Corticosteroids are drugs used to treat a wide variety of pathologies in veterinary medicine. Their powerful anti-inflammatory and immunosuppressive effects make them highly effective drugs for treating allergic and inflammatory processes, autoimmune and immune-mediated diseases, among others. However, it must be taken into account that its use is not exempt from the appearance of side effects that, although foreseeable, are not avoidable.
If you want to know more about corticosteroids for dogs, don't miss the following article on our site in which we talk about types, dosage and side effects of these drugs.
What are corticosteroids for dogs?
Before mentioning the different types of corticosteroids for dogs, we must explain what they are and what their function is. Corticosteroids are drugs analogous to corticosteroids or endogenous corticosteroids, that is, they are artificially synthesized molecules that mimic the effect of corticosteroid hormones produced naturally by the body of dogs.
Now then, what are corticosteroids used for in dogs? Next, we see the different types and their uses in these animals.
Types of corticosteroids for dogs and their uses
There are two groups of endogenous corticosteroids: glucocorticoids and mineralocorticoids. Each one of them has a function, so we will see below 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 at the level of the cortex of the adrenal glands, specifically in the fascicular zone, and its synthesis is regulated by the Hypothalamic-Pituitary-Adrenal axis, so that when cortisol levels in the blood increase, the axis and stops the synthesis of this hormone.
The most commonly used corticosteroids in veterinary medicine, including prednisone, hydrocortisone or dexamethasone, 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:
- They are powerful anti-inflammatories: since they inhibit phospholipase A2 and, consequently, prevent 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.
- They are immunosuppressive: when used at high doses, an immunosuppressive effect is achieved by altering the function of lymphocytes and macrophages and by inhibiting the synthesis of interferon gamma and different interleukins. Therefore, they are indicated for the treatment of autoimmune diseases, immune-mediated diseases and neoplasias.
Mineralocorticoids for dogs
Its main representative is aldosterone. Similarly, this hormone is synthesized in the adrenal cortex, although at the level of the zona glomerulosa. In this case, its synthesis is regulated by the Renin-Angiotensin-Aldosterone axis.
Although, as we have mentioned, most corticosteroid drugs have a greater glucocorticoid effect, there are also drugs in which the mineralocorticoid effect predominates, as is the case withfludrocortisone or the deoxycorticosterone deprived These drugs allow to maintain hydroelectrolyte balance in animals with a deficiency of aldosterone, the natural mineralocorticoid.
In any case, it should be borne in mind that corticosteroids are symptomatic treatments, that is, they serve to control the symptoms associated with certain pathologies, but once the administration of the drug is finished, the underlying pathology may reappear since the underlying cause is not treated.
Dose of corticosteroids for dogs
As we have explained, corticosteroids are drugs that have an anti-inflammatory effect at medium doses and an immunosuppressive effect at high doses.
Doses of corticosteroids for dogs will depend on the active ingredient 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 the intensity of adverse reactions and reduce 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, that is, the dose that allows controlling the disease and minimize the appearance of adverse reactions.
- Treatment withdrawal: When the clinical signs are controlled or the disease is cured, the treatment should be withdrawn. treatment. The objective of this phase is to reduce the dose of corticosteroids progressively until it is equal to the levels of endogenous corticosteroids that the animal had before treatment. To withdraw treatment with corticosteroids, it is essential to follow a rigorous protocol, since otherwise, harmful effects on the patient's he alth may occur. Next, we explain how to withdraw corticosteroid treatment in dogs.
How to withdraw corticosteroid treatment in dogs?
To understand the importance of withdrawing corticosteroid treatment, we must once again mention the Hypothalamus-Pituitary-Adrenal axis (HHA axis). As we explained at the beginning of the article, this axis is responsible for regulating the synthesis of endogenous corticosteroids in the body. When we administer corticosteroids exogenously, there is an increase in them in the blood, which inhibits the axis and prevents the adrenal glands from synthesizing endogenous corticosteroids. That is, during treatment with corticosteroids, the body does not synthesize these hormones, since detects that blood levels are sufficient.
Understanding this mechanism is essential when making a correct withdrawal of corticosteroid treatment. If a abrupt withdrawal of treatment is carried out, the adrenal glands will not be prepared to synthesize the levels of corticosteroids that the body needs and awill occur. acute adrenal insufficiency , characterized by the onset of lethargy, fever, muscle pain, hypertension and stress.
To prevent this withdrawal syndrome from occurring, it is important to reduce the dose gradually to stimulate the resumption of glandular activity adrenals.
- In short-term treatments (less than 9 days): the dose will be reduced the last two days to avoid the appearance of effects adverse.
- In long-term treatments (greater than two weeks): when it is decided to withdraw treatment, the dose will be reduced gradually. half every week until physiological levels of corticosteroids are reached. After that, the treatment will be continued on alternate days to finally completely withdraw the corticosteroids without the risk of adverse effects appearing.
Side effects of corticosteroids in dogs
Corticosteroids are drugs that act practically in all areas of the body, which makes them very useful therapeutic alternatives for treating a huge variety of pathologies. However, this same characteristic means that they are also drugs with a large number of side effectsAll administration of corticosteroids inherently entails the presentation of adverse reactions that, although foreseeable, are not avoidable. However, the rational management of these drugs makes it possible to reduce these unwanted effects and thus achieve a balance between disease control and the occurrence of adverse reactions.
Below, we explain the main side effects associated with corticosteroid treatment in dogs:
- Steroidal liver disease: Glucocorticoids produce an anabolic effect on carbohydrates, which means that they favor the formation of glucose and its storage as glycogen in the liver. This accumulation of excessive glycogen in the liver leads to an increase in the size of the organ, which is known as hepatomegaly. However, it is important to know that this alteration never leads to liver failure and that 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.
- Muscle weakness: unlike what happens with carbohydrates, corticosteroids produce a catabolic effect on proteins, that is, that is, they tend to break these molecules down to get 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.
- Gastrointestinal adverse reactions: at the digestive level, they reduce the production of mucus and inhibit the renewal of the epithelium, which favors the presentation of gastrointestinal ulcers. In addition, when used at immunosuppressive doses, they induce the appearance of bacterial-type diarrhoea.
- Dermatological adverse reactions: in medium and long-term treatments, fragile skin, symmetrical areas of alopecia, appearance of bruising due to muscle weakness and delayed healing. In addition, the appearance of Calcinosis cutis is frequent, a dystrophic calcification at the level of the dermis that manifests itself with a skin lesion in the form of a crusty plaque.
- Infections: its immunosuppressive effect makes the body more unprotected against pathogens, thus increasing the incidence of secondary infections, which can affect the skin, urinary tract, or gastrointestinal system.
- Hypertension: By favoring the reabsorption of potassium and water, and favoring the excretion of potassium, it increases blood pressure.
- Behavior changes: can range 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 in which their administration is counterproductive.
Below, we collect the main contraindications of corticosteroids for dogs:
- Bacterial, viral, fungal or parasitic infections: due to its immunosuppressive effect.
- Diabetes mellitus: because they increase blood glucose levels.
- Ulcers (both corneal and gastrointestinal ulcers, as well as skin ulcers): since they delay healing.
- Glaucoma: because they increase intraocular pressure by altering the drainage of aqueous humor.
- Hyperadrenocorticism or Cushing's Syndrome: since corticosteroid levels increase.
- Kidney disease or cardiovascular disease: due to its hypertensive effect.
- Puppies: since they can stunt growth.
- Pregnancy: May 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 its catabolic effect on proteins.
- Allergies to the active ingredient, to other corticosteroids or to the drug's excipients.
If these drugs cannot be administered, there are alternatives that the professional must assess. We talk about them in this article: "Alternatives to corticosteroids in dogs".
