Corticosteroids for Dogs - Types, Dosage and Side Effects
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Corticosteroids are drugs used to treat a wide variety of pathologies in veterinary medicine. They have powerful anti-inflammatory and immunosuppressive action. This action make them highly effective drugs for treating allergic and inflammatory processes, autoimmune and immune-mediated diseases, and other pathologies. Although effective, their strong pharmacodynamics means they can have strong side-effects, regardless of having a sensitivity to their active ingredients.
Learn more about corticosteroids for dogs with AnimalWised. We explain the types of of corticosteroids used in veterinary medicine, what they are used to treat, what side-effects of corticosteroids may present and we provide a guide on likely dosage. It is important to note from the outset that corticosteroids should never be administered without a veterinary prescription.
What are corticosteroids for dogs?
It is important to note the difference between the terms steroids and corticosteroids. Steroids refers to a diverse ground of active organic compounds which can both alter the action of cells and send signals to alter various molecules in an organism.
Corticosteroids are a specific class of steroids. They are produced in the adrenal cortex of vertebrates, but can also be produced synthetically. The artificially synthesized kind are the ones used as drug medication in human and veterinary medicine. Despite there being many different types, corticosteroids are often referred to simply as steroids. It is important to differentiate between these and other types of steroids such as anabolic steroids. The latter are those which are commonly used as performance-enhancing drugs.
Types of corticosteroids for dogs
There are two groups of endogenous corticosteroids: glucocorticoids and mineralocorticoids. Both of them have a specific function. Below we detail what corticosteroids for dogs are for depending on the type:
Glucocorticoids for dogs
The main representative of glucocorticoids is cortisol, colloquially known as the ‘stress hormone’. This hormone is produced in the cortex of the adrenal glands, specifically in the fascicular zone. Its synthesis is regulated by the hypothalamic-pituitary-adrenal axis (HPA axis). When cortisol levels in the blood increase, the HPA axis sets the directives which stops the synthesis of this hormone.
The most commonly used corticosteroids in veterinary medicine include prednisone, hydrocortisone and dexamethasone. These are synthetic steroids which can have an affect on various hormones of the dog's body, cortisol being one of the most common. They have a greater glucocorticoid than mineralocorticoid effect.
Glucocorticoids are drugs that act virtually throughout the body. They are among the most widely used drugs in veterinary medicine due to their two main effects:
- Anti-inflammatory: their action inhibits phospholipase A2 and consequently prevents the production of inflammatory mediators such as prostaglandins, prostacyclins and thromboxanes. This makes them very effective drugs for the treatment of allergic and inflammatory processes.
- Immunosuppressive: when used at high doses, an immunosuppressive effect is achieved by altering the function of lymphocytes and macrophages. This is due to inhibiting the synthesis of interferon gamma and different interleukins. For this reason, they are used for the treatment of autoimmune diseases, immune-mediated diseases and neoplasms.
Mineralocorticoids for dogs
The main representative of this type of corticosteroids for dogs is aldosterone. This hormone is also synthesized in the adrenal cortex, specifically in the zona glomerulosa (the outermost region of the adrenal cortex). In this case, its synthesis is regulated by the renin–angiotensin system (RAS).
As we have mentioned, most corticosteroid drugs have a greater glucocorticoid effect. However, insome drugs the mineralocorticoid effect predominates, as is the case of fludrocortisone or deoxycorticosterone deprivation. These drugs make it possible to maintain hydroelectrolytic balance in animals with a deficiency of aldosterone, the natural mineralocorticoid.
In any case, it must be taken into account that corticosteroids are symptomatic treatments, i.e. they serve to control the symptoms associated with certain pathologies. Once the administration of the drug is finished, the underlying pathology may reappear since they do not treat the underlying cause.
Corticosteroid dosage for dogs
Corticosteroids are drugs that have an anti-inflammatory effect when used at medium doses and an immunosuppressive effect at high doses. The dosage of corticosteroids for dogs will depend on the active ingredient that is prescribed. However, in all cases, the following corticotherapy protocol must be followed:
- Induction phase: high doses of corticosteroids are administered to control the disease. This phase can last from days to weeks.
- Transition phase: the dose is gradually decreased to reduce both the intensity of adverse reactions and the cost of treatment. This phase lasts from weeks to months.
- Maintenance phase: in this phase, the objective is to administer the minimum effective dose. This is the dose that allows the disease to be controlled and that minimizes the appearance of adverse reactions.
- Treatment withdrawal: when the clinical signs are controlled or the disease is cured, treatment should be withdrawn. The objective of this phase is to reduce the dose of corticosteroids progressively until it is equal to the levels of endogenous (organic) corticosteroids that the animal had before treatment. To withdraw treatment with corticosteroids, it is essential to follow a rigorous protocol. Otherwise, harmful effects on the patient's health may occur. Next, we explain how corticosteroid treatment should be withdrawn in dogs.
How to withdraw corticosteroid treatment in dogs
To understand the importance of withdrawing corticosteroid treatment, we need to return to the hypothalamus-pituitary-adrenal axis (HHA axis). This axis is responsible for regulating the synthesis of endogenous corticosteroids in the body.
When we administer corticosteroids exogenously (synthetic corticosteroids in the form of medication), they are increased in the blood. This inhibits the axis and prevents the adrenal glands from synthesizing endogenous corticosteroids. In other words, during treatment with corticosteroids, the dog's body does not synthesize these hormones, since it detects that blood levels are sufficient.
Understanding this mechanism is essential when making a correct withdrawal of corticosteroid treatment. If treatment is withdrawn abruptly, the adrenal glands will not be prepared to synthesize the levels of corticosteroids the body needs. Acute adrenal insufficiency will occur, characterized by the appearance of lethargy, fever, muscle pain, hypertension and stress.
To prevent this withdrawal syndrome from occurring, it is important to reduce the dose gradually. This stimulates the resumption of activity of the adrenal glands.
- Short-term treatments (: the dose will be reduced the last two days to avoid the appearance of adverse effects.
- Long-term treatments (>2 weeks): when it is decided to withdraw treatment, the dose will be reduced by half each week until physiological levels of corticosteroids are reached. After that, the treatment will continue on alternate days to afford complete withdraw of the corticosteroids without the risk of adverse effects appearing.
Side effects of corticosteroids in dogs
Corticosteroids are drugs that can act in almost all areas of the body. This makes them very useful therapeutic medications for treating a huge variety of pathologies. However, this same characteristic means they are also drugs with a large number of side effects.
All administration of corticosteroids inherently entails the presentation of adverse reactions that, although foreseeable, are not avoidable. However, clinical management of these drugs makes it possible to reduce these unwanted effects and achieve a balance between disease control and the occurrence of adverse reactions.
Next, we explain the main side effects associated with corticosteroid treatment in dogs:
- Steroid liver disease: glucocorticoids have an anabolic effect on carbohydrates, meaning they promote the formation of glucose and its storage as glycogen in the liver. This accumulation of excessive glycogen in the liver leads to engorgement of the organ, which is known as hepatomegaly. However, it is important to know this alteration never leads to liver failure and the situation reverses when corticosteroid treatment is withdrawn.
- Hyperglycemia: as a consequence of its anabolic effect on carbohydrates, there is an increase in blood glucose levels (hyperglycemia). They are considered diabetogenic drugs because their administration gives rise to typical clinical signs of diabetes, such as polyphagia, polydipsia and polyuria. Learn more about canine diabetes with our article on insulin for diabetic dogs.
- Muscle weakness: unlike what happens with carbohydrates, corticosteroids produce a catabolic effect on proteins. This means they can break down these molecules to obtain energy from them. For this reason, they produce muscle weakness, which is manifested by the presence of a pendulous abdomen and signs of respiratory distress, such as gasping or tachypnea (rapid breathing).
- Gastrointestinal adverse reactions: they reduce the production of mucus and inhibit the renewal of the gastrointestinal epithelium. This can encourage the presentation of gastrointestinal ulcers. When used at immunosuppressive doses, they also induce the appearance of bacterial-type diarrhea.
- Dermatological adverse reactions: in medium and long-term treatments skin breakages, alopecia, bruising due to muscle weakness and delayed healing can be observed. In addition, the appearance of Calcinosis cutis is frequent. This is a dystrophic calcification in the skin that manifests itself with a scabbed and crusty skin lesion.
- Infections: its immunosuppressive effect makes the body more vulnerable to pathogens, thereby increasing the incidence of secondary infections. These most commonly affect the skin, the urinary system or the gastrointestinal system.
- Hypertension: by encouraging the reabsorption of potassium and water, potassium in the blood is reduced and blood pressure is increased.
- Behavior changes: can vary from states of depression to states of excitability or nervousness.
Contraindications of corticosteroids in dogs
Knowing the main side effects associated with corticosteroid treatment in dogs, it will be easier for us to understand the main situations when their administration is counterproductive.
The main contraindications of corticosteroids for dogs are:
- Bacterial, viral, fungal or parasitic infections: due to its immunosuppressive effect.
- Diabetes mellitus: due to increase in blood glucose levels.
- Ulcers: these can be corneal and gastrointestinal ulcers, as well as skin ulcers, occurring to due the delay in healing.
- Glaucoma: because they increase intraocular pressure by altering the drainage of aqueous humor. See our related article on why there is blood in my dog's eye.
- Hyperadrenocorticism or Cushing's Syndrome: since corticosteroid levels increase. Learn more about Cushing's syndrome in dogs.
- Kidney disease or cardiovascular disease: due to their hypertensive effect.
- Puppies: since they can stunt growth.
- Pregnancy: can cause fetal abnormalities, miscarriage or premature delivery.
- Lactation: when excreted in milk, they can affect the growth of lactating puppies.
- Older or malnourished dogs: due to their catabolic effect on proteins.
- Allergies: to the active ingredient, to other corticosteroids or to the excipients of the drug.
Due to a relatively high number of contraindications, the veterinarian will need to asses alternatives. Only they will be able to prescribe the correct treatment. Do not treat your dog without consultation and never give corticosteroids to a dog without explicit direction from a trusted veterinarian.
This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.
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- Plum, D. C. (2006). Manual of Veterinary Pharmacology. Intermédica.
- Riviere, J. E., & Papich, M. G. (2018). Veterinary pharmacology and therapeutics. John Wiley & Sons