After reading a story in the Sunday’s Indiana Sunday Star story on Trifexis I begin to rethink if the medicine was worth the risk. This is not the first time I have wondered about heartworm medicine because I have had some bad experiences in the past.
When heartworm medicine was first introduced I started giving it to a large male collie and within a few weeks he begin to bleed out of his eyes,ears, and nose. I had to give him a vitamin K shot daily until one month I forgot to give him his heartworm medicine. The next month he did not require a vitamin K shot because he was no longer bleeding! The only difference was no heartworm medicine. It was later discovered that collies sometimes reacted to Ivermectin.
I also adopted a stray Dalmatian that was heartworm positive. We found this out when he collapsed running up to greet us which meant he had a serious problem. He was treated and ended up hemorrhaging and had to have a blood transfusion. He was given five years to live after that but made it to ten years without any problems other than a cough during cold weather outings.
So which is worst the fact that the medicine can cause serious problems in even death or taking a chance that the dog will get a serious case of heart worm?
Let’s start by looking at how heartworm attacks a dog.
According to the American Heartworm society “Heartworm disease is a serious and potentially fatal disease in pets in the United States and many other parts of the world. It is caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body. Heartworm disease affects dogs, cats and ferrets, but heartworms also live in other mammal species, including wolves, coyotes, foxes, sea lions and—in rare instances—humans. Because wild species such as foxes and coyotes live in proximity to many urban areas, they are considered important carriers of the disease.”
A female mosquito must bite an infected animal and pick up a baby worm. The worm then must develop and mature into “infective stage” larvae over a period of 10 to 14 days. The infective stage worm is than transmitted to a new host though an infected mosquito. Once inside a new host, it takes approximately 6 months for the larvae to mature into adult heartworms. Once mature, heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats. Fully mature adults at 6.5 months after infection reach lengths of 15-18 cm (5-6 in) for males and 25-30 cm (10-12 in) for females.
Symptoms of heartworm infestation can include labored breathing, coughing, vomiting, weight loss and listlessness, and fatigue after only moderate exercise. However, some dogs exhibit no symptoms at all until late stages of infection. A yearly blood test is an easy way to determine if your pet has heartworms.
Conventional veterinary medicine offers valuable options for heartworm treatment. You can elect to do the fast-kill method using Immiticide, or the slow-kill method using monthly Heartgard, either is preferable to leaving the dog untreated, or using unproven, alternative methods that may have no effect or even be harmful.
We know that before any of this can happen there must be an infected animal to begin the cycle. This is the 2013 map showing the average number of heartworm-positive cases per clinic according to the America Heartworm Society.
Most cases seem to be located in the south-east area of the United States.
Prevention medicine comes in many forms and with many concerns.
1. Heartgard for Dogs uses Ivermectin as the main heartworm preventive. It does not control any other
parasites. Given orally once a month to animals over the age of 6 weeks.
2. Heartgard Plus, Iverhart Plus, Iverhart Max, Triheart Plus, and Pet Trust Plus all use Ivermectin as the main heartworm preventive. They also contain pyrantel palmate, (Iverhart Max also has praziquantel) which controls hookworms. roundworms, (Iverhart Max also covers tapeworms). These are given orally monthly to dogs 6 weeks and older.
3. Sentinel and Sentinel Spectrum contain Milbemycin Oxime as the heartworm preventive. Sentinel contains Lufenuron for hookworms, roundworms, whipworms, and it sterilizes fleas. Sentinel Spectrum also contains praziquantel which controls tapeworms. These are given monthly orally to dogs 4 weeks and older.
4. Revolution contains Selamectin which covers heartworm, fleas, ticks, ear mites, and sarcoptic mange mites. It is applied tropical once a month to dogs 6 weeks and older.
5. Advantage Multi contains Moxidectin as the heartworm preventive and Imidocloprid to control fleas, hookworms, roundworms, and whipworms. It is applied tropical monthly to dogs 7 weeks and older.
6. Proheart6 contains Moxidectin which is injected into the dog twice a year. It also controls hookworms. The dog must be between the age of 6 months and 7 years.
7. Trifexis contains Milbemycin Oxime for heartworm prevention and Spinosad for control of fleas, hookworms, roundworms, and whipworms. This is given orally every month to dogs 8 weeks and older.
Dangers that have been associated with these drugs range from minor problems to death.
Ivermectin has been linked to many side effects in Collies, Shetland sheepdogs, Australian shepherds, and Old English sheepdogs, and some individual animals that are not members of these sensitive breeds. Side effects include but not limited to dilated pupils and drunken gait that can progress to respiratory paralysis and death if medication is not withdrawn and supportive care is not initiated.
Pyrantel parmoate can cause vomiting as well as facial swelling, hives, scratching, sudden onset of diarrhea, shock, seizures, pale gums, and coma.
Praziquantel can cause facial swelling, hives, scratching, sudden onset of diarrhea, shock, seizures, pale gums, coma, drooling, vomiting, loss of appetite, diarrhea, lethargy, or staggering.
Milbemycin Oxime can cause facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, coma, depression, lethargy, vomiting, staggering, loss of appetite, diarrhea, seizures, weakness, excessive salivation or death. I found this in a site directed towards veterinarians -” Do NOT use in doses higher than the heartworm prevention dose in collies or other herding breeds, except under veterinary supervision.” According to the FDA it ranks fifth for causing convulsions and ninth for causing deaths.
Lufenuron can cause lack of appetite, vomiting, diarrhea, lethargy, itching, difficulty breathing, or reddened skin.
Selamectin can cause loss of appetite, salivation (drooling), diarrhea, vomiting, muscle tremors, fever, rapid breathing, facial swelling, hives, scratching, shock, seizures, pale gums, cold limbs, or coma.
Moxidectin side effects can include scratching, rubbing, or licking the application site; lethargy, decreased appetite, or hyperactivity. If a dog ingests the product or licks the application site,serious adverse effects may occur including depression, salivation, incoordination, panting and tremors. Other possible side effects include facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma.
Imidocloprid side effect can include salivation and vomiting if ingested (It is considered mildly toxic.) Very high oral exposures may lead to lethargy, vomiting, diarrhea, salivation, muscle weakness and ataxia. Other side effects are uncoordinated gait, tremors, and reduced activity.
Spinosad can cause vomiting, depression/lethargy, decreased appetite, incoordination, diarrhea, itching, trembling, excessive salivation and seizures. When mixed with ivermectin, some dogs have experienced: trembling/twitching, salivation/drooling, seizures, ataxia, mydriasis, blindness and disorientation. This drug ranks third for reports of convulsions,fourth for blindness, sixth for aggression ans paralysis, and seventh for unconsciousness according to the FDA
The following adverse reactions have been reported to the FDA by the manufacturers:
HEARTGARD and TriHeartPlus (ivermectin): Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis (excessive pupil dilation), ataxia staggering, convulsions and hypersalivation. INTERCEPTOR (milbemycin oxime) reports the above reactions plus weakness. Sentinel (milbemycin oxime) reports vomiting, depression/lethargy, pruritus (itchy dermatologic condition), urticaria (hives), diarrhea, anorexia, skin congestion, ataxia (gross lack of coordination of muscle movements) , convulsions, hypersalivation and weakness.
REVOLUTION® (selamectin), Topical Parasiticide For Dogs and Cats: pre-approval reactions of vomiting, loose stool or diarrhea with or without blood, anorexia, lethargy, salivation, tachypnea, and muscle tremors. Post-approval experience included the above plus pruritis, urticaria, erythema (skin redness), ataxia, fever, and rare reports of death and seizures in dogs.
Proheart 6 : severe allergic reactions (anaphylaxis): facial swelling, itching, difficulty breathing, collapse; lethargy (sluggishness); not eating or losing interest in food; any change in activity level; seizures; vomiting and/or diarrhea (with and without blood); weight loss; pale gums, increased thirst or urination, weakness, bleeding, bruising; rare instances of death. This product was voluntarily withdrawn from the market in 2004 because of deaths but has been reintroduced.
All these products are designed to kill something and most carry the following caution. “In case of ingestion by humans, clients should be advised to contact a physician immediately. Physicians may contact a Poison Control Center for advice concerning cases of ingestion by humans.”
In the long run you have to decide which is the greatest risk. Taking a medicine every month that could possible cause death at random or having your dog get heartworm that can be fatal if not treated?
You could follow the package directions which usually call for a monthly dose. My vet told me that most of these have a two-week built safety zone so that they really only need to be given every 6 weeks but it is easier for people to mark a day on the calendar to remind them to give the medicine.
or you can follow Dr. Michele Yasson, DVM , holistic approach:
Her clients are given a choice between the following four options:
1. No specific preventative used. Blood test every 6 months. ( Dr. Martin Goldstein in The Nature Of Animal Healing says: “Only a small percentage of dogs who get heartworm die of it, especially if they’re routinely tested twice yearly for early detection. Even in untreated dogs, after a period of uncomfortable symptoms, the adult worms die….”)
2. *Homeopathic Nosode (remedy), monthly in mosquito season. Blood test every year.
3. * Ivermectin – based meds (Heartgard, Iverhart, Tri-Heart, etc) every 3 months, all year. Blood test every 1 -3 years..
4. *Milbemycin – based meds (Interceptor, Sentinel, Trifexis) every 2 months, all year. Blood test every 1-3 years.
*In 15+ years of recommending these protocols, in an effort to lower toxic burden while maintaining adequate protection, no patient has ever had failure of protection (positive heartworm test).
Dr. Michele Yasson, DVM has her office in New York.
Another option is to give the preventive medicine only during the months that it is needed. The medicine kills the worm inside the animal only when the worm is present. There is no need to give your dog dangerous drugs when the worm can not be in your animal. No mosquitoes means no worms. The larvae require approximately 30 consecutive days of 60-degree weather where the temperature does not dip below 57F (14C) in order to reach the L3 condition. Remember this is the stage that the larvae can be transmitted to the dog.
The maps indicate the months that your dog is at risk for heartworm disease. For example, in the first map northern Maine has an eight (8) which means that the first dose of heartworm prevention should be started on the first of the eighth month or August first. The second map has a ten (10) in northern Maine which means that you should continue prevention through the tenth month or October. Southern Florida has a one (1) in both maps which indicates that heartworm prevention should be used all year.
These dates are conservative and come from a detailed study using temperature data from 200 weather stations dating back 30 or more years. It is unlikely that you would need to extend these dates. Go with your gut instinct. If you are having unusually hot, wet weather before or after the map indicates the starting and ending dates for your area, then don’t hesitate to start heartworm prevention early or extend it another month.
If I used this method I would begin treatment on June 1 and end it on either November 1 or December 1 depending on the weather conditions. It should be stopped 30-45 days after weather is consistently below 57 F degrees and you see no mosquitoes.
Also back in June 4, 1998 it was proven that the low dosage of 0.1 mg milbemycin oxime per kg of body weight (0.05 mg/lb) would kill the larvae in the blood. They recommended : One tablet (2.3 mg) for a dog weighting 2 -50 lbs and One tablet (5.75 mg) for a dog weighting 50.1 -125lbs.
Compared to today dosage recommended for Trifexis : dogs 5 to 10 lbs (140mg/2.3mg)),
dogs 10.1 to 20 lbs (270mg/4.5mg)
dogs 20.1 to 40 lbs (560mg/9.3mg)
dogs 40.1 to 60 lbs (810mg/13.5mg)
dogs 60.1 to 120 lbs (1620mg/27mg).
2.3 mg for a 50 lbs dog compared to 560mg for a 40 lbs dog. Why are we giving so much more than what has been proven to work?I am only reporting my research. It is up to you to make the decision on how you wish to treat for heartworm.
Perfect Dog 