Intravenous administration of levothyroxine for treatment of suspected myxedema coma complicated by severe hypothermia in a dog

Retrospective evaluation of the etiology and clinical characteristics of peripheral edema in dogs

BACKGROUND

The prevalence and clinical characteristics of different etiologies of peripheral edema in dogs are unknown.

HYPOTHESIS/OBJECTIVES

To determine the prevalence of different etiologies of peripheral edema, describe clinical characteristics that vary among etiologies, and report survival times.

ANIMALS

Five hundred twenty-seven dogs with peripheral edema.

METHODS

Retrospective medical record review. Differences in clinical variables among etiology groups were assessed by Kruskal-Wallis testing with post hoc pairwise Dunn's testing and Chi-square testing with Monte Carlo simulation.

RESULTS

The most common etiologies of peripheral edema in dogs were vasculitis (n = 193, 37%), lymphatic/venous obstruction (LVO; 114, 22%), and hypoalbuminemia (94, 18%). Right-sided congestive heart failure (R-CHF) was uncommon (25, 5%). Edema was localized in 377 (72%) dogs and generalized in 142 (27%) dogs, and hypoalbuminemia was more likely to cause generalized edema compared to LVO or vasculitis (P < .0001). Concurrent abdominal effusion (155, 29%) was more common than pleural (77, 15%) or pericardial (12, 2%) effusion. Abdominal and pleural effusion occurred more commonly in dogs with hypoalbuminemia or R-CHF compared to LVO or vasculitis (P < .0001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Distribution of edema, concurrent cavitary effusions, and clinicopathological data can help predict the underlying etiology of peripheral edema in dogs.

Retrospective characterization of coma and stupor in dogs and cats presenting to a multicenter out-of-hours service (2012-2015): 386 animals

OBJECTIVE

To describe the signalment, etiology, and short-term outcome of dogs and cats presenting in a coma or stupor.

DESIGN

Retrospective study conducted between May 2012 and February 2015.

SETTING

Multicenter out-of-hours emergency service provider.

ANIMALS

Three hundred eighty-six patients presenting in a coma or stupor to a multicenter out-of-hours emergency care provider.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Records were reviewed to determine the most likely etiology of coma or stupor. Short-term outcomes were defined as deceased (died or euthanized) or transferred (case handed over to a daytime clinic or discharged). There were 168 dogs (coma n = 112, stupor n = 56) and 218 cats (coma n = 148, stupor n = 70) identified. Coma and stupor were more prevalent in cats compared to dogs, and Chihuahuas were over represented. Blood glucose concentrations were frequently outside established reference intervals. Excluding undetermined causes, the most common causes in dogs included traumatic brain injury (TBI) 16.0% (n = 27, deceased n = 22), hypoglycemia 10.7% (n = 18, deceased n = 8), shock 10.1% (n = 17, deceased n = 16), seizure 9.5% (n = 16, deceased n = 13), and renal or hepatic dysfunction 5.3% (n = 9, deceased n = 7). For cats, the most common causes included TBI 21.6% (n = 47, deceased n = 38), renal or hepatic dysfunction 13.3% (n = 29, deceased n = 25), intoxication 10.1% (n = 22, deceased n = 18), hypoglycemia 6.0% (n = 13, deceased n = 4), and shock 5.0% (n = 11, deceased n = 8). When treatment was attempted, 46.0% of dogs (n = 44/96) and 41.2% of cats (n = 35/85) survived to be transferred. Compared to all other etiologies, death was less likely when coma or stupor was attributed to hypoglycemia.

CONCLUSION

In cases where a cause was determined, TBI was the predominant etiology of coma and stupor for both species. With the exception of coma and stupor attributed to hypoglycemia, the overall short-term prognosis was poor.

The effect of experimentally induced hypothyroidism on the isoflurane minimum alveolar concentration in dogs

OBJECTIVE

To determine the effect of experimentally induced hypothyroidism on isoflurane (ISO) minimum alveolar concentration (MAC) in dogs.

STUDY DESIGN

Prospective experimental study.

ANIMALS

Eighteen adult female mongrel dogs, age 2-4 years and weighing 8.2-13.1 kg.

METHODS

Hypothyroidism was induced in nine dogs by the intravenous administration of 1 mCi kg(-1) of (131) Iodine. The remaining nine dogs served as controls. Dogs were studied 9-12 months after the induction of hypothyroidism. Anesthesia was induced with ISO in oxygen via a mask. The trachea was intubated, and anesthesia was maintained using ISO in oxygen using a semi-closed rebreathing circle system. The dogs were mechanically ventilated to maintain an end-tidal carbon dioxide concentration between 35 and 45 mmHg. End-tidal ISO concentrations were measured with an infrared gas analyzer. The MAC was determined in duplicate using a tail clamp technique. The mean values for the groups were compared using a two sample t-test.

RESULTS

The mean ± SD MAC of isoflurane in the hypothyroid and euthyroid dogs was 0.98 ± 0.31% and 1.11 ± 0.26%, respectively. The mean MAC of isoflurane in hypothyroid dogs was not significantly different from the mean MAC of isoflurane in the control dogs (p = 0.3553).

CONCLUSION AND CLINICAL RELEVANCE

The MAC of ISO in dogs was not significantly affected by experimentally induced hypothyroidism. The dose of ISO in dogs with hypothyroidism does not need to be altered.

Endocrine emergencies in dogs and cats

Success in treatment of endocrine emergencies is contingent on early recognition and treatment. Many endocrine diseases presenting emergently have nonspecific signs and symptoms. In addition, these endocrine crises are often precipitated by concurrent disease, further making early identification difficult. This article concentrates on recognition and emergency management of the most common endocrine crises in dogs and cats.

Iatrogenic, sulfonamide-induced hypothyroid crisis in a Labrador Retriever

This case report describes a sulfonamide-induced hypothyroid crisis in a 4-year-old Labrador Retriever bitch. Empirical therapy with high-dose trimethoprim-sulfamethoxazole for 10 days produced signs of weakness, ataxia and mental depression and the clinicopathological results supported hypothyroid-induced central nervous system depression. Short-term levothyroxine sodium therapy led to complete resolution of all clinical signs and follow-up thyroid hormone assays ruled out underlying thyroid pathology. This case report is the first to highlight this potentially life-threatening manifestation of sulfonamide-induced hypothyroidism. Sulfonamide combinations are widely used antimicrobials in veterinary medicine and early recognition of this syndrome is critical.

Clinical Signs and Concurrent Diseases of Hypothyroidism in Dogs and Cats

Canine hypothyroidism may present with a wide range of clinical signs. The most common clinical signs are those of a decreased metabolic rate and dermatologic manifestations; however, many other clinical signs have been associated with hypothyroidism. There is strong evidence for a causal relation between hypothyroidism and a variety of neurologic abnormalities; however, the association between hypothyroidism and other manifestations, such as reproductive dysfunction, clinical heart disease, and behavioral abnormalities, is less compelling. Further studies are necessary to determine the full spectrum of disorders caused by hypothyroidism.

Comparative dermatology—canine endocrine dermatoses

Endocrine diseases in the dog commonly manifest with dermatological lesions. Hypothyroidism is the most common endocrinopathy and usually presents with alopecia in areas of wear, seborrhea, and recurrent infections. Common clinical signs associated with hyperadrenocorticism include polyuria, polydipsia, and polyphagia. The most common dermatological manifestation of hyperadrenocorticism is bilaterally symmetrical alopecia sparing the head and distal extremities. Pyoderma is a common finding associated with immunosuppression. Less commonly, calcinosus cutis may occur. Sex hormone excess, primarily hyperestrogenism and hyperandrogenism, may also be associated with dermatological signs. Usually, dogs are intact, and the excess production is due to testicular or ovarian neoplasia.