Human Health Concerns When Working
With Medications Around Horses
Table of Contents
- Routes of Human Exposure to Livestock
- Problems with Specific Chemicals
- Protect yourself and others
- Who to Telephone for Help
There are a number of drugs which horse handlers must be careful with
for their own health and protection. Carelessness can result in various
degrees of risk from exposure to the product being used. Risk is the chance
of being harmed or suffering loss. The person handling the drugs assumes
risk each time an animal is given a treatment. Information about the potential
human health hazards appears on the product label. For health and safety
reasons, obey the details of these statements.
Routes of Human Exposure to Livestock
People expose themselves to potential injurious effects of drugs by five
main routes: dermal (skin), eyes, injection into body tissue, inhalation
(lungs), and ingestion.
- Dermal exposure refers to contamination of the skin with the product.
The amount of drug absorbed and the speed at which it is absorbed depends
upon: the condition of the skin (intact or cuts), the body part contaminated
and the drug itself (chemical properties). Injectable prostaglandins
spilled onto the skin pose a unique risk to pregnant women.
- Eye contamination is another form of dermal exposure. The common ways
of eye contamination are from wiping your eyes with contaminated hands
or from blow-backs. Blow-backs can occur because of choosing the wrong
size of needle; the medication flows slowly or only with force through
the needle. The needle becomes blocked either prior to placing the needle
into the injection site or during the introduction of the needle through
the skin, or the needle is improperly attached to the syringe. In all
cases, when pressure is placed on the syringe, the medication sprays
back into the face of the operator. Medications can be corrosive or
irritating to the eyes. The eyes are a common entry route into the body.
- Accidental injection usually occurs as a result of inappropriate restraint
of the animal or carelessness. It can also occur because of improper
disposal of sharps which include needles, syringes and blades. Sharps
of all types should be placed in a puncture proof container after use.
The container should be clearly marked "sharps". When the
container becomes half full, contact your veterinarian or the local
health unit for proper disposal.
- Oral contamination can occur from inappropriate handling of the product.
Removing or holding the plastic case, which normally protects the needle,
in your teeth can lead to absorption orally. This is a bad habit to
- Inhalation exposure is usually as a result of inhaling powders or
mists. This can occur when using fly sprays or disinfectants. Pay attention
to the product details and the cautions. Protective clothing may be
required. In some cases, the hiring of licensed professionals will be
Problems with Specific Chemicals
- Antibiotics, such as penicillin, are commonly used
as injectable products for horses. There is a proportion of the
human population who are allergic to it.
- Tranquilizers are commonly used to control horses
during transportation, dental and hoof care procedures, as well
as surgical procedures. These products are extremely useful but
accidental exposure to a single drop of xylazine (e.g., Rompun®)
can result in respiratory arrest in humans. The administration
of tranquilizers has significant risk to both the animal and the
person administering the product.
- Hormones are synthetic and natural chemicals which
can have major impacts on the reproductive cycles of animals and people
and have widespread action on many body systems.
- Prostaglandins have several pharmacological effects
on the female reproductive system. They are used in horses to synchronize
estrus cycles and as an aid in inducing heats in difficult breeders.
Because of their effect on the reproductive cycle, pregnant women
should not handle these drugs. In addition, asthmatics and those
with bronchial diseases should handle these products with extreme
caution. The prostaglandins are marketed in several products including
Estrumate® and Lutalyse®. (Plumb 1999)
- Regumate contains altrenogest which is a synthetic
progestational agent used clinically to assist mares to establish
the occurrence of estrus. Altrenogest can be absorbed from contact
with skin. This oil-based product can penetrate porous gloves. Absorption
can be increased from areas covered by occlusive materials, such
as latex or rubber gloves. In case of accidental exposure, wash
immediately with soap and water. If the eyes are exposed, flush
immediately with water for 15 minutes and get medical help. The
manufacturer warns against the following individuals handling the
product: pregnant women, women with undiagnosed bleeding, people
with thrombophlebitis disorders, those with estrogen dependant tumors,
those with coronary disease, those with known or suspected carcinoma
of the breast, people with benign or malignant tumors which developed
during the use of oral contraceptives or estrogen containing products.
- Anti-inflammatory Medications.DMSO is well known
to horse owners. The active ingredient is dimethyl sulphoxide
which is a powerful solvent. It reduces swelling due to trauma
because of its hygroscopic properties (takes up water). It can
increase the penetration of low molecular weight allergens like
penicillin G and can cause a marked local reaction if topically
administered substances like liniments are present on the skin.
Therefore, apply only to dry skin. Rubber gloves should be worn
while applying DMSO. Human exposure will cause a garlic-like breath
and might cause local skin reaction, headache and nausea. Use
in well ventilated areas and avoid inhalation and contact with
eyes. (Bayley 1999)
- Anthelmintics. Dewormers such as the ivermectins
(e.g., Eqvalan®) are powerful chemicals and are commonly used with
horses. The manufacturer recommends not eating or smoking while using
dewormers and to wash hands after use. Avoid contact with eyes. Dispose
of unused products and containers by incineration or in a land fill
because ivermectin may adversely affect fish or water borne organisms
if disposed in water.
Medications should only be administered by or under the direction
of a veterinarian. Veterinarians may only dispense medications to
clients where there is a valid veterinarian/client/patient relationship.
Because the veterinarian is responsible for the proper use of medications
dispensed by himself or herself, there will be variations in their
comfort levels when considering whether to dispense medications
to individual clients.
When using medications, ensure that you read the label and follow the
warnings about human health dangers.
Protect yourself and others:
- read and follow label warnings and precautions
- avoid skin contact
- restrain animals for treatment
- wash hands or bathe after using medicines
- change contaminated clothing
- do not smoke or eat when handling medicines
- lock storage rooms and cupboards
- wear protective clothing
- wear protective gloves
- wear protective goggles
Who to Telephone for Help:
- Your Physician
- The Drug Manufacturer
Poison Information Centres:
Poison Control Centre for Ontario 1-416-813-5900, 1-800-268-9017
Ottawa Children's Hospital for Eastern Ontario
Emergency Department (Bilingual) 1-613-737-1100
Human or Animal 1-800-267-1373 (From 613 area code)
- N.G. Anderson, D. M. Alves, T. Blackwell, M.A. Godkin, G. Rietveld,
D. Stark, and R. Tremblay. 1994. Livestock Medicines Manual, Second
Edition. Livestock Technology, Ontario Ministry of Agriculture,
Food and Rural Affairs.
- A. Bayley 1999. Compendium of Veterinary Products, 6th. edition..
North American Compendiums Ltd.
- D.C. Plump 1999. Veterinary Drug Handbook, Third Edition. Iowa State
For more information:
Toll Free: 1-877-424-1300