Prolonged Interestrus Interval in Bitches

Prolonged interestrus interval in bitches refers to an unusually extended period between consecutive estrus cycles, typically exceeding the normal 5 to 11 months.

This condition is often seen in older bitches, with intervals of 10 to 13 months being normal for those over 6 to 8 years old.

Etiology

Prolonged interestrus interval in bitches, caused by various reasons, includes:

1. Idiopathic Prolongation of the Interestrus Interval
2. Breed
3. Hypothyroidism

1. Idiopathic Prolongation of the Interestrus Interval

A thorough history should be obtained to make sure that, outside of the reproductive tract, the bitch is healthy.

Interestrous intervals increase as the bitch becomes older. An interval of 10 to 13 months for a bitch older than 6 to 8 years of age is not worrisome. However, such prolonged intervals are not typical of the 2 to 6 year old bitch.

2. Breed

Certain breeds like Basenji and the wolf-hybrid cycle on a yearly basis. The bitch that cycles less often than every 10 months and appears infertile is of greatest concern.

3. Hypothyroidism

A common endocrine disorder associated with longer interestrus intervals, as thyroid hormone imbalances can disrupt the ovarian cycle.

Diagnosis

Thorough physical examination is should follow only after obtaining a thorough history. A physical examination need not be too elaborate, but neither should it be omitted.

The finding of a serious heart murmur, unsuspected organomegaly, a mass that was not expected, or a variety of other problems must be investigated in order to better treat the patient and to understand any potential cause for delay in an ovarian cycle.

Increase in length between ovarian cycles in the bitch can occur secondary to:

• An underlying illness
• Any major medical disorder has the potential for delaying the onset of an ovarian cycle.

Treatment

Treatment for prolonged interestrus intervals in bitches is based on the underlying cause of the condition.

If the cause is hypothyroidism, the primary treatment is thyroid hormone replacement therapy with synthetic levothyroxine, which helps regulate the estrus cycle by restoring thyroid function.

For cases involving ovarian cysts or neoplasms, surgical removal of the ovaries or cysts is often necessary, and in some instances, hormonal treatments may also be considered to address cysts before surgery.