Bug Off! Understanding Parasite Prevention for Pets
A Complete Guide to Flea, Tick, and Heartworm Protection
As pet owners, we want our furry friends to stay happy and healthy—but parasites like fleas, ticks, and heartworms can pose serious risks. The good news? Prevention is easier and more affordable than treating an infection. In this guide, we’ll break down your options so you can choose the best protection for your pet’s lifestyle.
Topics Covered
What is Parasite Prevention?
Parasite prevention stops pests like fleas, ticks, and heartworms from harming your pets. These tiny troublemakers cause health issues ranging from itching to Lyme disease. In Southern Ontario, our humid summers and mild winters let parasites thrive year-round. That’s why regular prevention is a must.
Why Parasite Prevention Matters
Parasites aren’t just annoying—they can cause severe health problems:
🔹 Fleas can lead to skin allergies, anemia, and tapeworms.
🔹 Ticks transmit diseases like Lyme disease and Rocky Mountain spotted fever.
🔹 Heartworms are life-threatening and expensive to treat.
Preventative care keeps your pet safe and saves you from costly vet bills down the road.
Understanding the Costs of Tickborne Illnesses & Heartworm in Dogs
If your dog tests positive for Lyme disease, anaplasmosis, ehrlichiosis, or heartworm, treatment costs can vary depending on the severity of the infection and required diagnostics. Below is a general breakdown of what pet owners in Ontario might expect financially as per the OVMA 2025 Fee Guide for veterinary practices.
1. Diagnostic Testing Costs (e.g Accuplex, SNAP 4Dx, etc): $125 – $200
Checks for Lyme, anaplasmosis, ehrlichiosis, and heartworm in one blood test.
2. Follow-up and Confirmatory Testing: $150+
If your pet tests positive, additional testing may be needed to:
• Confirm the infection (some vaccines can cause false positives).
• Determine the severity (e.g., heartworm stage, kidney function in Lyme cases).
• Assess your pets overall health (bloodwork, urinalysis, or imaging).
3. Treatment Costs: varies greatly depending on the illness
While simple tickborne infections may only require an antibiotic course (ranging from $100+ based on pet’s weight and appropriate dosing), heartworm treatment can cost easily cost over $2000 due to the intensive protocol.
Our vets will recommend the most effective – yet cost-conscious – approach based on your pet’s specific condition.
The Bottom Line
Treating tickborne illnesses or heartworm can cost anywhere from $225 for a mild infection, to over $2,500 for advanced cases—but with year-round preventatives and annual testing, you can protect your pet for just a fraction of that cost. An ounce of prevention is worth a pound of cure!
Prevention (The Best Investment!)
Remember: Preventative care (year-round medications and annual testing) remains the most affordable way to protect your pet's health - and your wallet!
Flea & Tick Prevention: What Are Your Options?
1. Over-the-Counter (OTC) Topical Treatments
Examples: Advantage II®, K9 Advantix®, Zodiac® Flea Egg Collar
How They Work:
• Applied directly to your pet’s skin.
• Spread through the skins natural oils, creating an exterior protective barrier (translocation).
• Imidacloprid: Kills pests on contact—ideally, you won’t even see fleas or ticks*.
*If your pet is on Advantage® or Advantix® (with imidacloprid), ticks should die on contact before attaching. Found a tick anyway? This suggests a gap in protection—call your vet ASAP! They can help troubleshoot and keep your pet safe.
Pros:
✔Affordable
✔ Effective for low-risk, indoor pets
Cons:
Avoid baths/swimming for 48 hours (water washes off the product). Swimming may also wash off the product! Permethrin (found in some OTC dog products) is toxic to cats—never use near felines!
Best For: Pets who stay indoors and don’t swim often.
2. Prescription (Rx) Oral & Topical Medications
Examples: Bravecto®, Simparica®, SimparicaTRIO®, Bravecto®, NexGard®, NexgardSpectra®, Revolution®, Revolution Plus®
How They Work:
• Isoxazolines: Absorbed into the bloodstream to provide systemic protection.
• Kills parasites when they bite (but before they can transmit disease).
• Some medications like Bravecto last 8–12 weeks per dose, but others typically stay within your pet’s system for up to 30 days. This is why consistency in re-application is important!
Pros:
Waterproof—great for swimmers and adventurers! More reliable for active pets or those in high-risk areas (woods, tall grass). Safer for households with cats (no permethrin risk).
Cons:
Rarely, isoxazolines have been associated neurological side effects (e.g., tremors/seizures), so pets with histories of neurologic conditions should avoid taking this class of medications. Requires a vet prescription.
Best For:
• Outdoor-loving pets
• Multi-pet homes (especially with cats)
• Pets in tick-heavy regions
Heartworm Prevention: Don’t Skip This!
Heartworm disease is transmitted by mosquitoes and can be fatal if untreated. Prevention is much easier than treatment!
1. Over-the-Counter (OTC) Topical Treatments
Example: Advantage Multi®, K9 Advantix II® (Moxidectin)
• Topical application – applied to the skin, absorbed into the bloodstream. It kills heartworm larvae (microfilariae), and prevents them from maturing into adult worms, and also helps to controls fleas, roundworms, hookworms, and ear mites.
• Caution: Some herding breeds (e.g., Collies, Australian Shepherds) with the MDR1 gene mutation may be more sensitive to this class of drugs (macrocyclic lactones).
Best For:
• Pet owners who prefer non-pill options
• Low-activity pets that don’t swim or bathe frequently (bathing within 48 hours of application, and frequent bathing/swimming throughout the month can reduce flea and tick control effectiveness (though heartworm protection should remain in tact)
• Situations where basic flea control is sufficient (not ideal for heavy flea/tick areas)
• Households needing heartworm + intestinal parasite protection without needing strong tick defense
2. Prescription (Rx) Oral & Topical Medications
Example: SimparicaTRIO®, NexgardSpectra®, HeartgardPlus®
How They Work:
• Topical and Oral medications which are absorbed into the bloodstream to provide systemic protection. It prevents heartworm larvae (microfilariae) from maturing into adult worms, and also helps to controls fleas, roundworms, hookworms, and ear mites.
• Caution: Some herding breeds (e.g., Collies, Australian Shepherds) with the MDR1 gene mutation may be more sensitive to this class of drugs (macrocyclic lactones).
Best For:
• Dogs in high-risk mosquito areas.
• Owners who prefer easy-to-give chewables or long-lasting protection.
• Pets needing comprehensive parasite control (fleas, ticks, and worms).
How does Parasite Prevention work? An Active Look at Active Ingredients
Parasite preventatives work in different ways depending on how they’re administered. Some create a protective barrier on your pet’s skin, while others are absorbed into their bloodstream to combat parasites systemically. Understanding these differences helps explain why certain medications are better suited for specific pets or lifestyles.
Topical-Only Medications
These treatments spread through your pet’s skin oils (a process called translocation) but aren’t absorbed systemically. As such, they can only provide protection against certain external parasites,typically fleas and ticks.
🔹 Imidacloprid: Mimics nicotine to paralyze fleas on contact.
🔹 Pyriproxyfen: Disrupts flea development by mimicking insect hormones.
🔹 Permethrin: Neurotoxic to insects; repels and kills ticks/fleas.
Key Safety Notes:
🔹 Permethrin is highly toxic to cats—never use dog products containing permethrin in feline households.
🔹 Imidacloprid poses environmental risks (harmful to bees); dispose of unused product carefully.
Systemic Medications
These are absorbed into the bloodstream, offering whole-body protection. They are able to offer protection against both external parasites (like fleas and ticks), as well as internal parasites (like heartworm, and intestinal worms).
Macrocyclic Lactones (e.g., Moxidectin, Milbemycin, Selamectin, Eprinomectin):
🔹 Paralyze parasites by disrupting nerve signals.
Protect against heartworms, intestinal worms, and mites.
🔹 Safety Concern: Dogs with the MDR1 gene mutation (common in Collies, Australian Shepherds) may experience toxicity (tremors, seizures). This mutation can also occur in cats, though it is less studied. Avoid combining multiple medications in this class for sensitive pets.
Isoxazolines (e.g., Fluralaner, Afoxolaner):
🔹 Overstimulate parasites’ nerves, causing paralysis.
🔹 Effective against fleas and ticks for 1–3 months per dose.
🔹 Safety Concern: Rare neurological side effects (e.g., tremors) in pets with seizure history.
Rapid-Acting Oral Treatments:
🔹 Nitenpyram: Kills adult fleas within 30 minutes (short-term use).
🔹 Praziquantel: Targets tapeworms by causing muscle spasms.
When in doubt, ask your vet! They’ll consider your pet’s breed, health history, and lifestyle to recommend the safest option.
Parasite Prevention Puzzle: Finding the Right Fit 🧩
With so many options available, choosing the right parasite prevention medication for your pet can feel overwhelming. Here are some factors to consider:
1. Pet’s Lifestyle
Assess your pet’s lifestyle to determine their exposure to parasites. Do they spend a lot of time outdoors, hiking through wooded areas, or do they mostly stay indoors?
2. Parasite Coverage
Consider which parasites are prevalent in your area and ensure the medication you choose provides adequate coverage. For example, if ticks are common in your region, opt for a medication that specifically targets ticks.
3. Administration Method
Some pets may prefer chewable tablets, while others tolerate topical solutions better. Choose a medication that is easy to administer and fits your pet’s preferences.
4. Duration of Protection
Determine how long you want the protection to last. Monthly treatments may be convenient for some pet owners, while others may prefer longer-lasting options.
5. Additional Benefits
Some medications offer additional benefits, such as preventing heartworm or treating intestinal parasites. Consider whether these extras align with your pet’s needs.
6. Veterinary Recommendation
Consult your veterinarian for personalized advice. They can recommend the best medication based on your pet’s health status, risk factors, age, and lifestyle.
By considering these factors and consulting with your veterinarian, you can make an informed decision and choose the parasite prevention medication that’s right for your furry friend.
Common Issues with Parasite Prevention Medication:
While medications are highly effective, some common issues might arise:
Missed Dose: If you forget to give your pet their medication, administer it as soon as you remember and then continue with the regular schedule.
Adverse Reactions: Some pets may experience side effects, the most common of which is vomiting or lethargy. If this happens, contact your vet immediately.
When to Seek Veterinary Help 🩺🐾
Certain signs indicate it’s time to consult your vet:
🔹 Persistent Scratching or Biting: Even after treatment, if your pet continues to scratch or bite, it could indicate an underlying issue.
🔹 Visible Parasites: If you notice fleas or ticks on your pet despite treatment, a vet visit is essential.
🔹 Changes in Behavior: Lethargy, loss of appetite, or other behavioral changes warrant professional attention.
If you suspect your pet might have been exposed: It happens! Sometimes you forget to give them a dose, sometimes you run out of their medication. Sometimes, their weight can fluctuate and affect how well their medication can protect them at the current dose!
Thankfully there’s a way to check!
If pets were exposed to parasites like heartworm and ticks and caught something, antibodies about the infection show up in their blood within 4-6 weeks of exposure, and can be tested for. The most common lab test for this is Antech’s Accuplex and Idexx’s 4Dx which both screen for exposure to heartworm, and 3 common tick-borne illnesses (Lyme disease, ehrlichiosis, and anaplasmosis).
Every pet is different. Your vet can recommend the safest option based on breed, lifestyle, and health.
Contact Yonge Sheppard Animal Hospital at 647-260-8387 or yonge.sheppard.vets@gmail.com for personalized advice!
– The Yonge Sheppard Animal Hospital Team 