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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Dog
Satisfied Customers: 33322
Experience:  University of California at Davis graduate veterinarian with 45 years of experience.
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My dog has never come in to season

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My dog has never come in to season
Aloha! You're speaking to Dr. Michael Salkin
You've described a primary anestrus in Gizmo - a failure to show external signs of proestrus or estrus (failure to cycle). Abnormal physical findings may include a poor or excessive general body condition, overall immature appearance, and ambiguous or infantile external genitalia. The physical exam may, however, be unremarkable.

The diagnosis of anestrus is suspected based on the absence of estrus (heat) behaviors in an intact animal, followed by excluding anatomic abnormalities and endocrine-related (hormonal) illnesses. Confirmation requires histopathologic identification (biopsy) of oophoritis (inflammation of the ovaries) or diagnostic imaging (CT scan) demonstrating pituitary abnormalities. A specialist in veterinary reproduction is usually required for the advanced testing needed in pets such as Gizmo. Here are the differential diagnoses we consider:

1) silent heat - Gizmo cycles but imperceptibly
2) abnormalities in sexual differentiation such as hermaphrodism
3) hyperadrenocorticism/Cushing's disease - not in a 5 year old with no other symptoms
4) pituitary insufficiency - the pituitary gland isn't producing the hormones that stimulate the ovaries to ovulate
5) lymphocytic oophoritis - inflammation of the ovaries predominantly by one of the white blood cells called the lymphocyte
6) luteal ovarian cyst - the ovaries form abnormal and poorly functioning follicles
7) ovarian aplasia - normal ovarian tissue never developed
8) ovariohysterectomy - Gizmo had been spayed prior to your obtaining her

The initial database that a vet will recommend includes the following:

1) complete blood count and serum biochemistry profile for systemic health status
2) assessment of endocrine-related illness via thyroid hormone analysis
3) exclusion of silent heats, using exfoliative vaginal cytology examination (looking at the cell lining the vagina) and serum progesterone determinations
4) exclusion of abnormal reproductive tract, using abdominal ultrasonography
5) exclusion of abnormal karyotype (genetic defects in sexual differentiation)

I've thrown a lot at you at once. Please respond with further questions or concerns if you wish.
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Thank you for your kind accept. I appreciate it.

I'm going to check back with you in a few weeks for an update. Feel free to return to our conversation - even after rating - prior to my contacting you if you wish.

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