CARNIVORES
PRIMATES
UNGULATES
Bats and Rodents
MARINE
MAMMALS
Marsupials
HOW TO CHOOSE THE APPROPRIATE CONTRACEPTIVE METHOD
A variety
of factors such as efficacy and safety
of available methods, the animal’s age,
behavioral and social ramifications,
the practicality of different delivery
systems, and the individual’s reproductive
status must be considered when selecting an appropriate contraceptive
method. It is unlikely that the same
birth control method will be the most appropriate choice during all stages of
an animal’s life. Permanent
Sterilization or Participation in Contraceptive Studies is encouraged for
Surplus Animals.
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Methods and Administration
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Recommendations
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MGA (melengestrol
acetate) Implants
Manufacturer - ZooPharm division
of Wildlife Pharmaceuticals, Colorado, USA.
Product
Information - MGA implants are the most frequently used and
consequently the contraceptive method for which we have the most information in
the Wildlife Contraception
Center database. Melengestrol acetate is a synthetic
progestin. MGA implants contain 20%
melengestrol acetate by weight in a silastic matrix. Because different species require different
dosages, implants are not interchangeable. Although duration of MGA implant efficacy may
vary by individual and species, the continued recommendation is to replace them
at 2-year intervals.
Storage – Implants should be stored at
refrigeration temperatures (4°C).
Sterilization – MGA
implants should be inserted using sterile surgical technique. In addition, it is recommended that implants
be gas-sterilized
with ethylene oxide followed by de-gassing at room temperature for a
minimum of 2 weeks prior to use.
Because the implants are porous, they must be de-gassed longer than
metal instruments. Inadequate de-gassing
may result in residual gas that may evoke a tissue reaction. If ethylene oxide sterilization is not
available, the implant may be rinsed with alcohol and dried with sterile gauze
prior to placement. Sterilization with a
cold-soak solution is not recommended, because the chemicals can be absorbed
and/or MGA may be leached from the implant.
Possible effects of hydrogen peroxide sterilization (STERRAD) on MGA
implant release dynamics have not been tested, so it can not be recommended or
advised against at this time. Because
heat may change the structure of the MGA, implants should not be autoclaved.
Insertion - Implants should be inserted
between the scapulae intra-muscularly if possible, but, if subcutaneous
placement is necessary, place implant in a “tunnel” created by blunt dissection
of fascia away from the incision.
Migration may be controlled by suturing the implant in place at the time
of insertion.
Implant
loss can be reduced by properly sterilizing implants before insertion, using
sterile insertion technique, and separating the animal from conspecifics during
the period of healing. (NOTE: in some taxa such as the callitrichids
and small prosimians, steel sutures have been
successful in preventing over-grooming and implant removal by conspecifics,
thereby avoiding the need to separate animals).
The implant’s presence should be confirmed whenever the animal is
handled.
Monitoring implant
placement - Identification transponder microchips inserted in
MGA implants can be used to confirm presence and location. Implants cannot be supplied with transponders
already in place; however, chips can be inserted in implants that are longer
than the chip. Using sterile procedure,
puncture implant longitudinally with needle containing transponder chip (it
comes sterile) and insert into implant as you would under the skin. Insert implant into animal using standard
surgical technique as outlined above.
Secondly, stainless steel suture or comparable material may be
incorporated into the implant to make it visible on radiographs prior to
sterilization.
Implant disposal – used implants received from ZooPharm or Ed Plotka should
be disposed of in proper waste containers after use.
Latency to effectiveness - Although individuals vary, threshold levels of the
hormone should be reached in the blood within 1 to 3 days following IM
insertion and within 1 week after SQ insertion.
However, pre-ovulatory follicles are difficult to suppress, so, if cycle
stage is not known, extra time must be allowed.
Therefore, separation or alternative contraception should be used for at least
1week (if IM) or 2 weeks (if SQ) following insertion.
Estrous cycles during
treatment - MGA may effect contraception by blocking ovulation,
causing thickening of cervical mucus, slowing ovum transport, and/or
interfering with fertilization or implantation.
However, follicle growth may continue and sometimes be accompanied by
estrogen production sufficient to cause estrous behavior. Ovulation may occur even though pregnancy
does not ensue. Higher progestin doses
may be preferred, so that estrous behavior is prevented, but may not be
effective in completely suppressing follicle growth and some estradiol production.
Duration of efficacy
and reversibility - Implants are considered effective for at least 2
years and possibly much longer, depending on species and individual
differences, but in some cases have been found to be effective for as much as 5
years when left in place. This means that implants should be replaced every 2 years to
insure contraception, but should be removed when pregnancy is desired. Once the implant is removed, the circulating MGA
clears very rapidly, so that ovulation and conception may occur within days,
although actual latency is usually longer and will depend on the individual
(see Reversibility Considerations).
Use during pregnancy - Synthetic progestins like MGA are not recommended in pregnant
animals because of the possibility of prolonged gestation, stillbirth,
abortion, etc. in some species, although the effect may depend on dose. Progestins in late pregnancy seem not to
interfere with parturition in primates, but this may be a taxon-specific
phenomenon.
Use during lactation -
Progestins are sometimes prescribed for lactating women and are considered
generally safe for nursing infants.
Use in pre-pubertals or juveniles – Future reproduction was not affected
in calves of domestic cows on MGA-treated feed, but no studies of pre-pubertal
treatment with MGA or other progestins have been conducted with other species,
so possible long-term effects on fertility are not known.
Precautions – MGA can cause weight gain in all
species. Possible deleterious effects on
uterine and mammary tissues vary greatly by species; see cautions for each taxon.
Consideration for
seasonal breeders - Treatment should begin at least one month before
the anticipated onset of the breeding season.
However, in canids, treatment should begin more
than two months before the time of anticipated estrus, because proestrus
increases in estradiol can begin as much as two months before estrus, and it is
known that this endogenous estradiol can exacerbate deleterious effects of
progestins on the uterus and mammary glands.
This synergy of estradiol and progestins may also occur in other
carnivores, such as mustelids and ursids.
Reporting Requirements - All institutions must submit a
complete Contraception
Center Survey to the AZA
Wildlife Contraception Center.
The product will no longer be sold to any institution that fails to
submit the annual survey.
Request for purchase – MGA implants may
be purchased by prescription through ZooPharm.
All prescriptions should be written using their protocol and MUST include an authorization number designated
by the AZA Wildlife Contraception Center.
MGA implants cost $25/gram plus shipping and handling. To request authorization for ordering MGA
implants, please complete the Implant
Request Form and submit to:
Sally Boutelle, Program Coordinator
AZA Wildlife Contraception
Center
Saint
Louis Zoo
1 Government Drive
St.
Louis, MO 63110
314-646-4595; fax: 314-646-5534
Contraception@stlzoo.org
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MGA MILLED IN FEED
Manufacturer - Purina Mills LLC/Mazuri, St. Louis, USA.
Product Information
- Mazuri ADF-16 Herbivore pellet with MGA (a synthetic progestin)
provides an alternative contraceptive method particularly for ungulates housed
and fed in mixed species/mixed sex herds.
The product is considered suitable for bovids,
giraffes, cervids, camelids and hippos, but is not effective in suids or equids.
The product
is available only as part of an experimental trial coordinated by the AZA Wildlife
Contraception
Center in collaboration
with Purina Mills LLC/Mazuri brand. The
goal of the study is to obtain approval for use of MGA-treated feed as a
contraceptive method for exotic hoofstock species. However, at this time the feed must be
considered experimental and all participants must adhere to strict
protocols for data collection and reporting as dictated by the Food and Drug
Administration (FDA). The AZA Wildlife
Contraception
Center is responsible for
maintaining data collected by study participants and, in conjunction with
Purina Mills LLC, submits regular reports to the FDA. The FDA requires all medicated diets be
manufactured under an INAD (Investigational New Animal Drugs, 21 CFR
511.1(a)). Purina Mills LLC was granted
permission to manufacture MGA-treated herbivore pellet for use in this project
under their existing INAD on file with the FDA.
Therefore, all participating institutions must obtain the experimental
MGA feed through the AZA
Wildlife Contraception Center and Purina Mills LLC until such
time as it is approved by the FDA for general manufacture and feeding. NOTE:
Under the current INAD the product is only available for bovids, giraffes,
cervids, camelids, and hippos, and its use in other species or without
registering with the AZA
Contraception
Center is prohibited.
Safety to humans - When used as directed, this
product poses no health risk to humans.
Domestic cattle are 240 times more sensitive to MGA than are humans,
i.e., a human would have to ingest a dose 240 times higher than that ingested
by cattle to have the same effect. The
doses being recommended for exotic ungulates are within the range used for
cattle. Purina Mills, Inc. believes it
is not hazardous material according to the OSHA Hazard Communications Standard,
29 CFR 1910.1200 or the EPA Community Right-to-Know regulations. Questions about the Purina Mills MSDS program
should be directed to Mr. Paul Luther at 314-768-4630.
Safety to treated
animals - MGA has
been fed to domestic cattle for decades without untoward effects, which
suggests that it should be generally safe for ruminants. However, exotic species have not been treated
for more than 10 years, so possible longer term effects have not been
recognized. Also, species differences
may apply.
Recommended doses - Mazuri
ADF-16 0.5MA, containing 0.5 mg MGA/lb,
can be used either alone or in combination with standard Mazuri ADF-16 to
achieve the recommended daily MGA dose/animal for your individual feeding
program. The following daily MGA doses are recommended:
- 0.5 mg MGA/day/animal: for
species with body size smaller than an adult, female banteng. (about 800
lb).
- 1.0 mg MGA/day/animal: for
species with body size similar to or larger than an adult, female banteng
but smaller than a giraffe.
- 3.0 mg MGA/day/animal: giraffes
and hippos
The maximum
safe dose is considered to be more than 3 times those recommended here. NOTE:
If the full dose is not consumed every day, the female should be separated from
males, since follicle growth and ovulation may occur.
Nutritional
considerations - The amount of pellet used depends on the species,
the body size and on your particular feeding program. The MGA herbivore pellet is intended to
replace the regular herbivore pellet in the current diet. The pellet should still be fed in conjunction
with hay in an amount that meets the recommended minimum daily MGA dose, while
still meeting the nutritional needs of the animals.
In general,
ruminant herbivores have a daily diet intake of 1.5 – 4.0% body mass (BM), with
larger species consuming food at a smaller percentage of BM than medium or
small species. The amount of herbivore
pellet to feed is based largely on the quality of hay fed, and the pellet is
intended to correct the nutrient imbalances or deficits that might occur on a
diet of only hay. Regular analysis of
the nutrient content of your hay is highly recommended. It may be necessary to make adjustments in
your current feeding regimens in order to deliver the appropriate dose of MGA
via the new herbivore products. Current
recommendations from zoo nutritionists suggest that medium to large size
ruminant herbivores should receive 30-40% of the diet (by weight, as fed basis)
as a nutritionally complete herbivore pellet and 60-70% of the diet (by weight,
as fed basis) as hay. The type of hay(s)
used (e.g., legume or grass hay, species of hay) in the diet is dependent on
the nutrient content of the hay, the species being fed and hay types available
in your area.
If you
would like assistance in determining an appropriate feeding plan, please
contact Jan Dempsey, Nutritionist,
at Janet.Dempsey@purina.nestle.com.
Latency to
effectiveness - As with MGA implants, separation or alternative
contraception should be used for 1-2 weeks after initiation of the feed.
Estrous cycles during
contraceptive treatment - Synthetic progestins may affect contraception by
blocking ovulation, causing thickening of cervical mucus, slowing ovum
transport, and/or interfering with fertilization or implantation. However, follicle growth may continue and
sometimes be accompanied by estrogen production sufficient to cause estrous
behavior. Ovulation may occur even though
pregnancy does not ensue. Higher
progestin doses may be preferred so that estrous behavior is prevented, but may
not be effective in completely suppressing follicle growth and all estradiol
production.
Duration of efficacy
and reversibility - Duration of efficacy may not be much more than one
day, so the product must be administered daily. Following cessation of treatment,
rapid clearance can result in ovulation within a few days, but actual latency
to conception will vary by individual.
Use during pregnancy - Progestins are not recommended in
pregnant animals because of the possibility of prolonged gestation, stillbirth,
abortion, etc. in some species, although the effect may depend on dose. Progestins in late pregnancy seem not to
interfere with parturition in primates, but this is a taxon-specific
phenomenon.
Use during lactation -
Progestins are sometimes prescribed for lactating women and are considered
generally safe for nursing infants.
Use in pre-pubertals or juveniles Future reproduction was not affected in calves of
domestic cows on MGA-treated feed, but no studies of pre-pubertal treatment
with MGA or other progestins have been conducted with other species, so
possible long-term effects on fertility are not known.
Precautions –
Progestins likely cause weight gain in all species. Possible deleterious effects on uterine and
mammary tissues vary greatly by species; see cautions for each taxon.
Consideration for
seasonal breeders - Treatment should begin at least one month before
the anticipated onset of the breeding season.
Reporting requirements - All
institutions using MGA feed must submit a bi-annual MGA Feed
Survey to the AZA
Wildlife Contraception Center.
Any adverse effects must be reported in writing to the AZA Wildlife
Contraception
Center. The product will no longer be sold to any
institution that fails to submit the bi-annual survey.
Request for purchase - Before placing your first order with your Purina
product dealer, or to add species to an existing order, you must register with the AZA
Wildlife Contraception Center. The Center will then notify Purina
Mills, Inc. that you are an approved buyer, so you will be able to make the
purchase through your regular Purina product dealer. Please submit the MGA
Feed Registration Form to:
Sally
Boutelle, Program Coordinator
AZA Wildlife
Contraception
Center
Saint Louis Zoo
1 Government Drive
St. Louis, MO
63110
314-646-4595;
fax: 314-646-5534
Contraception@stlzoo.org
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MGA LIQUID
Manufacturer - ZooPharm division of
Wildlife Pharmaceuticals, Colorado, USA.
Product information - MGA, a
synthetic progestin dissolved in a special propylene glycol formulation for
orally delivered contraception, is considered suitable for species in which
orally delivered MGA has been shown to be safe and effective
Safety to humans - When used
as directed, this product poses no health risk to humans. ZooPharm believes this
MGA formulation is not a hazardous material according to the OSHA Hazard
Communications Standard, 29 CFR 1910.1200 or the EPA Community Right-to-Know
regulations. Therefore no Material
Safety Data Sheets (MSDS) have been produced.
If you have questions, call Dr. Bill Lance at 970-484-6267.
Safety to treated
animals - MGA has been administered orally to domestic cattle
for decades without untoward effects, which suggests that it should be
generally safe for ruminants. However, exotic
ruminants have not been treated orally with MGA for more than 10 years, so
possible longer term effects are unknown.
Also, as with most drugs, species differences apply. In particular, MGA liquid is
not recommended for carnivores, since synthetic progestins have been
shown to be associated with deleterious effects in this group. It may not be appropriate for primates, as a
higher concentration is necessary for efficacy.
It may not be effective in suids or equids.
Recommended doses - The
product comes as a solution of 1mg MGA/ml.
The following daily MGA doses are recommended:
- 0.1 mg MGA/day/animal - for
small mammals such as bats and rodents
- 0.5 mg MGA/day/animal - for
ungulates up to about 800 lbs
- 1.0 mg MGA/day/animal - for
ungulates larger than 800 lbs, except giraffe and hippopotamus.
- 2.0-3.0 mg MGA/day/animal- for
giraffe and hippopotamus
NOTE: If the full dose is not
consumed every day, the female should be separated from males, since follicle
growth and ovulation may occur.
Administration - MGA
liquid can be added to a treat and delivered to individual animals, can be
delivered directly into the mouth of animals such as hippos, or can be added to
the regular diet and fed individually or to groups. However, it is important to insure that each
female ingests at least the minimum effective dose every day or ovulation and
pregnancy can result. If a female
refuses to consume the dose, she should be separated from males until she is
has consumed the proper dose again for at least one week.
Although
progestin contraception can often be effective even when ovulation is not
blocked, to ensure efficacy we recommend that the dose be sufficiently high to
suppress estrous behavior. Please report
observations of estrous behavior in treated animals to Cheryl
Asa or Sally
Boutelle to discuss a higher dosage.
Latency to
effectiveness - As with MGA implants and feed, separation or
alternative contraception should be used for 1-2 weeks after initiation of the
product.
Estrous cycles during
contraceptive treatment - Synthetic progestins may effect contraception by
blocking ovulation, causing thickening of cervical mucus, slowing ovum
transport, and/or interfering with fertilization or implantation. However, follicle growth may continue and
sometimes be accompanied by estrogen production sufficient to cause estrous
behavior. Ovulation may occur even
though pregnancy does not ensue. Higher
progestin doses may be preferred, so that estrous behavior is prevented, but
may not be effective in completely suppressing follicle growth and all
estradiol production.
Duration of efficacy
and reversibility - Duration of efficacy may not be much more than one
day, so the product must be administered daily. Following cessation of
treatment, rapid clearance can result in ovulation within a few days, but
actual latency to conception will vary by individual.
Use during pregnancy - Progestins are not recommended in
pregnant animals because of the possibility of prolonged gestation, stillbirth,
abortion, etc. in some species, although the effect may depend on dose. Progestins in late pregnancy seem not to
interfere with parturition in primates, but this is probably a taxon-specific phenomenon.
Use during lactation - Progestins
are sometimes prescribed for lactating women and are considered generally safe
for nursing infants.
Use in pre-pubertals or juveniles - Future reproduction was not affected in calves of domestic cows
on MGA-treated feed, but no studies of pre-pubertal treatment with MGA or other
progestins have been conducted with other species, so possible long-term
effects on fertility are not known.
Precautions –
Progestins likely cause weight gain in all species. Possible deleterious effects on uterine and
mammary tissues vary greatly by species; see cautions for each taxon.
Consideration for
seasonal breeders - Treatment should begin at least one month before
the anticipated onset of the breeding season.
Reporting requirements - All institutions using MGA liquid
must submit a complete Contraception
Center Survey to the AZA
Wildlife Contraception Center.
The product will no longer be sold to any institution that fails to
submit the annual survey.
Request for purchase - Before placing your first order with Zoopharm, or to
add species to an existing order, you
must register with the AZA
Wildlife Contraception Center. The Center will then notify ZooPharm
that you are an approved buyer so you will be able to make the purchase through
a valid prescription faxed to ZooPharm at 307-721-3801. The formulation is compounded to a 1mg/ml
strength in a 30 ml vial, at a price of $25.00 plus shipping and handling. A more dilute strength can be provided on
request for smaller mammals. Cost of
special flavorings would be extra but should be minimal. Please submit the MGA
Liquid Registration Form to:
Sally
Boutelle, Program Coordinator
AZA Wildlife
Contraception
Center
Saint Louis Zoo
1 Government Drive
St. Louis, MO
63110
314-646-4595;
fax: 314-646-5534
Contraception@stlzoo.org
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DEPO-PROVERA® (medroxyprogesterone acetate) INJECTIONS
Manufacturer - Pfizer
Product information - With the second most numerous
records in the Wildlife Contraception
Center database, Depo-Provera® has been used
most often in reproductively seasonal species (e.g., prosimians,
bears, pinnipeds),
species in which anesthesia for implant insertion is problematic (e.g., giraffes, hippos), and as an immediately available
interim contraceptive (e.g., if an implant is found missing or has not been
ordered). Medroxyprogesterone acetate is
a synthetic derivative of progesterone administered
as an acetate salt with anti-estrogenic activity.
Dose - Dosage studies have not been conducted for most species. Recommended doses and injection intervals vary
according to species and experience.
Current reports have indicated that 2-5 mg/kg body weight every 2-3
months has been effective (the higher dose for smaller species and the lower
dose for larger ones). However, New World monkeys require as much as 20mg/kg
monthly. For especially large species
for which body weights may not be available, such as hippos, see Taxon-Specific Recommendations.
Latency to
effectiveness - IM injection is roughly equivalent to implant
insertion, i.e., separation or alternative contraception should be used,
conservatively, for 2 weeks, but at least for1 week.
Estrous cycles during
contraceptive treatment - Synthetic progestins may effect contraception by blocking
ovulation, causing thickening of cervical mucus, slowing ovum transport, and/or
interfering with fertilization or implantation.
However, follicle growth may continue and sometimes be accompanied by
estrogen production sufficient to cause estrous behavior. Ovulation may occur even though pregnancy
does not ensue. Higher progestin doses
may be preferred, so that estrous behavior is prevented, but may not be
effective in completely suppressing follicle growth and all estradiol
production.
Duration of efficacy
and reversibility - Duration of efficacy, and thus latency to
conception following last injection, can be extremely variable and has been
seen to vary from 4 weeks to 2 years in some individuals. In general, the recommended dose (2.5-5 mg/kg
BW) is effective for at least 2 months in most species. Hippos and giraffe have been treated at lower
doses and appear to need re-treatment every 6 weeks. New World
primates require higher doses at more frequent intervals.
Use during pregnancy - Progestins are not recommended in
pregnant animals because of the possibility of prolonged gestation, stillbirth,
abortion, etc. in some species, although the effect may depend on dose. Progestins in late pregnancy seem not to
interfere with parturition in primates, but this is a taxon-specific
phenomenon. Because of the variability
in duration of efficacy for Depo-Provera, special caution should be used when
treating females that might be pregnant.
Use during lactation -
Progestins are sometimes prescribed for lactating women and are considered
generally safe for nursing infants.
Use in pre-pubertals or juveniles - Future reproduction was not affected in calves of domestic
cows on MGA-treated feed, but no studies of pre-pubertal treatment with MGA or
other progestins have been conducted with other species, so possible long-term
effects on fertility are not known.
Consideration for
seasonal breeders - Treatment should begin at least one month before
the anticipated onset of the breeding season.
This does not include however canids or other carnivores due to the
potential for progestin side effects addressed in the corresponding taxonomic
sections below.
Precautions – Progestins likely cause weight
gain in all species. Possible
deleterious effects on uterine and mammary tissues vary greatly by species; see
cautions for each taxon. In the human
literature, Depo-Provera® has been linked to mood
changes. Because it binds readily to
androgen receptors and is anti-estrogenic, females may experience male-like
qualities (increased aggression, development of male secondary sex
characteristics, etc.)
Reporting requirements - All institutions using
Depo-Provera® are asked to submit a complete Contraception
Center Survey to the AZA
Wildlife Contraception Center. It is essential that accurate
records of doses and intervals be maintained and results reported to the
Wildlife Contraception Center
Database to contribute to dosage development.
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MEGESTROL ACETATE (e.g. MEGACE®) PILLS
Manufacturer – Megestrol
acetate – generic (e.g. Megace®: Bristol-Myers Squibb)
Product information – Megestrol acetate is a synthetic derivative of progesterone with
anti-estrogenic activity. Ovaban® is no longer on the market but megestrol acetate is
approved for use in domestic dogs for no more than 2 cycles. Megace® is
approved for treatment of estrogen-sensitive tumors and for anorexia in humans
because it increases appetite. Both have
been used occasionally for contraception in carnivores. Megestrol acetate can be used temporarily
during the initial stimulation phase of the GnRH agonist products. It is provided in various dose tablets. The domestic dog dose is 1mg/kg body weight,
but must be extrapolated for other taxa.
Latency to
effectiveness - As with implants and injections, separation or alternative
contraception should be used for 1-2 weeks after initiation of treatment.
Estrous cycles during
contraceptive treatment - Synthetic progestins may effect contraception by
blocking ovulation, causing thickening of cervical mucus, slowing ovum
transport, and/or interfering with fertilization or implantation. However, follicle growth may continue and
sometimes be accompanied by estrogen production sufficient to cause estrous
behavior. Ovulation may occur even
though pregnancy does not ensue. Higher
progestin doses may be preferred, so that estrous behavior is prevented, but
may not be effective in completely suppressing follicle growth and some
estradiol production.
Duration of efficacy
and reversibility - Duration of efficacy may not be much more than one
day, so must be administered daily. Following cessation of treatment, rapid
clearance can result in ovulation within a few days, but actual latency to
conception will vary by individual.
Use during pregnancy - Progestins are not recommended in
pregnant animals because of the possibility of prolonged gestation, stillbirth,
abortion, etc. in some species, although the effect may depend on dose. Progestins in late pregnancy seem not to
interfere with parturition in primates, but this is a taxon-specific
phenomenon.
Use during lactation -
Progestins are sometimes prescribed for lactating women and are considered
generally safe for nursing infants.
Use in pre-pubertals or juveniles - Future reproduction was not affected
in calves of domestic cows on MGA-treated feed, but no studies of pre-pubertal
treatment with MGA or other progestins have been conducted with other species,
so possible long-term effects on fertility are not known.
Consideration for
seasonal breeders - Treatment should begin at least one month before
the anticipated onset of the breeding season.
This does not inc
