Are Antihistamines Safe For Dogs?
Antihistamines are medications used for the ongoing treatment of allergies. Its use is not frequent in dogs, but exists in veterinary medicine.
Due to their widespread use in humans, it is common to ask: are these types of drugs safe for dogs? As always, the veterinarian will dictate the treatment to be followed, but here is some information about the antihistamines that will reassure all dog owners with allergies.
What is histamine?
As its name implies, the antihistamine acts on histamine. Histamine is a molecule released by the mammalian immune system in allergic processes and has a local reaction. In addition, it also plays other roles in the bloodstream and nervous system.
In the case of allergy, histamine participates in hypersensitivity reactions to an allergen (grass pollen, dust, some type of food…)
- Produces tissue inflammation. It increases blood volume by vasodilation, allows fluid to exit the detected area, and attracts leukocytes. Inflammation causes redness, heat, swelling and itching.
- Regulates sleep. It acts on the nervous system as a neurotransmitter. Histamine prolongs wakefulness and reduces sleep, acting the opposite of melatonin.
Types of Antihistamines for Dogs. How do they work?
Antihistamine drugs are divided into three different types, and each attenuates their effects differently:
- Physiological antagonists. These are chemical compounds that produce the opposite physiological effects of histamine: adrenaline, ephedrine, xanthine…
- Histamine Release Inhibitors. They reduce the consequences of histamine in the body, preventing its release into the bloodstream.
- Competitive pharmacological antagonists or antihistamines. They are drugs that occupy histamine receptors, so they cannot act on their cellular targets. Within this category, there are three different types of antihistamines in dogs, depending on the type of receptor they interact with: H1, H2 and H3.
Are Antihistamines Safe for Dogs?
Antihistamines are safe for dogs as long as they are correctly prescribed by a veterinarian and the dog’s guardian follows their instructions. Stopping symptoms caused by a large release of histamine (typical of allergic reactions) and protecting the gastrointestinal mucosa are its main effects.
H1 antihistamines act on histamine H1 receptors, responsible for vasodilation, vascular permeability and contraction of the bronchial and intestinal muscles. These types of medications are used in allergic reactions and anaphylactic shock. Also when there is itching, hives, dermatitis, eczema, insect bites, among others, in combination with other drugs.
Histamine H 2 receptors regulate the secretion of HCl in the stomach and have a cardiac-stimulating effect. Antihistamine antagonists of this receptor are used to alleviate effects on the digestive system, specifically gastroduodenal ulcers and gastritis.
H 2 receptor antagonist antihistamines are used because they have an antisecretory effect until the gastric protective barrier is restored.
Side Effects of Antihistamines in Dogs
Antihistamines are usually prescribed along with other medications to treat the symptoms caused by allergies, but the disappearance of the itching, one of the most striking symptoms in these cases, is not immediate. Its effect is enhanced by adding omega 3 or omega 6 acids to the dog’s normal diet.
These medications can have certain side effects, which are reported by the veterinarian before use. Drowsiness is the main side effect of antihistamines, but rarer ones may appear:
- Anorexia.
- Vomiting.
- Diarrhea.
- Increased itching.
It is very important that the veterinarian recommends the use of antihistamines. Do not self-medicate the dog, as these medications should be used with caution in animals with pregnancy, liver disease, seizures, urinary retention, glaucoma, and gastrointestinal atony.
There are alternatives to using antihistamines, either as oral medication or as a topical treatment, but you should always consult your veterinarian before applying them.
