Project Description

If you have any reason to suspect your pet has ingested something toxic, please contact your veterinarian or one of the other resources listed:
ASPCA Animal Poison Control Center 24-hour hotline at (888) 426-4435
• Pet Poison Helpline® 24-hour animal poison control service at (855) 764-7661


Estrogen containing products, including oral contraceptives and hormone replacement therapy, can cause serious adverse effects and toxicity in pets. While ingestion of these medications pose toxicity risks, topical exposure is also concerning. Notable hair loss has been seen in animals exposed to topical hormone replacement therapy products.


Dogs and ferrets are indicated for this toxicity.

Signs and symptoms of toxicity: Clinical signs of toxicity include hair loss, female genital swelling, male genital atrophy, weakness and loss of coordination.

Toxic consumption:
In dogs, greater than 1 mg/kg (0.45 mg/lb) of estrogen may be toxic. It should be noted that oral contraceptives typically contain 0.02-0.05mg of estrogen per tablet.

Dogs: Estrogen Toxic Consumption
Yorkie, Chihuahua
Pug, Boston Terrier, Poodle
Beagle, Scottish Terrier
Boxer, Cocker Spaniel
Retriever, German Shepherd
Great Dane, St. Bernard
1 – 10 lbs.
(0.45 – 4.6 kg)
11 – 25 lbs.
(5 – 11.4 kg)
26 – 40 lbs.
(11.8 – 18.2 kg)
41 – 70 lbs.
(18.6 – 31.8 kg)
71 – 90 lbs.
(32.3 – 40.9 kg)
91 – 110 lbs.
(41.4 – 50 kg)
dog1 dog2 dog3 dog4 dog7 dog6
> 0.45 mg > 5 mg > 11.8 mg > 18.6 mg > 32.3 mg > 41.4 mg

– Berger D. Canine Alopecia Secondary to Human Topical Hormone Replacement Therapy in Six Dogs. J Am Anim Hosp Assoc 2015;51:136-142. DOI 10.5326/JAAHA-MS-6247
– Sontas H. Estrogen-induced myelotoxicity in dogs: A review. Can Vet J 2009;50:1054-1058.

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