15 Aug 2016
Alex Gough takes a look at the latest studies and findings in veterinary medicine in his August column.
Alex Gough
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Labrador retrievers and Jack Russell terriers are predisposed to paroxysmal movement disorders, which can mimic seizures. Image: © Aureliy Movila/Freeimages.
Labrador retrievers and Jack Russell terriers (JRTs) are predisposed to paroxysmal movement disorders, which can mimic seizures.
Lowrie et al1 performed a retrospective study of the natural history of paroxysmal dyskinaesia in 36 Labrador retrievers and 23 JRTs, diagnosed clinically by video footage of events and history. Affected dogs had early onset – 75% were male, 36% of cases demonstrated clustering of events, 32% resolved spontaneously and 75% improved. Dogs with clusters were less likely to enter remission.
The diagnostic yield of tests, such as advanced imaging, was low in these cases. The authors noted any studies on response to treatment should take into account the high spontaneous remission rate of this condition.
Imepitoin is a recently licensed drug for the treatment of epilepsy. Phenobarbital, a commonly used antiepileptic drug, can affect thyroid hormone levels.
Bossens et al2 performed a prospective study to compare the effects of imepitoin and phenobarbital on thyroid function. Various thyroid parameters, plus cholesterol and triglycerides, were measured at 6, 12 and 18 weeks after starting treatment.
Imepitoin did not have a significant effect on thyroid hormone levels over the length of the study, whereas total T4 levels reduced in dogs given phenobarbital. However, cholesterol did increase over time in dogs given imepitoin, but not as high as often seen in dogs affected with primary hypothyroidism.
It is common to find material in the gall bladder during abdominal ultrasound examinations on dogs, in many cases this is thought to be an incidental finding.
Cook et al3 evaluated the gall bladder contents in 200 consecutive ultrasound scans, and the amount of gall bladder sludge was quantified on a scale of one to five. Stored images were used to retrospectively estimate gall bladder size.
Two-thirds of dogs had some hyperechoic material in the gall bladder lumen. Four dogs had biliary mucocele. Dogs with more than 25% of the gall bladder filled with sludge were significantly older than those with minimal sludge. Hyperadrenocorticism and hypothyroidism increased the likelihood of large amounts of gall bladder sludge, and more than 25% gall bladder sludge was associated with increased gall bladder volume. The authors believe this suggested gall bladder sludge affects gall bladder contractility.
Although not accepted practice in the UK, declawing is performed in some countries to reduce destructive behaviour.
The American Veterinary Medical Association stated scratching causes risk for rehoming and euthanasia, so declawing is an acceptable alternative. However, others claim declawing can lead to behavioural problems.
Fritscher et al4 performed a study to estimate the percentage of declawed cats in the general population and the percentage in shelter populations. Significantly fewer declawed cats were in shelters than in the general population and declawed cats spent less time in the shelter before being rehomed. No correlation was found between being declawed and biting behaviour, or between declawing and euthanasia.
The authors concluded common beliefs about the behavioural effects of declawing are not supported by this study.
Grapiprant is an EP4 prostaglandin receptor antagonist that has analgesic effects.
Rausch-Derra et al5 performed a placebo-controlled trial involving treatment of 262 dogs with grapiprant or placebo. Owners assessed pain using the Canine Brief Pain Inventory weekly, for four weeks. Veterinary assessments were made at days 14 and 28. Safety was assessed with physical and clinical pathology examinations. On day 28, grapiprant was found to have improved pain significantly, compared to the placebo.
Veterinary assessments and pain scores were significantly better in the grapiprant group than the placebo group, but there was increased vomiting.
The authors concluded grapiprant was safe and effective for relieving the pain of osteoarthritis in dogs and may be better tolerated than other treatments.
Symmetric dimethylarginine (SDMA) is a newly developed test for detecting chronic renal disease, found to be elevated in cats with chronic kidney disease (CKD) up to 17 months before serum creatinine becomes elevated.
Hall et al6 performed a retrospective study to assess the utility of SDMA measurements for detecting CKD in dogs, prior to elevations in serum creatinine. The study comprised of 19 dogs with CKD, including 10 that were not azotemic, 5 that had been persistently azotemic for more than three months, and 4 that were azotemic at the time of death. A total of 20 healthy controls were also included.
Serum SDMA increased before serum creatinine in 17 of the CKD dogs, with a mean of 10 months. There was a linear correlation between serum SDMA and creatinine, and both were significantly related to glomerular filtration rate.
The authors concluded serum SDMA was useful for early detection of kidney dysfunction and this may allow earlier disease intervention to slow disease progression.
