Page 49 - Cote clinical veterinary advisor dogs and cats 4th

2 Abortion, Spontaneous (Dog)

Abortion, Spontaneous (Dog)
VetBooks.ir

or placentas. Male-to-female venereal contact
BASIC INFORMATION
of all fetuses but may remain elevated for
is not a significant means of transmission. ○ Relaxin declines rapidly after the death
Definition some days.
The expulsion of one or more fetuses before GEOGRAPHY AND SEASONALITY • Pathogens that influence placental function
full-term pregnancy is uncommon; in the dog, • Canine brucellosis: endemic in parts of North (e.g., herpesvirus placentitis) may cause
resorption is more common. and South America and China abortion.
○ Although previously eradicated in Europe, • Cases of unexplained pregnancy loss or
Synonyms sporadic cases have been reported since abortion may be caused by an inadequate
Fetal loss, pregnancy wastage, miscarriage 2011. uterine environment and not a primary
• CHV-1: worldwide; serologic prevalence of infection.
Epidemiology 60%-80% • In dogs, fetal resorption is more common
SPECIES, AGE, SEX • Tick-borne diseases in spring and summer than abortion.
Sexually mature, intact, female dog • Fetal mummification occurs when the fetus
ASSOCIATED DISORDERS dies during the last third of pregnancy (i.e.,
GENETICS, BREED PREDISPOSITION Vaginal discharge, depression, lethargy after day 45-50) in a noninfected uterine
• Inbreeding (inbreeding coefficient > 0.25): Clinical Presentation environment after skeletal calcification has
early embryonic death, conceptus resorption taken place.
• Brachiocephalic breeds (high-risk pregnancy) HISTORY, CHIEF COMPLAINT • Fetal death due to infectious and nonin-
• Pregnant bitch whelps prematurely with fectious causes may give different clues.
RISK FACTORS live or dead pups, or no pups are born Infections often show characteristic gross
• Advanced maternal age at term. microscopic lesions that reveal the causative
• History of previous pregnancy loss (e.g., • Abnormal vulvar discharge (bloody, purulent) agent (typically herpesvirus). The noninfec-
recurrent hypoluteoidism) during pregnancy, fever, or signs of abdomi- tious causes may be more difficult to elucidate
• Malnutrition (pregnancy ketosis) nal pain may be reported by owner. due to the variety of mechanisms involved
• Endocrinopathies (hypothyroidism, hypolu- • Usually abortion is unnoticed by the owner (e.g., toxins, hypoluteoidism).
teoidism, diabetes mellitus, hyperadrenocorti- because the dam may consume the fetuses
cism) and aborted tissues. DIAGNOSIS
• Infections (e.g., Brucella canis, Listeria • Death of one or more fetuses may occur,
monocytogenes, Streptococcus canis [Lancefield whereas the remainder may continue to Diagnostic Overview
groups C, L, and M], Escherichia coli, develop normally. • Pregnancy diagnosis (pp. 816 and 819)
Campylobacter sp., Leptospira sp., Salmonella • Late-term abortions (between gestational • Abortion should be suspected when the
sp., Mycoplasma, Chlamydia sp., canine days 45 and 59) are typical of B. canis. pregnancy is previously confirmed and the
herpesvirus 1 [CHV-1], canine parvovirus bitch later presents nonpregnant or expelled
1 [minute virus of canines], bluetongue virus, PHYSICAL EXAM FINDINGS fetuses have been observed.
canine distemper virus, canine adenovirus • Often unremarkable • A diagnostic approach is outlined on p. 1396.
[infectious hepatitis], Leishmania infantum, • Vulvar discharge that is purulent, hemor-
Toxoplasma gondii, Borrelia burgdorferi, rhagic, greenish, blackish, or malodorous Differential Diagnosis
Ehrlichia spp., Anaplasma spp.) may indicate pregnancy complications that • Pseudocyesis (overt false pregnancy)
• Unsolicited treatment with an endocrine could lead to abortion. Normal vulvar dis- ○ Abdominal ultrasound examination after
disruptor, embryotoxic or teratogenic com- charge in pregnant bitches is clear to mucoid day 25 to confirm pregnancy status
pounds (e.g., itraconazole, griseofulvin, plant or pink-tinged and odorless. • Vaginal discharge due to vaginitis or metritis
toxins, insecticides, corticosteroids, polyester • In late-term abortion, abdominal contrac- (pyometra)
textiles) tions, and expulsion of one or several fetuses ○ Abdominal ultrasound recommended
○ The risk to the fetus is a result of the may be observed. • Induced abortion (p. 819)
ability of a drug or toxin to reach the fetal
circulation and produce toxic effects in Etiology and Pathophysiology Initial Database
the fetus. Special awareness is necessary • Canine pregnancy requires normal luteal • Serologic testing and/or polymerase chain
during the organogenesis period (i.e., until function throughout its duration. reaction (PCR) of affected dam
day 20 of pregnancy in dogs and cats). ○ Inadequate luteal function (hypoluteoid- ○ B. canis
• Inadequate vaccination or deworming ism) may cause resorption or abortion at ○ CHV-1 (p. 466)
programs any stage but generally occurs between • Virus or bacterial isolation from microbial
days 25-35 post breeding. cultures of fetuses, placenta, milk, or vaginal
CONTAGION AND ZOONOSIS ○ Any toxin or hormone that induces endog- secretions
• B. canis is zoonotic. enous release of prostaglandin F-2 alpha ○ For B. canis, blood culture with bacterio-
○ Venereal transmission is significant in the (PGF2a) and subsequent luteolysis may logic isolation provides a definitive
dog. Contact with infected canine blood cause abortion, including bacterial toxins diagnosis 5 weeks after exposure, but
and vaginal secretions is important for (e.g., coliforms, Staphylococcus sp.) and repeated samples may be necessary.
human infection. adrenergic agonists (e.g., phenylephrine). ○ For acute CHV-1 infections, viral isolation
• Salmonella sp. and Leptospira sp. also have • Fetal survival requires normal placental from infected tissues is possible for 2-3
zoonotic potential. function and placental relaxin production. weeks.
• CHV-1 and minute virus of canines: ○ Circulating relaxin concentration increases • Necropsy of fetus (e.g., subcapsular hemor-
transmission occurs through direct aerosol from day 26 and is detectable by relaxin rhages in the kidneys are pathognomonic for
contact or contact with aborted fetuses and/ assays from day 30 after mating. CHV-1) and visual inspection of placenta

www.ExpertConsult.com