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Veterinary Prescription Resources

Veterinary "Non-Human" Use of Medications

As more consumers look to have their veterinary prescriptions filled by a community or mail order pharmacy, pharmacists are playing an increasing - and important - complementary role in the health care of animal patients. Given this emerging role, it is important that pharmacists contact veterinarians directly with any concerns about the patient’s prescription.

It also is good to keep the following in mind when filling and dispensing prescriptions:

  • The federal government has clarified that veterinarians are not eligible to have a National Provider Identifier (NPI) number. This unique 10-digit identification number is only issued to human health care providers by the Centers for Medicare and Medicaid Services.
  • The Drug Enforcement Administration (DEA) advises veterinarians to not provide their DEA license number for non-controlled substance prescriptions. Pharmacies that dispense from a veterinarian’s prescription should instead request the veterinarian’s license number.
  • If a veterinarian writes “No Substitution” or “Dispense as Written” next to the prescribed product’s name, a pharmacist cannot provide the client with an equivalent product without the veterinarian’s authorization.  
  • Oregon pharmacies must have a veterinary reference readily accessible. References to consider include Plumb’s Veterinary Drug Handbook and The Merck Veterinary Manual.

Considerations for common veterinary prescriptions


​The NSAID should never be given to dogs or cats, as it can result in severe gastric ulcers or acute kidney failure. Drugs like Rimadyl, Deramaxx, and Meloxicam are NSAIDs that are approved by the FDA for use in animals.​


​Phenobarbital is the most widely prescribed medication for treating seizure disorders in dogs and usually is the first medication given to a dog with epilepsy. Phenobarbital is effective in 60 to 80 percent of dogs with idiopathic epilepsy. The barbiturate is prescribed for dogs at a much higher dose than used in humans to treat seizure disorders. Pharmacists are encouraged to contact the attending veterinarian directly with any concerns or questions they may have about the prescribed dosage.


​This medication is used for both dogs and cats, but the dosing is different depending on whether Gabapentin is being used for managing pain or to control seizures. To treat pain, dosing usually starts at once daily but can be increased to two-to-three times a day. Anti-seizure doses are three-to-ten times higher than analgesic doses to start. With dogs, the medication must be administered three-to-four times daily. Important note: Gabapentin oral solutions might be sweetened with Xylitol, which can be toxic to dogs.​


​This over-the-counter medication is useful in controlling arthritis in humans, but a product containing acetaminophen should never be given to cats. The drug interferes with oxygen in the blood of cats and can result in death if not treated promptly. Acetaminophen in high doses is also not safe for dogs and can cause irreversible liver damage.​

Latanoprost Eye Drops

​To treat glaucoma in humans, the drops are used once daily. However, for dogs, two to three times daily is a typical and often necessary treatment frequency.

Thyroid Hormone

​Thyroid disease is common in both the dog and cat. It is almost uniformly hypothyroidism for dogs and hyperthyroidism for cats. For dogs that have been diagnosed with a thyroid disorder, veterinarians might prescribe the same thyroid supplement that many humans take: Soloxine or Levothyroxine. Dogs will receive a much higher dosage of a thyroid medication than will people. A change in dosage can result in sub-therapeutic treatment for the animal and extra expense for the pet’s owner because of the need to run additional diagnostic testing to re-stabilize the patient’s hormone level.


​Community pharmacists must note that there are major differences between diabetes in cats and dogs versus diabetes in humans, specifically in regards to treatment options.  Even the slightest variation from a treatment plan can affect the health of the cat or dog, leading to poor glycemic control, which may lead to life-threatening diabetic ketoacidosis and hypoglycemia. While there are various forms of insulin, not all forms can be used to treat veterinary patients. Although an alternative form of insulin may be less expensive for the veterinary client, substitution should not be made without consulting with the prescribing veterinarian and obtaining his or her authorization. Example: Glargine has a higher cost, but NPH can be less effective in treating diabetic cats.

Prednisolone vs. Prednisone

​The two drugs are interchangeable in humans, but this is NOT the case with the dog and cat. Prednisone is one-half to one-third as effective as Prednisolone.​

Vitamin A

​This fat-soluble antioxidant is used in veterinary medicine to help a dog with its coat, muscles, nerves, skin and vision. It also helps female dogs maintain ovarian health and reproduce successfully, and it helps puppies grow and develop normally. With some dermatological conditions, Vitamin A may be prescribed in dosages higher than what a human would take.

Minoxidal (Rogaine)

​This product is used to help hair growth in the treatment of male pattern baldness, but it is not an acceptable treatment for alopecia in pets. It can cause cardiomyopathy in dogs.  ​


​While the natural, sugar-free sweetener is safe for humans, it can be harmful for dogs. When ingested in small amounts by dogs, it can cause life-threatening hypoglycemia within 10-15 minutes. Larger ingestions can result in liver failure. ​

Psychotropic Medications

​In general, the dose of Serotonin Reuptake Inhibitors (SSRIs) and other psychotropic medications is higher in dogs and cats than in people.

Flea and Tick medications

​Veterinary products that have been developed for treating fleas and ticks should only be used on the indicated species. Canine flea and tick medications can be extremely toxic to cats. One common complication is seizures. Also, a commonly used flea medication used in dogs and cats may be fatal to rabbits.

Overview of Feline and Canine Diabetes Mellitus for Community Pharmacists

*Contributed by Brian T. Bowers, PharmD, RPh, FSVHP, FACVP & Lauralei Schuster, PharmD, FSVHP and in cooperation with the Oregon Veterinary Medical Association.

Diabetes mellitus (DM) is a common disease encountered in canine and feline medicine.  As in human medicine, treatment of diabetes mellitus can be challenging, as it requires attention and committed efforts from both the owner and the veterinarian to adhere to a consistent protocol for glycemic control.  Community pharmacists must note, however, that there are major differences between diabetes in cats and dogs versus diabetes in humans, specifically in regards to treatment options.  Even the slightest variation from a treatment plan can affect the health of the cat or dog, leading to poor glycemic control, which, if left unattended, may lead to life-threatening diabetic ketoacidosis and hypoglycemia. 

Feline DM:  
Type 1 DM is rare in cats and most cats with diabetes have type 2 DM (80%), which is caused by insulin resistance and relative insulin deficiency secondary to β cell dysfunction.  Additionally, it is not unusual for cats to go into spontaneous clinical remission within 1-4 months after treatment is initiated, especially if clinical intervention is managed early, aggressively and effectively.  Predisposing risk factors for feline DM include: physical inactivity, obesity, older than 8 years of age, high-carbohydrate diet, gender (male neutered), certain breeds, drug therapy (i.e. corticosteroids), and concurrent conditions (i.e. infection, hyperthyroidism, and chronic renal insufficiency).  Clinical signs of feline DM may include: polyuria, polydipsia, polyphagia, obesity with recent weight loss, lethargy, dehydration, poor hair coat, hepatomegaly, and neuropathy representative of difficulty jumping, hind limb weakness, and plantigrade posture. 

Canine DM:
The majority of dogs that have diabetes mellitus are insulin-dependent or Type 1 and are likely to remain diabetic for life due to a relative or absolute lack of insulin secretion secondary to β cell dysfunction/absence which is irreversible.  Predisposing risk factors of canine DM include: breed, middle-aged/older females, and concurrent conditions (i.e. infection, drug therapy, obesity, immune-mediated destruction, and pancreatitis).  Clinical signs of canine DM include:  polydipsia, polyuria, polyphagia, weight loss, dehydration, electrolyte imbalances, metabolic acidosis, frequent urinary tract infections, osmotic diuresis, lameness (due to peripheral neuropathy), or vision loss from cataracts.  

Therapy Goals and Assessment:
The therapy goals and assessment for each animal patient is individualized, and treatment may be modified based on response.  Blood glucose levels should be maintained between 120 mg/dL to 250 mg/dL in cats and between 100 mg/dL to 250 mg/dL in dogs.  Blood glucose control is not as strict as in humans due to the risk of hypoglycemia.  While the administration of insulin is the foundation of medical therapy management, other factors are also important for managing DM in canine and feline patients.  These factors include clinical remission if possible (cat), minimizing clinical signs (i.e. polyuria/polydipsia), dietary selection, weight control, treatment of concurrent illness, avoiding complications such as ketoacidosis and hypoglycemia [blood glucose <60mg/dL (cat) and <80mg/dL (dog)], avoiding sequelae (i.e. neuropathy or cataracts), and frequent reassessment by the veterinarian.  

Choice of Insulin Treatment:
Veterinarians use a variety of veterinary and human insulin products.  Only Vetsulin® and ProZinc® are approved by the FDA for use in dogs and cats.  All other insulins are used extra-label.  It should be noted that veterinary insulins have a concentration of 40 units/mL and require U-40 syringes for dosing to avoid the risk for major dosing errors.  Oral hypoglycemics (i.e. glipizide) are not effective in dogs due to the absence of functional β cells.  Glipizide may be used in cats when owners are unable or unwilling to administer insulin.  However, it has been associated with the destruction of β cells and may become ineffective over time.

  • Vetsulin® 40 units/mL (porcine insulin zinc suspension; Merck Animal Health) 
    • Intermediate-acting insulin most commonly used in dogs
    • Initial dose in dogs is 0.25 units/kg subcutaneously every 12 hours after meals
    • Duration of action is between 10 to 14 hours in dogs
    • Usual dosage (euglycemia maintenance) in cats is 1 to 2 units subcutaneously every 12 hours with or immediately following a meal (this insulin is usually reserved for cats unresponsive to other types of insulin due to its short duration of action)
    • Must be shaken well before use to form homogeneous suspension 
    • Injections must be administered using U-40 syringes only 
    • Available in 10 mL vial or 2.7 mL pen cartridges (used with VetPen insulin pen)
    • Store in the refrigerator and use within 42 days of first puncture

  • Insulin glargine 100 units/mL (human recombinant; Lantus®; Sanofi) 
    • Long-acting insulin commonly used in cats due to its duration of action
    • Usual dosage (euglycemia maintenance) in cats is 1 unit subcutaneously every 12 hours with or immediately following a meal
    • Although glargine can be used in dogs it is not recommended for initial treatment of newly diagnosed diabetic patients due to unpredictable efficacy
    • Available in 10 mL vial or 3 mL prefilled syringe cartridge 
    • Store in refrigerator and use within 28 days of first puncture
    • Do not shake, dilute, or mix with other insulins

  • ProZinc® 40 units/mL (PZI human recombinant protamine zinc insulin; Boehringer Ingelheim Animal Health) 
    • Long-acting insulin for use in cats
    • Usual dosage (euglycemia maintenance) for cats is 1 unit subcutaneously every 12 hours with or immediately following a meal
    • Although PZI can be used in dogs, it is generally not recommended due to the risk of hypoglycemia
    • Injections must be administered using U-40 syringes only 
    • Available in 10 mL vial
    • Store in refrigerator
    • Manufacturer does not provide a discard date for punctured vials – owners should be counseled to consult with veterinarian on appropriate beyond use date
    • Vial should be rolled gently (not shaken) between palms of hands for to form a homogeneous suspension

  • Humulin®-N, Novolin®-N 100 units/mL (NPH U-100 recombinant, Neutral Protamine Hagedorn; Lilly, Nordisk)
    • Intermediate-acting insulin that is used in dogs
    • Initial dose is 0.25 units/kg subcutaneously every 12 hours
    • The duration of action of NPH (6 to 12 hours) may be too short for twice daily dosing in some dogs
    • NPH is not recommended for diabetic cats because it is very short acting in the species and does not result in good glycemic control
    • Store in refrigerator
    • Novolin N available as a 10 mL vial or 3 mL pen; Humulin N available as a 10 mL vial, 3 mL vial, or 3 mL pen
    • Vials should be rolled gently (not shaken) between palms of hands to form a homogeneous suspension
    • Do not substitute different manufacturers of NPH unless directed by a veterinarian

  • Insulin detemir 100 units/mL (Levemir®; Nordisk)
    • Long-acting insulin sometimes used in dogs and can be used in cats
    • Initial dosage of 0.1 to 0.2 units/kg subcutaneously every 12 to 24 hours, starting at the low end of the dosing range for dogs
    • Therapy should be initiated under the supervision of a veterinarian with a blood glucose curve due to long duration of action in some dogs
    • Similar dosage as with glargine in cats
    • Available as a 10 mL vial or 3 mL pen
    • Store both vial and pen in refrigerator until opened; pen should be stored at room temperature after opening (do not refrigerate)
    • Once opened, both pen and vial should be discarded after 42 days
    • Do not mix or dilute with any other solution or insulin
  • Compounded insulin products are not recommended because of concerns about production methods, diluents, sterility, and insulin concentration consistency between lots.

This article is not an all-inclusive practice management topic on diabetes management for dogs and cats but a brief overview of pharmacy practice highlights for the community pharmacists’ understanding.  For further information, practicing pharmacists and pharmacy technicians are encouraged to obtain continuing education via Power-Pak C.E.® ‘Veterinary Pharmacy Certificate’ program and to build a library of veterinary references and texts.

Veterinary Pharmacy Certificate POWER-PAK C.E. Continuing Education for Pharmacists and Pharmacy Technicians.  Module 7.  Providing Pharmaceutical Care and Products for Dogs.
Veterinary Pharmacy Certificate POWER-PAK C.E. Continuing Education for Pharmacists and Pharmacy Technicians.  Module 8.  Providing Pharmaceutical Care and Products for Cats.
Plumb, D.C. (2015).  Plumbs Veterinary Drug Handbook 8th Edition.  Ames, Iowa:  Wiley-Blackwell
Behrend, E., Holford, A., Lathan, P., Rucinsky, R., Schulman, R. (2018).  2018 AAHA Diabetes Management Guidelines for Dogs and Cats.  J Am Anim Hosp Assoc. 54(1): 1-21.