Page 991 - Small Animal Internal Medicine, 6th Edition

CHAPTER 55 Clinical Conditions of the Bitch and Queen 963

diagnosis of hypoluteiodism as the primary cause for repro-
ductive failure. Administration of progesterone to maintain
VetBooks.ir pregnancy in dams with primary fetal abnormalities, pla-
centitis, or intrauterine infection can cause continued fetal
growth with the possibility of dystocia and sepsis. Admin-
istration of excessive progesterone to maintain pregnancy
in a dam not actually requiring therapy can delay partu-
rition and diminish lactation, endangering the life of the
bitch and her fetuses, and can masculinize female fetuses (see
Chapter 56, Fig. 56.35). Historically, premature pregnancy
loss has been treated by administering injectable natural
progesterone or oral synthetic progestagens. In women,
prevention of preterm delivery or recurrent miscarriage
appears to be based on the use of only the natural metabolite
of progesterone, 17α-hydroxyprogesterone caproate (17P).
Total serum concentrations of progesterone can be moni-
tored only when supplemented with the natural product.
Progesterone in oil is given intramuscularly at 2 mg/kg q72h.
Altrenogest (Regumate [Hoechst-Roussel]), a synthetic pro-
gestagen manufactured for use in the mare, is dosed orally at
0.088 mg/kg q24h. Both forms of supplementation must be
discontinued in a timely fashion so as not to interfere with
normal parturition, within 24 hours of the due date with the
oral synthetic product, and within 72 hours with the natural
injectable depot form. This requires accurate identification
of gestational length via prior ovulation timing (see Chapter
54). Less accurate identification of gestational length can be
made from breeding dates, radiography, or ultrasound (see
A Chapter 54). The unfavorable side effects of exogenous pro-
gesterone supplementation must be outlined to clients and
make its use in premature labor unattractive. Studies have
shown that early tocolytic therapy prevents luteolysis and
precludes the use of progestational compounds in preterm
labor (Davidson, 2015).

PREGNANCY LOSS ASSOCIATED WITH
INFECTIOUS DISEASE

CANINE BRUCELLOSIS
Brucellosis is the primary contagious infectious venereal
disease of concern in canine reproduction. Canine brucel-
losis is caused by Brucella canis, a small, gram-negative, non–
spore-forming aerobic coccobacilli. B. canis was first isolated
B by Leland Carmichael in 1966. Brucella abortus, Brucella
melitensis, and Brucella suis have occasionally caused canine
FIG 55.8 infections but are comparatively rare. B. canis causes repro-
Tocodynamometry. (A) Left to right, Fetal Doppler, uterine
sensor, modem, and recorder. (B) Tocodynamometry ductive failure in both the male and female dog. Screening
session with a pregnant Chihuahua (A Courtesy for B. canis infection is an important part of the prebreeding
CooperSurgical and B Courtesy Micropath, Inc.). evaluation of any dog and should be included in the initial
diagnostics in any case of canine abortion, orchitis, epididy-
mitis, and apparent infertility in bitches or dogs. Because the
is difficult, requiring documentation of inadequate plasma incidence of canine brucellosis is low in many geographic
progesterone levels before abortion for which no other cause locations, breeder compliance with regular screening can
is found. Progesterone levels diminish in response to myo- wane, making continued veterinary vigilance important.
metrial activity and fetal death, so documentation of a low Notably, neutered and maiden or virgin dogs can also be
progesterone level after an abortion does not establish the infected. B. canis can also occasionally cause systemic disease