RED DEER – Super drugs to combat super bacteria are not necessary in most western Canadian veterinarian practices.
The Western College of Veterinary Medicine in Saskatoon has completed an analysis of common horse ailments and treatments seen at the college’s diagnostic clinic between 1998-2002.
It concluded that most infections are caused by easy-to-manage bacteria, said Trish Dowling, who teaches clinical pharmacology at the veterinary school.
The study was presented at the recent Alberta horse breeders and owners conference in Red Deer Jan. 12. It set out to prove there are few antibiotic resistance problems and that powerful drug cocktails are not necessary except in extreme cases.
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As a primary diagnostic clinic, the college receives local animals with ailments commonly seen in western Canadian veterinary practices.
Strains of the bacteria streptococcus and staphylococcus, as well as E. coli infections, are the most common disease-causing agents in western Canadian livestock, said Dowling.
Treatments are usually straightforward and do not require high powered drugs with the risk of major side effects.
“When I know what I am trying to treat, then I know how to go looking for the right drugs for an effective antibiotic therapy,” Dowling said.
However, antimicrobial therapy is not without risk. Farmers are able to buy common antibiotics over the counter in farm supply stores, but therapy on the farm can do more harm than good.
Bacterial flora in the horse’s gut are sensitive to changes caused by antibiotics. Diarrhea and other serious side effects, such as swelling, are possible. As well, the wrong medicine can be bought, which doesn’t help the animal.
“Use of antibiotics without a diagnosis, without knowing what you are going after, is very illogical,” Dowling said. “You can do greater harm to your horse.”
Streptococcus zooepidemicus is the most common pathogen detected in Western Canada. The bacteria is responsible for most upper respiratory tract infections and in most cases, penicillin is the most effective treatment. Ceftiofur, a broad spectrum antibiotic sold under the brand name Excenel, is also effective.
The study found a resistance problem with sulfa drugs. While they are common because they are easy to administer, they are only about 50 percent effective against strep infections.
Strangles is a horse disease that forms lymph node abscesses. Vaccinations are available and penicillin can be effective against the bacteria, but it is difficult for the drug to work through the fibrous outer layer of the abscess. More effective drugs for penetrating abscesses are erythromycin and enrofloxacin, sold as Baytril.
Pneumonias and pleuropneumonia are serious problems in horses. Shipping stress is the most common cause of pleuropneumonia.
A horse can become ill if its head is tied up during transport for long periods. Horses need to lower their heads to drain their noses and if tied up, infectious bacteria run down the trachea.
Once the disease sets in, other secondary bacteria can invade and the horse becomes ill.
“This is one of the most draining diseases you’ll ever see in a horse,” Dowling said.
Penicillin and ceftiofur work, but must be administered early.
“If we don’t turn them around quickly, the disease can get so severe we can’t win the war.”
A powerful combination of penicillin, gentamicin and enrofloxacin is required to save the horse. A more powerful drug, metronidazole, is used on the anaerobic bacteria responsible for secondary infection.
“When we try to treat these horses with this triple cocktail of very powerful drugs, this is the time we see the surviving bacteria that are the superbugs,” she said.
Reproductive tract diseases and uterine infections are often caused by strep bacteria and E. coli found in fecal matter.
A laboratory examination is important to determine which bacteria are responsible for these kinds of infections. They can be difficult to treat, but ceftiofur is the first drug of choice.
An array of bacteria found on the outside of the horse may invade post surgical incisions, lesions and wounds.
Bacterial cultures are often necessary to determine the best antibiotics for the condition following an infection of a wound.
Eye infections are most commonly caused by strep zoo and can be treated with a triple antibiotic ointment or gentamicin.
