CAHF Research Grants: 2012-2013

canine.vaccinationDistribution of antifungal agent voriconazole in body fluids of healthy dogs after repeated dosing
Drs. Susan Taylor, Julie Lemétayer, Patricia Dowling and Anthony Carr

Fungal infections, a significant cause of disease in dogs, frequently involve the lungs and eyes. Although long-term treatment of four to six months is typically required, systemic antifungal therapy often fails once the inflammation stops and drug concentrations decrease in the target tissues.

Failures are most common with tissues of the central nervous system, joints and eyes.  Voriconazole is a broad spectrum antifungal agent that has demonstrated good penetration in the cerebrospinal fluid, brain and eye during human and animal studies. This study will help researchers to predict its effectiveness for dogs by determining its distribution into specific body fluids after two weeks of treatment.

Six healthy dogs will receive oral dosages of voriconazole for two weeks. On day 15, blood samples will be taken at 0, 2, 6, 12, 18 and 24 hours after treatment, and samples of cerebrospinal fluid, pulmonary epithelial lining fluid, synovial fluid and aqueous humor will be taken between 6 and 8 hours after treatment.

Using high-performance liquid chromatography, researchers will then determine voriconazole concentrations. The results will provide evidence indicating whether voriconazole can effectively treat fungal infections in dogs.

Does the anesthetic agent alfaxalone affect intraocular pressure?
Drs. Bianca Bauer and Barbara Ambros

Alfaxalone, a new, injectable anesthetic licensed for cats and dogs, produces rapid and smooth anesthesia induction with excellent muscle relaxation. Although the cardiopulmonary effects of alfaxalone have been studied, its effects on intraocular pressure (IOP) have yet to be determined.

For certain ocular diseases such as glaucoma and corneal ulcers, maintaining a normal IOP throughout anesthesia is crucial for preventing complications and ocular damage. This study will determine the effects of alfaxalone on IOP when it is administered alone as well as in conjunction with commonly used premedication combinations.

Following a complete ophthalmologic examination, thirty-six dogs undergoing elective surgery will receive one of three possible anesthetic treatments. Group 1 will receive acepromazine and butorphanol followed by alfaxalone. Group 2 will receive dexmedetomidine and hydromorphone followed by alfaxalone and Group 3 will receive saline followed by alfaxalone.

Taking three averaged readings for each eye, researchers will measure IOP six times during the study: before premedication, 15 and 30 minutes after premedication, after pre-oxygenation prior to induction, immediately after alfaxalone is administered and immediately after intubation.

Results of the study will enable clinicians to make an informed decision regarding the suitability of alfaxalone, both alone and in combination with premedications, when they choose an anesthetic for ophthalmic cases requiring surgery.

How prevalent is enteropathogenic Eschedrichia coli in dogs with parvoviral enteritis?
Drs. Anthony Carr, Casey Gaunt, Joseph Rubin and Janet Hill

Parvoviral enteritis, a common condition affecting dogs, has a 36 per cent mortality rate, and the complication of a concurrent disease has been shown to increases its seriousness. Specifically, coinfection with Eschedrichia coli containing the eae gene (enteropathogenic E. coli) presents symptoms indistinguishable from parvovirus infection and may represent an important zoonotic risk due to shedding during diarrheic episodes.

This study will determine the prevalence of enteropathogenic E. coli, evaluate the eae subtypes and establish the difference in outcome when it is diagnosed along with parvoviral enteritis.

Researchers will analyze fecal samples collected at admission from 100 dogs brought to the WCVM with clinical signs of parvoviral enteritis between June 1, 2012, and October 15, 2013. The feces will be analysed for E. coli which will then be screened for the eae gene using polymerase chain reaction (PCR) to identify eae subtypes.

Medical records will be examined to compare survival rate, treatment cost and duration of hospital stay for patients with and without enteropathogenic E. coli.

This information will facilitate informed decisions regarding diagnosis and treatment and will result in an increased survival rate, shortened hospital stay and reduced costs. It will also provide more information about an important source of potentially zoonotic organisms.

Using direct computed tomography to describe the lymphatic system of the pelvic limb in dogs
Drs. Monique Mayer, James Montgomery, John Pharr, Tawni Silver, Cheryl Waldner and Michail Patsikas

Recent research and clinical experience have indicated that previous descriptions of the lymphatic drainage pattern in a dog’s pelvic limb may be inaccurate. Specifically, the popliteal lymph node may drain into the medial iliac and iliofemoral nodes rather than the superficial inguinal lymph node. Since this information affects the treatment and staging approach to dogs with certain malignant tumours of the pelvic limb, a further examination and revised description of the draining pattern of the popliteal lymph node is extremely important.

Using a previously validated technique, researchers will perform CT lymphography on 50 dogs already undergoing CT scans for reasons not involving the lymphatic system. They will inject a contrast agent into a popliteal lymph node, performing both a pre- and post-contrast scan of the mid-lumbar to popliteal region. Images will be reviewed by two radiologists and a radiation oncologist.

Precise descriptions of the drainage pattern of the popliteal lymph node will facilitate a more accurate prognosis and will affect treatment recommendations regarding irradiation and surgical node removal. The study will also provide useful information about the location of the medial iliac, hypogastric and iliofemoral lymph nodes in normal dogs of different breeds.

Can canine cancers be controlled by turning off their unfolded protein response (UPR)?
Drs. Vikram Misra, Kathleen Linn, Valerie MacDonald, Kristy Elliott and Elemir Simko

Cancer is devastating to both humans and animals, and although tremendous progress has been made in treating primary tumours, cancer cells still spread to other sites in the body causing secondary tumours.

Hypoxia, an insufficient oxygen supply found in most tumours, has been strongly linked with tumour development, growth, metastasis and poor response to therapy.  This ongoing study examines the unfolded protein response (UPR) – one of three signalling pathways that regulate the cell’s response to hypoxia.

Researchers have learned that the protein Zhangfei stops the genetic response that activates the UPR. It also induces cell death in dog osteosarcoma cells and suppresses the growth of canine hemangiosarcoma cells with no impact on normal cells.

After infecting tumour cells with Zhangfei, researchers will determine the causes behind any changes in their growth rate, viability and structure, considering each of four explanations for cell death: apoptosis, autophagy, macropinocytosis and necrosis.  They will also ascertain the molecular reason why tumour cells do not express the gene for Zhangfei.

Using drugs that affect the enzymes responsible for chromatin, the combination of DNA and proteins that make up chromosomes, the scientists will then attempt to reactivate expression of the gene for Zhangfei.

Developing an immunohistochemical panel for cats with mammary gland cancer
Drs. Elemir Simko, Kristyna Musil, Steven Mills, Steven Hendrick, Bruce Wobeser, Hélène Philibert, Beverly Kidney and Jennifer Davies

Feline mammary adenocarcinomas (MACs) are relatively common and often life-threatening, and current methods for predicting post-operative survival of the patients have proven unreliable. In human breast cancers, the identification of specific immunohistochemical markers has proven invaluable for selecting appropriate therapy, predicting response to therapy and predicting post-operative survival.

This study, the largest performed thus far, will identify similar markers in feline MACs. Facilitating reliable predictions regarding survival will enable evidence-based decisions by both the owner and the veterinarian and can ultimately increase the patient’s quality of life.

Using biopsies from 120 cases of MACs for which post-operative clinical and survival data have already been collected, researchers will perform immunohistochemistry to determine expression levels of six markers: estrogen and progesterone receptors, HER-2, Ki-67, AKT and PTEN. Using statistical analysis, they will then determine which combinations of immunohistochemical markers found in the cases with known survival outcomes will be suitable for future use in a prognostic immunohistochemical panel.

Based on the large sample size, the expertise of the investigative team and the high quality of immunohistochemical services, the study results should greatly enhance the prognostic accuracy for survival of cats following surgical removal of MACs.

Using synchrotron x-ray imaging to locate and characterize iron in feline bone marrow
Drs. Elisabeth Snead, Marion Jackson, Ingrid Pickering and Tasha Epp

Anemia of inflammatory disease (AID), the most common cause of feline anemia, is characterized by normal to increased iron stores in the bone marrow. Although bone marrow stains are reliable for evaluating those stores and providing important information for diagnosing AID in people and dogs, the stains are undependable for cats. This study will investigate synchrotron x-ray (SXR) imaging as a tool for measuring iron stores in feline bone marrow.

Using bone marrow samples from 12 healthy cats, researchers will utilize SXR imaging to determine the quantity, state and possibly the cellular location of iron. They will also compare the quantity of stored iron determined by SXR imaging to the quantity determined by two common cytological stains.

The scientists will then analyze bone marrow samples from 6 cats diagnosed with AID, comparing the iron content values found through SXR imaging to those found through cytological staining. They will also determine any correlation between the average iron concentration found in cats with AID and the average value of other parameters that are currently used for AID diagnosis.

Their results will validate a more sensitive, effective method for assessing iron status and definitively diagnosing feline AID.

Comments

Your email address will not be published. Required fields are marked *