Better Pork - August 2007

Herd Health

COCCIDIOSIS: Effective treatment remains in limbo

After Health Canada ordered the removal of Baycox from the market two years ago, producers have had to look to other means of controlling coccidiosis in suckling pigs. What are the alternatives?

by S. ERNEST SANFORD

It must have been some sort of premonition that caused me to revive concerns about coccidiosis (cocci) in our suckling pigs (see Better Pork, October 2004). It was just eight months after I wrote the alert about cocci being still alive and well in our suckling pigs that Baycox, the one drug that worked excellently against cocci, was removed from the marketplace by orders from Health Canada.

Here’s some background on how that happened and the subsequent fallout after Health Canada rescinded the provisional authorization for use of Baycox in June 2005.

Baycox (toltrazuril) is a veterinary drug manufactured by Bayer Animal Health. It had been in use in Canada since 1992 to treat cocci in newborn piglets. It had never been approved for sale in Canada, but was available to veterinarians from 1992 to 1998 via Health Canada’s Emergency Drug Release (EDR) program.

From 1998 to June 2005, it was available to a limited number of veterinarians across Canada who acted as clinical investigators under Health Canada’s Investigational New Drug Submission (INDS) program.  Health Canada evaluated data provided by Bayer under the INDS as part of the approval process.   Veterinarians participating in the INDS for Baycox were responsible for prescribing and evaluating its use and submitting safety and efficacy data to Bayer. Bayer then used the information for further research. About two to four per cent of the 32 million pigs produced in Canada annually (i.e. 640,000 to 1.28 million) were being treated with Baycox prior to its removal. 

Upon completion of its review of safety and efficacy data accumulated between 1992 and 2005, Health Canada determined that the risks of using Baycox in suckling pigs outweighed the benefits. Health Canada notified Bayer on June 13, 2005, that the INDS for Baycox was rescinded. Bayer stopped distribution of Baycox and recalled all unused units from veterinarians, in effect shutting down access to the drug across Canada. The number of pigs reported as being treated with Baycox seems incredibly low and the “risk” – supposedly, Baycox being a potentially cancer-causing substance – appears to be more myth than risk.

Paradoxically and significantly, Baycox had received regulatory license in several European Union countries for use in suckling pigs just the year before its removal in Canada, though Baycox is not approved for use in the United States.

Studies are currently underway to determine the level of coccidial activity in swine herds in Canada, which in turn could form the basis for obtaining approval for a suitable anti-coccidial drug, hopefully Baycox, for pigs. Preliminary results from these studies by Dr. Andrew Peregrine and his research team at the Ontario Veterinary College, University of Guelph, show that cocci is present and active in about 70 per cent of herds in Ontario, a level consistent with reported infection levels in many European and other countries around the world.

This level of cocci activity would also indicate that considerably more than the paltry two to four per cent of the pigs reportedly being treated with Baycox prior to its removal could benefit from treatment for cocci, a debilitating disease even at the subclinical level.
So what can the producer do?  Is there a suitable alternative drug for use against cocci? The first thing is to develop a plan of action. The plan can be laid out in a simple, straightforward, four-step format:

• Observe and recognize the clinical signs of cocci.
• Get a definitive diagnosis.
• Establish disinfection, hygiene and management procedures.
• Use an alternative treatment, if available.
•  

Clinical signs
Cocci is a protozoal (parasitic) infection that causes scours in suckling piglets usually at one to two weeks of age. The scour is pasty to watery and ranges from white to yellow or, more commonly, a pasty gray. It is notoriously unresponsive to antibiotics. Piglets continue to nurse but develop a rough hair coat, are dehydrated, depressed and become poor doers.

Severity of clinical signs may vary between litters in the same farrowing room and even between pigs in the same litter. Morbidity is high but mortality is usually low, unless secondary bacterial or viral infections occur.

Diagnosis
Diagnosis of cocci is best made by histological identification of various asexual and sexual stages of the coccidia in intestinal sections from pigs necropsied by your veterinarian or from pre-selected, live acutely scouring pigs submitted to the diagnostic laboratory. Examination of feces for cocci oocysts (eggs) is often unrewarding, unless specialized techniques are used and the fecal samples are taken later rather than earlier in the course of the disease.

Disinfection, hygiene and management. Cocci persists in the environment, specifically on the farrowing room floors, on the edges of slats or wherever fecal material is present. The sow plays a minor or nonexistent role in transmission of cocci. Furthermore, cocci eggs are resistant to most disinfectants.

Some disinfectants (cresolic acid or cresol-based compounds like Neopredisan, chlorine or ammonia in a 50 per cent solution) can kill cocci eggs. However, high-pressure hot water (at more than 70 C) washing of farrowing room floors and good old “elbow grease” are necessary for removal of egg-infested fecal material from pen floors, so that these disinfectants can get to do their job.

It is worth noting that high-pressure washers are actually capable of aerosolizing cocci eggs, which then fall back onto the pen floor when “the dust settles,” ready and waiting for the next litter of pigs to inhabit the pen. With this in mind, washing and cleaning should be followed by applying an effective disinfectant with a sprinkler can to avoid aerosolization.

Alternative treatment
Diclazuril (Clinicox) is an anti-coccidial drug very similar to toltrazuril that is currently licensed for use in poultry in Canada. Since the removal of Baycox, some vets have been using diclazuril to treat porcine cocci with apparent success. It must, nevertheless, be noted that researchers have been unable to show the efficacy of diclazuril in treating porcine cocci under controlled experimental conditions.

The following is an abbreviated version of a coccidiosis control program designed by Dr. Kevin Vilaca of Maitland Swine Services in Listowel. It starts with attention to the sanitation program.

Sanitation
A detergent is used to remove the biofilm. Thorough cleaning is required, including under heat mats and the sides of bars and feeders. Extra time and elbow grease should be used to make sure this is done properly.

Follow an initial wash by disinfecting with six per cent Javex (bleach) at a dilution of one part Javex to two parts water. Apply with a sprinkler can to avoid aerosolizing the cocci eggs.

Wear eye protection and a respirator during application procedure. Allow the leach to stand for 15-20 minutes, then rinse. Apply the final disinfectant and then allow the space to dry thoroughly before placing new pigs.

A sealer should be applied to the concrete surface if concrete is present anywhere in the creep area. Concrete is a notoriously porous material and the sealer effectively buries the eggs lodged in the porous concrete, blocking them from being picked up by successive litters that occupy the crate.

There is hope that studies being done at the University of Guelph will show that cocci is still an important infection in piglets, thus paving the way for the return of a dedicated anti-coccidial drug on the Canadian market. BP

S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) in Burlington. Email:esanford@bur.boehringer-ingelheim.com