Hartz UltraGuard Products for Fleas and Ticks in Dogs and Cats

Medically Reviewed by Joshua Conrad, PharmD on October 22, 2024
Written by Kathleen Claussen, DVM
14 min read

The Hartz UltraGuard product line (made by the Hartz Mountain Corporation) includes topical products (products that are applied to the skin) and collars (worn around the neck) that are effective against adult fleas, flea eggs, flea larvae, ticks (specifically deer ticks and brown dog ticks), and mosquitoes, depending on the product being used. Hartz UltraGuard products are approved by the Environmental Protection Agency (EPA) for the treatment and control of external parasites in dogs and cats. 

The Hartz UltraGuard product line has many products for cats and dogs, which can be confusing. But they can be divided into these categories:

  • Topical liquids for cats
  • Topical liquids for dogs
  • Collars for cats
  • Collars for dogs

Hartz UltraGuard topical liquid products for cats all contain the active ingredient etofenprox. Etofenprox is classified as a synthetic non-ester pyrethroid that is effective against fleas and ticks. Some of these products combine etofenprox with methoprene. Methoprene is classified as an insect growth regulator that prevents the maturation of flea and mosquito eggs and larvae.

  • Hartz UltraGuard Topical Liquid for Cats (etofenprox only)
  • Hartz UltraGuard Plus Topical Liquid for Cats (etofenprox and methoprene)
  • Hartz UltraGuard Pro Topical Liquid for Cats (etofenprox and methoprene)

Hartz UltraGuard Topical Liquid for Cats is a monthly (every 30 days) medicine that kills fleas and deer ticks. It also kills and repels mosquitoes. Cats and kittens need to be at least 12 weeks old and weigh at least 5 pounds (2.2 kilograms) to use this medicine.

Hartz UltraGuard Plus Topical Liquid for Cats is a monthly (every 30 days) medicine that kills fleas, deer ticks, and flea eggs. It also kills and repels mosquitoes. Cats and kittens need to be at least 12 weeks old and weigh at least 5 pounds (2.2 kilograms) to use this medicine. This product starts killing fleas within 15 minutes.

Hartz UltraGuard Pro Topical Liquid for Cats is a monthly (every 30 days) medicine that kills fleas, deer ticks, flea eggs, and flea larvae (young). It also kills and repels mosquitoes. It prevents flea eggs from hatching for up to 30 days. Cats and kittens need to be at least 12 weeks old and weigh at least 5 pounds (2.2 kilograms) to use this medicine.

Hartz UltraGuard topical liquid products for dogs all contain the active ingredients etofenprox (described above) and pyriproxyfen. Pyriproxyfen is classified as an insect growth regulator that helps control fleas and prevent fleas from returning. One of these products also contains methoprene (described above).

  • Hartz UltraGuard Dual Action Topical Liquid for Dogs (etofenprox and pyriproxyfen)
  • Hartz UltraGuard Plus Topical Liquid for Dogs (etofenprox and pyriproxyfen)
  • Hartz UltraGuard Pro Topical Liquid for Dogs (etofenprox, pyriproxyfen, and methoprene)

Hartz UltraGuard Dual Action Topical Liquid for Dogs is a monthly (every 30 days) medicine that kills fleas, brown dog ticks, deer ticks, and flea eggs. It also prevents and controls them from returning for up to 30 days. This product comes in four weight sizes: 5 to 14 pounds, 15 to 30 pounds, 31 to 60 pounds, and 61 to 150 pounds. Dogs and puppies need to be 12 weeks and older to use this medicine.

Hartz UltraGuard Plus Topical Liquid for Dogs is a monthly (every 30 days) medicine that kills fleas, brown dog ticks, and flea eggs. It also kills and repels mosquitoes for up to 30 days. This product comes in four weight sizes: 5 to 14 pounds, 15 to 30 pounds, 31 to 60 pounds, and 61 to 150 pounds. Dogs and puppies need to be 12 weeks and older to use this medicine.

Hartz UltraGuard Pro Topical Liquid for Dogs is a monthly (every 30 days) medicine that kills fleas, brown dog ticks, deer ticks, and flea larvae (young), and prevents flea eggs from hatching. It also kills and repels mosquitoes for up to 30 days. It comes with an easy-to-use, patented pro-glide angled applicator. Hartz UltraGuard Pro Topical Liquid for Dogs starts killing fleas within 15 minutes of application. This product comes in four weight sizes: 5 to 14 pounds, 15 to 30 pounds, 31 to 60 pounds, and 61 to 150 pounds. Dogs and puppies need to be 12 weeks and older to use this medicine.

Hartz UltraGuard collars for cats contain the active ingredient tetrachlorvinphos (TCVP), which is classified as an organophosphate insecticide used to control fleas, ticks, various flies, lice, and insect larvae (young) on pets. TCVP is sometimes combined with methoprene to prevent fleas from returning.

  • Hartz UltraGuard Collar for Cats (TCVP only)
  • Hartz UltraGuard Plus Collar for Cats (TCVP and methoprene)
  • Hartz UltraGuard Pro Collar for Cats (TCVP and methoprene)
  • Hartz UltraGuard ProMax Collar for Cats (TCVP and methoprene)

Cats and kittens need to be at least 12 weeks old to use these collars. It is also important to treat the cat’s bedding and sleeping areas for flea and tick control with a product labeled to treat these areas.

Hartz UltraGuard Collar for Cats is a fresh-scented and water-resistant breakaway collar that provides 7 months of protection from fleas and ticks. This collar kills ticks for five months and aids in their control for an additional two months. If a cat is exposed to severe flea and tick infestations, the collar may need to be changed after the first five months. This collar comes in white, purple, and white with a reflective strip that reflects direct light up to 300 feet for added visibility.

Hartz UltraGuard Plus Collar for Cats is a fresh-scented and water-resistant breakaway collar that provides seven months of protection and repels fleas, ticks, flea eggs, and flea larvae. It also prevents flea eggs from hatching. It also comes in a version with a reflective strip that reflects direct light up to 450 feet for added visibility.

Hartz UltraGuard Pro Collar for Cats is a fresh-scented and water-resistant breakaway collar that provides seven months of protection from fleas, ticks, flea eggs, and flea larvae. It also prevents flea eggs from hatching. 

Hartz UltraGuard ProMax Collar for Cats (purple color) is a soft and flexible collar with a smooth interior surface. It provides seven months of protection from fleas, ticks, flea eggs, and flea larvae. It also prevents flea eggs from hatching. Cats and kittens need to weigh at least 5 pounds (2.2 kilograms) to use this collar.

Most Hartz UltraGuard collars for dogs contain the active ingredients TCVP alone or TCVP with methoprene. One of these collars combines deltamethrin with methoprene. Deltamethrin is classified as a synthetic pyrethroid insecticide for killing fleas and ticks. It also repels mosquitoes for up to six months.

  • Hartz UltraGuard Collar for Dogs (TCVP only)
  • Hartz UltraGuard Plus Collar for Dogs (TCVP and methoprene)
  • Hartz UltraGuard Pro Collar for Dogs (TCVP and methoprene)
  • Hartz UltraGuard ProMax Collar for Dogs (deltamethrin and methoprene)

Dogs and puppies need to be 12 weeks and older to use these collars. It is also important to treat the dog’s bedding and sleeping areas for flea and tick control with a product labeled to treat these areas.

Hartz UltraGuard Collar for Dogs is a fresh-scented and water-resistant collar providing seven months of protection from fleas and ticks. This collar kills ticks for five months and aids in their control for an additional two months. If a dog is exposed to severe flea and tick infestations, the collar may need to be changed after the first five months. It comes in a white collar for puppies with up to a 15-inch neck, a white collar for dogs with up to a 20-inch neck, a white collar for large dogs with up to a 26-inch neck, and an white collar with a reflective strip that reflects direct light from up to 300 feet away for an added dimension of nighttime safety for dogs with up to a 20-inch neck.

Hartz UltraGuard Plus Collar for Dogs is a fresh-scented and water-resistant collar providing seven months of protection from fleas, ticks, flea eggs, and flea larvae. The collar also prevents flea eggs from hatching. It comes in three variations: a white collar for puppies with up to a 15-inch neck, a white collar for dogs with up to a 22-inch neck, and an orange collar with a reflective strip that reflects direct light from up to 300 feet away for an added dimension of nighttime safety for dogs with up to a 22-inch neck.

Hartz UltraGuard Pro Collar for Dogs is a water-resistant collar providing seven months of protection from fleas, ticks, flea eggs, and flea larvae. The collar also prevents flea eggs from hatching. It comes with a reflective strip that reflects direct light from up to 450 feet away for an added dimension of nighttime safety for dogs with up to a 26-inch neck.

Hartz UltraGuard ProMax Collar for Dogs kills fleas, deer ticks, flea eggs, and flea larvae for six months. It also kills and repels mosquitoes for six months and prevents flea eggs from hatching. It comes in a blue or gray color and fits up to a 26-inch neck.

Hartz UltraGuard products are usually well tolerated in animals. There is minimal risk for overdose, side effects, or drug interactions if used as labeled or as directed by your veterinarian.

Hartz UltraGuard products are available without a prescription. 

Hartz UltraGuard topical liquid products are applied to your pet’s skin once a month (every 30 days). In cats, the product is applied at the base of the skull. In dogs, it is applied in a line from between the shoulder blades to the tip of the tail. Hartz UltraGuard Collars are worn around a pet’s neck for five to seven months depending on the collar being used and the severity of the infestation.

To apply Hartz UltraGuard Topical Liquid for Cats or Hartz UltraGuard Plus Topical Liquid for Cats, remove one tube that is the appropriate dose for the cat’s weight. Hold the tube upright and remove the cap. Turn the cap over and push the other end into the tip of the tube to break the seal. Then part the cat’s hair until you can see the skin and squeeze the contents onto the skin at the base of the skull. Do not touch that area until it is completely dry. Do not allow your cat or other pets in the household to groom (rub or lick) the application site until it dries. Do not bathe your cat for 24 hours after application. Repeat application every month (every 30 days). 

To apply Hartz UltraGuard Pro Topical Liquid for Cats, make sure the skin at the base of the cat’s head is dry and healthy. Using the appropriate tube of drops, hold the tube upright and twist the applicator tip about one-half turn while pressing down to break the seal. Part the hair and squeeze the entire contents of the tube directly onto the skin at the base of the neck in one spot. Do not touch that area until it is completely dry. Do not allow your cat or other pets in the household to groom (rub or lick) the application site for 24 hours. You may bathe your pet 24 hours after application.

To use one of the many Hartz UltraGuard collars on a cat, remove the collar from the package and stretch the collar to activate it. Then place the collar on the cat’s neck, adjusting for proper fit, and buckle in place. The collar should be loose enough to move around the neck and allow for growth of a kitten. When it is properly fitted, it will snugly slide over the cat’s head when it is buckled in place. Leave 2 to 3 inches of extra collar for future adjustment and cut off any remaining length of collar, disposing of it properly.

To apply Hartz UltraGuard Dual Action Topical Liquid for Dogs, remove one tube that is the appropriate dose for the dog’s weight. Hold the tube upright and remove the cap. Turn the cap over and push the other end into the tip of the tube to break the seal. Then part the dog’s hair until you can see the skin and squeeze the entire contents of the tube directly onto the skin in a line starting at the base of the neck along the back to the tip of the tail.  Do not touch that area until it is completely dry. Do not allow your dog or other pets in the household to groom (rub or lick) the application site until it dries. Do not bathe or allow your dog to swim for 48 hours after application. Repeat application every month (every 30 days).

To apply Hartz UltraGuard Pro Topical Liquid for Dogs or Hartz UltraGuard Plus Topical Liquid for Dogs, make sure the skin at the base of the dog’s head and along the back is dry and healthy. Using the appropriate tube of drops, hold the tube upright and twist the applicator tip about one-half turn while pressing down to break the seal. Part the hair and squeeze the entire contents of the tube directly onto the skin in a line starting at the base of the neck along the back to the tip of the tail. Do not touch that area until it is completely dry. Do not allow your dog or other pet in the household to groom (rub or lick) the application site for 24 hours. You may bathe or allow your dog to swim for 48 hours after application. Repeat application every month (every 30 days).

To use one of the many Hartz UltraGuard collars on a dog, remove the collar from the package and stretch the collar to activate it. Then place the collar on the dog’s neck, adjusting for proper fit and buckle in place. The collar should be loose enough to move around the neck and allow for growth of a puppy. When it is properly fitted, it will snugly slide over the dog’s head when it is buckled in place. Leave 2 to 3 inches of extra collar for future adjustment and cut off any remaining length of collar, disposing of it properly.

Always follow your veterinarian’s directions for giving medicines to animals. Remember to tell your veterinarian about any medicines, vitamins, supplements, or herbal therapies that you are giving your pet. Talk to your veterinarian before stopping any pet medicines. 

  • Hartz UltraGuard products do not require a veterinary prescription. 
  • Hartz UltraGuard collars will start to kill fleas, ticks, flea eggs, and flea larvae immediately.
  • There are Hartz UltraGuard collars for both dogs and cats with a reflective strip to improve the pet’s visibility when outside.
  • Hartz UltraGuard flea and tick collars provide up to 5 or 7 months of flea and tick protection depending on the product being used and the severity of the infestation. 

You and your veterinarian should monitor your pet for signs that the medicine is working (absence of live fleas and ticks depending on the product being used), as well as for side effects of the medicine. There is no routine lab monitoring needed with Hartz UltraGuard products.

Do not use a Hartz UltraGuard product in an animal that is allergic to its ingredients. Do not use Hartz UltraGuard products in dogs or cats below the minimum age or weight on the product label. Do not use cat products on dogs and do not use dog products on cats. Use them with caution in frail, older, pregnant, or nursing dogs and cats. Do not allow your pet or their housemates to lick the topical application until dry. Do not get the topical product in the pet’s eyes or mouth. 

Your pet should not be able to lick the site of application if using any of the Hartz UltraGuard topical liquid products. Other pets may try to groom or lick at the application site, especially cats that clean each other. Try to prevent this from happening. If your pet ingests the medicine, they will usually have excessive salivation (drooling) and may even foam at the mouth. If your pet starts acting strangely, seek veterinary care.

Side effects are uncommon with Hartz UltraGuard products if they are used as directed on the label. Your pet may experience redness, itching, or other signs of discomfort at the application or collar site. If any of these symptoms occur, bathe your pet with mild soap and rinse with large amounts of water. If a collar is too tight, loosen it.

Other side effects with Hartz UltraGuard products containing TCVP may include:

  • Excessive salivation (drooling)
  • Vomiting
  • Diarrhea (loose stool)
  • Miosis (contracted or small pupil)
  • Incoordination
  • Weakness
  • Muscle tremors

If you think that your pet is having a serious side effect or may have been overdosed, call your veterinary clinic immediately. If it is outside of regular office hours, you may contact a local emergency veterinary hospital or an animal poison control center. 

You can reach the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.

Using multiple medicines can sometimes change how your pet’s medicines work or increase your pet’s risk for serious side effects. Always tell your veterinarian about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements that your pet is using.

Do not use multiple products containing TCVP on pets simultaneously or within 30 days before or after treatment with or exposure to cholinesterase inhibiting drugs, pesticides, or chemicals. Ask your veterinarian if you are unsure if other medicines your pet is getting contain these kinds of ingredients. Flea and tick collars may be replaced immediately.

  • Keep Hartz UltraGuard products out of the reach of children.
  • Wash your hands with soap thoroughly after handling Hartz UltraGuard products and before eating, drinking, chewing gum, using tobacco, or using the toilet.
  • Do not handle Hartz UltraGuard products if you are allergic to any of the ingredients.
  • Avoid getting Hartz UltraGuard topical liquid in your mouth or eyes or on your skin and clothing.

Hartz UltraGuard products are very well tolerated by animals and the risk of an overdose is low. If you are concerned your pet is having an adverse reaction or if you suspect your pet has gotten more medicine than intended, call your veterinarian or veterinary emergency clinic immediately.

If your pet misses a dose, give the dose when you remember and then restart the dosing interval from that date. Do not double the dose of the medicine. 

Store Hartz UltraGuard products in the original packaging in a cool, dry place. Do not contaminate food, feed, or water with Hartz UltraGuard products. Use care when disposing of certain Hartz UltraGuard products as they are extremely toxic to aquatic organisms, including fish and invertebrates. Do not reuse the used Hartz UltraGuard collars or containers.

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