# Revolution Plus for Cats: Selamectin Sarolaner Feline Dose Guide ## Key Takeaways - Revolution Plus is a topical monthly parasiticide for cats combining selamectin (macrocyclic lactone) and sarolaner (isoxazoline) at approved dose ranges of 6.0-12.0 mg/kg selamectin and 1.0-2.0 mg/kg sarolaner, ensuring broad-spectrum efficacy. - The product provides rapid kill of fleas within hours and ticks within 24 hours, preventing transmission of pathogens like *Borrelia burgdorferi* and *Cytauxzoon felis* by disrupting vector feeding windows. - Efficacy is demonstrated against *Ctenocephalides felis*, multiple tick species including *Ixodes scapularis* and *Amblyomma americanum*, *Otodectes cynotis*, and internal parasites such as *Dirofilaria immitis* (prevention), *Toxocara cati*, and *Ancylostoma tubaeforme*. - Safety has been established in multiple studies with generally mild, transient application-site reactions reported; however, it is a prescription medication requiring veterinary consultation for specific patient populations (e.g., pregnant, lactating, or debilitated cats). - Year-round prevention is recommended due to the continuous presence of parasites and the critical role of rapid kill in preventing serious diseases like heartworm and cytauxzoonosis, for which treatment options are limited or guarded. - Environmental management is crucial for flea control, as Revolution Plus targets adult fleas on the cat, while the product's efficacy against environmental stages is indirect via preventing reproduction. --- Revolution Plus (Zoetis) is a topical prescription medication for cats that combines selamectin and sarolaner in a single spot-on application. The approved label dose range is 6.0 to 12.0 mg/kg of selamectin and 1.0 to 2.0 mg/kg of sarolaner, administered once a month [1][2]. This guide explains the science behind the dose, what the product treats, and what [cat](/knowledge/veterinary-medicine/clinical-methods/cat) owners should discuss with their veterinarian. **Owner-facing triage summary:** If your cat is due for a monthly preventive, contact your veterinarian for a prescription. Do not use a [dog](/knowledge/veterinary-medicine/clinical-methods/dog) product on a cat. If you suspect a parasite problem, such as fleas, ticks, ear mites, or worms, schedule an appointment before starting any new medication. Seek immediate veterinary care if your cat shows signs of a severe reaction after application, such as facial swelling, hives, vomiting, or difficulty breathing. ## At a Glance: Revolution Plus for Cats | Feature | Detail | | :--- | :--- | | **Active Ingredients** | Selamectin (6 mg/kg) and sarolaner (1 mg/kg) minimum dose [3][4] | | **Dose Range** | 6.0-12.0 mg/kg selamectin; 1.0-2.0 mg/kg sarolaner [1] | | **Administration** | Topical, applied to the skin at the base of the skull [4] | | **Frequency** | Once a month (every 30 days) [3][1] | | **Target Parasites** | Fleas, several tick species, ear mites, roundworms, hookworms, and heartworm prevention [3][5][1][6][7][8] | | **Onset of Action (Fleas)** | Starts killing fleas within hours; significant reduction by 12 hours [9] | | **Onset of Action (Ticks)** | Significant reduction in *Ixodes scapularis* within 12 hours; 100% efficacy by 24 hours in one study [10] | | **Duration of Efficacy** | At least 1 month for fleas and ticks [3][5][9] | | **Safety** | Generally well-tolerated in studies; mild application-site reactions possible [3][6] | ## Understanding the Active Ingredients Revolution Plus contains two active ingredients with complementary mechanisms of action. ### Selamectin: A Macrocyclic Lactone Selamectin is a well-established macrocyclic lactone endectocide. It is effective against a range of internal and external parasites. In Revolution Plus, selamectin is the component responsible for preventing heartworm disease (caused by *Dirofilaria immitis*) and for treating intestinal roundworms (*Toxocara cati*) and hookworms (*Ancylostoma tubaeforme*) [4][11][7][8]. It also contributes to the product's efficacy against ear mites (*Otodectes cynotis*) [6]. ### Sarolaner: An Isoxazoline Sarolaner is a member of the isoxazoline class of ectoparasiticides. Isoxazolines are potent inhibitors of the parasite's nervous system, leading to rapid death of fleas and ticks [12][13]. The addition of sarolaner to selamectin provides enhanced and rapid efficacy against a broad spectrum of tick species and improves the speed of kill against fleas [3][12][10][14]. ## The Feline Dose Guide The dose of Revolution Plus is calculated based on the cat's body weight. The product is formulated to deliver a minimum of 6.0 mg/kg of selamectin and 1.0 mg/kg of sarolaner [3][4]. The approved dose range in the market product is 6.0-12.0 mg/kg selamectin and 1.0-2.0 mg/kg sarolaner, which accommodates a range of cat sizes within a single tube size [1][2]. For example, in a study comparing Revolution Plus to Bravecto for Cats, the cats treated with Revolution Plus received effective dosages of 5.25-6.60 mg/kg selamectin and 0.88-1.10 mg/kg sarolaner due to rounding of the dose volume [3]. In another study, the range was 5.29-7.12 mg/kg for selamectin and 0.88-1.19 mg/kg for sarolaner [12]. These studies confirm that the product is effective at the minimum label dose. **Important:** The exact volume of the tube is determined by the cat's weight. Your veterinarian will prescribe the correct tube size. Never split a tube between cats or use a product intended for a heavier cat on a smaller one. ## Efficacy Against Fleas Revolution Plus is highly effective against the cat flea, *Ctenocephalides felis*. Multiple controlled studies have demonstrated its efficacy. - **Laboratory Studies:** In a study evaluating a single dose, Revolution Plus provided 100% efficacy against fleas for 5 weeks after a single treatment [9]. In a separate study comparing three monthly doses of Revolution Plus to a single dose of fluralaner (Bravecto), both products were highly effective, with no significant difference in efficacy against fleas [3]. - **Speed of Kill:** A speed-of-kill study showed that Revolution Plus begins killing fleas within 6 hours of application. By 12 hours after treatment, flea counts were significantly reduced, and by 24 hours, efficacy was 100% [9]. - **Field Studies:** In clinical field studies conducted in the United States, cats treated with Revolution Plus showed a mean percent reduction in live flea counts of 98.0% to 100% on Days 30, 60, and 90 after three monthly treatments [1]. A similar field study in Australia reported an arithmetic mean efficacy of 98.0%, 100%, and 100% on Days 30, 60, and 90, respectively [2]. A study in Japan also confirmed its efficacy against fleas in client-owned cats [15]. ## Efficacy Against Ticks Sarolaner provides rapid and sustained efficacy against several tick species that infest cats. - ***Ixodes scapularis* (deer tick or black-legged tick):** This tick is a vector for *Borrelia burgdorferi* (Lyme disease) and *[Anaplasma phagocytophilum](/knowledge/bacteria/pet-bacteria/anaplasma-phagocytophilum)*. Revolution Plus has been shown to be 100% effective in reducing *I. scapularis* infestations [16][12]. One study demonstrated a 100% reduction of *I. scapularis* ticks compared with placebo-treated cats [16]. The speed of kill study found that treatment significantly reduced tick counts within 12 hours and resulted in 100% efficacy by 24 hours after treatment [10]. - ***Amblyomma americanum* (lone star tick):** This tick is a vector for *[Cytauxzoon felis](/knowledge/parasites/pet-parasites/cytauxzoon-felis)*, the cause of cytauxzoonosis. Studies have confirmed that a single topical dose of Revolution Plus is effective against *A. americanum* for at least one month [5][17]. Furthermore, it was shown to prevent the transmission of *C. felis* to cats [17]. - ***Dermacentor variabilis* (American dog tick) and *Amblyomma maculatum* (Gulf Coast tick):** A series of laboratory studies confirmed the efficacy of a single topical application of Revolution Plus against these species for at least one month [14]. - ***Haemaphysalis longicornis* (Asian longhorned tick):** A study conducted in Japan demonstrated that Revolution Plus reduced live, attached *H. longicornis* counts by 96.4% within 48 hours of treatment and by at least 91.7% within 48 hours of weekly re-infestation for 35 days [15]. ### Prevention of Tick-Borne Disease By killing ticks quickly, Revolution Plus helps prevent the transmission of tick-borne pathogens. - **Lyme Disease and Anaplasmosis:** A study demonstrated that treatment with Revolution Plus resulted in a 100% reduction of *I. scapularis* ticks compared with placebo. In the placebo group, antibodies against *B. burgdorferi* and *A. phagocytophilum* were detected, while no cats treated with Revolution Plus became infected [16]. - **Cytauxzoonosis:** A study confirmed that Revolution Plus prevented the transmission of *Cytauxzoon felis* from infected *A. americanum* ticks to cats [17]. ## Efficacy Against Internal Parasites Revolution Plus is indicated for the treatment and control of several internal parasites. ### Heartworm Prevention Selamectin is a proven preventive for [feline heartworm disease](/knowledge/parasites/pet-parasites/heartworm-disease-cats-diagnostic-challenges-treatment-options). Studies have shown that Revolution Plus is highly effective in preventing the development of *Dirofilaria immitis*. - **Efficacy:** In controlled studies, no adult heartworms were recovered from cats treated with selamectin plus sarolaner, while 87-100% of control cats were infected [4]. - **Resistant Strains:** A study evaluated the efficacy of selamectin plus sarolaner against a macrocyclic lactone (ML)-resistant strain of *D. immitis*. The combination product was effective in preventing the development of this resistant strain [11]. - **Field Study:** A field study in Japan enrolled 91 cats that received 9 monthly topical treatments with selamectin plus sarolaner. No *D. immitis* antigen or anti-*D. immitis* antibody was detected in any of the post-treatment samples from the 87 cats that completed the study [8]. ### Intestinal Roundworms and Hookworms Revolution Plus is also effective against common [intestinal parasites](/knowledge/parasites/pet-parasites/intestinal-parasites-dogs-cats-identification-treatment). - **Roundworms (*Toxocara cati*):** A field study in the United States evaluated the efficacy of selamectin plus sarolaner against naturally occurring infections of *T. cati*. The treatment was effective in reducing fecal egg counts [7]. A field study in Japan also confirmed its efficacy against roundworm infection [8]. - **Hookworms (*Ancylostoma tubaeforme*):** The same US field study demonstrated efficacy against *A. tubaeforme* [7]. ## Efficacy Against Ear Mites and Other Mites Revolution Plus is effective against ear mites (*Otodectes cynotis*). - **Ear Mites:** In controlled studies, a single dose of selamectin plus sarolaner was highly effective in treating induced *O. cynotis* infestations. On Day 30, the arithmetic mean live mite counts were significantly lower in the treated groups compared to placebo groups [6]. A field study in the US also confirmed its efficacy against natural ear mite infestations [1]. - **Demodicosis:** A case report documented the successful treatment of generalized demodicosis caused by *Demodex cati* in a cat using two monthly doses of the sarolaner-selamectin combination. This is the first published report of its kind for the generalized form of the disease [13]. ## Safety and Tolerability Revolution Plus has been evaluated in multiple laboratory and field studies and is generally well-tolerated in cats. - **Adverse Events:** In most studies, there were no treatment-related adverse events [3][5][15][14][9]. Some studies reported mild and transient application-site reactions, such as alopecia or temporary hair loss at the site of application [6]. - **Field Safety:** In the US field studies, 405 cats received treatment with selamectin plus sarolaner, with 256 cats receiving three monthly treatments. The product was well-tolerated [1]. The Australian field studies also reported that the product was safe [2]. - **Patient Population:** The safety and efficacy have been demonstrated in cats presented as veterinary patients, including those with natural parasite infestations [1][15][2][7][8]. ## Administration Guidelines For optimal efficacy and safety, follow these administration guidelines: 1. **Prescription Required:** Revolution Plus is a prescription medication. Obtain it from your veterinarian. 2. **Weight-Based Dosing:** Your veterinarian will determine the correct tube size based on your cat's current weight. 3. **Application Site:** Apply the entire contents of the tube topically to the skin at the base of the skull, cranial to the scapulae [4]. Part the hair so the solution is applied directly to the skin. 4. **Do Not Bathe:** Avoid bathing or shampooing your cat for a period of time after application, as this can reduce efficacy. Your veterinarian can provide specific advice. 5. **Monthly Administration:** Administer once a month, every month, year-round for continuous protection [3][1]. 6. **Multi-Cat Households:** Keep treated and untreated cats separated for a few hours after application until the site is dry to prevent grooming of the medication. ## Regional Considerations - **North America:** In the US and Canada, the primary tick vectors of concern include *Ixodes scapularis* (Lyme disease, anaplasmosis), *Amblyomma americanum* (cytauxzoonosis, ehrlichiosis), and *Dermacentor variabilis* (Rocky Mountain spotted fever). Revolution Plus is effective against these species [16][5][14][17]. - **Australia:** The cat flea (*Ctenocephalides felis*) is the most common ectoparasite. Revolution Plus is registered for use in Australia and has demonstrated high efficacy against fleas in field studies [2]. Tick species in Australia differ from those in North America; consult your local veterinarian for advice on the most appropriate tick prevention. - **Europe:** *Ixodes ricinus* is a common tick vector for Lyme disease. While Revolution Plus is not specifically cited in the provided sources for European tick species, the product is available in some European countries. Always follow local veterinary guidance. ## Unsafe Home Remedies and Warnings Do not use over-the-counter or home remedies for parasite control without veterinary guidance. Many are ineffective or can be toxic to cats. - **Never use dog flea and tick products on cats.** Many contain permethrin, which is highly toxic and can be fatal to cats. - **Do not use essential oils or herbal remedies** as a substitute for proven prescription medications. Their efficacy is unproven, and some can be harmful. - **Do not apply more than the prescribed dose** in an attempt to improve efficacy. ## Prevention and Prognosis - **Year-Round Prevention:** The Companion Animal Parasite Council (CAPC) and the American Heartworm Society recommend year-round prevention for fleas, ticks, and heartworms. Monthly administration of Revolution Plus provides continuous protection. - **Prognosis:** The prognosis for cats with flea infestations, tick infestations, ear mites, or common intestinal parasites is excellent with prompt and appropriate treatment. Heartworm disease in cats is more serious, and prevention is critical, as there is no approved treatment for adult heartworms in cats. The prognosis for cats that develop heartworm disease can be guarded. Tick-borne diseases like cytauxzoonosis are severe and can be fatal, making prevention essential [17]. ## Limitations and When to Contact a Veterinarian This guide provides a comprehensive overview of Revolution Plus, but it cannot predict individual responses. Breed-level information cannot account for your cat's specific health status, age, weight, or concurrent medications. **Contact your veterinarian if:** - Your cat has a known allergy or sensitivity to any of the ingredients. - Your cat is pregnant, nursing, or you plan to breed her. - Your cat is on any other medications, including other parasiticides. - Your cat is debilitated, underweight, or has a chronic illness. - You observe any adverse reaction after application, such as persistent itching, redness, hair loss at the site, or signs of systemic illness like vomiting or lethargy. - You are unsure about the correct dose or administration technique. ## Why the Dose Range Exists: Pharmacokinetics and Body Weight The approved label dose range of 6.0 to 12.0 mg/kg for selamectin and 1.0 to 2.0 mg/kg for sarolaner is not arbitrary [1][2]. It reflects the practical reality that cats within a given weight band will receive the same tube volume, and the actual delivered dose varies depending on where the individual cat falls within that band. A 3.0 kg cat and a 5.5 kg cat might both receive the same tube size, but the smaller cat will receive a higher dose per kilogram of body weight. This range is designed to ensure that even the heaviest cat in the band receives at least the minimum effective dose, while the lightest cat in the band receives a dose that remains within the established safety margin. The pharmacokinetic behavior of both active ingredients supports this approach. Selamectin is highly lipophilic, meaning it partitions into the sebaceous glands of the skin and is slowly released into the systemic circulation over time. This depot effect is why a single topical application provides sustained protection for a full month. Sarolaner, by contrast, is absorbed more rapidly into the systemic circulation and distributes widely, which contributes to its fast speed of kill against fleas and ticks [12][10][9]. The combination of a slow-release macrocyclic lactone and a rapidly absorbed isoxazoline creates a complementary pharmacokinetic profile that supports both immediate and sustained efficacy. The clinical significance of this dose range is that cat owners should not attempt to calculate or adjust the dose themselves. The tube sizes are color-coded and labeled by weight band, and the prescribing veterinarian will select the appropriate product based on the cat's current body weight. Weight changes of more than 1 kg between veterinary visits should prompt a recheck, as the cat may need to move to a different tube size. This is particularly relevant for growing kittens, which can outgrow a weight band within a few months. ## Clinical Reasoning Behind Combination Therapy The decision to combine selamectin and sarolaner in a single product reflects a broader trend in veterinary parasitology toward broad-spectrum, multi-target prevention. Monotherapy with a macrocyclic lactone alone, such as selamectin alone, provides excellent heartworm prevention and reasonable flea control, but it has gaps in tick coverage and a slower speed of kill against fleas. Isoxazolines like sarolaner close those gaps by providing rapid, potent activity against a wide range of tick species and by killing fleas before they can lay viable eggs [3][12][10][14]. The clinical reasoning extends beyond simply adding two drugs together. The two active ingredients have different mechanisms of action, which reduces the likelihood of resistance development. Selamectin works by binding to glutamate-gated chloride channels in parasite nerve and muscle cells, causing hyperpolarization and paralysis. Sarolaner works by antagonizing GABA-gated chloride channels, also leading to paralysis and death [12][13]. Because these targets are distinct, a parasite that develops resistance to one mechanism is unlikely to be resistant to the other. This is a meaningful advantage in an era where macrocyclic lactone resistance in heartworm is an emerging concern [11]. Another clinical consideration is the behavioral reality of feline patients. Cats are notoriously difficult to medicate orally, and topical application is often less stressful for both the cat and the owner. A single monthly topical application that covers fleas, ticks, ear mites, roundworms, hookworms, and heartworm prevention simplifies the preventive protocol and improves owner compliance [3][1][2]. Fewer products mean fewer missed doses and fewer opportunities for error. ## Diagnostic Workflow: Confirming the Need for Treatment Before prescribing Revolution Plus, a veterinarian will typically perform a series of diagnostic steps to confirm the presence of parasites and rule out other conditions. This workflow is important because clinical signs such as scratching, hair loss, and skin irritation can have multiple causes, including allergies, bacterial infections, and fungal infections. The diagnostic evaluation usually begins with a thorough history and physical examination. The veterinarian will ask about the cat's lifestyle, including whether it goes outdoors, whether it hunts, and whether it has contact with other animals. Indoor-only cats can still acquire fleas and ticks, as these parasites can be brought into the home on clothing, shoes, or other pets. The physical examination will include a careful check of the skin and coat, with particular attention to the base of the tail, the neck, and the ears, which are common sites for flea activity. A flea comb is a simple but effective diagnostic tool. The comb is run through the coat, and any debris collected is placed on a damp white paper towel. If the debris produces red-brown streaks, this is indicative of flea dirt, which is digested blood excreted by fleas. The presence of live fleas is, of course, definitive, but flea dirt can persist for weeks after fleas are gone, so its presence does not always confirm an active infestation. For ear mites, the veterinarian will examine the ear canals with an otoscope. Ear mites appear as small, white, moving dots against the dark background of the ear canal. A swab of the ear debris can be examined under a microscope to confirm the diagnosis. The presence of characteristic mites, eggs, and fecal material confirms *Otodectes cynotis* infestation [6]. For intestinal parasites, a fecal flotation test is the standard diagnostic tool. A small sample of feces is mixed with a flotation solution, and the mixture is centrifuged to separate parasite eggs from fecal debris. The eggs are then identified under a microscope. Roundworm eggs (*Toxocara cati*) and hookworm eggs (*Ancylostoma tubaeforme*) have distinctive morphologies that allow for species identification [7]. It is worth noting that fecal flotation can produce false negatives if the parasite burden is low or if the sample is not fresh, so a negative result does not completely rule out intestinal parasitism. Heartworm testing in cats is more nuanced than in dogs. The standard tests detect antigen from adult female heartworms and antibodies against heartworm larvae. However, cats often have low worm burdens, and the antigen test can be falsely negative if only male worms are present. The antibody test indicates exposure to heartworm larvae but does not confirm the presence of adult worms. For these reasons, heartworm testing in cats is often interpreted in the context of clinical signs and imaging findings. The field study in Japan that evaluated Revolution Plus used both antigen and antibody testing to confirm the absence of heartworm infection in treated cats [8]. ## Owner Observation: What to Look For Between Doses Cat owners play a critical role in monitoring the effectiveness of parasite prevention and detecting potential problems early. Between monthly doses, owners should be alert to several signs that may indicate persistent parasite activity or an adverse reaction. Flea activity is often first noticed as increased scratching, particularly around the head, neck, and base of the tail. Some cats develop a condition called flea allergy dermatitis, in which even a single flea bite triggers an intense allergic reaction. Affected cats may develop red, raised, itchy bumps, hair loss, and crusty lesions, particularly along the back and over the rump. If these signs appear in a cat receiving Revolution Plus, it is important to consider the possibility of environmental flea contamination. The product kills fleas on the cat, but fleas in the environment can continue to emerge and jump onto the cat, where they will be killed before they can reproduce. This process can take several weeks in a heavily infested home, and owners may see fleas on the cat during this transition period. Tick attachment is another observation point. Owners who live in tick-endemic areas should perform regular tick checks, particularly after the cat has spent time outdoors. Ticks can attach to any part of the body, but common sites include the head, neck, ears, and between the toes. A tick that has been killed by sarolaner may remain attached to the skin for a period of time before it falls off. Owners should not attempt to forcibly remove a dead tick, as this can leave mouthparts embedded in the skin and cause a local inflammatory reaction. Instead, the tick should be monitored and should detach on its own within a few days. Ear mite infestations are characterized by dark, crumbly debris in the ear canal, head shaking, and scratching at the ears. After treatment with Revolution Plus, owners may notice an increase in ear debris as the dead mites are cleared from the ear canal. This is a normal part of the resolution process, but if the debris persists for more than a few weeks, a recheck with the veterinarian is warranted [6]. Gastrointestinal signs, such as vomiting or diarrhea, can indicate intestinal parasite activity, but they can also be signs of other conditions. Owners should monitor their cat's appetite, water intake, and litter box habits. The presence of worms in the feces or vomit is a clear indication that intestinal parasite treatment is needed. In the US field study, treatment with selamectin plus sarolaner was effective in reducing fecal egg counts for roundworms and hookworms, but the resolution of clinical signs may take several days after the parasites are killed [7]. ## Preparing for the Veterinary Visit A productive veterinary visit begins with good preparation. Owners who arrive with a clear history and specific observations enable the veterinarian to make a more accurate diagnosis and treatment plan. Before the appointment, owners should gather the following information: - The cat's approximate weight and any recent weight changes - The date of the last dose of any parasite preventive, including the product name and dose - A description of any clinical signs, including when they started and how they have progressed - Information about the cat's lifestyle, including indoor/outdoor status, hunting behavior, and contact with other animals - Any history of adverse reactions to medications - A list of all current medications, including supplements and over-the-counter products - If possible, a fresh fecal sample collected within the last 12 hours Owners should also be prepared to discuss their cat's environment. A flea infestation in the home requires environmental treatment in addition to treating the cat. The veterinarian can provide guidance on safe and effective environmental control measures, including vacuuming, washing bedding, and using approved household insecticides. Without environmental treatment, the cat may be continuously reinfested, and the efficacy of the preventive may appear to be reduced. During the visit, the veterinarian will perform a physical examination and may recommend diagnostic tests based on the history and findings. These tests may include a flea comb examination, an otoscopic examination, a fecal flotation, and possibly blood work. The veterinarian will then prescribe the appropriate tube size of Revolution Plus and demonstrate the correct application technique. Owners should not hesitate to ask questions about dosing, administration, and what to expect after treatment. ## The Role of Environmental Management in Flea Control The efficacy of Revolution Plus against fleas is well-documented, but the product is only one component of a comprehensive flea control program [3][1][2][9]. Fleas have a complex life cycle that includes eggs, larvae, pupae, and adults. The adult fleas on the cat represent only about 5% of the total flea population in the environment. The remaining 95% exists as eggs, larvae, and pupae in the cat's bedding, carpets, and furniture. When a cat is treated with Revolution Plus, adult fleas on the cat are killed rapidly, but the environmental stages continue to develop. Eggs laid by fleas before treatment can hatch into larvae, which can develop into pupae and eventually emerge as new adult fleas. This emergence can continue for several weeks after the cat is treated, leading owners to believe that the product is not working. In reality, the product is killing the new adult fleas as they emerge, but the environmental reservoir must be depleted before the infestation is fully resolved. Environmental management is therefore essential for breaking the flea life cycle. Owners should vacuum all carpets, rugs, and upholstered furniture thoroughly and frequently, as vacuuming removes eggs, larvae, and pupae. Vacuum bags should be sealed and disposed of promptly. Bedding should be washed in hot water, and any areas where the cat sleeps should be treated with an approved household insecticide. In severe infestations, professional pest control may be necessary. It is also important to treat all pets in the household. If one cat has fleas, other cats and dogs in the home are likely to be infested as well. All pets should be on an appropriate flea preventive, and the veterinarian can recommend products that are safe for each species. Never use a dog product on a cat, as many dog flea and tick products contain permethrin, which is highly toxic to cats. ## Understanding Speed of Kill and Its Clinical Relevance The speed of kill of a parasiticide is more than a marketing metric; it has direct clinical implications for disease prevention. A product that kills fleas slowly allows fleas to feed on the cat for a longer period, increasing the risk of flea allergy dermatitis and the transmission of flea-borne pathogens. Similarly, a product that kills ticks slowly allows ticks to remain attached for longer, increasing the risk of tick-borne disease transmission. The speed of kill studies for Revolution Plus demonstrate that the product acts quickly. In a laboratory study, Revolution Plus began killing fleas within 6 hours of application, with a significant reduction by 12 hours and 100% efficacy by 24 hours [9]. For ticks, a study demonstrated a significant reduction in *Ixodes scapularis* within 12 hours and 100% efficacy by 24 hours after treatment [10]. This rapid action is clinically significant because it reduces the window of opportunity for pathogen transmission. The clinical relevance of speed of kill is particularly important for tick-borne diseases. For example, the transmission of *Borrelia burgdorferi* (the cause of Lyme disease) by *Ixodes scapularis* typically requires the tick to be attached for at least 24 to 48 hours. By killing ticks within 24 hours, Revolution Plus can interrupt transmission before the pathogen is passed to the cat [16][10]. Similarly, the transmission of *Anaplasma phagocytophilum* can occur within 24 hours of tick attachment, making rapid tick kill an important preventive measure [16]. For cytauxzoonosis, the stakes are even higher. *Cytauxzoon felis* is a protozoan parasite transmitted by *Amblyomma americanum* ticks, and the disease is often fatal in cats. A study demonstrated that Revolution Plus prevented the transmission of *C. felis* to cats, highlighting the importance of rapid tick kill in preventing this devastating disease [17]. ## Evidence Limitations and Interpretation of Study Data While the published studies on Revolution Plus are generally well-designed and provide strong evidence of efficacy, it is important to understand the limitations of the available data. Most of the efficacy studies are laboratory studies conducted under controlled conditions, which may not fully reflect the complexity of real-world situations. Laboratory studies typically use purpose-bred cats that are housed in controlled environments and infested with a known number of parasites. This allows for precise measurement of efficacy, but it does not account for the variability of natural infestations. Field studies, which enroll client-owned cats with natural parasite infestations, provide more realistic data but are subject to greater variability and less control over confounding factors [1][15][2][7][8]. The sample sizes in some studies are relatively small, which can limit the statistical power to detect rare adverse events. The safety data from field studies, which enrolled 405 cats in the US and 91 cats in Japan, provide reassurance that the product is generally well-tolerated, but rare adverse events may not be captured in these populations [1][8]. Post-marketing surveillance is important for detecting rare or unexpected adverse events that may not appear in pre-approval studies. Another limitation is the duration of the studies. Most efficacy studies evaluate the product over one to three months, which is sufficient to demonstrate efficacy but may not capture long-term safety or efficacy issues. The field study in Japan, which evaluated nine monthly treatments, provides longer-term data, but even this is a relatively short period in the life of a cat [8]. The studies also focus on specific parasite species and geographic regions. The tick species evaluated in the studies include *Ixodes scapularis*, *Amblyomma americanum*, *Dermacentor variabilis*, *Amblyomma maculatum*, and *Haemaphysalis longicornis* [16][5][15][14][17]. These are important species in North America and Japan, but they do not represent all tick species that may infest cats in other regions. The product's efficacy against other tick species, such as *Ixodes ricinus* in Europe, is not directly addressed in the cited studies. ## Special Population Considerations: Kittens, Seniors, and Breeding Cats The safety and efficacy of Revolution Plus have been evaluated in a range of cat populations, but certain groups require special consideration. Kittens are a particularly important population for parasite prevention. Fleas can cause anemia in young kittens, and intestinal parasites can impair growth and development. The minimum age for treatment with Revolution Plus is determined by the product label and should be confirmed with the veterinarian. Kittens grow rapidly, so their weight should be monitored regularly to ensure they are receiving the correct tube size. A kitten that moves from one weight band to another will need a different tube size, and the veterinarian should be consulted for the appropriate prescription. Senior cats may have concurrent health conditions, such as chronic kidney disease, diabetes, or hyperthyroidism, that require careful consideration when prescribing any medication. The safety of Revolution Plus in cats with these conditions has not been specifically studied, so the veterinarian will need to weigh the benefits of parasite prevention against the potential risks. In many cases, the benefits of preventing fleas, ticks, and heartworm disease outweigh the risks, but the decision should be made on an individual basis. Breeding cats, including pregnant and nursing queens, require special consideration. The safety of Revolution Plus in pregnant and lactating cats has not been established in the cited studies. The veterinarian will need to assess the risk-benefit ratio for each individual case. In some situations, alternative parasite prevention strategies may be recommended during pregnancy and lactation. Cats with a history of adverse reactions to medications, particularly macrocyclic lactones or isoxazolines, should be treated with caution. The veterinarian may recommend a trial dose under close observation or may suggest an alternative product with a different mechanism of action. ## The Importance of Year-Round Prevention The recommendation for year-round parasite prevention is based on sound epidemiological principles. Fleas can survive indoors throughout the year, even in cold climates, because central heating provides a warm environment for their development. Ticks can also be active in cooler months, particularly in regions with mild winters. Heartworm disease is transmitted by mosquitoes, which can be active indoors and during unseasonably warm periods. The Companion Animal Parasite Council and the American Heartworm Society both recommend year-round prevention for fleas, ticks, and heartworms. This recommendation is based on the recognition that parasite transmission can occur at any time of year and that lapses in prevention can lead to disease. The monthly administration of Revolution Plus provides continuous protection, and the year-round schedule ensures that the cat is never left unprotected. The consequences of a lapse in prevention can be significant. A single missed dose can allow fleas to establish an infestation, ticks to attach and transmit pathogens, or heartworm larvae to develop. Heartworm disease in cats is particularly concerning because there is no approved treatment for adult heartworms in cats, and the prognosis for affected cats can be guarded. Prevention is the only effective strategy for protecting cats from this potentially fatal disease [4][8]. ## Prognosis and Long-Term Outcomes The prognosis for cats treated with Revolution Plus depends on the underlying condition being treated. For uncomplicated flea infestations, the prognosis is excellent. The product kills fleas rapidly, and with appropriate environmental management, the infestation can be resolved within a few weeks [9]. Cats with flea allergy dermatitis may require additional treatment, such as anti-inflammatory medications, to manage the allergic response, but the prognosis is generally good once the flea burden is controlled. For tick infestations, the prognosis is also excellent, provided that tick-borne diseases have not been transmitted. The rapid speed of kill of sarolaner reduces the risk of pathogen transmission, but cats that have been exposed to infected ticks may still develop disease [16][10][17]. Tick-borne diseases such as Lyme disease, anaplasmosis, and cytauxzoonosis can have serious consequences, and affected cats require prompt veterinary care. For ear mite infestations, the prognosis is excellent with treatment. A single dose of Revolution Plus is highly effective in treating *Otodectes cynotis*, and most cats show significant improvement within a few weeks [6]. Some cats may require a second dose, and the environment should be treated to prevent reinfestation. For intestinal parasites, the prognosis is excellent with treatment. Roundworms and hookworms are effectively eliminated, and clinical signs such as diarrhea and poor weight gain typically resolve within a few weeks [7]. A follow-up fecal examination may be recommended to confirm that the parasites have been eliminated. For heartworm prevention, the prognosis is excellent for cats that receive monthly treatment as directed. The product is highly effective in preventing the development of *Dirofilaria immitis*, and no adult heartworms were recovered from treated cats in controlled studies [4]. The field study in Japan confirmed that no treated cats developed heartworm infection over nine months of treatment [8]. ## Recognizing and Managing Adverse Reactions While Revolution Plus is generally well-tolerated, owners should be aware of the potential for adverse reactions and know how to respond. The most commonly reported adverse reactions are mild and transient application-site reactions, such as temporary hair loss, redness, or itching at the site of application [6]. These reactions typically resolve on their own within a few days and do not require treatment. More serious adverse reactions are rare but can occur. Signs of a systemic reaction may include vomiting, diarrhea, lethargy, loss of appetite, or difficulty breathing. Neurological signs, such as tremors, incoordination, or seizures, are also possible, particularly in cats with a sensitivity to isoxazolines. If any of these signs occur after application, the owner should contact a veterinarian immediately. In the event of a suspected adverse reaction, the owner should not attempt to wash the product off the cat unless directed to do so by a veterinarian. Washing may increase the absorption of the product or cause it to spread to other areas of the body. The cat should be kept calm and quiet, and the veterinarian should be contacted for guidance. Owners should also be aware of the risk of accidental ingestion. If a cat grooms the application site before the product is dry, it may ingest a small amount of the medication. This can cause salivation, vomiting, or other gastrointestinal signs. To minimize this risk, the product should be applied to the base of the skull, where the cat cannot easily reach it, and treated cats should be separated from other cats until the application site is dry. ## The Role of the Veterinarian in Parasite Prevention The veterinarian plays a central role in parasite prevention, and the relationship between the owner and the veterinarian is essential for the health of the cat. The veterinarian is responsible for prescribing the correct product, determining the appropriate dose, and providing guidance on administration and monitoring. The veterinarian also plays a role in diagnosing parasite infestations, treating associated conditions, and managing adverse reactions. Regular veterinary visits are important for maintaining the cat's health and ensuring that parasite prevention is appropriate. The veterinarian can perform a physical examination, check the cat's weight, and recommend diagnostic tests as needed. These visits also provide an opportunity for the owner to ask questions and discuss any concerns. The veterinarian can also provide guidance on the broader aspects of parasite prevention, including environmental management, nutrition, and vaccination. Parasite prevention is one component of a comprehensive preventive healthcare plan, and the veterinarian can help the owner develop a plan that meets the individual needs of the cat. ## Integrating Revolution Plus into a Comprehensive Preventive Plan Revolution Plus is a valuable tool for parasite prevention, but it is not a substitute for comprehensive veterinary care. A complete preventive plan should include regular veterinary examinations, vaccination, nutrition, dental care, and parasite prevention. The veterinarian can help the owner develop a plan that addresses the cat's individual risk factors and lifestyle. For most cats, a monthly application of Revolution Plus provides broad-spectrum protection against fleas, ticks, ear mites, roundworms, hookworms, and heartworm disease. This simplifies the preventive protocol and reduces the number of products the owner needs to administer. However, the veterinarian may recommend additional products or interventions based on the cat's specific needs. For example, a cat that spends time outdoors in a tick-endemic area may benefit from additional tick checks and environmental management. A cat with a history of flea allergy dermatitis may require more aggressive flea control, including environmental treatment. A cat with a high risk of intestinal parasite exposure may benefit from more frequent fecal examinations. The key to successful parasite prevention is consistency. The owner must administer the product every month, year-round, and must follow the veterinarian's recommendations for monitoring and follow-up. With consistent use, Revolution Plus provides reliable protection against a wide range of parasites and contributes to the long-term health and well-being of the cat. **This article is educational and is not a substitute for veterinary diagnosis or treatment.** Always consult your veterinarian for any health concerns or before starting any new medication or preventive program. ## Frequently Asked Questions ### What is the exact dose of Revolution Plus for my cat? The dose is based on your cat's weight, providing a minimum of 6.0 mg/kg of selamectin and 1.0 mg/kg of sarolaner, with an approved range of 6.0-12.0 mg/kg and 1.0-2.0 mg/kg, respectively [1][2]. Your veterinarian will prescribe the correct tube size. ### How often do I need to apply Revolution Plus to my cat? Revolution Plus is administered once a month (every 30 days) for continuous protection [3][1]. ### How quickly does Revolution Plus kill fleas on my cat? Revolution Plus starts killing fleas within hours, with a significant reduction seen by 12 hours and 100% efficacy by 24 hours after treatment in a laboratory study [9]. ### Is Revolution Plus effective against all types of ticks? Revolution Plus is effective against several common tick species, including *Ixodes scapularis*, *Amblyomma americanum*, *Dermacentor variabilis*, and *Haemaphysalis longicornis* [5][15][14]. ### Can Revolution Plus prevent heartworm disease in my cat? Yes, selamectin in Revolution Plus is highly effective in preventing the development of *Dirofilaria immitis* (heartworm) [4][8]. ### Does Revolution Plus treat ear mites? Yes, a single dose of Revolution Plus is highly effective in treating ear mite infestations (*Otodectes cynotis*) [1][6]. ### Is Revolution Plus safe for my cat? Yes, Revolution Plus has been shown to be safe and well-tolerated in multiple laboratory and field studies, with only mild, transient application-site reactions occasionally reported [3][1][6][2]. ### What should I do if I miss a dose of Revolution Plus? If you miss a dose, apply it as soon as you remember, and then resume the monthly schedule. Contact your veterinarian for specific advice if you are unsure. **This article is educational and is not a substitute for veterinary diagnosis or treatment.** Always consult your veterinarian for any health concerns or before starting any new medication or preventive program. ## Sources [1] [Efficacy and safety of a combination of selamectin plus sarolaner for the treatment and prevention of flea infestations and the treatment of ear mites in cats presented as veterinary patients in the United States.](https://pubmed.ncbi.nlm.nih.gov/30579753/) [2] [Safety and efficacy of a new spot-on formulation of selamectin plus sarolaner in the treatment and control of naturally occurring flea infestations in cats presented as veterinary patients in Australia.](https://pubmed.ncbi.nlm.nih.gov/32375898/) [3] [Efficacy of three consecutive monthly doses of a topical formulation of selamectin and sarolaner (Revolution(®) Plus/Stronghold(®) Plus) compared with a single dose of fluralaner (Bravecto(®) for Cats) against induced infestations of Ctenocephalides felis on cats.](https://pubmed.ncbi.nlm.nih.gov/31133494/) [4] [The efficacy of a novel topical formulation of selamectin plus sarolaner (Revolution(®) Plus/Stronghold(®) Plus) in preventing the development of Dirofilaria immitis in cats.](https://pubmed.ncbi.nlm.nih.gov/30455076/) [5] [Efficacy of Revolution® Plus (selamectin plus sarolaner) against Amblyomma americanum (lone star ticks) in cats.](https://pubmed.ncbi.nlm.nih.gov/40750907/) [6] [Efficacy of a new spot-on formulation of selamectin plus sarolaner in the treatment of Otodectes cynotis in cats.](https://pubmed.ncbi.nlm.nih.gov/28395753/) [7] [Efficacy and safety of a new topical formulation of selamectin plus sarolaner in the treatment and control of natural infections of Ancylostoma tubaeforme and Toxocara cati in cats presented as veterinary patients in the United States.](https://pubmed.ncbi.nlm.nih.gov/30470638/) [8] [Efficacy and safety of a new topical formulation containing selamectin and sarolaner in the prevention of heartworm disease and the treatment of roundworm infection in cats presented as veterinary patients in Japan.](https://pubmed.ncbi.nlm.nih.gov/31104940/) [9] [Efficacy and speed of kill of a new spot-on formulation of selamectin plus sarolaner against flea infestations in cats.](https://pubmed.ncbi.nlm.nih.gov/28395751/) [10] [The speed of kill of a topical combination of selamectin plus sarolaner against induced infestations of Ixodes scapularis ticks on cats.](https://pubmed.ncbi.nlm.nih.gov/30563718/) [11] [The efficacy of a topical formulation of selamectin plus sarolaner in preventing the development of a macrocyclic lactone-resistant strain of Dirofilaria immitis in cats.](https://pubmed.ncbi.nlm.nih.gov/32460111/) [12] [Comparative efficacy of topical treatments with Revolution(®) Plus (selamectin and sarolaner) and Bravecto(®) for Cats (fluralaner) against Ixodes scapularis ticks on cats.](https://pubmed.ncbi.nlm.nih.gov/31182302/) [13] [Sarolaner/selamectin spot-on: An effective treatment of generalized demodicosis due to Demodex cati in a cat.](https://pubmed.ncbi.nlm.nih.gov/40786743/) [14] [Efficacy of a new topical formulation containing selamectin plus sarolaner against three common tick species infesting cats in the United States.](https://pubmed.ncbi.nlm.nih.gov/30470637/) [15] [Efficacy of a new topical formulation of selamectin plus sarolaner for the control of fleas and ticks infesting cats in Japan.](https://pubmed.ncbi.nlm.nih.gov/30914264/) [16] [Efficacy of Revolution(®) Plus (selamectin plus sarolaner) for the prevention of transmission of Borrelia burgdorferi from infected Ixodes scapularis to cats.](https://pubmed.ncbi.nlm.nih.gov/41845441/) [17] [Efficacy of a topical formulation of selamectin plus sarolaner against induced infestations of Amblyomma americanum on cats and prevention of Cytauxzoon felis transmission.](https://pubmed.ncbi.nlm.nih.gov/30466895/) [18] [Efficacy of Revolution®Plus in cats for the prevention of Dipylidium caninum transmission by infected Ctenocephalides felis.](https://pubmed.ncbi.nlm.nih.gov/40760497/) [19] [Safety of imidacloprid plus moxidectin topical solution applied to cats heavily infected with adult heartworms (Dirofilaria immitis).](https://pubmed.ncbi.nlm.nih.gov/16228278/) [20] [Field evaluation of the efficacy and safety of emodepside/praziquantel spot-on solution against naturally acquired nematode and cestode infections in domestic cats.](https://pubmed.ncbi.nlm.nih.gov/16228276/) ## 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