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Veterinarian Technician June 2012 (Vol 33, No 6)

Case Report: Big-Hearted Katie

by Sandra Rhodes, RAHT

    Click here to read the companion article.

    Dilated cardiomyopathy (DCM) continues to be one of the most common cardiovascular disorders in dogs; the presentation of patients with DCM varies considerably.1 This case describes DCM in my dog Katie after my husband, Michael Rhodes, DVM (of Nanton Veterinary Clinic, Nanton, Alberta), and I discovered it. This case highlights the need to fully examine a dog that appears physically well but “tires easily.” Clients should be encouraged to speak to a clinician about subtle signs of disease to facilitate early diagnosis.

    Patient History and Initial Findings

    Katie—a 23-kg (50.6-lb), ~2-year-old, spayed Labrador retriever–heeler mix—was found in a snow-covered ditch in February in southern Alberta by a Good Samaritan who realized the dog was whelping and took her home to finish the process. Katie’s medical history was unknown. After parturition, Katie and her eight newborn puppies were taken to a rescue group, where Katie was found to be underweight, to have numerous warts on the hard palate, and to likely have sarcoptic mange on the extremities. Katie was isolated (along with the puppies), given core vaccinations, and treated with selamectin. We adopted Katie in April, and she underwent an ovariohysterectomy and was given booster vaccinations and selamectin.

    Katie responded well in her new home: the oral warts disappeared as her overall health improved, and the treatment for mange was successful. Approximately 3 years later, a routine dental cleaning was performed, and a small epidermal inclusion cyst was surgically removed. Preanesthetic blood work results were normal.

    Approximately 2 years later, when Katie was ~7 years of age, our clinic installed a new radiography machine that required a new technique chart. Dr. Rhodes and I used Katie to create radiographs for the chart because she was medium sized, in good body condition, and cooperative. The first film was a lateral thoracic view (FIGURE 1) . Although I was pleased with the results of the technique, I was dismayed that the radiograph revealed an abnormal cardiac silhouette with increased sternal contact and a vertebral heart score of 11 (BOX 1).

    Box 1. Vertebral Heart Score

    JW Buchanan, DVM, developed the vertebral heart score—a system that indexes heart size to body size using mid-thoracic vertebrae. Since 1995, vertebral heart score has been the standard indicator of radiographic heart size in dogs. For more information: James Buchanan Cardiology Library. Vertebral heart size. http://www.vin.com/library/general/JB111VHS.htm. Accessed March 2012.

    A ventrodorsal view of the thorax demonstrated cardiomegaly, and a lateral abdominal view revealed splenomegaly, which is a common finding in dogs with right-sided heart failure.1 Dr. Rhodes performed a physical examination and found no abnormalities, including no abnormal heart sounds and a body condition score of 3/5, which is ideal. A complete blood count and a chemistry profile revealed poikilocytosis, a low mean cell hemoglobin concentration, an elevated eosinophil count, and slightly low ALP and globulin levels  (TABLE 1) .

    Katie was treated with a systemic anthelmintic because a common reason for an increase in eosinophils is the presence of internal parasites (Katie occasionally kills rodents). One possible cause of distortion in the red blood cell shape is circulatory problems caused by a heart failing to function properly; the red blood cells become distorted (mechanical damage) secondary to venous congestion and inadequate emptying of the heart chambers. A low mean cell hemoglobin concentration is not due to anemia but may be associated with decrease in hemoglobin saturation due to right-sided heart failure and DCM.1

    We realized in hindsight that Katie had been less active that spring, tired easily during socialization with other dogs, and had a decreased appetite, all of which was attributed to hot weather and the possibility that Katie could be older than estimated.

    Cardiac Examination and Diagnostic Imaging

    To determine a cause for cardiomegaly, electrocardiography (ECG) and cardiac ultrasonography  (FIGURE 2) were performed by Dr. Sheri Clarkson, BSc, DVM, DACVIM, of Clarkson Veterinary Internal Medicine Services, Fish Creek Pet Hospital, Calgary, Alberta.  TABLE 2 lists the results.

    Because the patient’s history was unknown, DCM could have resulted from several factors: poor nutrition in the neonatal period, parvovirus infection during puppyhood, or an idiopathic cause due to the patient’s breed (i.e., part Labrador retriever).

    Treatment

    The recommended treatment was administration of pimobendan (0.25 mg/kg PO bid), l-carnitine supplementation, and a prescription cardiac diet that has additional taurine and l-carnitine and is low in sodium. We were advised to repeat ECG 3 months after initiation of treatment and to watch for signs of syncope and CHF.

    Outcome

    Katie responded very well to pimobendan therapy. Her energy level returned to normal within the first few days of the initiation of treatment, and her appetite was good. Radiography of the thorax in October showed no significant change since July.  TABLE 3 summarizes Dr. Clarkson’s results of a follow-up examination in November.

    Update

    In December 2011, approximately 18 months after treatment with pimobendan began, Katie’s condition worsened: resting respiratory rate had increased, and jugular vein distention was evident. Thoracic radiography showed pulmonary venous congestion and a significant bulge of the right ventricle, while hepatosplenomegaly and mild ascites were noted in abdominal radiographs. Furosemide, benazepril, and spironolactone were added to the ongoing pimobendan therapy. We are confident that Katie’s life has been prolonged by early intervention with a positive inotropic medication, and monitoring the resting respiratory rate has allowed us to intervene before progression to respiratory distress.

    Conclusion

    Katie’s case serves as a reminder that although a patient may appear healthy, a subtle sign of exercise intolerance can be the first clue that disease is causing myocardial damage. We have adjusted Katie’s diet and exercise to address her 1-kg (2.2-lb) weight gain and to prevent additional workload on the cardiovascular system. In the short term, the prognosis is good: Katie is active and alert. However, because we are aware that DCM is a progressive and, ultimately, fatal disease, we are prepared for the possibility of sudden death.

    Click here for more articles in the Case Report series.

    1. Nelson RW, Guillermo CG. Small Animal Internal Medicine. 4th ed. St Louis, MO: Mosby Elsevier; 2009:7, 128, 1218.

    2. Boon JA. Two Dimensional and M-mode Echocardiography for the Small Animal Practitioner. Jackson, WY: Teton NewMedia; 2002.

    References »

    NEXT: Final View: Fetch, Anyone?

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