veterinarian specialized in canine and feline internal medicine and owns a small animal veterinary hospital in Ireland.

Are Steroids Safe For Pets?

Corticosteroid medications such as prednisolone and prednisone are widely used in both human and veterinary medicine to treat allergies, cancers, and autoimmune problems such as atopic skin disease, flea allergy, inflammatory bowel disease, and rheumatoid arthritis to name but a few. Used appropriately, steroids can greatly improve your pet's quality of life while helping to treat serious illness.

Unfortunately, steroids are often not used appropriately, either due to incorrect or incomplete diagnoses, or because of a lack of understanding by owners of the potential side effects of medications such as prednisone.

The following discussion aims to inform readers of these side effects, as well as suggesting possible methods to reduce steroid use in some specific conditions.

Common Side Effects

Corticosteroids are produced naturally in the adrenal glands, and have a number of important functions in the healthy pet. Cortisol, the predominant naturally occurring steroid, has

  • antiinflammatory
  • homeostatic
  • immune-modulating

functions, amongst others. These beneficial effects are dependent on the proper functioning of feedback mechanisms between the adrenal glands, pituitary gland, and hypothalamus, and the low levels of endogenous steroid are constantly fine-tuned by communication between these organs. When communication breaks down, an animal may develop serious problems such as Cushing's Syndrome or Addison's Disease.

When we administer corticosteroids in the form of prednisolone or prednisone, we override this sophisticated feedback mechanism, and are likely to cause at least some mild signs of Cushing's Syndrome. These signs are discussed below.

Appearance of Cushing's Syndrome

Yorkshire terrier with naturally occurring Cushing's Syndrome
Yorkshire terrier with naturally occurring Cushing's Syndrome


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Behavioral Changes

Effects of prednisone vary from one animal to the next, and while some pets will become agitated, hyperactive, or even aggressive, it is most common for owners to notice lethargy and reduced energy levels. While some of this effect seems to be due to a direct effect on the brain, exercise intolerance because of muscular and respiratory effects are likely to also play an important role in these changes.

Steroids Cause Increased Thirst and Urination

Corticosteroids have a massive impact on the body's ability to conserve water, increasing fluid loss through urination by several mechanisms. Increased levels of glucose in urine draw out water through the kidneys, while mineralocorticoid effects alter electrolyte levels, driving thirst and increasing excretion.

For these reasons, it is very common to notice an increase in water intake, and it is also possible that your well-trained indoor dog may start leaving puddles of urine in the house due to an increased frequency of urination coupled with weaker control of the bladder sphincter muscles.

Steroid Medications Make Your Dog Hungry

As mentioned above, a pet receiving steroids will experience mild-to-moderate diabetes symptoms. By reducing the effects of insulin in the body, prednisone will increase blood glucose levels, while reducing the body's uptake of nutrients (in lean tissues) and creating a feeling of hunger.

Unfortunately, corticosteroids also encourage the deposition of fat, so while pets with true diabetes will lose weight, those on prednisone and prednisolone will actually gain weight in the form of fat, while losing muscle mass.

Swollen, pot-bellied appearance of a dog on steroid treatment
Swollen, pot-bellied appearance of a dog on steroid treatment

Steroids Cause Muscle Wastage

As alluded to above, dogs on steroid treatment will exhibit marked muscle wastage. This is often most evident in the temporal muscles, giving the face and forehead a 'sharper' appearance. Loss of muscle strength in the abdominal wall leads to a characteristic pot-bellied appearance (as above), and muscle loss in the limbs contributes to exercise intolerance.

Another common complaint from owners is that their pets pant excessively; this again is due to muscle weakness in the chest wall and diaphragm, while house-soiling is at least partly due to effects on the sphincter muscles.

A rare complication of treatment is corticosteroid myopathy, which is a very painful condition due to depletion of intracellular levels of carnitine in skeletal muscle. If identified early, this can usuall be rectified by a reduction of dose and initiation of carnitine supplementation.

Supplements for Pets on Steroid Treatment

Nordic Naturals - Pet-Omega-3, Promotes Optimal Pet Health and Wellness, 180 Soft Gels
Nordic Naturals - Pet-Omega-3, Promotes Optimal Pet Health and Wellness, 180 Soft Gels

I recommend good quality Omega 3 oil supplements for all my patients on long term steroid treatment and find them to be very beneficial. As well as providing antiinflammatory effects, thus reducing the required dose of prednisone/prednisolone, Omega 3 helps prevent some serious side effects such as unwanted clot formation and hypertension.

Skin thinning and loss of elasticity due to steroid treatment
Skin thinning and loss of elasticity due to steroid treatment

Side Effects on Skin and Hair

Although prednisone and prednisolone are most often prescribed for skin disease, high doses can cause undesirable effects on coat and skin quality. Comedomes (blackheads) are commonly seen, while skin thinning and fragility can cause striae (stretch mark) formation, or even skin tearing in severe cases.

Calcinosis cutis, the deposition of calcium within the skin, can occur with very high doses, and can cause unsightly hard lumps to develop, often erupting through the skin surface.

Hair loss and a failure of hair to regrow following clipping are also extremely common effects.

Steroids Cause Immune Suppression

As well as causing the death of certain white blood cells (lymphocytes), corticosteroids inhibit communication between the components of the immune system, making unwanted bacterial infections a common complication of treatment.

Dental and urinary tract infections are most commonly seen, and any pet receiving long-term steroid medication should have regular oral examinations to detect the early stages of periodontal disease and hence prevent tooth loss. Regular monitoring of the pet's urine is also recommended to detect urinary tract disease, which often exists without obvious signs.

Less Common Side Effects of Steroids

Can cause myocardial thickening (rare)
PLiver & Pancreas
Hepatic lipidosis, pancreatitis
Hepatic lipidosis, pancreatitis
Vomiting, diarrhea, ulceration
Vomiting, diarrhea, ulceration
Blood clots / stroke
Blood clots / stroke

Reducing the Need for Steroid Medication

The key to reducing all of these unwanted side effects is to reduce the dose of steroid being administered. Your veterinarian should be advocating complementary therapies for your pets primary problem in order to achieve this. These other therapies will vary depending on the specific problem being treated.

Almost all pets with autoimmune or allergic problems will benefit from Omega 3 fish oil supplementation (see above). These oils are powerful antiinflammatories, as well as providing some protection from adverse steroid effects.

When dealing with allergic skin disease, it is crucial that any concurrent bacterial and fungal infections are controlled with appropriate topical and systemic treatments. Malaseb is a very useful shampoo when managing the first presentation of skin disease or when skin flares up, while a protectant shampoo such as Allermyl should be used for maintenance washing.

Pets with digestive problems will usually benefit from dietary change, meticulous parasite control, probiotic treatments, and low-dose antibiotic treatment. While steroids will usually still be required, the dose will often be greatly reduced.

Finally, one should be aware that steroids need not be used in isolation for treating any of these ailments. While prednisone and prednisolone will usually be the first-line treatments, other drugs such as oclacitinib, ciclosporine and azathioprine can often be used in combination to reduce side effects.

As a veterinarian, I can say without doubt that countless animals would lead poorer lives without the availability of steroid medication for the treatment of many common conditions. However, there is much scope on the parts of both veterinary surgeons and owners to exercise greater care in their use and to explore alternative treatment options in order to minimise potentially harmful side effects.

Please Share Your Experiences of Steroid Treatments

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      Janice Kay 7 weeks ago

      Causing skin issues and fatigue. Wish I could find something for colitis besides steroids.