Idiosyncrasies in greyhounds that can affect their medical care - Veterinary Medicine
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Idiosyncrasies in greyhounds that can affect their medical care
These athletes have been bred for speed and an even temper. But some irregularities in greyhounds will affect how to clinically assess and treat these dogs. Make sure you're prepared for the next greyhound that visits your practice.


VETERINARY MEDICINE


Treatment consists of high doses of essential fatty acids, immunosuppressive medications, and systemic and topical antibiotics as indicated.22 Some dermatologists have found that the combination of tetracycline, niacinamide, and high doses of essential fatty acids (180 mg eicosapentaenoic acid/10 lb) effectively controls this disease without concurrent corticosteroid administration. Long-term medication may be necessary to control the condition.22

ORTHOPEDIC IDIOSYNCRASY

Central tarsal bone fractures are one of the most common career-ending orthopedic injuries of active racing greyhounds.23 These injuries can often be surgically repaired, although many trainers and rescue groups lack the financial resources to treat surgically. Extended rest (six to 12 months) and casting are another treatment option often used. Although swelling and arthritis will develop in the affected tarsus if surgery is not performed, most greyhounds will still maintain a high quality of life.

REPRODUCTIVE IDIOSYNCRASIES

Clitoral hypertrophy occurs in many recently retired female greyhounds. Female greyhounds are routinely given testosterone injections at the racetrack to prevent estrous cycles. One of the long-term sequelae of these injections can be clitoral hypertrophy.24 In some cases this condition has been confused with hermaphroditism. If a greyhound is asymptomatic, the condition does not require treatment.24 Abnormalities in the internal reproductive organs would potentially be of concern and could be addressed at the time of neutering.

ANESTHETIC IDIOSYNCRASIES

Greyhounds have a reputation among veterinarians and owners as having many anesthetic idiosyncrasies. The nervous demeanor of some greyhounds and the stress of a hospital setting can lead to potential gastrointestinal upset, hyperthermia, and unreliable response to anesthetic premedications. A greyhound's body conformation can also predispose it to hypothermia during anesthesia. Greyhounds have a relatively high body surface-to-volume ratio and a low average body fat (17% average body fat for greyhounds compared with 35% average body fat for mixed breeds).25 Many safe anesthetic protocols are available for greyhounds. Monitoring preoperative and postoperative temperatures is important, as it is for any pet.

Anesthetic hyperthermia

Malignant hyperthermia and nonmalignant hyperthermia, or stress hyperthermia, can affect greyhounds. Malignant hyperthermia is a rare inherited genetic disorder of skeletal muscle that results in the mutation of calcium channel protein within muscle cells. This mutation results in muscle contraction and increased metabolism, which leads to the production of not only excess carbon dioxide but also excess heat, resulting in a life-threatening hyperthermia.26 Malignant hyperthermia can be triggered by gas anesthetics (not injectable anesthetics), extreme exercise, and stress. It is most likely to occur during the procedure or while the dog is exposed to inhalant anesthetics. The only treatment for true episodes of malignant hyperthermia is an intravenous injection of the muscle relaxant dantrolene in addition to supportive intravenous fluid therapy, immediate removal of the patient from gas anesthetics, external cooling, and respiratory support.27 Even with appropriate treatment, this disease can be fatal. Malignant hyperthermia is definitively diagnosed based on the results of a caffeine contracture test on fresh muscle tissue and suggestive serum chemistry and blood gas analysis results (elevated creatinine kinase or aspartate transaminase activities, elevated CO2 concentrations, low pH, and, occasionally, low bicarbonate concentrations) during a malignant hyperthermia episode.27 An erythrocyte osmotic fragility test can also be performed, but finding a commercial laboratory that performs this test may be difficult.28

Stress hyperthermia is more commonly seen in greyhounds than true malignant hyperthermia.29 It can occur at any time but is more likely in recovery. Greyhounds are well-known for their large muscle mass. Many greyhounds also suffer from separation anxiety or stress when hospitalized. I think both of these factors may help explain why greyhounds seem to suffer from stress hyperthermia more than other breeds. As animals awake from anesthesia, many shake or shiver as a natural response to mild hypothermia, pain, or disorientation. In some greyhounds, this response seems to be exaggerated, and many continue the warming process beyond normal body temperatures and may reach in excess of 105 F (40.5 C). These animals may respond well to supportive treatment (anti-inflammatories, intravenous fluids, external cooling, pain medications, muscle relaxants, and respiratory support) without the use of dantrolene if the condition is diagnosed early enough. Many anesthesiologists say that if a dog survives an episode of anesthetic hyperthermia without receiving dantrolene then the dog does not have malignant hyperthermia.29


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Source: VETERINARY MEDICINE,
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