Avocado Toxicity

An owner called the hospital today and wanted to know if avocado is poisonous. Specifically, she wanted to know if avocado is poisonous to dogs.

Short answer - no. Dogs can eat quite a bit of avocado without problem. The pits are mainly a problem if they are swallowed whole and end up becoming and obstruction. Too much avocado = bad diarrhea.

Here's a quote from Dr. Mark Grossman:
Avocado does contain the toxin persin. The leaves, fruit, bark, and seeds contain the toxin. In dogs and cats however, it does not seem to be as much of a problem as in cattle, horse, goats, rabbits, birds and fish.
Signs including vomiting, diarrhea, death, inflammation of mammary glands of rabbits, goats, cattle, and horses are seen. As well as cardiac failure in goats with respiratory distress, generalized congestion, fluid accumulation around the heart.
A few cases of dogs becomming sick exist but they have to consume large amounts.

In other words - don't feed your goat avocado! Dogs - OK.

This has also come up because of a popular new food called Avoderm. Dasuquin also has avocado in it. It's OK. By all measurements, Avoderm appears to be a good food. Don't let the avocado part of it worry you.

Dr. H-

Follower Question - Hyperthyroid Feline and Proper Drug Choice

Hello Dr. Herndon,
I've seen it mentioned a couple times in a couple places that injectable and/or all benadryl should be used with caution/not used at all in a hyperthyroid cat. But, I can't find out why or what to look for. Also can't find any info on benadryl's effects on CRF cats. [I have a 16yr old CFR (+peri-renal cysts)/hyperthyroid female that has some serious sinus issues, among other things.

My vet and I have been trying to find ways of dealing with it that don't torture the cat. She severely hates Afrin nasal spray. Saline drops don't seem to accomplish much. Today I stuck her in a cage "next to" a steam vaporizer for 1/2 hr--that seemed to help a little... At any rate, she has been on injectable benadryl since 6/20 at 0.05-0.07 mL/dose. Most days she only got 1 dose. On 7/4 she went off her food--nauseated style. Today received an anti-nausea and pepsid in the AM. She finally ate cat food around 5:30pm after the vaporizer session. She has other issues too so this could very well be unrelated to the benadryl, but wanted to check.]
Thank you so much for your time, Kelly S


I can't think of any good reason not to use Benadryl in a well controlled hyperthyroid cat. No worries there at therapeutic doses. It MIGHT cause the heart rate to increase a little. A cat in out-right heart failure might not do well with it, but I think you'll be fine.

Cats with upper respiratory congestion are difficult to treat. When a cat can't smell, a cat won't eat. When a cat don't eat, a cat gets worse. You're doing the right stuff. Here's a couple of suggestions to bring up to your doctor:

1) Consider having a PCR run to check for herpesvirus, calicivirus, and mycobacterium (PCR is a very sensitive test looking for virus or bacteria DNA). If this is viral, it may be smart to consider using an antiviral up the nose. There is an antiviral drug called idoxuridine that is sometimes used in the eye - I've used it once in the nose instead. If it's herpes, then you can also add the amino acid lysine to the diet - that helps slow the virus down. The other anti-herpesviral medications used in people don't work well in cats (acycolvir/valcyclovir).

2) I've sometimes used atropine ophthalmic drops in the nose (cats HATE THIS!) but that helps dry it up. I'll also mix atropine with an ophthalmic antibiotic drop. The antibiotics can sometimes help with secondary infection.

3) I've worked with a compounding pharmacy to have an antihistamine made in a trans-dermal gel. Transdermal gels are a substance you would smear on the inner surface of the ear. The drug then absorbs across the ear skin. Not all chemicals/drugs can do this, but the pharmacist can help your doctor find out what drugs might be worth trying.

Humid air helps - you are trying to break up the debris in the nose so the kitty will eat.

A 16yr old kitty with several major health issues is not an easy task. If she's feeling nauseous I'd have some bloodwork run. When the renal values get too high the toxins will cause upset stomach and mouth ulcers. Worth a check.

Dr. H

Heartworm Disease in Cats

http://www.knowheartworms.org/

Checkout this link. It has good information.

Here's the scoop - we always knew that cats could develop heartworms. We knew that occasional cats would develop an adult worm in the heart and that those cats were in a pretty dangerous position. If you tried to treat the adult worm, about 33% died outright, 33% were so sick they wished they were dead and 33% did great. Thankfully, the incidence of this disease was fairly low in cats and so prevention was recommended, but not encouraged as much as it should have been.



Guess what - we were wrong! Research completed at North Carolina State in 2005 confirmed that although true that few cats develop adult worms, the real story is that MOST cats kill the worm before it turns into an adult. That's great except that when this happens, these kitties often develop wicked asthma. I've treated dozens of cats for asthma. Feline asthma is considered a fairly common disease. We now know that many (most?) of those cats are heartworm disease!



Diagnosis of these kitties is difficult because of when they kill the heartworm larva. There is a very narrow window of time that a cat would be 'positive' on a test. By the time we see a sick kitty, it is quite likely that we will not be able to prove the presence of heatworm as the cause. Worse yet - our treatment at this point is supportive. I can't reverse the disease, I can only control it. There is now a name for this condition - HARD - Heartworm Associated Respiratory Disease. Heartworm is a misnomer in cats - lung disease is the primary problem, not heart disease.



So the major change in our thinking has been that PREVENTION is critical in cats. Many more cats are at risk that we ever though. Prevention is now seen as just as important in cats as it has always been seen in dogs.



But my cat is indoors. Heartworm disease is transmitted by mosquitoes, so how could my indoor cat be at risk?

There's the other shocking finding. In that same NC State study, roughly 30% of those cats diagnosed with heartworm disease (usually after death) were reported by their owners to be 100% INDOOR cats. So 1 in 3 cats dead of heartworms never left the house (according to their owners). We all know mosquitoes will get into the house. Now we have proof that they bring problems indoors with them.



Moral of the story?

Cat's get heartworm disease. Most frequently they get respiratory disease. Heartworm disease is often fatal in cats. It's hard to diagnose. It's hard to treat. It's also VERY PREVENTABLE if you use a monthly preventative prescribed by your veterinarian. Prevention, Prevention, Prevention, Prevention. My personal favorite is Revolution for cats. There are other excellent products like Heartguard, Iverheart, Advantage Multi, and Interceptor. Each of these have the added bonus of also controlling intestinal parasites.



AMH

Heartworm Preventatives

Now that I've talked about heartworm disease, here's the skinny on heartworm preventatives:

You now know that mosquitoes are the carrier for heartworm. Exposure to mosquitoes is therefore required. Risk is highest for dogs outdoors at the hours of dusk and dawn when the little buggars are out feeding.

HOWEVER...

Mosquitoes come indoors! Dogs go out to pee or at the very least poo (usually). Although your risk is lower as an indoor only cat - about 1 in 4 SICK cats are considered 100% indoor by their owner. There is no such thing as a dog that doesn't need preventative.

Preventatives are critical. One common misconception is that heartworm preventatives work for the NEXT month after they are given. What's happening is that the preventatives are killing off any larva that the pet has been infected with over the LAST month. In other words, we assume that the pet has been infected and the preventative is killing them before they grow to adults.

There are many different heartworm preventatives out there. They all do the same thing - they kill the larva. All of the preventatives you should be able to get today are in the same class of drugs. Some people are still using Filaribits (DEC) but if you are - STOP. Some preventatives have activities against other parasites - some kill intestinal parasites or fleas in addition to heartworm larvae.

Common products you'll find are:

• Heartguard (plus)
• Interceptor (or Sentinel)
• Advantage Multi
• Revolution
• Iverheart (plus)

They each have really pretty literature that shows how they are the best product on the market and all of their competition sucks. The truth is somewhere in the middle. They all have their ups and downs. Go with your veterinarian's recommendation. I'm a Heartguard man. Always have been. Always will be. All of these products are effective. All of these companies support their product claims. It's really a matter of your situation, what you think is easiest, and what your veterinarian recommends for your area.

The most important concept is that they are all intended to be given once a month. You have to use them once a month. The one exception out there is ProHeart. This is an injectable heartworm preventative that is given every 6 months.

AMH

Heartworm Disease Overview

http://www.heartwormsociety.org/

The link above will give you lots and lots of good information on this subject. The pictures above are small, I know. I don't have any larger pictures. Maybe someday I'll get a good heart to get pictures of.

I'm going to post a separate blog on preventative choices, feline heartworm disease, and heartworm treatment.


Here are a few common myths and answers. There's discussion below.

Myth: Heartworms are found in the stool. Your dog gets heartworms by coming in contact with another dog's stool.

Fact: Heartworms are exactly that - they are found in the heart. The larvae are found in the blood stream and they are transmitted by mosquitoes.

Myth: Only dogs get heartowrm.
Fact: We used to think so. We were WRONG. Cat's do get heartworm. So do people.

Myth: My dog is indoors, so I don't need preventative. Same argument for cats.
Fact: Turns out this is absolutely false as well.

Myth: Preventatives are over the counter. My vet is just being a pain in the butt about requiring me to come in.

Fact: See my previous posts on the importance of regular physical exams. Preventatives are all PRESCRIPTION products. This means we can't just sell it over the counter or we get huge fines and risk loosing our license. We're not being a PItA. We're following federal drug law.

Here's the skinny on heartworm disease.

These worms start out as baby larva in an infected dog. These larva are referred to as L1 larva. A mosquito comes along, takes a blood meal that includes the L1 larva and flies away. The larva grow and develop into L2 and then L3 larva. Same mosquito bites another dog and those little L3 larva come down the mosquito's mouth and climb into that tiny hole and into the dog (cat, human, wolf, fox, etc). The larva then continue to devlop into L4, L5, then adult worms. As L5 and adults they take up residence in the right side of the heart and the pulmonary artery leaving the right side of the heart and into the lungs. You must have both males and females to reproduce, but once you do - the life cycle begins over again. Adults live for about 5 years in the dog.

The canid is the definitive host - meaning they are the host the parasite is intended for. Dogs, fox, coyote, wolf are all routinely infected. Other species can be infected with the parasite, but the body kills it off before it can become an adult. In people, it's usually killed off in the skin but it is possible for it to migrate to the lung and form a little granuloma before it's dead.

We used to think that cats were an uncommon host for the parasite - we were incorrect. See my companion post about cats and heartworm disease.

It takes about 4 or 5 months for a worm to go from larva to adult. The preventatives only work during the first 30-45 days of this period. Tests used by your veterinarian are only positive when there are adult female heartworms present. It is therefore possible to have worms in the heart and a negative test if either 1) they are only 4 months old or 2) you have all males or less than 3 females. 100 males, 1 female = NEGATIVE test! (This is uncommon, but it happens!)

The timing on this is important because this means there is a period of time between when a larva can be killed and when the test would become positive. For this reason, a pet that has been off preventative cannot be considered negative until a repeat test is done 5-6 months later.

What happens if I don't treat or prevent heartworm disease? Honestly, a dog can probably tolerate a small worm burden (1 or 2 worms) for a lifetime. The will have changes in the blood vessels in the lungs and will have chronic bronchitis-type problems. Most dogs with the disease don't just have one or two worms and therefore get progressively get sicker and sicker with hearts that fail and lungs that don't work. They may develop clots in the lungs and can suffer sudden death. Untreated heartworm disease kills. It's pretty nasty.

Next posts will be on prevention, treatment, and feline heartworm disease.

AMH