September 12, 2018

Diagnosis and Treatment of Canine Pseudopregnancy

Nearly all responding general practitioners in the United Kingdom reported cases of pseudopregnancy, most often diagnosed by behavioral signs.
By Natalie Stilwell, DVM, MS, PhD
Pseudopregnancy occurs when a female dog displays physical and/or behavioral signs suggestive of pregnancy, despite not being pregnant. While pseudopregnancy occurs most frequently in intact females 6 to 8 weeks after estrus, spayed females may develop the condition particularly if spayed during diestrus.

No specific test is available to diagnose pseudopregnancy, and research literature on the topic is scarce; therefore, diagnosis usually occurs by identifying characteristic signs and excluding other conditions, such as pregnancy and pyometra. With this in mind, researchers recently conducted a questionnaire-based study to further understand the prevalence, diagnosis, and treatment of pseudopregnancy by general practitioners in the United Kingdom.

Study Design
In 2015, the investigators distributed a paper survey to 2000 randomly selected veterinarians practicing general small or mixed animal medicine in the United Kingdom. The survey questioned practitioners about the number of canine spay procedures performed within the previous 12 months, as well as frequency, signs, and treatment approach for diagnosed cases of pseudopregnancy.

Two hundred seventy-eight small animal and 118 mixed animal practitioners located throughout the United Kingdom responded to the survey. Ninety-seven percent of respondents had seen at least 1 pseudopregnancy case within the past year, and the median number of cases per practitioner was 10. Most cases occurred in intact females, although 49% of practitioners reported diagnosing pseudopregnancy in spayed female dogs within the previous year.

The most frequently observed physical signs, in descending order, were enlarged mammary glands and/or lactation, appetite loss, weight gain, and vomiting. Nesting behavior and collecting or mothering of objects were the most frequently reported behavioral signs, although changes in activity level and increased aggression were also observed. Behavioral signs were observed more frequently than were physical signs in dogs with pseudopregnancy.

Respondents chose to treat one-half of all pseudopregnancy cases with medication. Cabergoline was chosen in nearly all of these cases, with proligestone and megestrol used rarely in comparison. Treatment usually lasted 5 to 6 days, although longer or repeated treatments were necessary occasionally to resolve clinical signs. Junior veterinarians tended to vary treatment from case to case based on presence and duration of clinical signs more often than did senior vets. Veterinarians doing nonprofit and charity work most often managed pseudopregnancy cases using modifications to diet, exercise, and behavior.

Ninety-six percent of veterinarians indicated they prefer to delay spay procedures for dogs showing signs of pseudopregnancy, as spaying can lead to persistent pseudopregnancy.

Closing Points
General practitioners in the United Kingdom commonly encounter pseudopregnancy, and many dogs present with behavioral rather than physical signs. Survey results showed that senior veterinarians were more likely than were junior veterinarians to question owners on behavioral changes during routine consultation, highlighting a potential for underdiagnosis. Because pseudopregnancy may present with serious signs that impact both pet and owner, such as aggression, the authors encouraged increased surveillance for this common condition.

Dr. Stilwell received her DVM from Auburn University, followed by a MS in fisheries and aquatic sciences and a PhD in veterinary medical sciences from the University of Florida. She provides freelance medical writing and aquatic veterinary consulting services through her business, Seastar Communications and Consulting.

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