Page 985 - Small Animal Internal Medicine, 6th Edition

CHAPTER 55 Clinical Conditions of the Bitch and Queen 957

experiencing shortened interestrous intervals are normal in of pseudocyesis are probably under the influence of prolac-
other respects. Ovulation and luteinization occur, and the tin. Similar concentrations can be demonstrated in bitches
VetBooks.ir secondary oocyte is fertilized but fails to implant success- that have no clinical signs, suggesting that the former may
have increased target organ concentrations or heightened
fully. Documentation of this disorder requires serial vaginal
cytologic evaluations during estrus and diestrus, and serum
limiting, usually regressing in 1 to 3 weeks, and therapy is
progesterone concentrations during the luteal phase of at peripheral sensitivity to the hormone. The condition is self-
least two consecutive cycles. Currently, there is no reliable, not recommended unless the signs are unusually prolonged
commercially available, consistent preimplantation method or pronounced, such as causing mastitis. Unusually persis-
of confirming fertilization in the dog. The occurrence of tent cases of inappropriate lactation should be evaluated for
folliculogenesis without ovulation (split heat) and hypolu- hypothyroidism, in which elevated thyrotropin-releasing
teiodism (premature luteal failure) should be ruled out. Both hormone (TRH) may cause increases in prolactin.
require evaluation of serum progesterone concentrations. In Therapy for pseudocyesis, when recommended, is usually
the former, ovulation has not occurred and progesterone directed at decreasing or eliminating lactation. Therapy is
remains at baseline (<1.0 ng/mL); and in the latter, proges- pursued to reduce the likelihood of mastitis occurring sec-
terone concentrations are not maintained above 5.0 ng/mL ondary to milk stasis, or to diminish lactation-induced
for the normal length of diestrus (45+ days). True shortened household soiling. Minimal measures are recommended.
interestrous intervals occur because anestrus is abbreviated. Mammary stimulation via licking, mothering behavior, or
A defect in the hypothalamic-pituitary-ovarian axis could warm or cold compressing should be discontinued. Dopa-
exist, causing interference with the normal maintenance mine antagonists, of which phenothiazines are a class,
of anestrus. An imbalance of dopamine versus prolactin enhance prolactin secretion and should not be administered.
concentrations have been theorized as contributing to this Mild sedation with a nonphenothiazine tranquilizer may be
syndrome. One suggested therapy consists of prolonging helpful. A variety of hormonal and medical therapies have
anestrus through the use of progestational drugs during the been employed to reduce or stop lactation in pseudopreg-
first 3 days of the impending proestrus; this is undesirable nant bitches. Side effects, in most cases, outweigh the benefit
because an increased risk of pyometra can occur. Similarly, of most of these medications. Therapy with gonadal hor-
the advocated use of anabolic compounds to prevent cycling mones, progesterone, estrogen, or testosterone is not recom-
has never been studied critically; the fertility of bitches previ- mended owing to complications of repetitive cycles of
ously treated with anabolics is not known, and side effects pseudocyesis, symptoms of proestrus or estrus, and viriliza-
(epiphora, vaginitis, clitoral hypertrophy, hepatopathy, and tion behavior, respectively. Ergot alkaloids are potent prolac-
aggression) do occur. tin inhibitors (dopaminergic) and can be used to abbreviate
exaggerated pseudocyesis. Bromocriptine can be adminis-
EXAGGERATED PSEUDOCYESIS tered at 0.01 to 0.05 mg/kg/day in divided doses until
(PSEUDOPREGNANCY) lactation ceases. Vomiting, depression, and anorexia are
Owners often interpret nonpregnant bitches showing overt commonly reported side effects, usually more problematic
signs of pseudocyesis as abnormal. Signs exhibited during than the lactation. Cabergoline, administered at 5 µg/kg/day,
overt pseudocyesis include weight gain, mammary gland given divided or once daily for 3 to 5 days effectively decreases
development and lactation, mucoid vulvar discharge, inap- prolactin concentrations and diminishes signs of pseudocy-
petence, restlessness, nesting, and mothering of inanimate esis with fewer side effects but is expensive and must be
objects. Radiography (after 50+ days of diestrus) or ultraso- compounded for use in all but giant breeds. Acupuncture has
nography can establish the presence or absence of fetuses. been suggested to reduce the signs of pseudocyesis. Fasting/
Alternatively, owners could be concerned about bitches water deprivation has no effect on pseudocyesis. Permanent
showing overt signs of pseudocyesis because they find the resolution of clinical pseudocyesis requires ovariectomy.
behavior or physical symptoms objectionable in a bitch they
know is not pregnant. VAGINAL HYPERPLASIA
Pseudocyesis is a normal physiologic phenomenon expe- Estrogen produced during folliculogenesis normally causes
rienced by any nonpregnant bitch completing the luteal a generalized hyperplastic response of the vaginal mucosal
portion of an estrous cycle. These signs are the result of epithelium and cornification of the vaginal epithelial cells in
progesterone concentrations declining and prolactin, a preparation for the copulatory lock. This estrogen response
luteotroph, increasing. The clinical expression of pseu- can induce a hyperplastic vaginal periurethral mass in some
docyesis varies from indiscernible to (rarely) potentially bitches that can prolapse through the vulvar cleft if large
serious. Clinical signs of pseudocyesis usually are reported enough. The exposed vaginal tissue becomes traumatized
from 6 to 12 weeks after estrus. Signs of pseudocyesis are and contaminated, and urethral obstruction at the level of
often reported by owners when giving reproductive histo- the papilla can occur (Fig. 55.5, A). Follicular luteinization
ries as if its occurrence indicates a reproductive disorder, can be attempted to prematurely decrease estrogen produc-
when in fact pseudocyesis establishes that the bitch has a tion with GnRH (50-100 µg/bitch IM q 24-48h for up to
normal hypothalamic-pituitary-ovarian axis and estrous 3 doses) or hCG (500-1000 IU/bitch IM q 24-48h for up
cycle. Bitches that exhibit signs consistent with a diagnosis to 3 days); this can compromise fertility if a breeding is