12 Jul 2022
Alex Gough MA, VetMB, CertSAM, CertVC, PGCert(Neuroimaging), MRCVS, runs through some of the latest research for companion animals in his latest column from Vet Times.
Alex Gough
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Steroid-containing drops are used topically for the treatment of a number of eye conditions.
They are usually considered to have a lower systemic effect than other methods of administering steroids, such as oral or parenteral routes. However, topical ophthalmic administration can still lead to systemic absorption.
Ewald et al1 performed a study to determine the plasma concentrations of prednisolone and dexamethasone after topical ophthalmic administration. Twelve healthy beagles were included in the study, half of which received one drop of 1% prednisolone acetate and half of which received one drop of 0.1% dexamethasone.
Blood samples were collected from the jugular and a peripheral site on days 0, 1, 7 and 14, and analysed for drug and cortisol concentrations.
Both drugs were absorbed systemically and detected up to two weeks after administration. Higher concentrations were found in the jugular vein than peripherally. Plasma cortisol levels were lower than baseline two weeks after treatment with either drug.
This study shows that prednisolone and dexamethasone are absorbed into the circulation after ophthalmic administration to the extent that they affect cortisol levels, which can have implications for diagnostic tests for hyperadrenocorticism or hypoadrenocorticism and potentially for side effects with long‑term administration.
The authors noted further research was needed to assess the degree of systemic absorption when these drugs are applied to inflamed eyes.
The mean electrical axis (MEA) refers to the average of the electrical vectors occurring during depolarisation of the ventricles and can be calculated from an ECG.
Although some believe it was invented purely to aggravate students of cardiology, it does have some clinical utility.
Ackerman et al2 performed a retrospective cohort study to assess whether right axis deviation in the canine ECG was able to predict the severity of pulmonic stenosis.
A total of 218 dogs with pulmonic stenosis diagnosed by Doppler echocardiography were screened for the study, with the records of 88 dogs being included.
The mean MEA increased with the severity category of the stenosis – 62° for mild, 113° for moderate and 157° for severe. A 10° increase in MEA correlated with an approximate 5mmHg increase in pressure gradient.
Greater pulmonic stenosis severity was also associated with small breeds, overt clinical signs and loud murmurs.
The authors concluded that right axis deviation of the MEA can be a useful screening test for moderate to severe pulmonic stenosis.
A large variety of dog treats are available commercially, online and in pet shops, but their stated origin may not be accurate.
This can have implications for owners feeding elimination diets to dogs for diagnosis and treatment of food intolerance.
Marquez et al3 performed a DNA analysis of 8 treats and 20 supplements. A total of 88% of the treats and 40% of the supplements contained at least one source of mammalian DNA that were not declared on the ingredients. Porcine and bovine DNA were the most commonly identified undeclared species identified.
Two of the samples did not have any DNA for at least one of the species declared on the ingredients.
The authors suggested that treats and supplements are not fed during elimination diet trials because of the high incidence of undeclared mammalian DNA species discovered.
Cyclophosphamide is a commonly used and important chemotherapy drug, used, for example, in the treatment of lymphoma.
One of its most important side effects is sterile haemorrhagic cystitis (SHC), so furosemide is often co-administered with cyclophosphamide to reduce the incidence of this problem.
Iwaki et al4 performed a retrospective study to assess the incidence of SHC in dogs treated with oral cyclophosphamide and oral furosemide at a dose of 1mg/kg.
The study included 81 dogs that were given a total of 252 doses of a single oral maximum tolerated dose of cyclophosphamide. Only 2 dogs had suspected SHC.
The authors concluded that the concurrent use of furosemide at a dose of 1mg/kg with cyclophosphamide led to a similar incidence of SHC as when higher doses of furosemide were used.
Dogs can find consulting rooms stressful places, and ways to decrease stress can improve their welfare, as well as make examinations and procedures easier for the vet.
Two papers by the same team – Girault et al5 and Helsly et al6 – examined the interactions between owner and pet in the consulting room.
The first study aimed to assess whether the presence of owners in consulting rooms affected their dogs’ behaviour.
A total of 25 dog-owner dyads were included in the study. Two consultations were video recorded, one with – and one without – the owner present.
No significant difference was found in stress‑related behaviour of the dog or the vet’s ability to examine the animal between consultations with and without the owner. However, the dogs were more willing to enter the consulting room if the owner was present and tended to look towards the owner if they were present, or towards the door if they were not.
The authors concluded that the welfare of the dog was improved by the presence of the owner.
The second study used the videos from the first study to investigate the relationship between owners’ actions and dog behaviour.
The investigators assessed whether dogs interacted more when the owner was interactive, whether owner stress affected dog stress and dog actions, and whether canine stress was associated with more eye contact with owners.
Negative behaviours by the owners were found to amplify the stress of the dogs, but visual and verbal attempts to comfort the dogs had no effect. Scolding increased stress.
However, the more dogs displayed stress‑related behaviours, the more they attempted eye contact with their owners, suggesting they were seeking information or reassurance.
Oesophageal foreign bodies are life‑threatening emergencies that can lead to oesophageal perforation.
Endoscopic retrieval is possible in some – but not all – cases, and surgery is required if retrieval is unsuccessful or oesophageal perforation is detected.
Beer et al7 performed a retrospective study to identify short‑term and long‑term outcomes and complications associated with surgical treatment of oesophageal foreign bodies in dogs.
A total of 63 dogs were included in the study – 86% of the dogs underwent the surgery because of a failed attempt to retrieve the foreign body using a minimally invasive technique, or identification of a perforation following retrieval.
An oesophageal perforation was present in 67% of cases, while 59% of dogs underwent a left‑sided intercostal thoracotomy.
In total, 29% of cases had an intraoperative complication and 50% had a postoperative complication, of which half were considered minor. In three cases, dehiscence of the oesophagotomy occurred.
Three-quarters of the dogs survived to discharge. Preoperative presence of oesophageal perforation, undergoing a thoracotomy and the placement of a gastrostomy tube were all negative prognostic indicators for survival to discharge.
A quarter of owners reported occasional vomiting or regurgitation after discharge.
The authors concluded that surgical management of oesophageal foreign bodies can have a high success rate and should be considered where a foreign body cannot be retrieved or oesophageal perforation was present.
