Analysing clinical signs for dogs and cats with chyloabdomen

Chylothorax is a pleural effusion encountered uncommonly in practice, and can be idiopathic or secondary to heart disease, neoplasia and trauma. Much rarer still is chyloabdomen.

Hatch et al¹ performed a retrospective analysis of 53 dogs and cats with chyloabdomen to characterise the clinical signs, diagnostic test results and prognosis. The incidence of chyloabdomen was calculated as 2 cases per 100,000 admissions for cats and 2.8 per 100,000 for dogs. The mean age of diagnosis for cats was older than for dogs at 11.3 years compared to 6.9 years, respectively.

The most common clinical signs were non-specific, particularly lethargy and anorexia, with only 43% showing abdominal distension; 47% had concurrent chylothorax. Malignant neoplasia was the most common underlying diagnosis, affecting 45% of cases.

Median survival time was only 31 days for all cases, and 8 days for those with malignant neoplasia, compared to 73 days for patients without neoplasia. Multiple causes of chyloabdomen were diagnosed and the outcome was dependent on the cause.

Distinguishing dogs with primary hypothyroidism to those with NTI

It can be difficult in practice to differentiate between primary hypothyroidism and non-thyroidal illness (NTI), even when total thyroxine (T4) and thyroid-stimulating hormone (TSH) are both measured. However, hypothyroidism causes an increase in TSH-releasing hormone (TRH)-induced growth hormone (GH) release.

Pijnacker et al² performed a case-control study aiming to assess whether basal and TRH-induced GH concentrations could distinguish dogs with primary hypothyroidism from dogs with NTI.

A total of 21 dogs were included in the study, which had clinical signs consistent with hypothyroidism, low plasma total T4 and normal plasma TSH.

Thyroid scintigraphy was performed as the reference test to ascertain whether the dogs had primary hypothyroidism or NTI. All dogs had a TRH stimulation test performed, and TSH and GH were measured before and after administration of TRH.

Primary hypothyroidism was found in 11 cases and 10 had NTI. The basal plasma GH was significantly higher in hypothyroid dogs than NTI dogs, with minimal overlap. After stimulation, no overlap occurred, with GH increasing after stimulation in hypothyroid dogs, but not in NTI dogs. TSH did not increase significantly after stimulation in hypothyroid dogs, whereas it did increase in NTI dogs.

The authors concluded basal GH and post-stimulation GH and TSH concentrations can be helpful in distinguishing dogs with NTI and primary hypothyroidism.

Opsoclonus study

A saccade is a fast and simultaneous movement of both eyes between two or more stages of fixation. Involuntary saccadic oscillations are reported in human medicine due to disorders of the control of the saccadic eye movements.

Ives et al³ described a case series of three dogs and one cat that had signs consistent with opsoclonus – rapid, uncontrolled and multivectorial eye movements.

All the cases had signs of cerebellar disease and the authors noted the presence of opsoclonus is suggestive of cerebellar disease. The underlying diseases included idiopathic generalised tremor syndrome and neuronal ceroid lipofuscinosis. Opsoclonus is likely to be under-diagnosed and under-reported in veterinary medicine.

Causes and outcomes of comas

Coma and stupor are profound alterations in consciousness associated with various brain disorders.

Parratt et al⁴ performed a retrospective study to describe the underlying causes and outcomes of dogs and cats presenting with coma or stupor. A total of 168 dogs and 218 cats were included in the study. Cases were presented to a multi-centre out-of-hours service provider. Chihuahuas were noted to be over-represented.

In dogs, 16% of cases, where a diagnosis was made, were caused by traumatic brain injury. Hypoglycaemia, shock and seizures were other common causes in dogs.

For cats, 22% of cases, where a diagnosis was made, were caused by traumatic brain injury. Renal or hepatic dysfunction, intoxication, hypoglycaemia and shock were common underlying causes in cats. With the exception of cases caused by hypoglycaemia, the short-term outlook for cases of stupor and coma was poor.

Treating hypercalcaemia using zoledronate

Bisphosphonates, such as pamidronate or aledronate, are often used in the treatment of hypercalcaemia, which can be life-threatening if not treated promptly; for example, by causing renal damage.

Schenk et al⁵ performed a study of the treatment of hypercalcaemia in four dogs using zoledronate. One dog had a local hypersensitivity reaction, but the treatment was otherwise well tolerated. All dogs showed a decrease in total and ionised calcium after treatment.

Controlling parvoviral enteritis

Parvoviral enteritis can be challenging to treat because of the associated severe gastrointestinal signs. Antiemetics have an important role in reducing the severity of vomiting in these cases.

Sullivan et al⁶ performed a blind, randomised, prospective study to compare the efficacy of maropitant and ondansetron in dogs with parvoviral enteritis. All dogs were treated with maropitant or ondansetron, and were all given IV fluids, cefoxitin and enteral nutrition.

Various parameters, such as clinical severity, bodyweight and food intake, were measured. No differences were noted between the two groups for duration of hospitalisation, requirement for a rescue antiemetic, duration of vomiting or the time to return of voluntary food intake.

The authors conclude maropitant and ondansetron are equally effective in controlling the clinical signs of parvoviral enteritis.

• Some of the medications discussed in this article are not licensed for veterinary use.