Preventing Disease Spread

Introduction

When bacterial and viral outbreaks, such as strangles and rhinopneumonitis respectively, occur in barns, owners commonly ask:

• • How long will the bacteria, virus, or other disease agent stay in the barn?

• How do I stop the agent from spreading from horse-to-horse or from barn-to-barn?

• How can I disinfect the barn?

Many disease agents (bacteria, such as Streptococcus equi which causes strangles, viruses, and parasites) can remain in a barn for considerable time. They can be harboured in the horses themselves, in the fecal and organic matter, which has been ground into the wood and cement of the barn, in the soil in the pasture, and in rodents or birds that live in the barn. Horse handlers can also be a reservoir or source of the disease agent, either by harbouring disease agents such as salmonella or methicillin-resistant Staphylococcus aureus (MRSA) or by carrying the agent on their clothing and shoes.

Personal Hygiene

The horse industry is very lax when it comes to personal hygiene as a means of preventing the spread of disease. To prevent the spread of disease, the swine and poultry industries require that their employees “shower in and shower out” of their facilities. Horse people, however, commonly go from barn to barn and from a show to home without any concern for disease spread.

Horse handlers should dedicate boots and clothing for use only on that farm. If this is not possible, boots should be cleaned prior to entering the premise and freshly laundered clothing should be worn. A freshly laundered pair of coveralls would also suffice. This is also true when returning from a horse show. Handlers should be encouraged not to wear the same clothing home or to at least change clothes before entering their barn, as there is the potential for them to carry a problem back to their farm.

Hand Washing

Hand-washing facilities should be suitably located around the barn/farm to encourage the frequent washing of hands. Research at a human hospital showed that, as the access to a hand-washing facility increased, the hand-washing compliance increased¹. Thorough hand washing with soap is adequate in most cases. Antiseptic soaps (e.g., chlorhexidine) or iodophor shampoo/washes (e.g. Betadine scrub) may also be used and should be located at the sink in an easy dispensing container. The use of alcohol based hand gel disinfectant may be an alternative or adjunct to hand hygiene in horse barns. Dispensers could be attached to the handler’s belt or outside of the stalls, allowing horse handlers the opportunity to disinfect their hands after working with an individual horse. These products require 15 seconds for the disinfectant to dry and provide good hand disinfection. They reduce the overall time required to disinfect one’s hands. Choose a product that doesn’t dry out the skin or cause skin irritation. Hand washing is also important to prevent chemical contamination of the workplace when working with horse medicines. Products such as the progesterone product, Regu-Mate®, and the horse dewormer, Eqvalan®, are commonly used around horse barns. They should be washed off immediately if they come in contact with bare skin. If workers are required to walk a long distance and open doors to reach a sink, the hand washing won’t occur and door handles and other objects will become contaminated.

Cleaning the Barn and Stalls

The number one rule for disease control is cleaning. Clean means free of dirt and organic matter such as manure. This means the removal of all manure and feed, followed by washing, scrubbing and rinsing, or pressure washing, all surfaces with hot water and detergent. This is followed by the use of a disinfectant according to label directions. (Complete label details for many of the common disinfectants are included in the Compendium of Veterinary Products, available in your veterinarian’s office.) Thorough cleaning will remove most of the contamination and allow disinfectants to penetrate surfaces and kill microorganisms. Thorough cleaning is a must. This is difficult to accomplish in many horse barns due to the presence of wooden walls, dirt floors, open ceilings and lack of drains. When building a new barn, choose a design and materials that will make cleaning easier. Incorporate drains in appropriate locations. In barns with sand or other porous floors, thorough cleaning may entail replacing the sand or clay from the stalls.

Types of Disinfectants

A disinfectant is a chemical or substance that kills microorganisms and is applied to objects. Disinfectants are too toxic, irritating or corrosive for use on living animals, including people. Disinfectants kill microorganisms but may not kill bacterial spores, which are a dormant form of some bacteria, e.g., Clostridia.

The “Active Ingredients” section of the label on the container of disinfectant will identify the type of product. Most commonly, they fall into the chemical categories as listed in Table 1.

The presence of organic material, including bedding, manure, blood, and pus, interferes with the action of most disinfectants. This is the reason that the directions on most disinfectants recommend thorough cleaning of the surface to be disinfected before applying the product. Some products include the use of both a detergent and a disinfectant. Thorough cleaning will remove the majority of the organisms and expose the rest to the action of the disinfectant. Follow the label directions before using. The product label will often state a dilution rate when being used either as a germicidal cleaner (killing microorganisms) or as a sanitizer (reducing the number of microorganisms). A minimum contact time is normally stated on the label. The minimum contact time is the time required to kill microorganisms. The kill time is affected by the presence of organic matter, temperature, pH, hardness of water and concentration of disinfectant.

Special Uses for Some Types of Disinfectants

Needles and syringes can not be sterilized completely by chemical disinfectants. Boiling in water for 30 minutes will sterilize needles and syringes. Chemical disinfectants will kill most microorganisms. Refer to the following list for the specifics for the common disinfectants. Regardless of disinfectant, you must follow the labelled directions for contact time and mixing directions and rinse the equipment prior to use in order to remove traces of the chemical disinfectants.

• Glutaraldehyde solutions are commonly used in hospitals to disinfect instruments. Glutaraldehyde kills most viruses and bacteria.

• Alcohol is commonly used for cleaning equipment on the farm but does not kill bacterial spores.

• Chlorhexidine is not active against all bacteria that are found on the skin or some viruses.

• Quarternary ammonium compounds are active against most bacteria fungi and viruses but not against bacterial spores and some viruses.

• It is best to use new sterile disposable syringes and needles each time.

For washing animals or washing your hands, use chlorhexidine or iodophor surgical scrub, shampoo or washes (e.g., Betadine scrub). As a skin antiseptic prior to a surgical procedure, chlorhexidine or iodophor skin antiseptic, e.g., Betadine solution, are applied.

Table 1: Disinfectants: Examples and Factors Affecting their Action

The products mentioned below are to assist horse owners when choosing a disinfectant. This is not an endorsement of these products.