Due to COVID-19 and a shortage of veterinary personnel, spay/neuter surgeries across the country are significantly delayed and waitlists continue to grow. Because it is not uncommon for a female cat to become pregnant or have kittens while waiting to be spayed, Cat Adoption Team (CAT) has partnered with ACC&D to conduct a pilot program to deploy the only contraceptive for cats that can be accessed—megestrol acetate (MA).

CAAT has made appointments available to see if MA can be used as a tool to prevent unwanted litters and help owners while cats wait for spay appointments.

MA is a prescription drug that can be used to prevent a cat from becoming pregnant while waiting for a spay appointment. MA can also prevent or relieve the headache caused by a cat showing signs of heat such as yowling, spraying, and trying to escape.

During the clinic a veterinarian will conduct a free physical exam of your cat to determine if she is a good candidate for MA a.k.a. “kitty birth control.”

MA is an oral contraceptive that can be used to prevent pregnancy and estrus (heat) cycles in dogs and cats, as well as other mammals. It has also been prescribed to treat certain skin and behavior issues in dogs and cats. In the U.S., any use of MA in cats is considered “off label." This means that it has not been submitted to or reviewed or approved by the Federal Drug Administration (FDA). MA has received regulatory approval in several other countries and has been used extensively in Europe to manage reproduction of both cats and dogs. Please note that many drugs commonly used in veterinary medicine in the U.S. are considered off-label by regulatory standards.

In general, good candidates for MA are healthy female cats weighing at least 4 lbs. and are not already pregnant. Additionally, ideal candidates for this program are female cats who:
• Go outdoors (including balconies);
• Are indoor-only but share the home with an unneutered male cat; or
• Exhibit heat-related behaviors that are problematic for their owners

Yes. MA is a temporary method of fertility control. Currently, surgical spaying is the only available option for permanently sterilizing female cats.

In addition to preventing kittens from being born while you wait for your cat to be spayed, suppressing a cat from going into heat means preventing the cat from exhibiting heat-related behaviors such as increased vocalization, urine marking, attention-seeking and demanding behaviors, and begging to go outside. These behaviors persist frequently until breeding and pregnancy occur. An added benefit of participation is that your cat will be prioritized when surgeries are scheduled. Presently, wait times for spay/neuter surgeries at CAT can be as long as 6 months or more.

Cats who participate in the birth control clinic will be given a date for their spay appointment when they attend the birth control clinic. As such they will be removed from the appointment waitlist.

Research strongly suggests side effects are more common with higher doses and longer durations of use. Clinic veterinarians will only prescribe low-dose MA for short-term use (2.5 mg once a week, up to 30 weeks). Potential side effects associated with low-dose MA are:
• Increased hunger and weight gain (common)
• Behavioral changes such as increased friendliness, placidity, or aggressiveness (common)
• Effects on fetal development (stillborn or masculinization of kittens)
• Inability to lactate

Potential side effects associated with higher doses (>2.5 mg per day)
• Uterine infections (requires emergency surgery)
• Diabetes mellitus (often reversible but can be permanent)
• Mammary gland swelling or cancer
• Adrenal gland suppression (stress hormone changes)

Most side effects are reversible once the drug has been discontinued for several weeks, but some may be permanent.

MA is administered orally. MA purchased from CAT will be in the form of a liquid suspension dispensed in prefilled syringes. MA can be mixed into wet food. If you have other pets and MA is mixed into food, take precautions to ensure only the specific cat MA is prescribed for receives the medication, this includes feeding cats separately and promptly removing dishes once food is consumed.

Yes, however, the low dose for cats showing signs of heat is higher at 5 mg/cat daily for 3 days followed by the 2.5 mg/cat dose weekly after that.

MA hasn’t been commonly used in the U.S. where both rates of spaying and concerns about MA’s side effects are high. In numerous countries outside of the U.S., MA has been approved for and used as a contraceptive for dogs and cats at varying doses. Research strongly suggests that when considering use of MA to prevent estrus, the dosage and treatment duration is important to minimize the likelihood of side effects. Because of this only low-dose MA will be prescribed at our clinic.

There is no fee for the physical exam, however, you will need to pay for the medication. The cost for 2-month supply of MA for a cat that is not in heat is $10. If your cat is in heat, the cost will be $12.

No. This clinic is designed to specifically provide cat owners with an option for preventing their cat from going into heat while waiting to for spay surgery. To help as many cats as possible, staff won’t be able to address other medical issues your cat may have.

If you are a client or prospective client please email questions to hospital@catadoptionteam.org.

Additional details about MA can be found here.

Thinking about conducting your own MA program? Feel free to email us with questions.