An Update on the Serodiagnosis of Canine Lyme Borreliosis

The first report of canine Lyme borreliosis was published in 1984, and since that time there have been numerous reports. Clinical manifestations have varied, and serology is often used to make the diagnosis. This review is designed to inform veterinary clinicians about the current serologic tests and their limitations. In endemic areas, the fact that up to 50% of the canine population can be asymptomatic, yet seropositive, suggests that positive antibody titers do not necessarily indicate the presence of disease. Instead, the presence of a positive antibody titer should be considered evidence of exposure to the agent. Many dogs apparently are exposed to the agent of Lyme borreliosis but do not come down with the disease. Immunoblots are not able to distinguish between infection versus exposure. Newer diagnostic tests, such as antigen assays, are being evaluated. However, the fact that spirochetes have been isolated from 8% of asymptomatic dogs living in an endemic area is evidence that these tests will also need to be cautiously interpreted. Our inability to characterize the relationship between clinical signs and serology has hampered our understanding of canine Lyme disease. Presently, the diagnosis should be one of exclusion. A diagnosis of Lyme borreliosis should be considered confirmed only when other diseases are completely ruled out.     

Effects of spray-dried animal plasma on intake and apparent digestibility in dogs

Effects of spray-dried animal plasma (SDAP) on intake and apparent digestibility of major dietary components were determined using 22 adult Beagles. Trials 1 and 2 used six and eight dogs, respectively, in a switchback design using 10-d periods. Trial 3 used eight dogs in a replicated 4 x 4 Latin square design with 15-d periods. The final 5 d of each period were used for measurement of intake and fecal collections. In Trial 1, dry extruded dog food kibbles were coated with 5% tallow, 2% commercial flavor, and 0 or 2% SDAP (as-fed basis). In Trial 2, commercially available dry dog food, previously coated with fat and flavor were coated with 0 or 2% SDAP. In Trial 3, SDAP (0, 1, 2, or 3%) was blended with other ingredients and extruded (as-fed basis). Kibbles were subsequently coated with 5% poultry fat and 1% commercial flavor. Intake, fecal consistency, and apparent digestibility of nutrients were determined. Addition of SDAP did not markedly affect chemical composition of diets and did not affect intake. Digestibility of DM was improved (P < 0.04) an average of 3.2% when 2% SDAP was included in the diet for all trials. Organic matter digestibility was improved (P < 0.01) in Trials 2 and 3 by an average of 2.9%. Also, digestibility of crude fiber (Trials 1 and 2) or total dietary fiber (Trial 3) was increased with addition of SDAP to the diet (P < 0.01). Fecal DM excretion was decreased by an average of 15% across all trials with the addition of SDAP. Spray-dried animal plasma was an acceptable ingredient in dry dog food preparations, resulting in improved digestion and decreased fecal output. Changes in digestion that occurred with addition of SDAP suggested alteration in digestive capacity in dogs.     

Cerebrospinal Fluid Myelin Basic Protein as a Prognostic Biomarker in Dogs with Thoracolumbar Intervertebral Disk Herniation

Background: Release of myelin basic protein (MBP) into the cerebrospinal fluid (CSF) is associated with active demyelination and correlates with outcome in various neurological diseases. Hypothesis/Objectives: To describe associations among CSF MBP concentration, initial neurological dysfunction, and long‐term ambulatory outcome in dogs with acute thoracolumbar intervertebral disk herniation (IVDH). Animals: Five hundred and seventy‐four dogs with acute thoracolumbar IVDH and 16 clinically normal dogs. Methods: Prospective case series clinical study. Signalment, initial neurological dysfunction as determined by a modified Frankel score (MFS), and ambulatory outcome at >3‐month follow‐up were recorded. Cisternal CSF MBP concentration was determined by an ELISA. Associations were estimated between CSF MBP concentration and various clinical parameters. Results: Dogs with thoracolumbar IVDH that did not ambulate at follow‐up had a higher CSF MBP concentration (median, 3.56 ng/mL; range, 0.59–51.2 ng/mL) compared with control dogs (median, 2.22 ng/mL; range, 0–3.82 ng/mL) (P= .032). A CSF MBP concentration of ≥3 ng/mL had a sensitivity of 78% and specificity of 76% to predict an unsuccessful outcome based on receiver‐operating characteristics curve analysis (area under the curve =0.688, P= .079). Affected dogs with a CSF MBP concentration ≥3 ng/mL had 0.09 times the odds of ambulation at follow‐up compared with affected dogs with CSF MBP concentration <3 ng/mL when adjusted for initial MFS (95% confidence interval 0.01–0.66, P= .018). Conclusions and Clinical Importance: These results would suggest that CSF MBP concentration may be useful as an independent prognostic indicator in dogs with thoracolumbar IVDH.     

In-hospital development of an aorto-cardiac fistula in a Warmblood gelding with chronic renal disease

A 20-year-old Warmblood gelding presented for evaluation and treatment of ventral oedema and azotaemia of unknown aetiology. On presentation, a diastolic heart murmur was appreciated and echocardiography revealed moderate aortic insufficiency due to chronic degenerative valve disease. The horse was hospitalised and failed to respond to oral and i.v. fluids and diuretics. Following discontinuation of all fluid and diuretic therapy, the horse became acutely agitated and developed monomorphic ventricular tachycardia. The ventricular tachycardia spontaneously converted to normal sinus rhythm, however the heart murmur changed in timing to a right basilar continuous murmur and bounding jugular pulses were noted. Repeat echocardiogram revealed an aorto-cardiac fistula with dissection into the basilar interventricular septum and left-sided chamber volume overload that was not previously present. Attempts at stabilisation were unsuccessful and euthanasia was elected. Post-mortem examination confirmed chronic renal disease of unknown aetiology in addition to an aorto-cardiac fistula originating from the right sinus of Valsalva with subsequent dissection into the basilar interventricular septum.     

Macrocyclic lactone toxicity due to abamectin in farm dogs without the ABCB1 gene mutation

Abstract

CASE HISTORY: A 5-year-old entire female Huntaway from a sheep and beef farm was one of four dogs that developed clinical signs including hypersalivation, depression, blindness and ataxia after the death of another dog. A 4-year-old female Huntaway farm dog from a second farm was observed to be sitting down more often than usual on the day after being fed part of a calf carcass that had been treated with an abamectin pour-on.

CLINICAL FINDINGS: The first dog was ataxic and depressed but did respond to sound. The second dog presented with an acute onset of blindness, mydriasis, absence of a menace response, hypersalivation, gait abnormalities (e.g. high stepping gait and ataxia), and depression. Other presenting signs included muscle tremors, dehydration and difficulty eating. No abnormalities were detected from routine haematology and biochemistry. Analysis of samples of plasma from both dogs revealed concentrations of abamectin of 0.149 mg/L and 0.260 mg/L for the first and second dogs, respectively. Buccal swabs taken from the first dog for DNA testing for the ABCB1 gene mutation, gave a negative result.

DIAGNOSIS: In addition to the presenting signs which suggested a toxicosis, both dogs had measurable concentrations of abamectin in plasma confirming exposure.

CLINICAL RELEVANCE: Farm dogs exposed to concentrated pour-on products containing abamectin have been poisoned and recover or die. The product labels do not carry any warnings as to the risk of poisoning to dogs. This paper discusses two incidents affecting six farm dogs, but the authors are aware of more toxicoses in farm dogs exposed to abamectin.     

MENSURATION OF THE NORMAL PITUITARY GLAND FROM MAGNETIC RESONANCE IMAGES IN 96 DOGS

The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy.