Ivermectin is a commonly used veterinary drug that may cause serious problems in overdose situations. A retrospective study was completed, which evaluated canine exposures to ivermectin from 1998 to 2005. The cases were evaluated based on ivermectin dosage, clinical signs seen, signalment of the animal involved, and the potential that the animal could have a p-glycoprotein defect. Results showed that clinical signs may be seen in some animals at doses lower than previously reported. Some dogs may have p-glycoprotein defects or other reasons for increased susceptibility to ivermectin toxicosis. The clinician should be aware that clinical signs may develop even at dosages previously thought to be of little risk (e.g., 0.2 to 2.5 mg/kg in breeds historically considered to have normal p-glycoprotein function).

Although osteoarthritis (OA) is a common and debilitating condition in the canine patient, few data are available on OA of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints. Review of medical records of 49 dogs with a radiographic diagnosis of MCP or MTP OA presented over a 7-year period demonstrated that OA was an “incidental finding” for the majority of animals (n=35), while 14 dogs were identified as clinically lame as a result of MCP or MTP OA. Dogs that were clinically lame as a result of MCP or MTP OA were significantly more likely to have visible swelling over the affected digits. Five times as many dogs were diagnosed with MCP OA than with MTP OA, and the majority of dogs had radiographic changes on multiple digits. Review and scoring of radiographs (n=44 dogs) for six radiographic signs of OA followed by logistic regression analysis demonstrated that the two lateral digits of the front limb were significantly more likely to have osteophytosis and enthesophytosis than the two medial digits. Osteoarthritis of MCP and MTP joints has unique radiographic features that are not seen in the stifle, hip, shoulder, or elbow; these features can complicate accurate diagnosis, particularly differentiation from primary bone neoplasia. These data underscore the clinical relevance of this condition and provide useful information detailing which and how many digits are most commonly affected, potentially assisting discrimination between OA and neoplasia.

Eighty-six dogs were selected based upon Ehrlichia (E.) canis SNAP 3Dx positive results to determine clinical relevance of annual E. canis screening. Immunofluorescence assay showed 72 (84%) of 86 dogs were seroreactive for E. canis. Polymerase chain reaction (PCR) revealed that 12 (14%) of 86 dogs had Ehrlichia deoxyribonucleic acid; seven had E. canis, four had E. ewingii, and one was coinfected with E. chaffeensis and E. ewingii. Thrombocytopenia (<164,000 platelets/μL) was found in 28 (39%) of 72 dogs. In this study, thrombocytopenia was frequently detected in healthy Ehrlichia SNAP 3Dx-positive dogs, whereas active infection was infrequently confirmed by PCR. Therefore, treatment based upon screening results alone is not recommended.

Unfractionated heparin therapy was initiated at a standard dosage of 300 IU/kg subcutaneously q 6 hours to 18 dogs with immune-mediated hemolytic anemia. Heparin’s prolongation of activated partial thromboplastin time and change in factor Xa inhibition (anti-Xa activity) were serially monitored during the first 40 hours of therapy. During the initial 40 hours, only eight of 18 dogs had attained anti-Xa activities of ≥0.35 U/mL. No dogs had clinical signs of hemorrhage. Fifteen dogs survived to discharge; 11 dogs were alive at 1 year, and thrombosis was identified in three of six nonsurvivors that were necropsied.

A 2-year-old dog was presented with a 3-month history of increasing respiratory effort and rate, inappetence, and lethargy. Chest radiographs demonstrated significant pleural effusion, which was consistent with chyle on biochemical and cytological evaluations. Further diagnostic evaluation, including a thoracic computed tomographic scan, revealed a peritoneopericardial diaphragmatic hernia (PPDH) resulting in a large, fat-attenuating mass within the pericardium. The dog was taken to surgery for repair of the PPDH, pericardectomy, and cisterna chyli ablation. Rapid and permanent resolution of the chylothorax occurred postoperatively. This is the first reported case of chylothorax secondary to PPDH.

A 9-year-old Bouvier des Flandres was presented with coughing, lethargy, chylous pleural effusion, and a heart murmur. An echocardiogram revealed the presence of an intracardiac mass causing right ventricular outflow tract obstruction. The mass was successfully removed surgically, using total inflow occlusion. Histopathology and immunohistochemistry identified the tumor as an ectopic thyroid carcinoma. The dog was euthanized 11 months after diagnosis at the request of the owner because of nonresolving chylothorax.

A 9-year-old, castrated male, domestic longhaired cat was evaluated for persistent regurgitation over the previous month. The cat had presented 9 months earlier and was diagnosed with esophageal obstruction secondary to a trichobezoar. The trichobezoar had been removed endoscopically, and the cat was subsequently fed a canned prescription diet. The owners noted only infrequent regurgitation over the following 9 months. After signs recurred, contrast radiography with fluoroscopy revealed an esophageal diverticulum at the thoracic inlet, with an ovoid filling defect. Decreased esophageal motility was noted distal to the diverticulum. Esophagoscopy confirmed the presence of a trichobezoar within an esophageal diverticulum. Following removal of the trichobezoar and therapy to prevent trichobezoar formation, the cat did well for 2 months until it died suddenly with signs of hyperventilation and open-mouth breathing.

An 11-year-old, spayed female miniature schnauzer with diabetes mellitus was presumptively diagnosed with Evans’ syndrome (ES). Because of the potential adverse effects of immunosuppressive doses of glucocorticoids in a diabetic dog, a single infusion of human intravenous immunoglobulin and oral leflunomide were used as first-line immunomodulatory therapy, after informed owner consent was received. This treatment resulted in complete remission of the ES, and leflunomide was discontinued after 10 months of therapy. Over a 19-month follow-up, the dog did not relapse and has remained a well-regulated diabetic.