19 Nov 2024
Myelopathy in cats, treating IMPA with leflunomide, the use of sildenafil in cats and leptomeningeal gliomatosis in dogs are among the topics under the microscope in Alex Gough’s latest Research Review column.
Alex Gough
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Allergy to domestic animals can be troublesome for many, but for veterinarians it can sometimes be career threatening.
Zahradnik et al1 described a study called AllergoVet, which aims to examine how animal exposure influences sensitisation and allergies in vet students.
It was noted that most of the students had contact with animals prior to the start of the study, so the aim of the current analysis was to investigate lifelong animal exposure and prevalence of allergies that existed at the start of the study.
Questionnaires were used to capture data on exposure history, including duration and intensity, and prevalence, of allergy symptoms. Tests for immunoglobulin E for ubiquitous inhaled allergens and animal allergens were also performed. All study participants had previous exposure to animals, including around 90% for both dogs and cats.
38% had sensitivity to ubiquitous allergens; 11% showed evidence of sensitisations to cats, 7% to dogs and 5% to horses.
However, few of these laboratory findings were associated with self-reported symptoms of allergies. It was noted that a history of increased duration of contact with dogs was associated with a decrease in dog-specific sensitisations. Interestingly, none of the 40 students who grew up on farms had any sensitisation to animals.
The authors concluded that exposure to animals at a young age was associated with a protection against sensitisation.
Intervertebral disc disease is common in dogs – especially of small breeds – but is less commonly considered in cats.
Soteras et al2 performed a retrospective study of cats with suspected myelopathy that had undergone spinal MRI to assess the clinical significance of various changes. A total of 114 cats were included in the study. Clinical findings, including neurolocalisation, diagnosis and MRI changes, were extracted from hospital records.
Seventy per cent of the cats in this study were found to have at least one degenerative spinal change, with intervertebral disc degeneration being the most common, and with spondylosis deformans and intervertebral disc protrusion also noted. Intervertebral disc extrusion was uncommon to rare. Degenerative spinal disease was more common in older and heavier cats.
Where intervertebral disc extrusion was present, it was always considered to be responsible for the clinical signs, whereas intervertebral disc protrusion was thought to be rarely linked to the observed clinical signs.
Immune-mediated polyarthritis (IMPA) is a cause of multi-limb lameness in dogs. As with many other immune-mediated diseases, immunosuppressive treatment is usually required, and various medications can be used for this purpose, some of which have marked adverse effects.
Chesne et al3 performed a retrospective study of dogs with IMPA treated with leflunomide that had long-term follow-up to assess safety and tolerance of the drug. Twenty-seven dogs were included in the study. 33% of dogs had adverse effects including vomiting, diarrhoea, inappetence, polyuria, polydipsia and secondary infections. Dogs treated with leflunomide plus prednisolone had liver enzyme elevations, but this was uncommon in dogs treated with leflunomide plus NSAIDs.
The authors concluded that leflunomide is well tolerated for long-term treatment of IMPA, but dogs co-treated with prednisolone had more hepatotoxicity than those co-treated with NSAIDs.
Sildenafil is used to treat a variety of cardiopulmonary diseases in people and is often used in dogs to treat pulmonary hypertension. However, data on the use of this drug in cats is limited.
Huynh et al4 reported a retrospective study to review records of cats that were treated with sildenafil. Fifty-five cats that had received sildenafil for at least 24 hours were included; 28 of these had acquired heart disease, 15 had congenital heart disease and 12 had primary respiratory disease.
Side effects were uncommon, with one cat having systemic hypotension and one having polydipsia. Sildenafil was discontinued in three other cats due to lack of clinical response. Treatment duration was between 2 and 2,362 days.
The authors concluded that sildenafil is well tolerated, but more data is needed to assess whether it is effective at improving survival times or quality of life.
Dogs and cats undergoing bronchoscopy and/or bronchoalveolar lavage (BAL) often have an already compromised respiratory system, a situation that is worsened by the introduction of the endoscope and lavage fluid.
Dartencet et al5 performed a pilot study that aimed to explore the safety and feasibility of high-flow oxygen therapy (HFOT) compared to conventional oxygen therapy (COT) during bronchoscopy in dogs and cats. Six patients were randomised to HFOT or COT, which were commenced at the start of the bronchoscopy. Peripheral oxygen saturation (SpO2) was assessed regularly with pulse oximetry.
No complications were found when administering HFOT. No significant difference was found in the number of episodes of desaturation between the two groups, but no HFOT patients experienced severe desaturation (SpO2 less than 90%), while two COT patients did experience severe oxygen desaturation. The mean SpO2 was significantly higher in the HFOT group than the COT group at a number of time points.
The authors concluded that HFOT is feasible and safe during bronchoscopy, and it may improve oxygenation during the procedure.
Intravenous lipid emulsion can be used as a treatment for suspected intoxication in dogs and cats.
Kiwitz et al6 performed a retrospective study to report the clinical signs of the treated intoxications and the adverse effects of the lipid emulsion. Eighty-two dogs and cats with suspected poisoning were included in the study.
Physical and laboratory findings, and modified Glasgow coma scale, were recorded at baseline and three hours after ceasing administration of the lipid emulsion. Triglyceride concentrations increased markedly while sodium, potassium and ionised calcium all decreased. Higher triglyceride concentrations were associated with a worse modified Glasgow coma scale.
54% of patients had adverse effects that were thought to be attributable to the lipid emulsion, but all of these resolved within 33 hours.
Systemic inflammatory response syndrome (SIRS) is an exaggerated immune response to stressors such as trauma and infection, resulting from dysregulation of pro-inflammatory and anti-inflammatory pathways.
Fortuny-Clanchet7 performed a prospective study to determine the prevalence of anterior uveitis in dogs and cats with SIRS. Forty-two dogs and cats with SIRS were included in the study, and 26 dogs and cats hospitalised without a diagnosis of SIRS served as controls.
Physical and ophthalmological examinations were performed while the patients were hospitalised. Diagnosis of anterior uveitis was based on signs such as aqueous flare, low intraocular pressure and miosis. 38% of patients with SIRS developed anterior uveitis compared to 7.7% of controls.
The authors concluded that anterior uveitis is more common in patients with SIRS than without, suggesting that all patients with SIRS should undergo a complete ophthalmic examination.
