4 Jun 2024
Chemotherapy diets, tuberculosis in dogs, seizure control 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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Meningoencephalitis of unknown origin (MUO) can be hard to diagnose in dogs, even when using advanced imaging and cerebrospinal fluid (CSF) analysis.
Cavalerie et al1 performed a study to assess whether concentrations of C-reactive protein (CRP) could be of use in the diagnosis and prognosis of this disease. A total of 30 dogs with MUO – 15 dogs with steroid-responsive meningitis arteritis (SMRA), which acted as a positive control group, and 15 healthy dogs as negative controls – were included in the study.
Blood and CSF CRP were measured in the MUO and SMRA groups, but only blood CRP in the healthy group. MRI and traditional CSF analysis were also performed.
Of dogs with MUO, 30% had an increase in CRP in blood and 10% had a measurable CRP in their CSF. No difference was recorded between the blood CRP concentrations in the healthy and MUO group, but this was lower than the SMRA group.
No association was recorded between blood CRP concentration and survival to six months.
The authors concluded that CRP is of limited use in the diagnosis and prognosis of MUO in dogs.
Chemotherapy is an important tool in treating cancer in dogs, but its use is limited by its expense and its adverse effects, perceived or real.
It has been noted that human patients with cancer perceive more severe chemotherapy side effects than do their doctors.
Leonardi et al2 performed a study of 152 pet owners and 111 veterinary oncologists to assess whether owners and vets also differ in their perception of side effects of chemotherapy.
Different surveys were sent to pet owners and veterinary oncologists, but all were asked to give their assessment of the maximum acceptable scores and risks of adverse effects for cure, life extension and improvement of quality of life.
The veterinary oncologists were prepared to accept worse adverse effects if the goal was cure or extension of length of life, but owners accepted higher side effects if the goal was to improve quality of life.
Overall, though, owners were prepared to accept a greater risk of moderate or serious adverse effects compared to vets.
The authors concluded that these results might help with discussions between vets and owners about chemotherapy.
Endoscopic retrieval of gastric foreign bodies is a highly useful technique to allow removal of ingested items with minimal invasiveness.
Unfortunately, not all shapes and sizes of foreign bodies are amenable to removal with traditional grasping forceps and snares.
Le Boedec et al3 reported a series of cases where bottle liners were used to assist in the procedure. A bottle liner was pushed into the stomach ahead of the endoscope, and, with forceps passed through the endoscope, the foreign body was pushed into the liner. The liner was then retrieved using traction threads.
A total of 12 dogs were included in the study, 5 with foreign bodies that were too smooth to grasp or too sharp to remove safely and 7 in which it was a rescue procedure.
Foreign body retrieval was successful in all 12 dogs, and only minor complications such as erosions and bleeding were seen in 5 dogs. This simple technique might be a useful, minimally invasive and low cost alternative to gastrotomy for removal of problematic gastric foreign bodies.
Tuberculosis is a moderately common presentation in cats in certain geographic areas, but is much less commonly reported in dogs.
O’Halloran et al4 performed a retrospective-prospective observational study of dogs infected with Mycobacterium tuberculosis-complex (MTBC) organisms. Just less than 600 cases were included in the study.
Diagnosis was made with a variety of techniques including culture, PCR and interferon-gamma release assay. In those cases where species identification was performed, all cases were caused by either M tuberculosis, M bovis or M microti, this last not having been reported in UK-based dogs before.
Clinical signs were often non-specific and long term, although rapidly progressive in the terminal phase. 44% of cases were primarily pulmonary in location, with 15% being abdominal; 13 dogs were treated with combination antibiotics, with a good response being seen in 12 of these.
Seizure control in cats is largely based on the use of phenobarbital as a first-line drug. However, a lack of evidence exists for use of treatments when seizures are insufficiently controlled with phenobarbital.
Djani et al5 performed a retrospective study to compare seizure frequency before and after treatment with oral zonisamide. A total of 57 cats with a history of seizures were included in the study, and seizure frequency, adverse events and clinicopathological data were recorded.
A median decrease of one seizure a day per month and one seizure per month was found after treatment – 17% of cats exhibited signs of sedation, with small numbers showing ataxia, inappetence and vomiting.
Clinicopathology showed a mild non-regenerative anaemia in one cat and mild increases in alanine transaminase and alkaline phosphatase in six cats.
The authors concluded that zonisamide is safe and effective in the treatment of seizures in cats.
Leptomeningeal gliomatosis (LG) is a rare neoplastic disease in which cancerous glial cells spread extensively in the subarachnoid space.
Primary LG occurs without an intraparenchymal glioma, while secondary LG is found with an intraparenchymal glioma.
Rissi et al6 reported on the findings of a case series of 14 dogs with LG. More than 90% of patients were brachycephalic, and their mean age was around seven years.
Clinical signs were varied, but were progressive. MRI findings were available in seven dogs and showed meningeal enhancement and/or intraparenchymal space occupying lesions. All dogs were euthanised; 12 cases had gross pathological changes mainly comprising gelatinous thickening of the meninges, as well as one or more masses in the brain. All the neoplasias were consistent histopathologically with oligodendrogliomas.
Three cases were considered to be primary and 11 secondary.
Optimising nutrition is a vital part of cancer care to, for example, ensure adequate calorie and protein intake and maintain quality of life. However, little data exists on the use of diets in dogs undergoing chemotherapy.
Heinze et al7 performed a randomised, controlled, double-blinded trial to evaluate a high-protein, high-fibre diet fortified with omega-3 fatty acids in dogs undergoing chemotherapy for cancer.
Dogs with grade two or higher mast cell tumours which were unresectable or could not be completely resected, and dogs with multicentric lymphoma, were allocated randomly to the investigation diet or a control diet for a period of eight weeks. Quality of life and faecal scores and blood concentrations of CRP and monocyte chemo-attractant protein-1 were assessed.
Some improvement in some of the quality of life scores was observed compared to baseline, but little difference was recorded between the groups. However, no significant difference was recorded in adverse events or in the laboratory tests between the two groups.
The authors concluded that the lack of adverse events suggested a larger trial might be useful to further assess the usefulness of the diet in this setting.
