Parasite treatment evolved to create two distinct management methods. Initially, treatment with products such as Fenbenzodol and/or Avermectin every six months as the prescribed treatment was standard practice. This is called the Prophylactic Method. Parasite resistance to drugs promoted an evolution that relied on more tolerance for parasites, and parasite identification prior to treatment.
M-worm
Before we delve into understanding the two methods of parasite treatment we need to point out the one exception when discussing parasites and that is M-worm. M-worm travels through the spinal column to the brain resulting in death. This cannot be tested by fecal and is only verified in necropsy. If threat of m-worm is present and you as a herd manager choose to accept the risk then treatment using Ivermectin every 28 days is the only prevention.
Prophylactic Method Defined
The Prophylactic treatment method periodically medicates every alpaca in the herd generally twice a year regardless of parasite presence. The theory works on the premise of substantial reduction or elimination of all parasites at one time in the herd. This is often coupled with pasture rotation placing the “now clean” alpacas on virgin ground making re-infection less probable.
Reason to Change
Problems with parasite resistance to many common drugs along with a supporting theory how to weaken parasites evolved into a new approach to parasite treatment, probably best thought of as parasite control. It relies on the fact that all alpacas carry parasites and conditions of stress disable natural resistance and allow a parasite bloom. This does not necessarily happen throughout the herd at one time.
Identification Method Applied
The Identification Method works well in small and large herds by taking representative samples from a certain percent of the population of commonly housed group. When the parasite count hits critical then treatment is applied. Critical counts depend upon the type of parasite discovered. Strongyles, specifically Barber Pole would receive treatment at a lower count than say Tapeworms or Nematodirus due to the impact each presents to the alpaca.
The Three A's - Appetite, Appearance, Attitude
The Identification Method and assumed risk of M-worm are conducive to employing the Three A’s. The Three A’s are Appetite, Appearance, and Attitude. An alpaca that is off feed even one day is a caution. Two days would indicate taking the vitals which minimally include a fecal and temperature. If longer a vet and blood draw are recommended as this might indicate a serious condition.
Appearance
If the alpaca is showing physical issues such as a limp, hunched, kushed or prone more than usual, circle walking, longevity at the poop pile without voiding or frequent trips, and standoff from the herd are some of the concerns of appearance. Alpacas are extremely stoic. Our standard here is if we see an issue in appearance we are probably already dealing with a serious if not life threatening problem and error on caution. One appearance that is not associated to physical appearance of the alpaca is beans that are either pudding or projectile diarrhea in consistency. Soft or poorly organized beans can result for many reasons such as new grass if pasture or hay. If concerned take a fecal and temperature.
Attitude
Last of the three A’s is attitude. If your alpaca no longer demonstrates its personal attitude attention is warranted. As you can see the Three A’s rely on knowing your individual alpacas nature and general behavioral characteristics. Knowing your alpacas intimately is the second best approach to capturing problems before they evolve into critical emergencies requiring a veterinary intervention and help.
Weigh In for Health
Before venturing into the pros and cons between prophylactic or identified treatment we would like to provide the single best method to catch 99% of parasite problems short of fecal. Weigh your alpacas regularly – monthly minimally, but if you really want to stay on top of your herd health weekly will be a real eye opener. Weight will fluctuate but it is the ever downward reduction in weight that raises the alarm even if ½ pound a week. Taking weight consistently over the same interval of days and about the same time usually provides the best comparative results. Weighing a percent of the herd each time till all have been weighed will provide insight and reduce physical efforts.
Pro-Con Prophylactic vs Identification
Well what is the better method – prophylactic or Identified? We have had success using either method. When we utilized the prophylactic method we timed our treatments to coincide with changing weather conditions treating once in the spring after frost was out of the ground and then in the fall after freeze up. Our plan was to start with a clean pasture in the spring and clean dry lot during winter. This worked.
Reason to Change
While we employed the prophylactic method we heard about resistant strains of parasites and that we should start using the identification system. Being relatively new the reasons behind converting were not relevant and what we were doing worked right up to our first resistant parasites. We got the veterinary involved who took fecal and blood. Tests demonstrated what we had and that told us how to treat. We pulled fecal 10 days later and learned we had only a 7% reduction. We stepped up to the next drug, waited and then retested in 10 days. That was better but we only reduced the parasite population by 23%. This required the veterinary to do some research and then administer a risky drug but one found effective. That worked but now we had a half dozen alpacas that had lost 1/3 of their weight and outside temperatures were sub 20’s. Not the best conditions to recover weight.
With added expenses supplementing and feed we recovered all but one 6 month cria. When we added up the extra feed cost, veterinary charges, extra cost for drugs, loss of an exceptional alpaca, and time commitment along with worry, the Identification Method had our attention. This along with an observation from the veterinary wondering, “Where would you be if the last drug had not worked”, convinced us we needed to change.
Under Dosing
It is a good time to pass along an observation from our veterinary. He pointed out that resistance can only occur due to under dosing. As he said, “When you treat properly, the parasites die, they cannot become resistant.” Under dosing is generally unintentional. When weight determines dosage, weight is often estimated or relied upon from a prior weigh in. Oral drugs when administered may be partially spit out and how much must be given without over dosing is seldom accurate or done. Parasites can go dormant in the gut and build a cocoon of sorts and never receive toxic levels of the drug.
Refugia
So where does this leave us. Identification Method right? Refugia defined as the ability of a population to withstand toxic conditions. Well that would be resistance right? When one applies the Prophylactic Method the only parasites that remain are those resistant to the drugs. Resistant parasites breed and become the dominate population. The Identification Method allows some non-resistant parasites to remain and interbreed with resistant parasites with the theoretical result making resistant parasites vulnerable to the drugs.
We have had good success employing the Identification Method. Our medical costs have gone down, we have fewer out breaks, and the general herd health is much improved. We also become responsible herdsmen protecting the industry from a catastrophic problem insuring alpaca herds into our and others future.