Warning: This
blog contains veterinary images that some may consider graphic and
inappropriate for our younger blog readers.
We have a guest blogger this week, Dr. Kadie Anderson, DVM
at Point Defiance Zoo & Aquarium!
The Red Wolf
Species Survival Plan currently manages 199 wolves, of which 59 are housed
at Point Defiance Zoo & Aquarium (PDZA)
red wolf facilities. In the summer of
2011, staff veterinarians at PDZA noticed an
increase in the number of middle aged to older female wolves developing severe
uterine infections (e.g. pyometra). In
many instances, wolves diagnosed with these infections had to be spayed. This action removes the animal from
contributing genetically to the population and can complicate the management of
a critically endangered species such as the red wolf. Managers of small, genetically restricted populations
often select older individuals for breeding purposes to maximize their genetic contribution
to the population. As middle aged to
older animals are predisposed to the development of pyometra (and yet are often
selected for breeding), further investigation was needed to better understand
this condition in red wolves.
Female red wolf
“Millie” at PDZA with a litter of pups in 2012.
Veterinarians
are well informed about how pyometra develops in the domestic dog but are still
working to understand how the process differs in non-domestic species such as
the red wolf. In the domestic dog,
pyometra is often accompanied by cystic endometrial hyperplasia (CEH). This describes changes in the uterus which
causes a cystic and thickened uterine lining and predisposes the uterine
environment to bacterial infection and pyometra at certain stages of the
reproductive cycle. In the domestic dog,
hormones, reproductive history (e.g. litters produced), and age are all
believed to contribute to the development of this syndrome. Shortly after PDZA
identified pyometra as an issue in red wolves, an assessment by the AZA Canid
Taxon Advisory Group supported PDZA’s clinical findings, showing that of the
canid species examined, red wolves showed an increased prevalence of CEH and
pyometra.
Veterinarian Dr.
Nordberg-Wilke ultrasounds a red wolf while PDZA keeper Alicia Pike assists.
Ultrasonographic
appearance of an infected uterus.
In our
study, 13 adult female red wolves housed at PDZA
(ranging in age from 5-10 years) were evaluated for reproductive disease by
using ultrasound examination and serum hormone analysis. PDZA partnered with veterinary
ultrasonographer Dr. Cindy Nordberg-Wilke to evaluate 13 wolves in December
2011 with 7 of these wolves receiving a follow-up examination in July 2012 for
presence or absence of reproductive disease.
As hormonal influence has a known role in the development of this
disease in domestic dogs, hormone levels were also evaluated and compared
against expected ranges.
A normal uterine horn with a grossly
distended and infected uterine horn on
the right side of the image and a cystic
and enlarged ovary on the right.
A
fairly normal red wolf uterus is seen on the right for comparison.
The results of this research project are currently being
summarized for publication, but it is expected that the findings in this study
will help guide veterinarians toward earlier diagnosis of reproductive disease
in red wolves and perhaps improve disease outcome (e.g. females still capable
of reproducing). This research has also
led to discussion about improving management options in the SSP population for
reproductive success and has led to recommendations on how to manage and
evaluate at risk females for disease.